2018-12-20 14:55:19 +01:00
<!DOCTYPE HTML>
< html lang = "en" class = "sidebar-visible no-js" >
< head >
<!-- Book generated using mdBook -->
< meta charset = "UTF-8" >
< title > chainerror< / title >
< meta content = "text/html; charset=utf-8" http-equiv = "Content-Type" >
2018-12-21 13:55:46 +01:00
< meta name = "description" content = "A tutorial for the chainerror rust crate." >
2018-12-20 14:55:19 +01:00
< meta name = "viewport" content = "width=device-width, initial-scale=1" >
< meta name = "theme-color" content = "#ffffff" / >
< link rel = "shortcut icon" href = "favicon.png" >
< link rel = "stylesheet" href = "css/variables.css" >
< link rel = "stylesheet" href = "css/general.css" >
< link rel = "stylesheet" href = "css/chrome.css" >
< link rel = "stylesheet" href = "css/print.css" media = "print" >
<!-- Fonts -->
< link rel = "stylesheet" href = "FontAwesome/css/font-awesome.css" >
< link href = "https://fonts.googleapis.com/css?family=Open+Sans:300italic,400italic,600italic,700italic,800italic,400,300,600,700,800" rel = "stylesheet" type = "text/css" >
< link href = "https://fonts.googleapis.com/css?family=Source+Code+Pro:500" rel = "stylesheet" type = "text/css" >
<!-- Highlight.js Stylesheets -->
< link rel = "stylesheet" href = "highlight.css" >
< link rel = "stylesheet" href = "tomorrow-night.css" >
< link rel = "stylesheet" href = "ayu-highlight.css" >
<!-- Custom theme stylesheets -->
< / head >
< body class = "light" >
<!-- Provide site root to javascript -->
< script type = "text/javascript" >
var path_to_root = "";
var default_theme = "light";
< / script >
<!-- Work around some values being stored in localStorage wrapped in quotes -->
< script type = "text/javascript" >
try {
var theme = localStorage.getItem('mdbook-theme');
var sidebar = localStorage.getItem('mdbook-sidebar');
if (theme.startsWith('"') & & theme.endsWith('"')) {
localStorage.setItem('mdbook-theme', theme.slice(1, theme.length - 1));
}
if (sidebar.startsWith('"') & & sidebar.endsWith('"')) {
localStorage.setItem('mdbook-sidebar', sidebar.slice(1, sidebar.length - 1));
}
} catch (e) { }
< / script >
<!-- Set the theme before any content is loaded, prevents flash -->
< script type = "text/javascript" >
var theme;
try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { }
if (theme === null || theme === undefined) { theme = default_theme; }
document.body.className = theme;
document.querySelector('html').className = theme + ' js';
< / script >
<!-- Hide / unhide sidebar before it is displayed -->
< script type = "text/javascript" >
var html = document.querySelector('html');
var sidebar = 'hidden';
if (document.body.clientWidth >= 1080) {
try { sidebar = localStorage.getItem('mdbook-sidebar'); } catch(e) { }
sidebar = sidebar || 'visible';
}
html.classList.remove('sidebar-visible');
html.classList.add("sidebar-" + sidebar);
< / script >
< nav id = "sidebar" class = "sidebar" aria-label = "Table of contents" >
2019-03-04 11:46:17 +01:00
< ol class = "chapter" > < li class = "affix" > < a href = "index.html" > chainerror< / a > < / li > < li > < a href = "tutorial1.html" > < strong aria-hidden = "true" > 1.< / strong > Simple String Errors< / a > < / li > < li > < a href = "tutorial2.html" > < strong aria-hidden = "true" > 2.< / strong > Simple Chained String Errors< / a > < / li > < li > < a href = "tutorial3.html" > < strong aria-hidden = "true" > 3.< / strong > Mapping Errors< / a > < / li > < li > < a href = "tutorial4.html" > < strong aria-hidden = "true" > 4.< / strong > Saving coding chars< / a > < / li > < li > < a href = "tutorial5.html" > < strong aria-hidden = "true" > 5.< / strong > The source() of Errors< / a > < / li > < li > < a href = "tutorial6.html" > < strong aria-hidden = "true" > 6.< / strong > Downcast the Errors< / a > < / li > < li > < a href = "tutorial7.html" > < strong aria-hidden = "true" > 7.< / strong > The root cause of all Errors< / a > < / li > < li > < a href = "tutorial8.html" > < strong aria-hidden = "true" > 8.< / strong > Finding an Error cause< / a > < / li > < li > < a href = "tutorial9.html" > < strong aria-hidden = "true" > 9.< / strong > Selective Error Handling< / a > < / li > < li > < a href = "tutorial10.html" > < strong aria-hidden = "true" > 10.< / strong > ErrorKind to the rescue< / a > < / li > < li > < a href = "tutorial11.html" > < strong aria-hidden = "true" > 11.< / strong > Debug for the ErrorKind< / a > < / li > < li > < a href = "tutorial12.html" > < strong aria-hidden = "true" > 12.< / strong > Deref for the ErrorKind< / a > < / li > < li > < a href = "tutorial13.html" > < strong aria-hidden = "true" > 13.< / strong > Writing a library< / a > < / li > < li class = "affix" > < a href = "end.html" > The End< / a > < / li > < / ol >
2018-12-20 14:55:19 +01:00
< / nav >
< div id = "page-wrapper" class = "page-wrapper" >
< div class = "page" >
< div id = "menu-bar" class = "menu-bar" >
< div id = "menu-bar-sticky-container" >
< div class = "left-buttons" >
< button id = "sidebar-toggle" class = "icon-button" type = "button" title = "Toggle Table of Contents" aria-label = "Toggle Table of Contents" aria-controls = "sidebar" >
< i class = "fa fa-bars" > < / i >
< / button >
< button id = "theme-toggle" class = "icon-button" type = "button" title = "Change theme" aria-label = "Change theme" aria-haspopup = "true" aria-expanded = "false" aria-controls = "theme-list" >
< i class = "fa fa-paint-brush" > < / i >
< / button >
< ul id = "theme-list" class = "theme-popup" aria-label = "Themes" role = "menu" >
< li role = "none" > < button role = "menuitem" class = "theme" id = "light" > Light (default)< / button > < / li >
< li role = "none" > < button role = "menuitem" class = "theme" id = "rust" > Rust< / button > < / li >
< li role = "none" > < button role = "menuitem" class = "theme" id = "coal" > Coal< / button > < / li >
< li role = "none" > < button role = "menuitem" class = "theme" id = "navy" > Navy< / button > < / li >
< li role = "none" > < button role = "menuitem" class = "theme" id = "ayu" > Ayu< / button > < / li >
< / ul >
< button id = "search-toggle" class = "icon-button" type = "button" title = "Search. (Shortkey: s)" aria-label = "Toggle Searchbar" aria-expanded = "false" aria-keyshortcuts = "S" aria-controls = "searchbar" >
< i class = "fa fa-search" > < / i >
< / button >
< / div >
< h1 class = "menu-title" > chainerror< / h1 >
< div class = "right-buttons" >
< a href = "print.html" title = "Print this book" aria-label = "Print this book" >
< i id = "print-button" class = "fa fa-print" > < / i >
< / a >
< / div >
< / div >
< / div >
< div id = "search-wrapper" class = "hidden" >
< form id = "searchbar-outer" class = "searchbar-outer" >
< input type = "search" name = "search" id = "searchbar" name = "searchbar" placeholder = "Search this book ..." aria-controls = "searchresults-outer" aria-describedby = "searchresults-header" >
< / form >
< div id = "searchresults-outer" class = "searchresults-outer hidden" >
< div id = "searchresults-header" class = "searchresults-header" > < / div >
< ul id = "searchresults" >
< / ul >
< / div >
< / div >
<!-- Apply ARIA attributes after the sidebar and the sidebar toggle button are added to the DOM -->
< script type = "text/javascript" >
document.getElementById('sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible');
document.getElementById('sidebar').setAttribute('aria-hidden', sidebar !== 'visible');
Array.from(document.querySelectorAll('#sidebar a')).forEach(function(link) {
link.setAttribute('tabIndex', sidebar === 'visible' ? 0 : -1);
});
< / script >
< div id = "content" class = "content" >
< main >
2018-12-21 13:55:46 +01:00
< a class = "header" href = "#chainerror" id = "chainerror" > < h1 > chainerror< / h1 > < / a >
2019-02-07 09:02:01 +01:00
< p > < a href = "https://travis-ci.org/haraldh/chainerror" > < img src = "https://travis-ci.org/haraldh/chainerror.svg?branch=master" alt = "Build Status" / > < / a >
< a href = "https://crates.io/crates/chainerror" > < img src = "https://img.shields.io/crates/v/chainerror.svg" alt = "Crate" / > < / a >
< a href = "https://docs.rs/chainerror/" > < img src = "https://img.shields.io/badge/api-rustdoc-blue.svg" alt = "Rust Documentation" / > < / a > < / p >
2018-12-21 13:55:46 +01:00
< p > < code > chainerror< / code > provides an error backtrace like < code > failure< / code > without doing a real backtrace, so even after you < code > strip< / code > your
binaries, you still have the error backtrace.< / p >
< p > < code > chainerror< / code > has no dependencies!< / p >
< p > < code > chainerror< / code > uses < code > .source()< / code > of < code > std::error::Error< / code > along with < code > line()!< / code > and < code > file()!< / code > to provide a nice debug error backtrace.
It encapsulates all types, which have < code > Display + Debug< / code > and can store the error cause internally.< / p >
< p > Along with the < code > ChainError< T> < / code > struct, < code > chainerror< / code > comes with some useful helper macros to save a lot of typing.< / p >
< p > Debug information is worth it!< / p >
< p > Now continue reading the
< a href = "https://haraldh.github.io/chainerror/tutorial1.html" > Tutorial< / a > < / p >
< a class = "header" href = "#example" id = "example" > < h2 > Example:< / h2 > < / a >
< p > Output:< / p >
< pre > < code > $ cargo run -q --example example
Main Error Report: func1 error calling func2
Error reported by Func2Error: func2 error: calling func3
The root cause was: std::io::Error: Kind(
NotFound
)
Debug Error:
examples/example.rs:45: func1 error calling func2
Caused by:
examples/example.rs:20: Func2Error(func2 error: calling func3)
Caused by:
examples/example.rs:13: Error reading 'foo.txt'
Caused by:
Kind(NotFound)
< / code > < / pre >
< pre > < code class = "language-rust ignore" > use chainerror::*;
use std::error::Error;
use std::io;
use std::result::Result;
fn do_some_io() -> Result< (), Box< Error> > {
Err(io::Error::from(io::ErrorKind::NotFound))?;
Ok(())
}
fn func3() -> Result< (), Box< Error> > {
let filename = " foo.txt" ;
do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
Ok(())
}
derive_str_cherr!(Func2Error);
fn func2() -> ChainResult< (), Func2Error> {
func3().map_err(mstrerr!(Func2Error, " func2 error: calling func3" ))?;
Ok(())
}
enum Func1Error {
Func2,
IO(String),
}
impl ::std::fmt::Display for Func1Error {
fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
match self {
Func1Error::Func2 => write!(f, " func1 error calling func2" ),
Func1Error::IO(filename) => write!(f, " Error reading '{}'" , filename),
}
}
}
impl ::std::fmt::Debug for Func1Error {
fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
write!(f, " {}" , self)
}
}
fn func1() -> ChainResult< (), Func1Error> {
func2().map_err(|e| cherr!(e, Func1Error::Func2))?;
let filename = String::from(" bar.txt" );
do_some_io().map_err(|e| cherr!(e, Func1Error::IO(filename)))?;
Ok(())
}
fn main() {
if let Err(e) = func1() {
match e.kind() {
Func1Error::Func2 => eprintln!(" Main Error Report: func1 error calling func2" ),
Func1Error::IO(filename) => {
eprintln!(" Main Error Report: func1 error reading '{}'" , filename)
}
}
if let Some(e) = e.find_chain_cause::< Func2Error> () {
eprintln!(" \nError reported by Func2Error: {}" , e)
}
if let Some(e) = e.root_cause() {
let ioerror = e.downcast_ref::< io::Error> ().unwrap();
eprintln!(" \nThe root cause was: std::io::Error: {:#?}" , ioerror);
}
eprintln!(" \nDebug Error:\n{:?}" , e);
}
}
< / code > < / pre >
< a class = "header" href = "#features" id = "features" > < h2 > Features< / h2 > < / a >
< p > < code > no-fileline< / code >
: completely turn off storing filename and line< / p >
< p > < code > display-cause< / code >
: turn on printing a backtrace of the errors in < code > Display< / code > < / p >
< p > < code > no-debug-cause< / code >
: turn off printing a backtrace of the errors in < code > Debug< / code > < / p >
< a class = "header" href = "#simple-string-errors" id = "simple-string-errors" > < h1 > Simple String Errors< / h1 > < / a >
< p > An easy way of doing error handling in rust is by returning < code > String< / code > as a < code > Box< std::error::Error> < / code > .< / p >
< p > If the rust < code > main< / code > function returns an < code > Err()< / code > , this < code > Err()< / code > will be displayed with < code > std::fmt::Debug< / code > .< / p >
< p > As you can see by running the example (by pressing the " Play" button in upper right of the code block),
this only
2018-12-20 16:37:43 +01:00
prints out the last < code > Error< / code > .< / p >
2018-12-21 13:55:46 +01:00
< pre > < code > Error: StringError(" func1 error" )
< / code > < / pre >
< p > The next chapters of this tutorial show how < code > chainerror< / code > adds more information
and improves inspecting the sources of an error.< / p >
< p > You can also run the tutorial examples in the checked out
< a href = "https://github.com/haraldh/chainerror" > chainerror git repo< / a > .< / p >
< pre > < code > $ cargo run -q --example tutorial1
< / code > < / pre >
2018-12-20 15:12:59 +01:00
< pre > < pre class = "playpen" > < code class = "language-rust" > use std::error::Error;
2018-12-21 13:55:46 +01:00
use std::io;
2018-12-20 14:55:19 +01:00
use std::result::Result;
fn do_some_io() -> Result< (), Box< Error> > {
2018-12-21 13:55:46 +01:00
Err(io::Error::from(io::ErrorKind::NotFound))?;
2018-12-20 14:55:19 +01:00
Ok(())
}
fn func2() -> Result< (), Box< Error> > {
if let Err(_) = do_some_io() {
Err(" func2 error" )?;
}
Ok(())
}
fn func1() -> Result< (), Box< Error> > {
if let Err(_) = func2() {
Err(" func1 error" )?;
}
Ok(())
}
fn main() -> Result< (), Box< Error> > {
func1()
}
2018-12-21 13:55:46 +01:00
2018-12-20 14:55:19 +01:00
< / code > < / pre > < / pre >
2018-12-20 16:37:43 +01:00
< a class = "header" href = "#simple-chained-string-errors" id = "simple-chained-string-errors" > < h1 > Simple Chained String Errors< / h1 > < / a >
2018-12-21 13:55:46 +01:00
< p > With relatively small changes and the help of the < code > cherr!< / code > macro of the < code > chainerror< / code > crate
the < code > String< / code > errors are now chained together.< / p >
2018-12-20 15:12:59 +01:00
< p > Press the play button in the upper right corner and see the nice debug output.< / p >
2019-03-04 11:46:17 +01:00
< pre > < pre class = "playpen" > < code class = "language-rust" > use chainerror::*;
2018-12-21 13:55:46 +01:00
2018-12-20 14:55:19 +01:00
use std::error::Error;
2018-12-21 13:55:46 +01:00
use std::io;
2018-12-20 14:55:19 +01:00
use std::result::Result;
fn do_some_io() -> Result< (), Box< Error> > {
2018-12-21 13:55:46 +01:00
Err(io::Error::from(io::ErrorKind::NotFound))?;
2018-12-20 14:55:19 +01:00
Ok(())
}
fn func2() -> Result< (), Box< Error> > {
if let Err(e) = do_some_io() {
Err(cherr!(e, " func2 error" ))?;
}
Ok(())
}
fn func1() -> Result< (), Box< Error> > {
if let Err(e) = func2() {
Err(cherr!(e, " func1 error" ))?;
}
Ok(())
}
fn main() -> Result< (), Box< Error> > {
func1()
}
2019-03-04 11:46:17 +01:00
2018-12-20 14:55:19 +01:00
# #[allow(dead_code)]
# mod chainerror {
2019-02-07 09:02:01 +01:00
# //! `chainerror` provides an error backtrace without doing a real backtrace, so even after you `strip` your
# //! binaries, you still have the error backtrace.
# //!
# //! `chainerror` has no dependencies!
# //!
# //! `chainerror` uses `.source()` of `std::error::Error` along with `line()!` and `file()!` to provide a nice debug error backtrace.
# //! It encapsulates all types, which have `Display + Debug` and can store the error cause internally.
# //!
# //! Along with the `ChainError< T> ` struct, `chainerror` comes with some useful helper macros to save a lot of typing.
# //!
# //! ## Features
# //!
# //! `no-fileline`
# //! : completely turn off storing filename and line
# //!
# //! `display-cause`
# //! : turn on printing a backtrace of the errors in `Display`
# //!
# //! `no-debug-cause`
# //! : turn off printing a backtrace of the errors in `Debug`
# //!
# //!
# //! # Tutorial
# //!
# //! Read the [Tutorial](https://haraldh.github.io/chainerror/tutorial1.html)
# //!
# //! # Examples
# //!
# //! ~~~rust
# //! use chainerror::*;
# //! use std::error::Error;
# //! use std::io;
# //! use std::result::Result;
# //!
# //! fn do_some_io() -> Result< (), Box< Error> > {
# //! Err(io::Error::from(io::ErrorKind::NotFound))?;
# //! Ok(())
# //! }
# //!
# //! fn func2() -> Result< (), Box< Error> > {
# //! let filename = " foo.txt" ;
# //! do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# //! Ok(())
# //! }
# //!
# //! fn func1() -> Result< (), Box< Error> > {
# //! func2().map_err(mstrerr!(" func1 error" ))?;
# //! Ok(())
# //! }
# //!
# //! fn main() {
# //! if let Err(e) = func1() {
# //! #[cfg(not(windows))]
# //! assert_eq!(
# //! format!(" \n{:?}\n" , e), r#"
# //! src/lib.rs:20: func1 error
# //! Caused by:
# //! src/lib.rs:15: Error reading 'foo.txt'
# //! Caused by:
# //! Kind(NotFound)
# //! " #
# //! );
# //! }
# //! # else {
# //! # unreachable!();
# //! # }
# //! }
# //! ~~~
# //!
# //!
# //! ~~~rust
# //! use chainerror::*;
# //! use std::error::Error;
# //! use std::io;
# //! use std::result::Result;
# //!
# //! fn do_some_io() -> Result< (), Box< Error> > {
# //! Err(io::Error::from(io::ErrorKind::NotFound))?;
# //! Ok(())
# //! }
# //!
# //! fn func3() -> Result< (), Box< Error> > {
# //! let filename = " foo.txt" ;
# //! do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# //! Ok(())
# //! }
# //!
# //! derive_str_cherr!(Func2Error);
# //!
# //! fn func2() -> ChainResult< (), Func2Error> {
# //! func3().map_err(mstrerr!(Func2Error, " func2 error: calling func3" ))?;
# //! Ok(())
# //! }
# //!
# //! enum Func1Error {
# //! Func2,
# //! IO(String),
# //! }
# //!
# //! impl ::std::fmt::Display for Func1Error {
# //! fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# //! match self {
# //! Func1Error::Func2 => write!(f, " func1 error calling func2" ),
# //! Func1Error::IO(filename) => write!(f, " Error reading '{}'" , filename),
# //! }
# //! }
# //! }
# //!
# //! impl ::std::fmt::Debug for Func1Error {
# //! fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# //! write!(f, " {}" , self)
# //! }
# //! }
# //!
# //! fn func1() -> ChainResult< (), Func1Error> {
# //! func2().map_err(|e| cherr!(e, Func1Error::Func2))?;
# //! let filename = String::from(" bar.txt" );
# //! do_some_io().map_err(|e| cherr!(e, Func1Error::IO(filename)))?;
# //! Ok(())
# //! }
# //!
# //! fn main() {
# //! if let Err(e) = func1() {
# //! assert!(
# //! match e.kind() {
# //! Func1Error::Func2 => {
# //! eprintln!(" Main Error Report: func1 error calling func2" );
# //! true
# //! }
# //! Func1Error::IO(filename) => {
# //! eprintln!(" Main Error Report: func1 error reading '{}'" , filename);
# //! false
# //! }
# //! }
# //! );
# //!
# //! assert!(e.find_chain_cause::< Func2Error> ().is_some());
# //!
# //! if let Some(e) = e.find_chain_cause::< Func2Error> () {
# //! eprintln!(" \nError reported by Func2Error: {}" , e)
# //! }
# //!
# //!
# //! assert!(e.root_cause().is_some());
# //!
# //! if let Some(e) = e.root_cause() {
# //! let ioerror = e.downcast_ref::< io::Error> ().unwrap();
# //! eprintln!(" \nThe root cause was: std::io::Error: {:#?}" , ioerror);
# //! }
# //!
# //! #[cfg(not(windows))]
# //! assert_eq!(
# //! format!(" \n{:?}\n" , e), r#"
# //! src/lib.rs:47: func1 error calling func2
# //! Caused by:
# //! src/lib.rs:22: Func2Error(func2 error: calling func3)
# //! Caused by:
# //! src/lib.rs:15: Error reading 'foo.txt'
# //! Caused by:
# //! Kind(NotFound)
# //! " #
# //! );
# //! }
# //! # else {
# //! # unreachable!();
# //! # }
# //! }
# //! ~~~
2018-12-21 13:55:46 +01:00
#
# use std::any::TypeId;
2018-12-20 14:55:19 +01:00
# use std::error::Error;
# use std::fmt::{Debug, Display, Formatter, Result};
#
2019-02-07 09:02:01 +01:00
# /// chains an inner error kind `T` with a causing error
2018-12-20 14:55:19 +01:00
# pub struct ChainError< T> {
# #[cfg(not(feature = " no-fileline" ))]
# occurrence: Option< (u32, & 'static str)> ,
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# }
#
2018-12-21 13:55:46 +01:00
# /// convenience type alias
# pub type ChainResult< O, E> = std::result::Result< O, ChainError< E> > ;
2018-12-20 14:55:19 +01:00
#
# impl< T: 'static + Display + Debug> ChainError< T> {
# #[cfg(not(feature = " no-fileline" ))]
2018-12-21 13:55:46 +01:00
# /// Use the `cherr!()` or `mstrerr!()` macro instead of calling this directly
2018-12-20 14:55:19 +01:00
# pub fn new(
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# occurrence: Option< (u32, & 'static str)> ,
# ) -> Self {
# Self {
# occurrence,
# kind,
# error_cause,
# }
# }
#
# #[cfg(feature = " no-fileline" )]
2018-12-21 13:55:46 +01:00
# /// Use the `cherr!()` or `mstrerr!()` macro instead of calling this directly
2018-12-20 14:55:19 +01:00
# pub fn new(
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# _occurrence: Option< (u32, & 'static str)> ,
# ) -> Self {
# Self { kind, error_cause }
# }
#
2018-12-21 13:55:46 +01:00
# /// return the root cause of the error chain, if any exists
2018-12-20 14:55:19 +01:00
# pub fn root_cause(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.iter().last()
# }
#
# /// Find the first error cause of type U, if any exists
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// fn do_some_io() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# ///
# /// fn main() {
# /// if let Err(e) = func1() {
# /// if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# ///
# /// assert!(f1err.find_cause::< io::Error> ().is_some());
# ///
# /// assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// }
# /// # else {
# /// # panic!();
# /// # }
# /// }
# /// # else {
# /// # unreachable!();
# /// # }
# /// }
# /// ~~~
2018-12-20 14:55:19 +01:00
# pub fn find_cause< U: Error + 'static> (& self) -> Option< & U> {
2019-02-07 09:02:01 +01:00
# self.iter().filter_map(Error::downcast_ref::< U> ).next()
# }
#
# /// Find the first error cause of type `ChainError< U> `, if any exists
# ///
# /// Same as `find_cause`, but hides the `ChainError< U> ` implementation internals
# ///
# /// # Examples
# ///
# /// ~~~rust,ignore
# /// // Instead of writing
# /// err.find_cause::< ChainError< FooError> > ();
# ///
# /// // leave out the ChainError< FooError> implementation detail
# /// err.find_chain_cause::< FooError> ();
# /// ~~~
2018-12-20 14:55:19 +01:00
# pub fn find_chain_cause< U: Error + 'static> (& self) -> Option< & ChainError< U> > {
2019-02-07 09:02:01 +01:00
# self.iter()
# .filter_map(Error::downcast_ref::< ChainError< U> > )
# .next()
# }
#
# /// Find the first error cause of type `ChainError< U> ` or `U`, if any exists and return `U`
# ///
# /// Same as `find_cause` and `find_chain_cause`, but hides the `ChainError< U> ` implementation internals
# ///
# /// # Examples
# ///
# /// ~~~rust,ignore
# /// // Instead of writing
# /// err.find_cause::< ChainError< FooErrorKind> > ();
# /// // and/or
# /// err.find_chain_cause::< FooErrorKind> ();
# /// // and/or
# /// err.find_cause::< FooErrorKind> ();
# ///
# /// // leave out the ChainError< FooErrorKind> implementation detail
# /// err.find_chain_or_kind::< FooErrorKind> ();
# /// ~~~
# pub fn find_kind_or_cause< U: Error + 'static> (& self) -> Option< & U> {
# self.iter()
# .filter_map(|e| {
# e.downcast_ref::< ChainError< U> > ()
# .map(|e| e.kind())
# .or_else(|| e.downcast_ref::< U> ())
# })
# .next()
# }
#
# /// Return a reference to T of `ChainError< T> `
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// fn do_some_io() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// #[derive(Debug)]
# /// enum Func1ErrorKind {
# /// Func2,
# /// IO(String),
# /// }
# ///
# /// /// impl ::std::fmt::Display for Func1ErrorKind {…}
# /// # impl ::std::fmt::Display for Func1ErrorKind {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # Func1ErrorKind::Func2 => write!(f, " func1 error calling func2" ),
# /// # Func1ErrorKind::IO(filename) => write!(f, " Error reading '{}'" , filename),
# /// # }
# /// # }
# /// # }
# ///
# /// fn func1() -> ChainResult< (), Func1ErrorKind> {
# /// func2().map_err(|e| cherr!(e, Func1ErrorKind::Func2))?;
# /// do_some_io().map_err(|e| cherr!(e, Func1ErrorKind::IO(" bar.txt" .into())))?;
# /// Ok(())
# /// }
# ///
# /// fn main() {
# /// if let Err(e) = func1() {
# /// match e.kind() {
# /// Func1ErrorKind::Func2 => {},
# /// Func1ErrorKind::IO(filename) => panic!(),
# /// }
# /// }
# /// # else {
# /// # unreachable!();
# /// # }
# /// }
# /// ~~~
# pub fn kind(& self) -> & T {
# & self.kind
2018-12-21 13:55:46 +01:00
# }
#
2019-02-07 09:02:01 +01:00
# /// Returns an Iterator over all error causes/sources
# ///
# /// # Example
# ///
# ///
# pub fn iter(& self) -> impl Iterator< Item = & (dyn Error + 'static)> {
# ErrorIter {
# current: Some(self),
# }
2018-12-21 13:55:46 +01:00
# }
2019-02-07 09:02:01 +01:00
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# struct ErrorIter< 'a> {
# current: Option< & 'a (dyn Error + 'static)> ,
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# impl< 'a> Iterator for ErrorIter< 'a> {
# type Item = & 'a (dyn Error + 'static);
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# fn next(& mut self) -> Option< Self::Item> {
# let current = self.current;
# self.current = self.current.and_then(Error::source);
# current
2018-12-21 13:55:46 +01:00
# }
2019-02-07 09:02:01 +01:00
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# impl< T: 'static + Display + Debug> std::ops::Deref for ChainError< T> {
# type Target = T;
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# fn deref(& self) -> & Self::Target {
2018-12-20 14:55:19 +01:00
# & self.kind
# }
# }
#
2019-02-07 09:02:01 +01:00
# /// Convenience trait to hide the `ChainError< T> ` implementation internals
2018-12-20 14:55:19 +01:00
# pub trait ChainErrorDown {
2019-02-07 09:02:01 +01:00
# /// Test if of type `ChainError< T> `
2018-12-20 14:55:19 +01:00
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool;
2019-02-07 09:02:01 +01:00
# /// Downcast to a reference of `ChainError< T> `
2018-12-20 14:55:19 +01:00
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > ;
2019-02-07 09:02:01 +01:00
# /// Downcast to a mutable reference of `ChainError< T> `
2018-12-20 14:55:19 +01:00
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > ;
# }
#
# impl< U: 'static + Display + Debug> ChainErrorDown for ChainError< U> {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# TypeId::of::< T> () == TypeId::of::< U> ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# if self.is_chain::< T> () {
2019-02-07 09:02:01 +01:00
# #[allow(clippy::cast_ptr_alignment)]
# unsafe {
# Some(& *(self as *const dyn Error as *const & ChainError< T> ))
# }
2018-12-20 14:55:19 +01:00
# } else {
# None
# }
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# if self.is_chain::< T> () {
2019-02-07 09:02:01 +01:00
# #[allow(clippy::cast_ptr_alignment)]
# unsafe {
# Some(& mut *(self as *mut dyn Error as *mut & mut ChainError< T> ))
# }
2018-12-20 14:55:19 +01:00
# } else {
# None
# }
# }
# }
#
# impl ChainErrorDown for dyn Error + 'static {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl ChainErrorDown for dyn Error + 'static + Send {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl ChainErrorDown for dyn Error + 'static + Send + Sync {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl< T: 'static + Display + Debug> Error for ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.error_cause.as_ref().map(|e| e.as_ref())
2018-12-20 14:55:19 +01:00
# }
# }
#
# impl< T: 'static + Display + Debug> Error for & ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.error_cause.as_ref().map(|e| e.as_ref())
2018-12-20 14:55:19 +01:00
# }
# }
#
# impl< T: 'static + Display + Debug> Error for & mut ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.error_cause.as_ref().map(|e| e.as_ref())
2018-12-20 14:55:19 +01:00
# }
# }
#
# impl< T: 'static + Display + Debug> Display for ChainError< T> {
# fn fmt(& self, f: & mut Formatter) -> Result {
# write!(f, " {}" , self.kind)?;
#
# #[cfg(feature = " display-cause" )]
# {
# if let Some(e) = self.source() {
# writeln!(f, " \nCaused by:" )?;
# Display::fmt(& e, f)?;
# }
# }
# Ok(())
# }
# }
#
# impl< T: 'static + Display + Debug> Debug for ChainError< T> {
# fn fmt(& self, f: & mut Formatter) -> Result {
# #[cfg(not(feature = " no-fileline" ))]
# {
# if let Some(o) = self.occurrence {
# write!(f, " {}:{}: " , o.1, o.0)?;
# }
# }
#
2018-12-21 13:55:46 +01:00
# if self.is_chain::< String> () {
# Display::fmt(& self.kind, f)?;
# } else {
# Debug::fmt(& self.kind, f)?;
# }
2018-12-20 14:55:19 +01:00
#
# #[cfg(not(feature = " no-debug-cause" ))]
# {
# if let Some(e) = self.source() {
# writeln!(f, " \nCaused by:" )?;
# Debug::fmt(& e, f)?;
# }
# }
# Ok(())
# }
# }
#
2019-02-07 09:02:01 +01:00
# pub trait ChainErrorFrom< T> : Sized {
# fn chain_error_from(_: T, line_filename: Option< (u32, & 'static str)> ) -> ChainError< Self> ;
# }
#
# pub trait IntoChainError< T> : Sized {
# fn into_chain_error(self, line_filename: Option< (u32, & 'static str)> ) -> ChainError< T> ;
# }
#
# impl< T, U> IntoChainError< U> for T
# where
# U: ChainErrorFrom< T> ,
# {
# fn into_chain_error(self, line_filename: Option< (u32, & 'static str)> ) -> ChainError< U> {
# U::chain_error_from(self, line_filename)
# }
# }
#
# impl< T, U> ChainErrorFrom< T> for U
# where
# T: Into< U> ,
# U: 'static + Display + Debug,
# {
# fn chain_error_from(t: T, line_filename: Option< (u32, & 'static str)> ) -> ChainError< Self> {
# let e: U = t.into();
# ChainError::< _> ::new(e, None, line_filename)
# }
# }
#
2018-12-20 14:55:19 +01:00
# #[macro_export]
2019-02-07 09:02:01 +01:00
# macro_rules! minto_cherr {
# ( ) => {
# |e| e.into_chain_error(Some((line!(), file!())))
2018-12-20 14:55:19 +01:00
# };
# }
#
# #[macro_export]
2019-02-07 09:02:01 +01:00
# macro_rules! into_cherr {
# ( $t:expr ) => {
# $t.into_chain_error(Some((line!(), file!())))
2018-12-20 14:55:19 +01:00
# };
# }
#
2019-02-07 09:02:01 +01:00
# /// Creates a new `ChainError< T> `
# ///
# /// # Examples
# ///
# /// Create a new ChainError< FooError> , where `FooError` must implement `Display` and `Debug`.
# /// ~~~rust
# /// # use chainerror::*;
# /// #
# /// # #[derive(Debug)]
# /// enum FooError {
# /// Bar,
# /// Baz(& 'static str),
# /// }
# /// #
# /// # impl ::std::fmt::Display for FooError {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # FooError::Bar => write!(f, " Bar Error" ),
# /// # FooError::Baz(s) => write!(f, " Baz Error: '{}'" , s),
# /// # }
# /// # }
# /// # }
# ///
# /// // impl ::std::fmt::Display for FooError
# ///
# /// fn do_some_stuff() -> bool {
# /// false
# /// }
# ///
# /// fn func() -> ChainResult< (), FooError> {
# /// if ! do_some_stuff() {
# /// Err(cherr!(FooError::Baz(" Error" )))?;
# /// }
# /// Ok(())
# /// }
# /// #
# /// # pub fn main() {
# /// # match func().unwrap_err().kind() {
# /// # FooError::Baz(s) if s == & " Error" => {},
# /// # _ => panic!(),
# /// # }
# /// # }
# /// ~~~
# ///
# /// Additionally an error cause can be added.
# ///
# /// ~~~rust
# /// # use chainerror::*;
# /// # use std::io;
# /// # use std::error::Error;
# /// #
# /// # #[derive(Debug)]
# /// # enum FooError {
# /// # Bar,
# /// # Baz(& 'static str),
# /// # }
# /// #
# /// # impl ::std::fmt::Display for FooError {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # FooError::Bar => write!(f, " Bar Error" ),
# /// # FooError::Baz(s) => write!(f, " Baz Error: '{}'" , s),
# /// # }
# /// # }
# /// # }
# /// #
# /// fn do_some_stuff() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// fn func() -> ChainResult< (), FooError> {
# /// do_some_stuff().map_err(
# /// |e| cherr!(e, FooError::Baz(" Error" ))
# /// )?;
# /// Ok(())
# /// }
# /// #
# /// # pub fn main() {
# /// # match func().unwrap_err().kind() {
# /// # FooError::Baz(s) if s == & " Error" => {},
# /// # _ => panic!(),
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! cherr {
# ( $k:expr ) => ({
# ChainError::< _> ::new($k, None, Some((line!(), file!())))
# });
# ( None, $k:expr ) => ({
# ChainError::< _> ::new($k, None, Some((line!(), file!())))
# });
# ( None, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!(None, format!($fmt, $($arg)+ ))
# });
# ( None, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!(None, format!($fmt, $($arg)+ ))
# });
# ( $e:path, $k:expr ) => ({
# ChainError::< _> ::new($k, Some(Box::from($e)), Some((line!(), file!())))
# });
# ( $e:path, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!($e, format!($fmt, $($arg)+ ))
# });
#
# }
#
# /// Convenience macro for `|e| cherr!(e, format!(…))`
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(" func1 error" ))?;
# /// Ok(())
# /// }
# ///
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # #[cfg(not(windows))]
# /// # assert_eq!(
# /// # format!(" \n{:?}\n" , e), r#"
# /// # src/lib.rs:20: func1 error
# /// # Caused by:
# /// # src/lib.rs:15: Error reading 'foo.txt'
# /// # Caused by:
# /// # Kind(NotFound)
# /// # " #
# /// # );
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# ///
# /// `mstrerr!()` can also be used to map a new `ChainError< T> `, where T was defined with
# /// `derive_str_cherr!(T)`
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! mstrerr {
# ( $t:path, $msg:expr ) => ({
# |e| cherr!(e, $t ($msg.to_string()))
# });
# ( $t:path, $msg:expr, ) => ({
# |e| cherr!(e, $t ($msg.to_string()))
# });
# ( $t:path, $fmt:expr, $($arg:tt)+ ) => ({
# |e| cherr!(e, $t (format!($fmt, $($arg)+ )))
# });
# ($msg:expr) => ({
# |e| cherr!(e, $msg.to_string())
# });
# ($msg:expr, ) => ({
# |e| cherr!(e, $msg.to_string())
# });
# ($fmt:expr, $($arg:tt)+) => ({
# |e| cherr!(e, format!($fmt, $($arg)+ ))
# });
# }
#
# /// Convenience macro for `cherr!(T(format!(…)))` where `T(String)`
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::result::Result;
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> ChainResult< (), Func2Error> {
# /// let filename = " foo.txt" ;
# /// Err(strerr!(Func2Error, " Error reading '{}'" , filename))
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! strerr {
# ( $t:path, $msg:expr ) => ({
# cherr!($t ($msg.to_string()))
# });
# ( $t:path, $msg:expr, ) => ({
# cherr!($t ($msg.to_string()))
# });
# ( $t:path, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!($t (format!($fmt, $($arg)+ )))
# });
# ($msg:expr) => ({
# cherr!($msg.to_string())
# });
# ($msg:expr, ) => ({
# cherr!($msg.to_string())
# });
# ($fmt:expr, $($arg:tt)+) => ({
# cherr!(format!($fmt, $($arg)+ ))
# });
# }
#
# /// Convenience macro to create a " new type" T(String) and implement Display + Debug for T
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> ChainResult< (), Func2Error> {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
2018-12-20 14:55:19 +01:00
# #[macro_export]
# macro_rules! derive_str_cherr {
# ($e:ident) => {
2019-02-07 09:02:01 +01:00
# pub struct $e(pub String);
2018-12-20 14:55:19 +01:00
# impl ::std::fmt::Display for $e {
# fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# write!(f, " {}" , self.0)
# }
# }
# impl ::std::fmt::Debug for $e {
# fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# write!(f, " {}({})" , stringify!($e), self.0)
# }
# }
# impl ::std::error::Error for $e {}
# };
# }
# }
< / code > < / pre > < / pre >
2018-12-20 16:02:24 +01:00
< a class = "header" href = "#what-did-we-do-here" id = "what-did-we-do-here" > < h3 > What did we do here?< / h3 > < / a >
< pre > < code class = "language-rust ignore" > if let Err(e) = do_some_io() {
Err(cherr!(e, " func2 error" ))?;
}
< / code > < / pre >
2018-12-21 13:55:46 +01:00
< p > The macro < code > cherr!(olderror, newerror)< / code > stores < code > olderror< / code > as the source/cause of < code > newerror< / code >
along with the filename (< code > file!()< / code > ) and line number (< code > line!()< / code > )
and returns < code > newerror< / code > .< / p >
< p > < code > Err()?< / code > then returns the inner error applying < code > .into()< / code > , so that we
2018-12-20 16:02:24 +01:00
again have a < code > Err(Box< Error> )< / code > as a result.< / p >
< p > The < code > Debug< / code > implementation of < code > ChainError< T> < / code > (which is returned by < code > cherr!()< / code > )
prints the < code > Debug< / code > of < code > T< / code > prefixed with the stored filename and line number.< / p >
2018-12-21 13:55:46 +01:00
< p > < code > ChainError< T> < / code > in our case is < code > ChainError< String> < / code > .< / p >
2018-12-20 16:37:43 +01:00
< a class = "header" href = "#mapping-errors" id = "mapping-errors" > < h1 > Mapping Errors< / h1 > < / a >
2018-12-20 16:02:24 +01:00
< p > Now let's get more rust idiomatic by using < code > .map_err()< / code > .< / p >
2019-03-04 11:46:17 +01:00
< pre > < pre class = "playpen" > < code class = "language-rust" > use chainerror::*;
2018-12-21 13:55:46 +01:00
2018-12-20 14:55:19 +01:00
use std::error::Error;
2018-12-21 13:55:46 +01:00
use std::io;
2018-12-20 14:55:19 +01:00
use std::result::Result;
fn do_some_io() -> Result< (), Box< Error> > {
2018-12-21 13:55:46 +01:00
Err(io::Error::from(io::ErrorKind::NotFound))?;
2018-12-20 14:55:19 +01:00
Ok(())
}
fn func2() -> Result< (), Box< Error> > {
do_some_io().map_err(|e| cherr!(e, " func2 error" ))?;
Ok(())
}
fn func1() -> Result< (), Box< Error> > {
func2().map_err(|e| cherr!(e, " func1 error" ))?;
Ok(())
}
fn main() -> Result< (), Box< Error> > {
if let Err(e) = func1() {
eprintln!(" {:?}" , e);
}
Ok(())
}
2019-03-04 11:46:17 +01:00
2018-12-20 14:55:19 +01:00
# #[allow(dead_code)]
# mod chainerror {
2019-02-07 09:02:01 +01:00
# //! `chainerror` provides an error backtrace without doing a real backtrace, so even after you `strip` your
# //! binaries, you still have the error backtrace.
# //!
# //! `chainerror` has no dependencies!
# //!
# //! `chainerror` uses `.source()` of `std::error::Error` along with `line()!` and `file()!` to provide a nice debug error backtrace.
# //! It encapsulates all types, which have `Display + Debug` and can store the error cause internally.
# //!
# //! Along with the `ChainError< T> ` struct, `chainerror` comes with some useful helper macros to save a lot of typing.
# //!
# //! ## Features
# //!
# //! `no-fileline`
# //! : completely turn off storing filename and line
# //!
# //! `display-cause`
# //! : turn on printing a backtrace of the errors in `Display`
# //!
# //! `no-debug-cause`
# //! : turn off printing a backtrace of the errors in `Debug`
# //!
# //!
# //! # Tutorial
# //!
# //! Read the [Tutorial](https://haraldh.github.io/chainerror/tutorial1.html)
# //!
# //! # Examples
# //!
# //! ~~~rust
# //! use chainerror::*;
# //! use std::error::Error;
# //! use std::io;
# //! use std::result::Result;
# //!
# //! fn do_some_io() -> Result< (), Box< Error> > {
# //! Err(io::Error::from(io::ErrorKind::NotFound))?;
# //! Ok(())
# //! }
# //!
# //! fn func2() -> Result< (), Box< Error> > {
# //! let filename = " foo.txt" ;
# //! do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# //! Ok(())
# //! }
# //!
# //! fn func1() -> Result< (), Box< Error> > {
# //! func2().map_err(mstrerr!(" func1 error" ))?;
# //! Ok(())
# //! }
# //!
# //! fn main() {
# //! if let Err(e) = func1() {
# //! #[cfg(not(windows))]
# //! assert_eq!(
# //! format!(" \n{:?}\n" , e), r#"
# //! src/lib.rs:20: func1 error
# //! Caused by:
# //! src/lib.rs:15: Error reading 'foo.txt'
# //! Caused by:
# //! Kind(NotFound)
# //! " #
# //! );
# //! }
# //! # else {
# //! # unreachable!();
# //! # }
# //! }
# //! ~~~
# //!
# //!
# //! ~~~rust
# //! use chainerror::*;
# //! use std::error::Error;
# //! use std::io;
# //! use std::result::Result;
# //!
# //! fn do_some_io() -> Result< (), Box< Error> > {
# //! Err(io::Error::from(io::ErrorKind::NotFound))?;
# //! Ok(())
# //! }
# //!
# //! fn func3() -> Result< (), Box< Error> > {
# //! let filename = " foo.txt" ;
# //! do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# //! Ok(())
# //! }
# //!
# //! derive_str_cherr!(Func2Error);
# //!
# //! fn func2() -> ChainResult< (), Func2Error> {
# //! func3().map_err(mstrerr!(Func2Error, " func2 error: calling func3" ))?;
# //! Ok(())
# //! }
# //!
# //! enum Func1Error {
# //! Func2,
# //! IO(String),
# //! }
# //!
# //! impl ::std::fmt::Display for Func1Error {
# //! fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# //! match self {
# //! Func1Error::Func2 => write!(f, " func1 error calling func2" ),
# //! Func1Error::IO(filename) => write!(f, " Error reading '{}'" , filename),
# //! }
# //! }
# //! }
# //!
# //! impl ::std::fmt::Debug for Func1Error {
# //! fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# //! write!(f, " {}" , self)
# //! }
# //! }
# //!
# //! fn func1() -> ChainResult< (), Func1Error> {
# //! func2().map_err(|e| cherr!(e, Func1Error::Func2))?;
# //! let filename = String::from(" bar.txt" );
# //! do_some_io().map_err(|e| cherr!(e, Func1Error::IO(filename)))?;
# //! Ok(())
# //! }
# //!
# //! fn main() {
# //! if let Err(e) = func1() {
# //! assert!(
# //! match e.kind() {
# //! Func1Error::Func2 => {
# //! eprintln!(" Main Error Report: func1 error calling func2" );
# //! true
# //! }
# //! Func1Error::IO(filename) => {
# //! eprintln!(" Main Error Report: func1 error reading '{}'" , filename);
# //! false
# //! }
# //! }
# //! );
# //!
# //! assert!(e.find_chain_cause::< Func2Error> ().is_some());
# //!
# //! if let Some(e) = e.find_chain_cause::< Func2Error> () {
# //! eprintln!(" \nError reported by Func2Error: {}" , e)
# //! }
# //!
# //!
# //! assert!(e.root_cause().is_some());
# //!
# //! if let Some(e) = e.root_cause() {
# //! let ioerror = e.downcast_ref::< io::Error> ().unwrap();
# //! eprintln!(" \nThe root cause was: std::io::Error: {:#?}" , ioerror);
# //! }
# //!
# //! #[cfg(not(windows))]
# //! assert_eq!(
# //! format!(" \n{:?}\n" , e), r#"
# //! src/lib.rs:47: func1 error calling func2
# //! Caused by:
# //! src/lib.rs:22: Func2Error(func2 error: calling func3)
# //! Caused by:
# //! src/lib.rs:15: Error reading 'foo.txt'
# //! Caused by:
# //! Kind(NotFound)
# //! " #
# //! );
# //! }
# //! # else {
# //! # unreachable!();
# //! # }
# //! }
# //! ~~~
2018-12-21 13:55:46 +01:00
#
# use std::any::TypeId;
2018-12-20 14:55:19 +01:00
# use std::error::Error;
# use std::fmt::{Debug, Display, Formatter, Result};
#
2019-02-07 09:02:01 +01:00
# /// chains an inner error kind `T` with a causing error
2018-12-20 14:55:19 +01:00
# pub struct ChainError< T> {
# #[cfg(not(feature = " no-fileline" ))]
# occurrence: Option< (u32, & 'static str)> ,
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# }
#
2018-12-21 13:55:46 +01:00
# /// convenience type alias
# pub type ChainResult< O, E> = std::result::Result< O, ChainError< E> > ;
2018-12-20 14:55:19 +01:00
#
# impl< T: 'static + Display + Debug> ChainError< T> {
# #[cfg(not(feature = " no-fileline" ))]
2018-12-21 13:55:46 +01:00
# /// Use the `cherr!()` or `mstrerr!()` macro instead of calling this directly
2018-12-20 14:55:19 +01:00
# pub fn new(
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# occurrence: Option< (u32, & 'static str)> ,
# ) -> Self {
# Self {
# occurrence,
# kind,
# error_cause,
# }
# }
#
# #[cfg(feature = " no-fileline" )]
2018-12-21 13:55:46 +01:00
# /// Use the `cherr!()` or `mstrerr!()` macro instead of calling this directly
2018-12-20 14:55:19 +01:00
# pub fn new(
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# _occurrence: Option< (u32, & 'static str)> ,
# ) -> Self {
# Self { kind, error_cause }
# }
#
2018-12-21 13:55:46 +01:00
# /// return the root cause of the error chain, if any exists
2018-12-20 14:55:19 +01:00
# pub fn root_cause(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.iter().last()
# }
#
# /// Find the first error cause of type U, if any exists
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// fn do_some_io() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# ///
# /// fn main() {
# /// if let Err(e) = func1() {
# /// if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# ///
# /// assert!(f1err.find_cause::< io::Error> ().is_some());
# ///
# /// assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// }
# /// # else {
# /// # panic!();
# /// # }
# /// }
# /// # else {
# /// # unreachable!();
# /// # }
# /// }
# /// ~~~
# pub fn find_cause< U: Error + 'static> (& self) -> Option< & U> {
# self.iter().filter_map(Error::downcast_ref::< U> ).next()
# }
#
# /// Find the first error cause of type `ChainError< U> `, if any exists
# ///
# /// Same as `find_cause`, but hides the `ChainError< U> ` implementation internals
# ///
# /// # Examples
# ///
# /// ~~~rust,ignore
# /// // Instead of writing
# /// err.find_cause::< ChainError< FooError> > ();
# ///
# /// // leave out the ChainError< FooError> implementation detail
# /// err.find_chain_cause::< FooError> ();
# /// ~~~
# pub fn find_chain_cause< U: Error + 'static> (& self) -> Option< & ChainError< U> > {
# self.iter()
# .filter_map(Error::downcast_ref::< ChainError< U> > )
# .next()
# }
#
# /// Find the first error cause of type `ChainError< U> ` or `U`, if any exists and return `U`
# ///
# /// Same as `find_cause` and `find_chain_cause`, but hides the `ChainError< U> ` implementation internals
# ///
# /// # Examples
# ///
# /// ~~~rust,ignore
# /// // Instead of writing
# /// err.find_cause::< ChainError< FooErrorKind> > ();
# /// // and/or
# /// err.find_chain_cause::< FooErrorKind> ();
# /// // and/or
# /// err.find_cause::< FooErrorKind> ();
# ///
# /// // leave out the ChainError< FooErrorKind> implementation detail
# /// err.find_chain_or_kind::< FooErrorKind> ();
# /// ~~~
# pub fn find_kind_or_cause< U: Error + 'static> (& self) -> Option< & U> {
# self.iter()
# .filter_map(|e| {
# e.downcast_ref::< ChainError< U> > ()
# .map(|e| e.kind())
# .or_else(|| e.downcast_ref::< U> ())
# })
# .next()
# }
#
# /// Return a reference to T of `ChainError< T> `
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// fn do_some_io() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// #[derive(Debug)]
# /// enum Func1ErrorKind {
# /// Func2,
# /// IO(String),
# /// }
# ///
# /// /// impl ::std::fmt::Display for Func1ErrorKind {…}
# /// # impl ::std::fmt::Display for Func1ErrorKind {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # Func1ErrorKind::Func2 => write!(f, " func1 error calling func2" ),
# /// # Func1ErrorKind::IO(filename) => write!(f, " Error reading '{}'" , filename),
# /// # }
# /// # }
# /// # }
# ///
# /// fn func1() -> ChainResult< (), Func1ErrorKind> {
# /// func2().map_err(|e| cherr!(e, Func1ErrorKind::Func2))?;
# /// do_some_io().map_err(|e| cherr!(e, Func1ErrorKind::IO(" bar.txt" .into())))?;
# /// Ok(())
# /// }
# ///
# /// fn main() {
# /// if let Err(e) = func1() {
# /// match e.kind() {
# /// Func1ErrorKind::Func2 => {},
# /// Func1ErrorKind::IO(filename) => panic!(),
# /// }
# /// }
# /// # else {
# /// # unreachable!();
# /// # }
# /// }
# /// ~~~
# pub fn kind(& self) -> & T {
# & self.kind
# }
#
# /// Returns an Iterator over all error causes/sources
# ///
# /// # Example
# ///
# ///
# pub fn iter(& self) -> impl Iterator< Item = & (dyn Error + 'static)> {
# ErrorIter {
# current: Some(self),
2018-12-20 14:55:19 +01:00
# }
# }
2019-02-07 09:02:01 +01:00
# }
2018-12-20 14:55:19 +01:00
#
2019-02-07 09:02:01 +01:00
# struct ErrorIter< 'a> {
# current: Option< & 'a (dyn Error + 'static)> ,
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# impl< 'a> Iterator for ErrorIter< 'a> {
# type Item = & 'a (dyn Error + 'static);
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# fn next(& mut self) -> Option< Self::Item> {
# let current = self.current;
# self.current = self.current.and_then(Error::source);
# current
2018-12-21 13:55:46 +01:00
# }
2019-02-07 09:02:01 +01:00
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# impl< T: 'static + Display + Debug> std::ops::Deref for ChainError< T> {
# type Target = T;
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# fn deref(& self) -> & Self::Target {
# & self.kind
2018-12-21 13:55:46 +01:00
# }
2019-02-07 09:02:01 +01:00
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# /// Convenience trait to hide the `ChainError< T> ` implementation internals
# pub trait ChainErrorDown {
# /// Test if of type `ChainError< T> `
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool;
# /// Downcast to a reference of `ChainError< T> `
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > ;
# /// Downcast to a mutable reference of `ChainError< T> `
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > ;
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# impl< U: 'static + Display + Debug> ChainErrorDown for ChainError< U> {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# TypeId::of::< T> () == TypeId::of::< U> ()
2018-12-21 13:55:46 +01:00
# }
#
2019-02-07 09:02:01 +01:00
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# if self.is_chain::< T> () {
# #[allow(clippy::cast_ptr_alignment)]
# unsafe {
# Some(& *(self as *const dyn Error as *const & ChainError< T> ))
2018-12-21 13:55:46 +01:00
# }
2019-02-07 09:02:01 +01:00
# } else {
# None
2018-12-21 13:55:46 +01:00
# }
# }
2018-12-20 14:55:19 +01:00
#
2019-02-07 09:02:01 +01:00
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# if self.is_chain::< T> () {
# #[allow(clippy::cast_ptr_alignment)]
# unsafe {
# Some(& mut *(self as *mut dyn Error as *mut & mut ChainError< T> ))
2018-12-20 14:55:19 +01:00
# }
2019-02-07 09:02:01 +01:00
# } else {
# None
2018-12-20 14:55:19 +01:00
# }
# }
2019-02-07 09:02:01 +01:00
# }
2018-12-20 14:55:19 +01:00
#
2019-02-07 09:02:01 +01:00
# impl ChainErrorDown for dyn Error + 'static {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# impl ChainErrorDown for dyn Error + 'static + Send {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
2018-12-20 14:55:19 +01:00
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl ChainErrorDown for dyn Error + 'static + Send + Sync {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl< T: 'static + Display + Debug> Error for ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.error_cause.as_ref().map(|e| e.as_ref())
2018-12-20 14:55:19 +01:00
# }
# }
#
# impl< T: 'static + Display + Debug> Error for & ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.error_cause.as_ref().map(|e| e.as_ref())
2018-12-20 14:55:19 +01:00
# }
# }
#
# impl< T: 'static + Display + Debug> Error for & mut ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.error_cause.as_ref().map(|e| e.as_ref())
2018-12-20 14:55:19 +01:00
# }
# }
#
# impl< T: 'static + Display + Debug> Display for ChainError< T> {
# fn fmt(& self, f: & mut Formatter) -> Result {
# write!(f, " {}" , self.kind)?;
#
# #[cfg(feature = " display-cause" )]
# {
# if let Some(e) = self.source() {
# writeln!(f, " \nCaused by:" )?;
# Display::fmt(& e, f)?;
# }
# }
# Ok(())
# }
# }
#
# impl< T: 'static + Display + Debug> Debug for ChainError< T> {
# fn fmt(& self, f: & mut Formatter) -> Result {
# #[cfg(not(feature = " no-fileline" ))]
# {
# if let Some(o) = self.occurrence {
# write!(f, " {}:{}: " , o.1, o.0)?;
# }
# }
#
2018-12-21 13:55:46 +01:00
# if self.is_chain::< String> () {
# Display::fmt(& self.kind, f)?;
# } else {
# Debug::fmt(& self.kind, f)?;
# }
2018-12-20 14:55:19 +01:00
#
# #[cfg(not(feature = " no-debug-cause" ))]
# {
# if let Some(e) = self.source() {
# writeln!(f, " \nCaused by:" )?;
# Debug::fmt(& e, f)?;
# }
# }
# Ok(())
# }
# }
#
2019-02-07 09:02:01 +01:00
# pub trait ChainErrorFrom< T> : Sized {
# fn chain_error_from(_: T, line_filename: Option< (u32, & 'static str)> ) -> ChainError< Self> ;
# }
#
# pub trait IntoChainError< T> : Sized {
# fn into_chain_error(self, line_filename: Option< (u32, & 'static str)> ) -> ChainError< T> ;
# }
#
# impl< T, U> IntoChainError< U> for T
# where
# U: ChainErrorFrom< T> ,
# {
# fn into_chain_error(self, line_filename: Option< (u32, & 'static str)> ) -> ChainError< U> {
# U::chain_error_from(self, line_filename)
# }
# }
#
# impl< T, U> ChainErrorFrom< T> for U
# where
# T: Into< U> ,
# U: 'static + Display + Debug,
# {
# fn chain_error_from(t: T, line_filename: Option< (u32, & 'static str)> ) -> ChainError< Self> {
# let e: U = t.into();
# ChainError::< _> ::new(e, None, line_filename)
# }
# }
#
2018-12-20 14:55:19 +01:00
# #[macro_export]
2019-02-07 09:02:01 +01:00
# macro_rules! minto_cherr {
# ( ) => {
# |e| e.into_chain_error(Some((line!(), file!())))
2018-12-20 14:55:19 +01:00
# };
# }
#
# #[macro_export]
2019-02-07 09:02:01 +01:00
# macro_rules! into_cherr {
# ( $t:expr ) => {
# $t.into_chain_error(Some((line!(), file!())))
2018-12-20 14:55:19 +01:00
# };
# }
#
2019-02-07 09:02:01 +01:00
# /// Creates a new `ChainError< T> `
# ///
# /// # Examples
# ///
# /// Create a new ChainError< FooError> , where `FooError` must implement `Display` and `Debug`.
# /// ~~~rust
# /// # use chainerror::*;
# /// #
# /// # #[derive(Debug)]
# /// enum FooError {
# /// Bar,
# /// Baz(& 'static str),
# /// }
# /// #
# /// # impl ::std::fmt::Display for FooError {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # FooError::Bar => write!(f, " Bar Error" ),
# /// # FooError::Baz(s) => write!(f, " Baz Error: '{}'" , s),
# /// # }
# /// # }
# /// # }
# ///
# /// // impl ::std::fmt::Display for FooError
# ///
# /// fn do_some_stuff() -> bool {
# /// false
# /// }
# ///
# /// fn func() -> ChainResult< (), FooError> {
# /// if ! do_some_stuff() {
# /// Err(cherr!(FooError::Baz(" Error" )))?;
# /// }
# /// Ok(())
# /// }
# /// #
# /// # pub fn main() {
# /// # match func().unwrap_err().kind() {
# /// # FooError::Baz(s) if s == & " Error" => {},
# /// # _ => panic!(),
# /// # }
# /// # }
# /// ~~~
# ///
# /// Additionally an error cause can be added.
# ///
# /// ~~~rust
# /// # use chainerror::*;
# /// # use std::io;
# /// # use std::error::Error;
# /// #
# /// # #[derive(Debug)]
# /// # enum FooError {
# /// # Bar,
# /// # Baz(& 'static str),
# /// # }
# /// #
# /// # impl ::std::fmt::Display for FooError {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # FooError::Bar => write!(f, " Bar Error" ),
# /// # FooError::Baz(s) => write!(f, " Baz Error: '{}'" , s),
# /// # }
# /// # }
# /// # }
# /// #
# /// fn do_some_stuff() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// fn func() -> ChainResult< (), FooError> {
# /// do_some_stuff().map_err(
# /// |e| cherr!(e, FooError::Baz(" Error" ))
# /// )?;
# /// Ok(())
# /// }
# /// #
# /// # pub fn main() {
# /// # match func().unwrap_err().kind() {
# /// # FooError::Baz(s) if s == & " Error" => {},
# /// # _ => panic!(),
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! cherr {
# ( $k:expr ) => ({
# ChainError::< _> ::new($k, None, Some((line!(), file!())))
# });
# ( None, $k:expr ) => ({
# ChainError::< _> ::new($k, None, Some((line!(), file!())))
# });
# ( None, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!(None, format!($fmt, $($arg)+ ))
# });
# ( None, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!(None, format!($fmt, $($arg)+ ))
# });
# ( $e:path, $k:expr ) => ({
# ChainError::< _> ::new($k, Some(Box::from($e)), Some((line!(), file!())))
# });
# ( $e:path, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!($e, format!($fmt, $($arg)+ ))
# });
#
# }
#
# /// Convenience macro for `|e| cherr!(e, format!(…))`
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(" func1 error" ))?;
# /// Ok(())
# /// }
# ///
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # #[cfg(not(windows))]
# /// # assert_eq!(
# /// # format!(" \n{:?}\n" , e), r#"
# /// # src/lib.rs:20: func1 error
# /// # Caused by:
# /// # src/lib.rs:15: Error reading 'foo.txt'
# /// # Caused by:
# /// # Kind(NotFound)
# /// # " #
# /// # );
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# ///
# /// `mstrerr!()` can also be used to map a new `ChainError< T> `, where T was defined with
# /// `derive_str_cherr!(T)`
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! mstrerr {
# ( $t:path, $msg:expr ) => ({
# |e| cherr!(e, $t ($msg.to_string()))
# });
# ( $t:path, $msg:expr, ) => ({
# |e| cherr!(e, $t ($msg.to_string()))
# });
# ( $t:path, $fmt:expr, $($arg:tt)+ ) => ({
# |e| cherr!(e, $t (format!($fmt, $($arg)+ )))
# });
# ($msg:expr) => ({
# |e| cherr!(e, $msg.to_string())
# });
# ($msg:expr, ) => ({
# |e| cherr!(e, $msg.to_string())
# });
# ($fmt:expr, $($arg:tt)+) => ({
# |e| cherr!(e, format!($fmt, $($arg)+ ))
# });
# }
#
# /// Convenience macro for `cherr!(T(format!(…)))` where `T(String)`
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::result::Result;
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> ChainResult< (), Func2Error> {
# /// let filename = " foo.txt" ;
# /// Err(strerr!(Func2Error, " Error reading '{}'" , filename))
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! strerr {
# ( $t:path, $msg:expr ) => ({
# cherr!($t ($msg.to_string()))
# });
# ( $t:path, $msg:expr, ) => ({
# cherr!($t ($msg.to_string()))
# });
# ( $t:path, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!($t (format!($fmt, $($arg)+ )))
# });
# ($msg:expr) => ({
# cherr!($msg.to_string())
# });
# ($msg:expr, ) => ({
# cherr!($msg.to_string())
# });
# ($fmt:expr, $($arg:tt)+) => ({
# cherr!(format!($fmt, $($arg)+ ))
# });
# }
#
# /// Convenience macro to create a " new type" T(String) and implement Display + Debug for T
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> ChainResult< (), Func2Error> {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
2018-12-20 14:55:19 +01:00
# #[macro_export]
# macro_rules! derive_str_cherr {
# ($e:ident) => {
2019-02-07 09:02:01 +01:00
# pub struct $e(pub String);
2018-12-20 14:55:19 +01:00
# impl ::std::fmt::Display for $e {
# fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# write!(f, " {}" , self.0)
# }
# }
# impl ::std::fmt::Debug for $e {
# fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# write!(f, " {}({})" , stringify!($e), self.0)
# }
# }
# impl ::std::error::Error for $e {}
# };
# }
# }
< / code > < / pre > < / pre >
2018-12-20 16:02:24 +01:00
< p > If you compare the output to the previous example, you will see,
that:< / p >
< pre > < code > Error: src/main.rs:19: " func1 error"
< / code > < / pre >
< p > changed to just:< / p >
< pre > < code > src/main.rs:16: " func1 error"
< / code > < / pre >
< p > This is, because we caught the error of < code > func1()< / code > in < code > main()< / code > and print it out ourselves.< / p >
< p > We can now control, whether to output in < code > Debug< / code > or < code > Display< / code > mode.
Maybe depending on < code > --debug< / code > as a CLI argument.< / p >
2018-12-20 16:37:43 +01:00
< a class = "header" href = "#saving-coding-chars" id = "saving-coding-chars" > < h1 > Saving coding chars< / h1 > < / a >
2018-12-20 16:02:24 +01:00
< p > Because decorating an error with more information should not
let you jump through hoops, < code > chainerror< / code > has a quick macro for that.< / p >
< p > < code > mstrerror!()< / code > fits right into < code > .map_err()< / code > letting you quickly add
more debug strings.< / p >
< p > < code > mstrerror!()< / code > even understands < code > format!()< / code > syntax like < code > println!()< / code > .< / p >
2019-03-04 11:46:17 +01:00
< pre > < pre class = "playpen" > < code class = "language-rust" > use chainerror::*;
2018-12-20 14:55:19 +01:00
use std::error::Error;
2018-12-21 13:55:46 +01:00
use std::io;
2018-12-20 14:55:19 +01:00
use std::result::Result;
fn do_some_io() -> Result< (), Box< Error> > {
2018-12-21 13:55:46 +01:00
Err(io::Error::from(io::ErrorKind::NotFound))?;
2018-12-20 14:55:19 +01:00
Ok(())
}
fn func2() -> Result< (), Box< Error> > {
2018-12-20 16:02:24 +01:00
let filename = " foo.txt" ;
do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
2018-12-20 14:55:19 +01:00
Ok(())
}
fn func1() -> Result< (), Box< Error> > {
func2().map_err(mstrerr!(" func1 error" ))?;
Ok(())
}
fn main() -> Result< (), Box< Error> > {
if let Err(e) = func1() {
eprintln!(" {:?}" , e);
}
Ok(())
}
2019-03-04 11:46:17 +01:00
2018-12-20 14:55:19 +01:00
# #[allow(dead_code)]
# mod chainerror {
2019-02-07 09:02:01 +01:00
# //! `chainerror` provides an error backtrace without doing a real backtrace, so even after you `strip` your
# //! binaries, you still have the error backtrace.
# //!
# //! `chainerror` has no dependencies!
# //!
# //! `chainerror` uses `.source()` of `std::error::Error` along with `line()!` and `file()!` to provide a nice debug error backtrace.
# //! It encapsulates all types, which have `Display + Debug` and can store the error cause internally.
# //!
# //! Along with the `ChainError< T> ` struct, `chainerror` comes with some useful helper macros to save a lot of typing.
# //!
# //! ## Features
# //!
# //! `no-fileline`
# //! : completely turn off storing filename and line
# //!
# //! `display-cause`
# //! : turn on printing a backtrace of the errors in `Display`
# //!
# //! `no-debug-cause`
# //! : turn off printing a backtrace of the errors in `Debug`
# //!
# //!
# //! # Tutorial
# //!
# //! Read the [Tutorial](https://haraldh.github.io/chainerror/tutorial1.html)
# //!
# //! # Examples
# //!
# //! ~~~rust
# //! use chainerror::*;
# //! use std::error::Error;
# //! use std::io;
# //! use std::result::Result;
# //!
# //! fn do_some_io() -> Result< (), Box< Error> > {
# //! Err(io::Error::from(io::ErrorKind::NotFound))?;
# //! Ok(())
# //! }
# //!
# //! fn func2() -> Result< (), Box< Error> > {
# //! let filename = " foo.txt" ;
# //! do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# //! Ok(())
# //! }
# //!
# //! fn func1() -> Result< (), Box< Error> > {
# //! func2().map_err(mstrerr!(" func1 error" ))?;
# //! Ok(())
# //! }
# //!
# //! fn main() {
# //! if let Err(e) = func1() {
# //! #[cfg(not(windows))]
# //! assert_eq!(
# //! format!(" \n{:?}\n" , e), r#"
# //! src/lib.rs:20: func1 error
# //! Caused by:
# //! src/lib.rs:15: Error reading 'foo.txt'
# //! Caused by:
# //! Kind(NotFound)
# //! " #
# //! );
# //! }
# //! # else {
# //! # unreachable!();
# //! # }
# //! }
# //! ~~~
# //!
# //!
# //! ~~~rust
# //! use chainerror::*;
# //! use std::error::Error;
# //! use std::io;
# //! use std::result::Result;
# //!
# //! fn do_some_io() -> Result< (), Box< Error> > {
# //! Err(io::Error::from(io::ErrorKind::NotFound))?;
# //! Ok(())
# //! }
# //!
# //! fn func3() -> Result< (), Box< Error> > {
# //! let filename = " foo.txt" ;
# //! do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# //! Ok(())
# //! }
# //!
# //! derive_str_cherr!(Func2Error);
# //!
# //! fn func2() -> ChainResult< (), Func2Error> {
# //! func3().map_err(mstrerr!(Func2Error, " func2 error: calling func3" ))?;
# //! Ok(())
# //! }
# //!
# //! enum Func1Error {
# //! Func2,
# //! IO(String),
# //! }
# //!
# //! impl ::std::fmt::Display for Func1Error {
# //! fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# //! match self {
# //! Func1Error::Func2 => write!(f, " func1 error calling func2" ),
# //! Func1Error::IO(filename) => write!(f, " Error reading '{}'" , filename),
# //! }
# //! }
# //! }
# //!
# //! impl ::std::fmt::Debug for Func1Error {
# //! fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# //! write!(f, " {}" , self)
# //! }
# //! }
# //!
# //! fn func1() -> ChainResult< (), Func1Error> {
# //! func2().map_err(|e| cherr!(e, Func1Error::Func2))?;
# //! let filename = String::from(" bar.txt" );
# //! do_some_io().map_err(|e| cherr!(e, Func1Error::IO(filename)))?;
# //! Ok(())
# //! }
# //!
# //! fn main() {
# //! if let Err(e) = func1() {
# //! assert!(
# //! match e.kind() {
# //! Func1Error::Func2 => {
# //! eprintln!(" Main Error Report: func1 error calling func2" );
# //! true
# //! }
# //! Func1Error::IO(filename) => {
# //! eprintln!(" Main Error Report: func1 error reading '{}'" , filename);
# //! false
# //! }
# //! }
# //! );
# //!
# //! assert!(e.find_chain_cause::< Func2Error> ().is_some());
# //!
# //! if let Some(e) = e.find_chain_cause::< Func2Error> () {
# //! eprintln!(" \nError reported by Func2Error: {}" , e)
# //! }
# //!
# //!
# //! assert!(e.root_cause().is_some());
# //!
# //! if let Some(e) = e.root_cause() {
# //! let ioerror = e.downcast_ref::< io::Error> ().unwrap();
# //! eprintln!(" \nThe root cause was: std::io::Error: {:#?}" , ioerror);
# //! }
# //!
# //! #[cfg(not(windows))]
# //! assert_eq!(
# //! format!(" \n{:?}\n" , e), r#"
# //! src/lib.rs:47: func1 error calling func2
# //! Caused by:
# //! src/lib.rs:22: Func2Error(func2 error: calling func3)
# //! Caused by:
# //! src/lib.rs:15: Error reading 'foo.txt'
# //! Caused by:
# //! Kind(NotFound)
# //! " #
# //! );
# //! }
# //! # else {
# //! # unreachable!();
# //! # }
# //! }
# //! ~~~
2018-12-21 13:55:46 +01:00
#
# use std::any::TypeId;
2018-12-20 14:55:19 +01:00
# use std::error::Error;
# use std::fmt::{Debug, Display, Formatter, Result};
#
2019-02-07 09:02:01 +01:00
# /// chains an inner error kind `T` with a causing error
2018-12-20 14:55:19 +01:00
# pub struct ChainError< T> {
# #[cfg(not(feature = " no-fileline" ))]
# occurrence: Option< (u32, & 'static str)> ,
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# }
#
2018-12-21 13:55:46 +01:00
# /// convenience type alias
# pub type ChainResult< O, E> = std::result::Result< O, ChainError< E> > ;
2018-12-20 14:55:19 +01:00
#
# impl< T: 'static + Display + Debug> ChainError< T> {
# #[cfg(not(feature = " no-fileline" ))]
2018-12-21 13:55:46 +01:00
# /// Use the `cherr!()` or `mstrerr!()` macro instead of calling this directly
2018-12-20 14:55:19 +01:00
# pub fn new(
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# occurrence: Option< (u32, & 'static str)> ,
# ) -> Self {
# Self {
# occurrence,
# kind,
# error_cause,
# }
# }
#
# #[cfg(feature = " no-fileline" )]
2018-12-21 13:55:46 +01:00
# /// Use the `cherr!()` or `mstrerr!()` macro instead of calling this directly
2018-12-20 14:55:19 +01:00
# pub fn new(
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# _occurrence: Option< (u32, & 'static str)> ,
# ) -> Self {
# Self { kind, error_cause }
# }
#
2018-12-21 13:55:46 +01:00
# /// return the root cause of the error chain, if any exists
2018-12-20 14:55:19 +01:00
# pub fn root_cause(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.iter().last()
# }
#
# /// Find the first error cause of type U, if any exists
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// fn do_some_io() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# ///
# /// fn main() {
# /// if let Err(e) = func1() {
# /// if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# ///
# /// assert!(f1err.find_cause::< io::Error> ().is_some());
# ///
# /// assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// }
# /// # else {
# /// # panic!();
# /// # }
# /// }
# /// # else {
# /// # unreachable!();
# /// # }
# /// }
# /// ~~~
2018-12-20 14:55:19 +01:00
# pub fn find_cause< U: Error + 'static> (& self) -> Option< & U> {
2019-02-07 09:02:01 +01:00
# self.iter().filter_map(Error::downcast_ref::< U> ).next()
# }
#
# /// Find the first error cause of type `ChainError< U> `, if any exists
# ///
# /// Same as `find_cause`, but hides the `ChainError< U> ` implementation internals
# ///
# /// # Examples
# ///
# /// ~~~rust,ignore
# /// // Instead of writing
# /// err.find_cause::< ChainError< FooError> > ();
# ///
# /// // leave out the ChainError< FooError> implementation detail
# /// err.find_chain_cause::< FooError> ();
# /// ~~~
2018-12-20 14:55:19 +01:00
# pub fn find_chain_cause< U: Error + 'static> (& self) -> Option< & ChainError< U> > {
2019-02-07 09:02:01 +01:00
# self.iter()
# .filter_map(Error::downcast_ref::< ChainError< U> > )
# .next()
# }
#
# /// Find the first error cause of type `ChainError< U> ` or `U`, if any exists and return `U`
# ///
# /// Same as `find_cause` and `find_chain_cause`, but hides the `ChainError< U> ` implementation internals
# ///
# /// # Examples
# ///
# /// ~~~rust,ignore
# /// // Instead of writing
# /// err.find_cause::< ChainError< FooErrorKind> > ();
# /// // and/or
# /// err.find_chain_cause::< FooErrorKind> ();
# /// // and/or
# /// err.find_cause::< FooErrorKind> ();
# ///
# /// // leave out the ChainError< FooErrorKind> implementation detail
# /// err.find_chain_or_kind::< FooErrorKind> ();
# /// ~~~
# pub fn find_kind_or_cause< U: Error + 'static> (& self) -> Option< & U> {
# self.iter()
# .filter_map(|e| {
# e.downcast_ref::< ChainError< U> > ()
# .map(|e| e.kind())
# .or_else(|| e.downcast_ref::< U> ())
# })
# .next()
# }
#
# /// Return a reference to T of `ChainError< T> `
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// fn do_some_io() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// #[derive(Debug)]
# /// enum Func1ErrorKind {
# /// Func2,
# /// IO(String),
# /// }
# ///
# /// /// impl ::std::fmt::Display for Func1ErrorKind {…}
# /// # impl ::std::fmt::Display for Func1ErrorKind {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # Func1ErrorKind::Func2 => write!(f, " func1 error calling func2" ),
# /// # Func1ErrorKind::IO(filename) => write!(f, " Error reading '{}'" , filename),
# /// # }
# /// # }
# /// # }
# ///
# /// fn func1() -> ChainResult< (), Func1ErrorKind> {
# /// func2().map_err(|e| cherr!(e, Func1ErrorKind::Func2))?;
# /// do_some_io().map_err(|e| cherr!(e, Func1ErrorKind::IO(" bar.txt" .into())))?;
# /// Ok(())
# /// }
# ///
# /// fn main() {
# /// if let Err(e) = func1() {
# /// match e.kind() {
# /// Func1ErrorKind::Func2 => {},
# /// Func1ErrorKind::IO(filename) => panic!(),
# /// }
# /// }
# /// # else {
# /// # unreachable!();
# /// # }
# /// }
# /// ~~~
# pub fn kind(& self) -> & T {
# & self.kind
2018-12-21 13:55:46 +01:00
# }
#
2019-02-07 09:02:01 +01:00
# /// Returns an Iterator over all error causes/sources
# ///
# /// # Example
# ///
# ///
# pub fn iter(& self) -> impl Iterator< Item = & (dyn Error + 'static)> {
# ErrorIter {
# current: Some(self),
# }
2018-12-21 13:55:46 +01:00
# }
2019-02-07 09:02:01 +01:00
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# struct ErrorIter< 'a> {
# current: Option< & 'a (dyn Error + 'static)> ,
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# impl< 'a> Iterator for ErrorIter< 'a> {
# type Item = & 'a (dyn Error + 'static);
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# fn next(& mut self) -> Option< Self::Item> {
# let current = self.current;
# self.current = self.current.and_then(Error::source);
# current
2018-12-21 13:55:46 +01:00
# }
2019-02-07 09:02:01 +01:00
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# impl< T: 'static + Display + Debug> std::ops::Deref for ChainError< T> {
# type Target = T;
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# fn deref(& self) -> & Self::Target {
2018-12-20 14:55:19 +01:00
# & self.kind
# }
# }
#
2019-02-07 09:02:01 +01:00
# /// Convenience trait to hide the `ChainError< T> ` implementation internals
2018-12-20 14:55:19 +01:00
# pub trait ChainErrorDown {
2019-02-07 09:02:01 +01:00
# /// Test if of type `ChainError< T> `
2018-12-20 14:55:19 +01:00
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool;
2019-02-07 09:02:01 +01:00
# /// Downcast to a reference of `ChainError< T> `
2018-12-20 14:55:19 +01:00
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > ;
2019-02-07 09:02:01 +01:00
# /// Downcast to a mutable reference of `ChainError< T> `
2018-12-20 14:55:19 +01:00
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > ;
# }
#
# impl< U: 'static + Display + Debug> ChainErrorDown for ChainError< U> {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# TypeId::of::< T> () == TypeId::of::< U> ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# if self.is_chain::< T> () {
2019-02-07 09:02:01 +01:00
# #[allow(clippy::cast_ptr_alignment)]
# unsafe {
# Some(& *(self as *const dyn Error as *const & ChainError< T> ))
# }
2018-12-20 14:55:19 +01:00
# } else {
# None
# }
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# if self.is_chain::< T> () {
2019-02-07 09:02:01 +01:00
# #[allow(clippy::cast_ptr_alignment)]
# unsafe {
# Some(& mut *(self as *mut dyn Error as *mut & mut ChainError< T> ))
# }
2018-12-20 14:55:19 +01:00
# } else {
# None
# }
# }
# }
#
# impl ChainErrorDown for dyn Error + 'static {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl ChainErrorDown for dyn Error + 'static + Send {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl ChainErrorDown for dyn Error + 'static + Send + Sync {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl< T: 'static + Display + Debug> Error for ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.error_cause.as_ref().map(|e| e.as_ref())
2018-12-20 14:55:19 +01:00
# }
# }
#
# impl< T: 'static + Display + Debug> Error for & ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.error_cause.as_ref().map(|e| e.as_ref())
2018-12-20 14:55:19 +01:00
# }
# }
#
# impl< T: 'static + Display + Debug> Error for & mut ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.error_cause.as_ref().map(|e| e.as_ref())
2018-12-20 14:55:19 +01:00
# }
# }
#
# impl< T: 'static + Display + Debug> Display for ChainError< T> {
# fn fmt(& self, f: & mut Formatter) -> Result {
# write!(f, " {}" , self.kind)?;
#
# #[cfg(feature = " display-cause" )]
# {
# if let Some(e) = self.source() {
# writeln!(f, " \nCaused by:" )?;
# Display::fmt(& e, f)?;
# }
# }
# Ok(())
# }
# }
#
# impl< T: 'static + Display + Debug> Debug for ChainError< T> {
# fn fmt(& self, f: & mut Formatter) -> Result {
# #[cfg(not(feature = " no-fileline" ))]
# {
# if let Some(o) = self.occurrence {
# write!(f, " {}:{}: " , o.1, o.0)?;
# }
# }
#
2018-12-21 13:55:46 +01:00
# if self.is_chain::< String> () {
# Display::fmt(& self.kind, f)?;
# } else {
# Debug::fmt(& self.kind, f)?;
# }
2018-12-20 14:55:19 +01:00
#
# #[cfg(not(feature = " no-debug-cause" ))]
# {
# if let Some(e) = self.source() {
# writeln!(f, " \nCaused by:" )?;
# Debug::fmt(& e, f)?;
# }
# }
# Ok(())
# }
# }
#
2019-02-07 09:02:01 +01:00
# pub trait ChainErrorFrom< T> : Sized {
# fn chain_error_from(_: T, line_filename: Option< (u32, & 'static str)> ) -> ChainError< Self> ;
# }
#
# pub trait IntoChainError< T> : Sized {
# fn into_chain_error(self, line_filename: Option< (u32, & 'static str)> ) -> ChainError< T> ;
# }
#
# impl< T, U> IntoChainError< U> for T
# where
# U: ChainErrorFrom< T> ,
# {
# fn into_chain_error(self, line_filename: Option< (u32, & 'static str)> ) -> ChainError< U> {
# U::chain_error_from(self, line_filename)
# }
# }
#
# impl< T, U> ChainErrorFrom< T> for U
# where
# T: Into< U> ,
# U: 'static + Display + Debug,
# {
# fn chain_error_from(t: T, line_filename: Option< (u32, & 'static str)> ) -> ChainError< Self> {
# let e: U = t.into();
# ChainError::< _> ::new(e, None, line_filename)
# }
# }
#
2018-12-20 14:55:19 +01:00
# #[macro_export]
2019-02-07 09:02:01 +01:00
# macro_rules! minto_cherr {
# ( ) => {
# |e| e.into_chain_error(Some((line!(), file!())))
2018-12-20 14:55:19 +01:00
# };
# }
#
# #[macro_export]
2019-02-07 09:02:01 +01:00
# macro_rules! into_cherr {
# ( $t:expr ) => {
# $t.into_chain_error(Some((line!(), file!())))
2018-12-20 14:55:19 +01:00
# };
# }
#
2019-02-07 09:02:01 +01:00
# /// Creates a new `ChainError< T> `
# ///
# /// # Examples
# ///
# /// Create a new ChainError< FooError> , where `FooError` must implement `Display` and `Debug`.
# /// ~~~rust
# /// # use chainerror::*;
# /// #
# /// # #[derive(Debug)]
# /// enum FooError {
# /// Bar,
# /// Baz(& 'static str),
# /// }
# /// #
# /// # impl ::std::fmt::Display for FooError {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # FooError::Bar => write!(f, " Bar Error" ),
# /// # FooError::Baz(s) => write!(f, " Baz Error: '{}'" , s),
# /// # }
# /// # }
# /// # }
# ///
# /// // impl ::std::fmt::Display for FooError
# ///
# /// fn do_some_stuff() -> bool {
# /// false
# /// }
# ///
# /// fn func() -> ChainResult< (), FooError> {
# /// if ! do_some_stuff() {
# /// Err(cherr!(FooError::Baz(" Error" )))?;
# /// }
# /// Ok(())
# /// }
# /// #
# /// # pub fn main() {
# /// # match func().unwrap_err().kind() {
# /// # FooError::Baz(s) if s == & " Error" => {},
# /// # _ => panic!(),
# /// # }
# /// # }
# /// ~~~
# ///
# /// Additionally an error cause can be added.
# ///
# /// ~~~rust
# /// # use chainerror::*;
# /// # use std::io;
# /// # use std::error::Error;
# /// #
# /// # #[derive(Debug)]
# /// # enum FooError {
# /// # Bar,
# /// # Baz(& 'static str),
# /// # }
# /// #
# /// # impl ::std::fmt::Display for FooError {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # FooError::Bar => write!(f, " Bar Error" ),
# /// # FooError::Baz(s) => write!(f, " Baz Error: '{}'" , s),
# /// # }
# /// # }
# /// # }
# /// #
# /// fn do_some_stuff() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// fn func() -> ChainResult< (), FooError> {
# /// do_some_stuff().map_err(
# /// |e| cherr!(e, FooError::Baz(" Error" ))
# /// )?;
# /// Ok(())
# /// }
# /// #
# /// # pub fn main() {
# /// # match func().unwrap_err().kind() {
# /// # FooError::Baz(s) if s == & " Error" => {},
# /// # _ => panic!(),
# /// # }
# /// # }
# /// ~~~
2018-12-20 14:55:19 +01:00
# #[macro_export]
2019-02-07 09:02:01 +01:00
# macro_rules! cherr {
# ( $k:expr ) => ({
# ChainError::< _> ::new($k, None, Some((line!(), file!())))
# });
# ( None, $k:expr ) => ({
# ChainError::< _> ::new($k, None, Some((line!(), file!())))
# });
# ( None, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!(None, format!($fmt, $($arg)+ ))
# });
# ( None, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!(None, format!($fmt, $($arg)+ ))
# });
# ( $e:path, $k:expr ) => ({
# ChainError::< _> ::new($k, Some(Box::from($e)), Some((line!(), file!())))
# });
# ( $e:path, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!($e, format!($fmt, $($arg)+ ))
# });
#
# }
#
# /// Convenience macro for `|e| cherr!(e, format!(…))`
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(" func1 error" ))?;
# /// Ok(())
# /// }
# ///
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # #[cfg(not(windows))]
# /// # assert_eq!(
# /// # format!(" \n{:?}\n" , e), r#"
# /// # src/lib.rs:20: func1 error
# /// # Caused by:
# /// # src/lib.rs:15: Error reading 'foo.txt'
# /// # Caused by:
# /// # Kind(NotFound)
# /// # " #
# /// # );
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# ///
# /// `mstrerr!()` can also be used to map a new `ChainError< T> `, where T was defined with
# /// `derive_str_cherr!(T)`
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! mstrerr {
# ( $t:path, $msg:expr ) => ({
# |e| cherr!(e, $t ($msg.to_string()))
# });
# ( $t:path, $msg:expr, ) => ({
# |e| cherr!(e, $t ($msg.to_string()))
# });
# ( $t:path, $fmt:expr, $($arg:tt)+ ) => ({
# |e| cherr!(e, $t (format!($fmt, $($arg)+ )))
# });
# ($msg:expr) => ({
# |e| cherr!(e, $msg.to_string())
# });
# ($msg:expr, ) => ({
# |e| cherr!(e, $msg.to_string())
# });
# ($fmt:expr, $($arg:tt)+) => ({
# |e| cherr!(e, format!($fmt, $($arg)+ ))
# });
# }
#
# /// Convenience macro for `cherr!(T(format!(…)))` where `T(String)`
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::result::Result;
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> ChainResult< (), Func2Error> {
# /// let filename = " foo.txt" ;
# /// Err(strerr!(Func2Error, " Error reading '{}'" , filename))
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! strerr {
# ( $t:path, $msg:expr ) => ({
# cherr!($t ($msg.to_string()))
# });
# ( $t:path, $msg:expr, ) => ({
# cherr!($t ($msg.to_string()))
# });
# ( $t:path, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!($t (format!($fmt, $($arg)+ )))
# });
# ($msg:expr) => ({
# cherr!($msg.to_string())
# });
# ($msg:expr, ) => ({
# cherr!($msg.to_string())
# });
# ($fmt:expr, $($arg:tt)+) => ({
# cherr!(format!($fmt, $($arg)+ ))
# });
# }
#
# /// Convenience macro to create a " new type" T(String) and implement Display + Debug for T
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> ChainResult< (), Func2Error> {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! derive_str_cherr {
# ($e:ident) => {
# pub struct $e(pub String);
# impl ::std::fmt::Display for $e {
# fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
2018-12-20 14:55:19 +01:00
# write!(f, " {}" , self.0)
# }
# }
# impl ::std::fmt::Debug for $e {
# fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# write!(f, " {}({})" , stringify!($e), self.0)
# }
# }
# impl ::std::error::Error for $e {}
# };
# }
# }
< / code > < / pre > < / pre >
2018-12-20 16:37:43 +01:00
< a class = "header" href = "#the-source-of-errors" id = "the-source-of-errors" > < h1 > The source() of Errors< / h1 > < / a >
2018-12-20 16:02:24 +01:00
< p > Sometimes you want to inspect the < code > source()< / code > of an < code > Error< / code > .
< code > chainerror< / code > implements < code > std::error::Error::source()< / code > , so you can get the cause of an error.< / p >
2019-03-04 11:46:17 +01:00
< pre > < pre class = "playpen" > < code class = "language-rust" > use chainerror::*;
2018-12-20 14:55:19 +01:00
use std::error::Error;
use std::io;
use std::result::Result;
fn do_some_io() -> Result< (), Box< Error> > {
Err(io::Error::from(io::ErrorKind::NotFound))?;
Ok(())
}
fn func2() -> Result< (), Box< Error> > {
let filename = " foo.txt" ;
do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
Ok(())
}
fn func1() -> Result< (), Box< Error> > {
if let Err(e) = func2() {
if let Some(s) = e.source() {
eprintln!(" func2 failed because of '{}'" , s);
Err(e).map_err(mstrerr!(" func1 error" ))?;
}
}
Ok(())
}
fn main() -> Result< (), Box< Error> > {
if let Err(e) = func1() {
eprintln!(" {}" , e);
}
Ok(())
}
2019-03-04 11:46:17 +01:00
2018-12-20 14:55:19 +01:00
# #[allow(dead_code)]
# mod chainerror {
2019-02-07 09:02:01 +01:00
# //! `chainerror` provides an error backtrace without doing a real backtrace, so even after you `strip` your
# //! binaries, you still have the error backtrace.
# //!
# //! `chainerror` has no dependencies!
# //!
# //! `chainerror` uses `.source()` of `std::error::Error` along with `line()!` and `file()!` to provide a nice debug error backtrace.
# //! It encapsulates all types, which have `Display + Debug` and can store the error cause internally.
# //!
# //! Along with the `ChainError< T> ` struct, `chainerror` comes with some useful helper macros to save a lot of typing.
# //!
# //! ## Features
# //!
# //! `no-fileline`
# //! : completely turn off storing filename and line
# //!
# //! `display-cause`
# //! : turn on printing a backtrace of the errors in `Display`
# //!
# //! `no-debug-cause`
# //! : turn off printing a backtrace of the errors in `Debug`
# //!
# //!
# //! # Tutorial
# //!
# //! Read the [Tutorial](https://haraldh.github.io/chainerror/tutorial1.html)
# //!
# //! # Examples
# //!
# //! ~~~rust
# //! use chainerror::*;
# //! use std::error::Error;
# //! use std::io;
# //! use std::result::Result;
# //!
# //! fn do_some_io() -> Result< (), Box< Error> > {
# //! Err(io::Error::from(io::ErrorKind::NotFound))?;
# //! Ok(())
# //! }
# //!
# //! fn func2() -> Result< (), Box< Error> > {
# //! let filename = " foo.txt" ;
# //! do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# //! Ok(())
# //! }
# //!
# //! fn func1() -> Result< (), Box< Error> > {
# //! func2().map_err(mstrerr!(" func1 error" ))?;
# //! Ok(())
# //! }
# //!
# //! fn main() {
# //! if let Err(e) = func1() {
# //! #[cfg(not(windows))]
# //! assert_eq!(
# //! format!(" \n{:?}\n" , e), r#"
# //! src/lib.rs:20: func1 error
# //! Caused by:
# //! src/lib.rs:15: Error reading 'foo.txt'
# //! Caused by:
# //! Kind(NotFound)
# //! " #
# //! );
# //! }
# //! # else {
# //! # unreachable!();
# //! # }
# //! }
# //! ~~~
# //!
# //!
# //! ~~~rust
# //! use chainerror::*;
# //! use std::error::Error;
# //! use std::io;
# //! use std::result::Result;
# //!
# //! fn do_some_io() -> Result< (), Box< Error> > {
# //! Err(io::Error::from(io::ErrorKind::NotFound))?;
# //! Ok(())
# //! }
# //!
# //! fn func3() -> Result< (), Box< Error> > {
# //! let filename = " foo.txt" ;
# //! do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# //! Ok(())
# //! }
# //!
# //! derive_str_cherr!(Func2Error);
# //!
# //! fn func2() -> ChainResult< (), Func2Error> {
# //! func3().map_err(mstrerr!(Func2Error, " func2 error: calling func3" ))?;
# //! Ok(())
# //! }
# //!
# //! enum Func1Error {
# //! Func2,
# //! IO(String),
# //! }
# //!
# //! impl ::std::fmt::Display for Func1Error {
# //! fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# //! match self {
# //! Func1Error::Func2 => write!(f, " func1 error calling func2" ),
# //! Func1Error::IO(filename) => write!(f, " Error reading '{}'" , filename),
# //! }
# //! }
# //! }
# //!
# //! impl ::std::fmt::Debug for Func1Error {
# //! fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# //! write!(f, " {}" , self)
# //! }
# //! }
# //!
# //! fn func1() -> ChainResult< (), Func1Error> {
# //! func2().map_err(|e| cherr!(e, Func1Error::Func2))?;
# //! let filename = String::from(" bar.txt" );
# //! do_some_io().map_err(|e| cherr!(e, Func1Error::IO(filename)))?;
# //! Ok(())
# //! }
# //!
# //! fn main() {
# //! if let Err(e) = func1() {
# //! assert!(
# //! match e.kind() {
# //! Func1Error::Func2 => {
# //! eprintln!(" Main Error Report: func1 error calling func2" );
# //! true
# //! }
# //! Func1Error::IO(filename) => {
# //! eprintln!(" Main Error Report: func1 error reading '{}'" , filename);
# //! false
# //! }
# //! }
# //! );
# //!
# //! assert!(e.find_chain_cause::< Func2Error> ().is_some());
# //!
# //! if let Some(e) = e.find_chain_cause::< Func2Error> () {
# //! eprintln!(" \nError reported by Func2Error: {}" , e)
# //! }
# //!
# //!
# //! assert!(e.root_cause().is_some());
# //!
# //! if let Some(e) = e.root_cause() {
# //! let ioerror = e.downcast_ref::< io::Error> ().unwrap();
# //! eprintln!(" \nThe root cause was: std::io::Error: {:#?}" , ioerror);
# //! }
# //!
# //! #[cfg(not(windows))]
# //! assert_eq!(
# //! format!(" \n{:?}\n" , e), r#"
# //! src/lib.rs:47: func1 error calling func2
# //! Caused by:
# //! src/lib.rs:22: Func2Error(func2 error: calling func3)
# //! Caused by:
# //! src/lib.rs:15: Error reading 'foo.txt'
# //! Caused by:
# //! Kind(NotFound)
# //! " #
# //! );
# //! }
# //! # else {
# //! # unreachable!();
# //! # }
# //! }
# //! ~~~
2018-12-21 13:55:46 +01:00
#
# use std::any::TypeId;
2018-12-20 14:55:19 +01:00
# use std::error::Error;
# use std::fmt::{Debug, Display, Formatter, Result};
#
2019-02-07 09:02:01 +01:00
# /// chains an inner error kind `T` with a causing error
2018-12-20 14:55:19 +01:00
# pub struct ChainError< T> {
# #[cfg(not(feature = " no-fileline" ))]
# occurrence: Option< (u32, & 'static str)> ,
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# }
#
2018-12-21 13:55:46 +01:00
# /// convenience type alias
# pub type ChainResult< O, E> = std::result::Result< O, ChainError< E> > ;
2018-12-20 14:55:19 +01:00
#
# impl< T: 'static + Display + Debug> ChainError< T> {
# #[cfg(not(feature = " no-fileline" ))]
2018-12-21 13:55:46 +01:00
# /// Use the `cherr!()` or `mstrerr!()` macro instead of calling this directly
2018-12-20 14:55:19 +01:00
# pub fn new(
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# occurrence: Option< (u32, & 'static str)> ,
# ) -> Self {
# Self {
# occurrence,
# kind,
# error_cause,
# }
# }
#
# #[cfg(feature = " no-fileline" )]
2018-12-21 13:55:46 +01:00
# /// Use the `cherr!()` or `mstrerr!()` macro instead of calling this directly
2018-12-20 14:55:19 +01:00
# pub fn new(
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# _occurrence: Option< (u32, & 'static str)> ,
# ) -> Self {
# Self { kind, error_cause }
# }
#
2018-12-21 13:55:46 +01:00
# /// return the root cause of the error chain, if any exists
2018-12-20 14:55:19 +01:00
# pub fn root_cause(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.iter().last()
# }
#
# /// Find the first error cause of type U, if any exists
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// fn do_some_io() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# ///
# /// fn main() {
# /// if let Err(e) = func1() {
# /// if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# ///
# /// assert!(f1err.find_cause::< io::Error> ().is_some());
# ///
# /// assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// }
# /// # else {
# /// # panic!();
# /// # }
# /// }
# /// # else {
# /// # unreachable!();
# /// # }
# /// }
# /// ~~~
2018-12-20 14:55:19 +01:00
# pub fn find_cause< U: Error + 'static> (& self) -> Option< & U> {
2019-02-07 09:02:01 +01:00
# self.iter().filter_map(Error::downcast_ref::< U> ).next()
# }
#
# /// Find the first error cause of type `ChainError< U> `, if any exists
# ///
# /// Same as `find_cause`, but hides the `ChainError< U> ` implementation internals
# ///
# /// # Examples
# ///
# /// ~~~rust,ignore
# /// // Instead of writing
# /// err.find_cause::< ChainError< FooError> > ();
# ///
# /// // leave out the ChainError< FooError> implementation detail
# /// err.find_chain_cause::< FooError> ();
# /// ~~~
2018-12-20 14:55:19 +01:00
# pub fn find_chain_cause< U: Error + 'static> (& self) -> Option< & ChainError< U> > {
2019-02-07 09:02:01 +01:00
# self.iter()
# .filter_map(Error::downcast_ref::< ChainError< U> > )
# .next()
# }
#
# /// Find the first error cause of type `ChainError< U> ` or `U`, if any exists and return `U`
# ///
# /// Same as `find_cause` and `find_chain_cause`, but hides the `ChainError< U> ` implementation internals
# ///
# /// # Examples
# ///
# /// ~~~rust,ignore
# /// // Instead of writing
# /// err.find_cause::< ChainError< FooErrorKind> > ();
# /// // and/or
# /// err.find_chain_cause::< FooErrorKind> ();
# /// // and/or
# /// err.find_cause::< FooErrorKind> ();
# ///
# /// // leave out the ChainError< FooErrorKind> implementation detail
# /// err.find_chain_or_kind::< FooErrorKind> ();
# /// ~~~
# pub fn find_kind_or_cause< U: Error + 'static> (& self) -> Option< & U> {
# self.iter()
# .filter_map(|e| {
# e.downcast_ref::< ChainError< U> > ()
# .map(|e| e.kind())
# .or_else(|| e.downcast_ref::< U> ())
# })
# .next()
# }
#
# /// Return a reference to T of `ChainError< T> `
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// fn do_some_io() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// #[derive(Debug)]
# /// enum Func1ErrorKind {
# /// Func2,
# /// IO(String),
# /// }
# ///
# /// /// impl ::std::fmt::Display for Func1ErrorKind {…}
# /// # impl ::std::fmt::Display for Func1ErrorKind {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # Func1ErrorKind::Func2 => write!(f, " func1 error calling func2" ),
# /// # Func1ErrorKind::IO(filename) => write!(f, " Error reading '{}'" , filename),
# /// # }
# /// # }
# /// # }
# ///
# /// fn func1() -> ChainResult< (), Func1ErrorKind> {
# /// func2().map_err(|e| cherr!(e, Func1ErrorKind::Func2))?;
# /// do_some_io().map_err(|e| cherr!(e, Func1ErrorKind::IO(" bar.txt" .into())))?;
# /// Ok(())
# /// }
# ///
# /// fn main() {
# /// if let Err(e) = func1() {
# /// match e.kind() {
# /// Func1ErrorKind::Func2 => {},
# /// Func1ErrorKind::IO(filename) => panic!(),
# /// }
# /// }
# /// # else {
# /// # unreachable!();
# /// # }
# /// }
# /// ~~~
# pub fn kind(& self) -> & T {
# & self.kind
2018-12-21 13:55:46 +01:00
# }
#
2019-02-07 09:02:01 +01:00
# /// Returns an Iterator over all error causes/sources
# ///
# /// # Example
# ///
# ///
# pub fn iter(& self) -> impl Iterator< Item = & (dyn Error + 'static)> {
# ErrorIter {
# current: Some(self),
# }
2018-12-21 13:55:46 +01:00
# }
2019-02-07 09:02:01 +01:00
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# struct ErrorIter< 'a> {
# current: Option< & 'a (dyn Error + 'static)> ,
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# impl< 'a> Iterator for ErrorIter< 'a> {
# type Item = & 'a (dyn Error + 'static);
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# fn next(& mut self) -> Option< Self::Item> {
# let current = self.current;
# self.current = self.current.and_then(Error::source);
# current
2018-12-21 13:55:46 +01:00
# }
2019-02-07 09:02:01 +01:00
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# impl< T: 'static + Display + Debug> std::ops::Deref for ChainError< T> {
# type Target = T;
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# fn deref(& self) -> & Self::Target {
2018-12-20 14:55:19 +01:00
# & self.kind
# }
# }
#
2019-02-07 09:02:01 +01:00
# /// Convenience trait to hide the `ChainError< T> ` implementation internals
2018-12-20 14:55:19 +01:00
# pub trait ChainErrorDown {
2019-02-07 09:02:01 +01:00
# /// Test if of type `ChainError< T> `
2018-12-20 14:55:19 +01:00
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool;
2019-02-07 09:02:01 +01:00
# /// Downcast to a reference of `ChainError< T> `
2018-12-20 14:55:19 +01:00
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > ;
2019-02-07 09:02:01 +01:00
# /// Downcast to a mutable reference of `ChainError< T> `
2018-12-20 14:55:19 +01:00
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > ;
# }
#
# impl< U: 'static + Display + Debug> ChainErrorDown for ChainError< U> {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# TypeId::of::< T> () == TypeId::of::< U> ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# if self.is_chain::< T> () {
2019-02-07 09:02:01 +01:00
# #[allow(clippy::cast_ptr_alignment)]
# unsafe {
# Some(& *(self as *const dyn Error as *const & ChainError< T> ))
# }
2018-12-20 14:55:19 +01:00
# } else {
# None
# }
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# if self.is_chain::< T> () {
2019-02-07 09:02:01 +01:00
# #[allow(clippy::cast_ptr_alignment)]
# unsafe {
# Some(& mut *(self as *mut dyn Error as *mut & mut ChainError< T> ))
# }
2018-12-20 14:55:19 +01:00
# } else {
# None
# }
# }
# }
#
# impl ChainErrorDown for dyn Error + 'static {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl ChainErrorDown for dyn Error + 'static + Send {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl ChainErrorDown for dyn Error + 'static + Send + Sync {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl< T: 'static + Display + Debug> Error for ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.error_cause.as_ref().map(|e| e.as_ref())
2018-12-20 14:55:19 +01:00
# }
# }
#
# impl< T: 'static + Display + Debug> Error for & ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.error_cause.as_ref().map(|e| e.as_ref())
2018-12-20 14:55:19 +01:00
# }
# }
#
# impl< T: 'static + Display + Debug> Error for & mut ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.error_cause.as_ref().map(|e| e.as_ref())
2018-12-20 14:55:19 +01:00
# }
# }
#
# impl< T: 'static + Display + Debug> Display for ChainError< T> {
# fn fmt(& self, f: & mut Formatter) -> Result {
# write!(f, " {}" , self.kind)?;
#
# #[cfg(feature = " display-cause" )]
# {
# if let Some(e) = self.source() {
# writeln!(f, " \nCaused by:" )?;
# Display::fmt(& e, f)?;
# }
# }
# Ok(())
# }
# }
#
# impl< T: 'static + Display + Debug> Debug for ChainError< T> {
# fn fmt(& self, f: & mut Formatter) -> Result {
# #[cfg(not(feature = " no-fileline" ))]
# {
# if let Some(o) = self.occurrence {
# write!(f, " {}:{}: " , o.1, o.0)?;
# }
# }
#
2018-12-21 13:55:46 +01:00
# if self.is_chain::< String> () {
# Display::fmt(& self.kind, f)?;
# } else {
# Debug::fmt(& self.kind, f)?;
# }
2018-12-20 14:55:19 +01:00
#
# #[cfg(not(feature = " no-debug-cause" ))]
# {
# if let Some(e) = self.source() {
# writeln!(f, " \nCaused by:" )?;
# Debug::fmt(& e, f)?;
# }
# }
# Ok(())
# }
# }
#
2019-02-07 09:02:01 +01:00
# pub trait ChainErrorFrom< T> : Sized {
# fn chain_error_from(_: T, line_filename: Option< (u32, & 'static str)> ) -> ChainError< Self> ;
# }
#
# pub trait IntoChainError< T> : Sized {
# fn into_chain_error(self, line_filename: Option< (u32, & 'static str)> ) -> ChainError< T> ;
# }
#
# impl< T, U> IntoChainError< U> for T
# where
# U: ChainErrorFrom< T> ,
# {
# fn into_chain_error(self, line_filename: Option< (u32, & 'static str)> ) -> ChainError< U> {
# U::chain_error_from(self, line_filename)
# }
# }
#
# impl< T, U> ChainErrorFrom< T> for U
# where
# T: Into< U> ,
# U: 'static + Display + Debug,
# {
# fn chain_error_from(t: T, line_filename: Option< (u32, & 'static str)> ) -> ChainError< Self> {
# let e: U = t.into();
# ChainError::< _> ::new(e, None, line_filename)
# }
# }
#
2018-12-20 14:55:19 +01:00
# #[macro_export]
2019-02-07 09:02:01 +01:00
# macro_rules! minto_cherr {
# ( ) => {
# |e| e.into_chain_error(Some((line!(), file!())))
2018-12-20 14:55:19 +01:00
# };
# }
#
# #[macro_export]
2019-02-07 09:02:01 +01:00
# macro_rules! into_cherr {
# ( $t:expr ) => {
# $t.into_chain_error(Some((line!(), file!())))
2018-12-20 14:55:19 +01:00
# };
# }
#
2019-02-07 09:02:01 +01:00
# /// Creates a new `ChainError< T> `
# ///
# /// # Examples
# ///
# /// Create a new ChainError< FooError> , where `FooError` must implement `Display` and `Debug`.
# /// ~~~rust
# /// # use chainerror::*;
# /// #
# /// # #[derive(Debug)]
# /// enum FooError {
# /// Bar,
# /// Baz(& 'static str),
# /// }
# /// #
# /// # impl ::std::fmt::Display for FooError {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # FooError::Bar => write!(f, " Bar Error" ),
# /// # FooError::Baz(s) => write!(f, " Baz Error: '{}'" , s),
# /// # }
# /// # }
# /// # }
# ///
# /// // impl ::std::fmt::Display for FooError
# ///
# /// fn do_some_stuff() -> bool {
# /// false
# /// }
# ///
# /// fn func() -> ChainResult< (), FooError> {
# /// if ! do_some_stuff() {
# /// Err(cherr!(FooError::Baz(" Error" )))?;
# /// }
# /// Ok(())
# /// }
# /// #
# /// # pub fn main() {
# /// # match func().unwrap_err().kind() {
# /// # FooError::Baz(s) if s == & " Error" => {},
# /// # _ => panic!(),
# /// # }
# /// # }
# /// ~~~
# ///
# /// Additionally an error cause can be added.
# ///
# /// ~~~rust
# /// # use chainerror::*;
# /// # use std::io;
# /// # use std::error::Error;
# /// #
# /// # #[derive(Debug)]
# /// # enum FooError {
# /// # Bar,
# /// # Baz(& 'static str),
# /// # }
# /// #
# /// # impl ::std::fmt::Display for FooError {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # FooError::Bar => write!(f, " Bar Error" ),
# /// # FooError::Baz(s) => write!(f, " Baz Error: '{}'" , s),
# /// # }
# /// # }
# /// # }
# /// #
# /// fn do_some_stuff() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// fn func() -> ChainResult< (), FooError> {
# /// do_some_stuff().map_err(
# /// |e| cherr!(e, FooError::Baz(" Error" ))
# /// )?;
# /// Ok(())
# /// }
# /// #
# /// # pub fn main() {
# /// # match func().unwrap_err().kind() {
# /// # FooError::Baz(s) if s == & " Error" => {},
# /// # _ => panic!(),
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! cherr {
# ( $k:expr ) => ({
# ChainError::< _> ::new($k, None, Some((line!(), file!())))
# });
# ( None, $k:expr ) => ({
# ChainError::< _> ::new($k, None, Some((line!(), file!())))
# });
# ( None, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!(None, format!($fmt, $($arg)+ ))
# });
# ( None, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!(None, format!($fmt, $($arg)+ ))
# });
# ( $e:path, $k:expr ) => ({
# ChainError::< _> ::new($k, Some(Box::from($e)), Some((line!(), file!())))
# });
# ( $e:path, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!($e, format!($fmt, $($arg)+ ))
# });
#
# }
#
# /// Convenience macro for `|e| cherr!(e, format!(…))`
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(" func1 error" ))?;
# /// Ok(())
# /// }
# ///
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # #[cfg(not(windows))]
# /// # assert_eq!(
# /// # format!(" \n{:?}\n" , e), r#"
# /// # src/lib.rs:20: func1 error
# /// # Caused by:
# /// # src/lib.rs:15: Error reading 'foo.txt'
# /// # Caused by:
# /// # Kind(NotFound)
# /// # " #
# /// # );
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# ///
# /// `mstrerr!()` can also be used to map a new `ChainError< T> `, where T was defined with
# /// `derive_str_cherr!(T)`
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! mstrerr {
# ( $t:path, $msg:expr ) => ({
# |e| cherr!(e, $t ($msg.to_string()))
# });
# ( $t:path, $msg:expr, ) => ({
# |e| cherr!(e, $t ($msg.to_string()))
# });
# ( $t:path, $fmt:expr, $($arg:tt)+ ) => ({
# |e| cherr!(e, $t (format!($fmt, $($arg)+ )))
# });
# ($msg:expr) => ({
# |e| cherr!(e, $msg.to_string())
# });
# ($msg:expr, ) => ({
# |e| cherr!(e, $msg.to_string())
# });
# ($fmt:expr, $($arg:tt)+) => ({
# |e| cherr!(e, format!($fmt, $($arg)+ ))
# });
# }
#
# /// Convenience macro for `cherr!(T(format!(…)))` where `T(String)`
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::result::Result;
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> ChainResult< (), Func2Error> {
# /// let filename = " foo.txt" ;
# /// Err(strerr!(Func2Error, " Error reading '{}'" , filename))
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! strerr {
# ( $t:path, $msg:expr ) => ({
# cherr!($t ($msg.to_string()))
# });
# ( $t:path, $msg:expr, ) => ({
# cherr!($t ($msg.to_string()))
# });
# ( $t:path, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!($t (format!($fmt, $($arg)+ )))
# });
# ($msg:expr) => ({
# cherr!($msg.to_string())
# });
# ($msg:expr, ) => ({
# cherr!($msg.to_string())
# });
# ($fmt:expr, $($arg:tt)+) => ({
# cherr!(format!($fmt, $($arg)+ ))
# });
# }
#
# /// Convenience macro to create a " new type" T(String) and implement Display + Debug for T
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> ChainResult< (), Func2Error> {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
2018-12-20 14:55:19 +01:00
# #[macro_export]
# macro_rules! derive_str_cherr {
# ($e:ident) => {
2019-02-07 09:02:01 +01:00
# pub struct $e(pub String);
2018-12-20 14:55:19 +01:00
# impl ::std::fmt::Display for $e {
# fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# write!(f, " {}" , self.0)
# }
# }
# impl ::std::fmt::Debug for $e {
# fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# write!(f, " {}({})" , stringify!($e), self.0)
# }
# }
# impl ::std::error::Error for $e {}
# };
# }
# }
< / code > < / pre > < / pre >
2018-12-21 13:55:46 +01:00
< p > Note, that because we changed the output of the error in < code > main()< / code > from
< code > Debug< / code > to < code > Display< / code > , we don't see the error backtrace with filename and line number.< / p >
2018-12-20 16:02:24 +01:00
< p > To enable the < code > Display< / code > backtrace, you have to enable the feature < code > display-cause< / code > for < code > chainerror< / code > .< / p >
2018-12-20 16:37:43 +01:00
< a class = "header" href = "#downcast-the-errors" id = "downcast-the-errors" > < h1 > Downcast the Errors< / h1 > < / a >
2018-12-21 13:55:46 +01:00
< p > < code > std::error::Error< / code > comes with some helper methods to get to the original object of the
< code > & (dyn Error + 'static)< / code > returned by < code > .source()< / code > .< / p >
< pre > < code class = "language-rust ignore" > pub fn downcast_ref< T: Error + 'static> (& self) -> Option< & T>
pub fn downcast_mut< T: Error + 'static> (& mut self) -> Option< & mut T>
< / code > < / pre >
< p > This is how it looks like, when using those:< / p >
2019-03-04 11:46:17 +01:00
< pre > < pre class = "playpen" > < code class = "language-rust" > use chainerror::*;
2018-12-20 14:55:19 +01:00
use std::error::Error;
use std::io;
use std::result::Result;
fn do_some_io() -> Result< (), Box< Error> > {
Err(io::Error::from(io::ErrorKind::NotFound))?;
Ok(())
}
fn func2() -> Result< (), Box< Error> > {
let filename = " foo.txt" ;
do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
Ok(())
}
fn func1() -> Result< (), Box< Error> > {
func2().map_err(mstrerr!(" func1 error" ))?;
Ok(())
}
fn main() -> Result< (), Box< Error> > {
if let Err(e) = func1() {
eprintln!(" Error: {}" , e);
let mut s = e.as_ref();
while let Some(c) = s.source() {
if let Some(ioerror) = c.downcast_ref::< io::Error> () {
eprintln!(" caused by: std::io::Error: {}" , ioerror);
match ioerror.kind() {
io::ErrorKind::NotFound => eprintln!(" of kind: std::io::ErrorKind::NotFound" ),
_ => {}
}
} else {
eprintln!(" caused by: {}" , c);
}
s = c;
}
}
Ok(())
}
2019-03-04 11:46:17 +01:00
2018-12-20 14:55:19 +01:00
# #[allow(dead_code)]
# mod chainerror {
2019-02-07 09:02:01 +01:00
# //! `chainerror` provides an error backtrace without doing a real backtrace, so even after you `strip` your
# //! binaries, you still have the error backtrace.
# //!
# //! `chainerror` has no dependencies!
# //!
# //! `chainerror` uses `.source()` of `std::error::Error` along with `line()!` and `file()!` to provide a nice debug error backtrace.
# //! It encapsulates all types, which have `Display + Debug` and can store the error cause internally.
# //!
# //! Along with the `ChainError< T> ` struct, `chainerror` comes with some useful helper macros to save a lot of typing.
# //!
# //! ## Features
# //!
# //! `no-fileline`
# //! : completely turn off storing filename and line
# //!
# //! `display-cause`
# //! : turn on printing a backtrace of the errors in `Display`
# //!
# //! `no-debug-cause`
# //! : turn off printing a backtrace of the errors in `Debug`
# //!
# //!
# //! # Tutorial
# //!
# //! Read the [Tutorial](https://haraldh.github.io/chainerror/tutorial1.html)
# //!
# //! # Examples
# //!
# //! ~~~rust
# //! use chainerror::*;
# //! use std::error::Error;
# //! use std::io;
# //! use std::result::Result;
# //!
# //! fn do_some_io() -> Result< (), Box< Error> > {
# //! Err(io::Error::from(io::ErrorKind::NotFound))?;
# //! Ok(())
# //! }
# //!
# //! fn func2() -> Result< (), Box< Error> > {
# //! let filename = " foo.txt" ;
# //! do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# //! Ok(())
# //! }
# //!
# //! fn func1() -> Result< (), Box< Error> > {
# //! func2().map_err(mstrerr!(" func1 error" ))?;
# //! Ok(())
# //! }
# //!
# //! fn main() {
# //! if let Err(e) = func1() {
# //! #[cfg(not(windows))]
# //! assert_eq!(
# //! format!(" \n{:?}\n" , e), r#"
# //! src/lib.rs:20: func1 error
# //! Caused by:
# //! src/lib.rs:15: Error reading 'foo.txt'
# //! Caused by:
# //! Kind(NotFound)
# //! " #
# //! );
# //! }
# //! # else {
# //! # unreachable!();
# //! # }
# //! }
# //! ~~~
# //!
# //!
# //! ~~~rust
# //! use chainerror::*;
# //! use std::error::Error;
# //! use std::io;
# //! use std::result::Result;
# //!
# //! fn do_some_io() -> Result< (), Box< Error> > {
# //! Err(io::Error::from(io::ErrorKind::NotFound))?;
# //! Ok(())
# //! }
# //!
# //! fn func3() -> Result< (), Box< Error> > {
# //! let filename = " foo.txt" ;
# //! do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# //! Ok(())
# //! }
# //!
# //! derive_str_cherr!(Func2Error);
# //!
# //! fn func2() -> ChainResult< (), Func2Error> {
# //! func3().map_err(mstrerr!(Func2Error, " func2 error: calling func3" ))?;
# //! Ok(())
# //! }
# //!
# //! enum Func1Error {
# //! Func2,
# //! IO(String),
# //! }
# //!
# //! impl ::std::fmt::Display for Func1Error {
# //! fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# //! match self {
# //! Func1Error::Func2 => write!(f, " func1 error calling func2" ),
# //! Func1Error::IO(filename) => write!(f, " Error reading '{}'" , filename),
# //! }
# //! }
# //! }
# //!
# //! impl ::std::fmt::Debug for Func1Error {
# //! fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# //! write!(f, " {}" , self)
# //! }
# //! }
# //!
# //! fn func1() -> ChainResult< (), Func1Error> {
# //! func2().map_err(|e| cherr!(e, Func1Error::Func2))?;
# //! let filename = String::from(" bar.txt" );
# //! do_some_io().map_err(|e| cherr!(e, Func1Error::IO(filename)))?;
# //! Ok(())
# //! }
# //!
# //! fn main() {
# //! if let Err(e) = func1() {
# //! assert!(
# //! match e.kind() {
# //! Func1Error::Func2 => {
# //! eprintln!(" Main Error Report: func1 error calling func2" );
# //! true
# //! }
# //! Func1Error::IO(filename) => {
# //! eprintln!(" Main Error Report: func1 error reading '{}'" , filename);
# //! false
# //! }
# //! }
# //! );
# //!
# //! assert!(e.find_chain_cause::< Func2Error> ().is_some());
# //!
# //! if let Some(e) = e.find_chain_cause::< Func2Error> () {
# //! eprintln!(" \nError reported by Func2Error: {}" , e)
# //! }
# //!
# //!
# //! assert!(e.root_cause().is_some());
# //!
# //! if let Some(e) = e.root_cause() {
# //! let ioerror = e.downcast_ref::< io::Error> ().unwrap();
# //! eprintln!(" \nThe root cause was: std::io::Error: {:#?}" , ioerror);
# //! }
# //!
# //! #[cfg(not(windows))]
# //! assert_eq!(
# //! format!(" \n{:?}\n" , e), r#"
# //! src/lib.rs:47: func1 error calling func2
# //! Caused by:
# //! src/lib.rs:22: Func2Error(func2 error: calling func3)
# //! Caused by:
# //! src/lib.rs:15: Error reading 'foo.txt'
# //! Caused by:
# //! Kind(NotFound)
# //! " #
# //! );
# //! }
# //! # else {
# //! # unreachable!();
# //! # }
# //! }
# //! ~~~
2018-12-21 13:55:46 +01:00
#
# use std::any::TypeId;
2018-12-20 14:55:19 +01:00
# use std::error::Error;
# use std::fmt::{Debug, Display, Formatter, Result};
#
2019-02-07 09:02:01 +01:00
# /// chains an inner error kind `T` with a causing error
2018-12-20 14:55:19 +01:00
# pub struct ChainError< T> {
# #[cfg(not(feature = " no-fileline" ))]
# occurrence: Option< (u32, & 'static str)> ,
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# }
#
2018-12-21 13:55:46 +01:00
# /// convenience type alias
# pub type ChainResult< O, E> = std::result::Result< O, ChainError< E> > ;
2018-12-20 14:55:19 +01:00
#
# impl< T: 'static + Display + Debug> ChainError< T> {
# #[cfg(not(feature = " no-fileline" ))]
2018-12-21 13:55:46 +01:00
# /// Use the `cherr!()` or `mstrerr!()` macro instead of calling this directly
2018-12-20 14:55:19 +01:00
# pub fn new(
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# occurrence: Option< (u32, & 'static str)> ,
# ) -> Self {
# Self {
# occurrence,
# kind,
# error_cause,
# }
# }
#
# #[cfg(feature = " no-fileline" )]
2018-12-21 13:55:46 +01:00
# /// Use the `cherr!()` or `mstrerr!()` macro instead of calling this directly
2018-12-20 14:55:19 +01:00
# pub fn new(
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# _occurrence: Option< (u32, & 'static str)> ,
# ) -> Self {
# Self { kind, error_cause }
# }
#
2018-12-21 13:55:46 +01:00
# /// return the root cause of the error chain, if any exists
2018-12-20 14:55:19 +01:00
# pub fn root_cause(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.iter().last()
# }
#
# /// Find the first error cause of type U, if any exists
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// fn do_some_io() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# ///
# /// fn main() {
# /// if let Err(e) = func1() {
# /// if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# ///
# /// assert!(f1err.find_cause::< io::Error> ().is_some());
# ///
# /// assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// }
# /// # else {
# /// # panic!();
# /// # }
# /// }
# /// # else {
# /// # unreachable!();
# /// # }
# /// }
# /// ~~~
# pub fn find_cause< U: Error + 'static> (& self) -> Option< & U> {
# self.iter().filter_map(Error::downcast_ref::< U> ).next()
# }
#
# /// Find the first error cause of type `ChainError< U> `, if any exists
# ///
# /// Same as `find_cause`, but hides the `ChainError< U> ` implementation internals
# ///
# /// # Examples
# ///
# /// ~~~rust,ignore
# /// // Instead of writing
# /// err.find_cause::< ChainError< FooError> > ();
# ///
# /// // leave out the ChainError< FooError> implementation detail
# /// err.find_chain_cause::< FooError> ();
# /// ~~~
# pub fn find_chain_cause< U: Error + 'static> (& self) -> Option< & ChainError< U> > {
# self.iter()
# .filter_map(Error::downcast_ref::< ChainError< U> > )
# .next()
# }
#
# /// Find the first error cause of type `ChainError< U> ` or `U`, if any exists and return `U`
# ///
# /// Same as `find_cause` and `find_chain_cause`, but hides the `ChainError< U> ` implementation internals
# ///
# /// # Examples
# ///
# /// ~~~rust,ignore
# /// // Instead of writing
# /// err.find_cause::< ChainError< FooErrorKind> > ();
# /// // and/or
# /// err.find_chain_cause::< FooErrorKind> ();
# /// // and/or
# /// err.find_cause::< FooErrorKind> ();
# ///
# /// // leave out the ChainError< FooErrorKind> implementation detail
# /// err.find_chain_or_kind::< FooErrorKind> ();
# /// ~~~
# pub fn find_kind_or_cause< U: Error + 'static> (& self) -> Option< & U> {
# self.iter()
# .filter_map(|e| {
# e.downcast_ref::< ChainError< U> > ()
# .map(|e| e.kind())
# .or_else(|| e.downcast_ref::< U> ())
# })
# .next()
# }
#
# /// Return a reference to T of `ChainError< T> `
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// fn do_some_io() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// #[derive(Debug)]
# /// enum Func1ErrorKind {
# /// Func2,
# /// IO(String),
# /// }
# ///
# /// /// impl ::std::fmt::Display for Func1ErrorKind {…}
# /// # impl ::std::fmt::Display for Func1ErrorKind {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # Func1ErrorKind::Func2 => write!(f, " func1 error calling func2" ),
# /// # Func1ErrorKind::IO(filename) => write!(f, " Error reading '{}'" , filename),
# /// # }
# /// # }
# /// # }
# ///
# /// fn func1() -> ChainResult< (), Func1ErrorKind> {
# /// func2().map_err(|e| cherr!(e, Func1ErrorKind::Func2))?;
# /// do_some_io().map_err(|e| cherr!(e, Func1ErrorKind::IO(" bar.txt" .into())))?;
# /// Ok(())
# /// }
# ///
# /// fn main() {
# /// if let Err(e) = func1() {
# /// match e.kind() {
# /// Func1ErrorKind::Func2 => {},
# /// Func1ErrorKind::IO(filename) => panic!(),
# /// }
# /// }
# /// # else {
# /// # unreachable!();
# /// # }
# /// }
# /// ~~~
# pub fn kind(& self) -> & T {
# & self.kind
# }
#
# /// Returns an Iterator over all error causes/sources
# ///
# /// # Example
# ///
# ///
# pub fn iter(& self) -> impl Iterator< Item = & (dyn Error + 'static)> {
# ErrorIter {
# current: Some(self),
2018-12-20 14:55:19 +01:00
# }
# }
2019-02-07 09:02:01 +01:00
# }
2018-12-20 14:55:19 +01:00
#
2019-02-07 09:02:01 +01:00
# struct ErrorIter< 'a> {
# current: Option< & 'a (dyn Error + 'static)> ,
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# impl< 'a> Iterator for ErrorIter< 'a> {
# type Item = & 'a (dyn Error + 'static);
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# fn next(& mut self) -> Option< Self::Item> {
# let current = self.current;
# self.current = self.current.and_then(Error::source);
# current
2018-12-21 13:55:46 +01:00
# }
2019-02-07 09:02:01 +01:00
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# impl< T: 'static + Display + Debug> std::ops::Deref for ChainError< T> {
# type Target = T;
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# fn deref(& self) -> & Self::Target {
# & self.kind
2018-12-21 13:55:46 +01:00
# }
2019-02-07 09:02:01 +01:00
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# /// Convenience trait to hide the `ChainError< T> ` implementation internals
# pub trait ChainErrorDown {
# /// Test if of type `ChainError< T> `
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool;
# /// Downcast to a reference of `ChainError< T> `
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > ;
# /// Downcast to a mutable reference of `ChainError< T> `
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > ;
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# impl< U: 'static + Display + Debug> ChainErrorDown for ChainError< U> {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# TypeId::of::< T> () == TypeId::of::< U> ()
2018-12-21 13:55:46 +01:00
# }
#
2019-02-07 09:02:01 +01:00
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# if self.is_chain::< T> () {
# #[allow(clippy::cast_ptr_alignment)]
# unsafe {
# Some(& *(self as *const dyn Error as *const & ChainError< T> ))
2018-12-21 13:55:46 +01:00
# }
2019-02-07 09:02:01 +01:00
# } else {
# None
2018-12-21 13:55:46 +01:00
# }
# }
2018-12-20 14:55:19 +01:00
#
2019-02-07 09:02:01 +01:00
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# if self.is_chain::< T> () {
# #[allow(clippy::cast_ptr_alignment)]
# unsafe {
# Some(& mut *(self as *mut dyn Error as *mut & mut ChainError< T> ))
2018-12-20 14:55:19 +01:00
# }
2019-02-07 09:02:01 +01:00
# } else {
# None
2018-12-20 14:55:19 +01:00
# }
# }
2019-02-07 09:02:01 +01:00
# }
2018-12-20 14:55:19 +01:00
#
2019-02-07 09:02:01 +01:00
# impl ChainErrorDown for dyn Error + 'static {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
2018-12-20 14:55:19 +01:00
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl ChainErrorDown for dyn Error + 'static + Send {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl ChainErrorDown for dyn Error + 'static + Send + Sync {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl< T: 'static + Display + Debug> Error for ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.error_cause.as_ref().map(|e| e.as_ref())
2018-12-20 14:55:19 +01:00
# }
# }
#
# impl< T: 'static + Display + Debug> Error for & ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.error_cause.as_ref().map(|e| e.as_ref())
2018-12-20 14:55:19 +01:00
# }
# }
#
# impl< T: 'static + Display + Debug> Error for & mut ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.error_cause.as_ref().map(|e| e.as_ref())
2018-12-20 14:55:19 +01:00
# }
# }
#
# impl< T: 'static + Display + Debug> Display for ChainError< T> {
# fn fmt(& self, f: & mut Formatter) -> Result {
# write!(f, " {}" , self.kind)?;
#
# #[cfg(feature = " display-cause" )]
# {
# if let Some(e) = self.source() {
# writeln!(f, " \nCaused by:" )?;
# Display::fmt(& e, f)?;
# }
# }
# Ok(())
# }
# }
#
# impl< T: 'static + Display + Debug> Debug for ChainError< T> {
# fn fmt(& self, f: & mut Formatter) -> Result {
# #[cfg(not(feature = " no-fileline" ))]
# {
# if let Some(o) = self.occurrence {
# write!(f, " {}:{}: " , o.1, o.0)?;
# }
# }
#
2018-12-21 13:55:46 +01:00
# if self.is_chain::< String> () {
# Display::fmt(& self.kind, f)?;
# } else {
# Debug::fmt(& self.kind, f)?;
# }
2018-12-20 14:55:19 +01:00
#
# #[cfg(not(feature = " no-debug-cause" ))]
# {
# if let Some(e) = self.source() {
# writeln!(f, " \nCaused by:" )?;
# Debug::fmt(& e, f)?;
# }
# }
# Ok(())
# }
# }
#
2019-02-07 09:02:01 +01:00
# pub trait ChainErrorFrom< T> : Sized {
# fn chain_error_from(_: T, line_filename: Option< (u32, & 'static str)> ) -> ChainError< Self> ;
# }
#
# pub trait IntoChainError< T> : Sized {
# fn into_chain_error(self, line_filename: Option< (u32, & 'static str)> ) -> ChainError< T> ;
# }
#
# impl< T, U> IntoChainError< U> for T
# where
# U: ChainErrorFrom< T> ,
# {
# fn into_chain_error(self, line_filename: Option< (u32, & 'static str)> ) -> ChainError< U> {
# U::chain_error_from(self, line_filename)
# }
# }
#
# impl< T, U> ChainErrorFrom< T> for U
# where
# T: Into< U> ,
# U: 'static + Display + Debug,
# {
# fn chain_error_from(t: T, line_filename: Option< (u32, & 'static str)> ) -> ChainError< Self> {
# let e: U = t.into();
# ChainError::< _> ::new(e, None, line_filename)
# }
# }
#
2018-12-20 14:55:19 +01:00
# #[macro_export]
2019-02-07 09:02:01 +01:00
# macro_rules! minto_cherr {
# ( ) => {
# |e| e.into_chain_error(Some((line!(), file!())))
2018-12-20 14:55:19 +01:00
# };
# }
#
# #[macro_export]
2019-02-07 09:02:01 +01:00
# macro_rules! into_cherr {
# ( $t:expr ) => {
# $t.into_chain_error(Some((line!(), file!())))
2018-12-20 14:55:19 +01:00
# };
# }
#
2019-02-07 09:02:01 +01:00
# /// Creates a new `ChainError< T> `
# ///
# /// # Examples
# ///
# /// Create a new ChainError< FooError> , where `FooError` must implement `Display` and `Debug`.
# /// ~~~rust
# /// # use chainerror::*;
# /// #
# /// # #[derive(Debug)]
# /// enum FooError {
# /// Bar,
# /// Baz(& 'static str),
# /// }
# /// #
# /// # impl ::std::fmt::Display for FooError {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # FooError::Bar => write!(f, " Bar Error" ),
# /// # FooError::Baz(s) => write!(f, " Baz Error: '{}'" , s),
# /// # }
# /// # }
# /// # }
# ///
# /// // impl ::std::fmt::Display for FooError
# ///
# /// fn do_some_stuff() -> bool {
# /// false
# /// }
# ///
# /// fn func() -> ChainResult< (), FooError> {
# /// if ! do_some_stuff() {
# /// Err(cherr!(FooError::Baz(" Error" )))?;
# /// }
# /// Ok(())
# /// }
# /// #
# /// # pub fn main() {
# /// # match func().unwrap_err().kind() {
# /// # FooError::Baz(s) if s == & " Error" => {},
# /// # _ => panic!(),
# /// # }
# /// # }
# /// ~~~
# ///
# /// Additionally an error cause can be added.
# ///
# /// ~~~rust
# /// # use chainerror::*;
# /// # use std::io;
# /// # use std::error::Error;
# /// #
# /// # #[derive(Debug)]
# /// # enum FooError {
# /// # Bar,
# /// # Baz(& 'static str),
# /// # }
# /// #
# /// # impl ::std::fmt::Display for FooError {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # FooError::Bar => write!(f, " Bar Error" ),
# /// # FooError::Baz(s) => write!(f, " Baz Error: '{}'" , s),
# /// # }
# /// # }
# /// # }
# /// #
# /// fn do_some_stuff() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// fn func() -> ChainResult< (), FooError> {
# /// do_some_stuff().map_err(
# /// |e| cherr!(e, FooError::Baz(" Error" ))
# /// )?;
# /// Ok(())
# /// }
# /// #
# /// # pub fn main() {
# /// # match func().unwrap_err().kind() {
# /// # FooError::Baz(s) if s == & " Error" => {},
# /// # _ => panic!(),
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! cherr {
# ( $k:expr ) => ({
# ChainError::< _> ::new($k, None, Some((line!(), file!())))
# });
# ( None, $k:expr ) => ({
# ChainError::< _> ::new($k, None, Some((line!(), file!())))
# });
# ( None, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!(None, format!($fmt, $($arg)+ ))
# });
# ( None, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!(None, format!($fmt, $($arg)+ ))
# });
# ( $e:path, $k:expr ) => ({
# ChainError::< _> ::new($k, Some(Box::from($e)), Some((line!(), file!())))
# });
# ( $e:path, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!($e, format!($fmt, $($arg)+ ))
# });
#
# }
#
# /// Convenience macro for `|e| cherr!(e, format!(…))`
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(" func1 error" ))?;
# /// Ok(())
# /// }
# ///
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # #[cfg(not(windows))]
# /// # assert_eq!(
# /// # format!(" \n{:?}\n" , e), r#"
# /// # src/lib.rs:20: func1 error
# /// # Caused by:
# /// # src/lib.rs:15: Error reading 'foo.txt'
# /// # Caused by:
# /// # Kind(NotFound)
# /// # " #
# /// # );
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# ///
# /// `mstrerr!()` can also be used to map a new `ChainError< T> `, where T was defined with
# /// `derive_str_cherr!(T)`
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! mstrerr {
# ( $t:path, $msg:expr ) => ({
# |e| cherr!(e, $t ($msg.to_string()))
# });
# ( $t:path, $msg:expr, ) => ({
# |e| cherr!(e, $t ($msg.to_string()))
# });
# ( $t:path, $fmt:expr, $($arg:tt)+ ) => ({
# |e| cherr!(e, $t (format!($fmt, $($arg)+ )))
# });
# ($msg:expr) => ({
# |e| cherr!(e, $msg.to_string())
# });
# ($msg:expr, ) => ({
# |e| cherr!(e, $msg.to_string())
# });
# ($fmt:expr, $($arg:tt)+) => ({
# |e| cherr!(e, format!($fmt, $($arg)+ ))
# });
# }
#
# /// Convenience macro for `cherr!(T(format!(…)))` where `T(String)`
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::result::Result;
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> ChainResult< (), Func2Error> {
# /// let filename = " foo.txt" ;
# /// Err(strerr!(Func2Error, " Error reading '{}'" , filename))
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! strerr {
# ( $t:path, $msg:expr ) => ({
# cherr!($t ($msg.to_string()))
# });
# ( $t:path, $msg:expr, ) => ({
# cherr!($t ($msg.to_string()))
# });
# ( $t:path, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!($t (format!($fmt, $($arg)+ )))
# });
# ($msg:expr) => ({
# cherr!($msg.to_string())
# });
# ($msg:expr, ) => ({
# cherr!($msg.to_string())
# });
# ($fmt:expr, $($arg:tt)+) => ({
# cherr!(format!($fmt, $($arg)+ ))
# });
# }
#
# /// Convenience macro to create a " new type" T(String) and implement Display + Debug for T
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> ChainResult< (), Func2Error> {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
2018-12-20 14:55:19 +01:00
# #[macro_export]
# macro_rules! derive_str_cherr {
# ($e:ident) => {
2019-02-07 09:02:01 +01:00
# pub struct $e(pub String);
2018-12-20 14:55:19 +01:00
# impl ::std::fmt::Display for $e {
# fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# write!(f, " {}" , self.0)
# }
# }
# impl ::std::fmt::Debug for $e {
# fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# write!(f, " {}({})" , stringify!($e), self.0)
# }
# }
# impl ::std::error::Error for $e {}
# };
# }
# }
< / code > < / pre > < / pre >
2018-12-20 16:37:43 +01:00
< a class = "header" href = "#the-root-cause-of-all-errors" id = "the-root-cause-of-all-errors" > < h1 > The root cause of all Errors< / h1 > < / a >
2018-12-21 13:55:46 +01:00
< p > < code > chainerror< / code > also has some helper methods:< / p >
< pre > < code class = "language-rust ignore" > fn is_chain< T: 'static + Display + Debug> (& self) -> bool
fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> >
fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> >
fn root_cause(& self) -> Option< & (dyn Error + 'static)>
fn find_cause< U: Error + 'static> (& self) -> Option< & U>
fn find_chain_cause< U: Error + 'static> (& self) -> Option< & ChainError< U> >
fn kind< 'a> (& 'a self) -> & 'a T
< / code > < / pre >
< p > Using < code > downcast_chain_ref::< String> ()< / code > gives a < code > ChainError< String> < / code > , which can be used
to call < code > .find_cause::< io::Error> ()< / code > .< / p >
< pre > < code class = "language-rust ignore" > if let Some(s) = e.downcast_chain_ref::< String> () {
if let Some(ioerror) = s.find_cause::< io::Error> () {
< / code > < / pre >
< p > or to use < code > .root_cause()< / code > , which of course can be of any type implementing < code > std::error::Error< / code > .< / p >
< pre > < code class = "language-rust ignore" > if let Some(e) = s.root_cause() {
< / code > < / pre >
2019-03-04 11:46:17 +01:00
< pre > < pre class = "playpen" > < code class = "language-rust" > use chainerror::*;
2018-12-20 14:55:19 +01:00
use std::error::Error;
use std::io;
use std::result::Result;
fn do_some_io() -> Result< (), Box< Error> > {
Err(io::Error::from(io::ErrorKind::NotFound))?;
Ok(())
}
fn func2() -> Result< (), Box< Error> > {
let filename = " foo.txt" ;
do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
Ok(())
}
fn func1() -> Result< (), Box< Error> > {
func2().map_err(mstrerr!(" func1 error" ))?;
Ok(())
}
fn main() -> Result< (), Box< Error> > {
if let Err(e) = func1() {
eprintln!(" Error: {}" , e);
if let Some(s) = e.downcast_chain_ref::< String> () {
if let Some(ioerror) = s.find_cause::< io::Error> () {
eprintln!(" caused by: std::io::Error: {}" , ioerror);
match ioerror.kind() {
io::ErrorKind::NotFound => eprintln!(" of kind: std::io::ErrorKind::NotFound" ),
_ => {}
}
}
if let Some(e) = s.root_cause() {
let ioerror = e.downcast_ref::< io::Error> ().unwrap();
eprintln!(" The root cause was: std::io::Error: {:#?}" , ioerror);
}
}
}
Ok(())
}
2019-03-04 11:46:17 +01:00
2018-12-20 14:55:19 +01:00
# #[allow(dead_code)]
# mod chainerror {
2019-02-07 09:02:01 +01:00
# //! `chainerror` provides an error backtrace without doing a real backtrace, so even after you `strip` your
# //! binaries, you still have the error backtrace.
# //!
# //! `chainerror` has no dependencies!
# //!
# //! `chainerror` uses `.source()` of `std::error::Error` along with `line()!` and `file()!` to provide a nice debug error backtrace.
# //! It encapsulates all types, which have `Display + Debug` and can store the error cause internally.
# //!
# //! Along with the `ChainError< T> ` struct, `chainerror` comes with some useful helper macros to save a lot of typing.
# //!
# //! ## Features
# //!
# //! `no-fileline`
# //! : completely turn off storing filename and line
# //!
# //! `display-cause`
# //! : turn on printing a backtrace of the errors in `Display`
# //!
# //! `no-debug-cause`
# //! : turn off printing a backtrace of the errors in `Debug`
# //!
# //!
# //! # Tutorial
# //!
# //! Read the [Tutorial](https://haraldh.github.io/chainerror/tutorial1.html)
# //!
# //! # Examples
# //!
# //! ~~~rust
# //! use chainerror::*;
# //! use std::error::Error;
# //! use std::io;
# //! use std::result::Result;
# //!
# //! fn do_some_io() -> Result< (), Box< Error> > {
# //! Err(io::Error::from(io::ErrorKind::NotFound))?;
# //! Ok(())
# //! }
# //!
# //! fn func2() -> Result< (), Box< Error> > {
# //! let filename = " foo.txt" ;
# //! do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# //! Ok(())
# //! }
# //!
# //! fn func1() -> Result< (), Box< Error> > {
# //! func2().map_err(mstrerr!(" func1 error" ))?;
# //! Ok(())
# //! }
# //!
# //! fn main() {
# //! if let Err(e) = func1() {
# //! #[cfg(not(windows))]
# //! assert_eq!(
# //! format!(" \n{:?}\n" , e), r#"
# //! src/lib.rs:20: func1 error
# //! Caused by:
# //! src/lib.rs:15: Error reading 'foo.txt'
# //! Caused by:
# //! Kind(NotFound)
# //! " #
# //! );
# //! }
# //! # else {
# //! # unreachable!();
# //! # }
# //! }
# //! ~~~
# //!
# //!
# //! ~~~rust
# //! use chainerror::*;
# //! use std::error::Error;
# //! use std::io;
# //! use std::result::Result;
# //!
# //! fn do_some_io() -> Result< (), Box< Error> > {
# //! Err(io::Error::from(io::ErrorKind::NotFound))?;
# //! Ok(())
# //! }
# //!
# //! fn func3() -> Result< (), Box< Error> > {
# //! let filename = " foo.txt" ;
# //! do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# //! Ok(())
# //! }
# //!
# //! derive_str_cherr!(Func2Error);
# //!
# //! fn func2() -> ChainResult< (), Func2Error> {
# //! func3().map_err(mstrerr!(Func2Error, " func2 error: calling func3" ))?;
# //! Ok(())
# //! }
# //!
# //! enum Func1Error {
# //! Func2,
# //! IO(String),
# //! }
# //!
# //! impl ::std::fmt::Display for Func1Error {
# //! fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# //! match self {
# //! Func1Error::Func2 => write!(f, " func1 error calling func2" ),
# //! Func1Error::IO(filename) => write!(f, " Error reading '{}'" , filename),
# //! }
# //! }
# //! }
# //!
# //! impl ::std::fmt::Debug for Func1Error {
# //! fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# //! write!(f, " {}" , self)
# //! }
# //! }
# //!
# //! fn func1() -> ChainResult< (), Func1Error> {
# //! func2().map_err(|e| cherr!(e, Func1Error::Func2))?;
# //! let filename = String::from(" bar.txt" );
# //! do_some_io().map_err(|e| cherr!(e, Func1Error::IO(filename)))?;
# //! Ok(())
# //! }
# //!
# //! fn main() {
# //! if let Err(e) = func1() {
# //! assert!(
# //! match e.kind() {
# //! Func1Error::Func2 => {
# //! eprintln!(" Main Error Report: func1 error calling func2" );
# //! true
# //! }
# //! Func1Error::IO(filename) => {
# //! eprintln!(" Main Error Report: func1 error reading '{}'" , filename);
# //! false
# //! }
# //! }
# //! );
# //!
# //! assert!(e.find_chain_cause::< Func2Error> ().is_some());
# //!
# //! if let Some(e) = e.find_chain_cause::< Func2Error> () {
# //! eprintln!(" \nError reported by Func2Error: {}" , e)
# //! }
# //!
# //!
# //! assert!(e.root_cause().is_some());
# //!
# //! if let Some(e) = e.root_cause() {
# //! let ioerror = e.downcast_ref::< io::Error> ().unwrap();
# //! eprintln!(" \nThe root cause was: std::io::Error: {:#?}" , ioerror);
# //! }
# //!
# //! #[cfg(not(windows))]
# //! assert_eq!(
# //! format!(" \n{:?}\n" , e), r#"
# //! src/lib.rs:47: func1 error calling func2
# //! Caused by:
# //! src/lib.rs:22: Func2Error(func2 error: calling func3)
# //! Caused by:
# //! src/lib.rs:15: Error reading 'foo.txt'
# //! Caused by:
# //! Kind(NotFound)
# //! " #
# //! );
# //! }
# //! # else {
# //! # unreachable!();
# //! # }
# //! }
# //! ~~~
2018-12-21 13:55:46 +01:00
#
# use std::any::TypeId;
2018-12-20 14:55:19 +01:00
# use std::error::Error;
# use std::fmt::{Debug, Display, Formatter, Result};
#
2019-02-07 09:02:01 +01:00
# /// chains an inner error kind `T` with a causing error
2018-12-20 14:55:19 +01:00
# pub struct ChainError< T> {
# #[cfg(not(feature = " no-fileline" ))]
# occurrence: Option< (u32, & 'static str)> ,
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# }
#
2018-12-21 13:55:46 +01:00
# /// convenience type alias
# pub type ChainResult< O, E> = std::result::Result< O, ChainError< E> > ;
2018-12-20 14:55:19 +01:00
#
# impl< T: 'static + Display + Debug> ChainError< T> {
# #[cfg(not(feature = " no-fileline" ))]
2018-12-21 13:55:46 +01:00
# /// Use the `cherr!()` or `mstrerr!()` macro instead of calling this directly
2018-12-20 14:55:19 +01:00
# pub fn new(
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# occurrence: Option< (u32, & 'static str)> ,
# ) -> Self {
# Self {
# occurrence,
# kind,
# error_cause,
# }
# }
#
# #[cfg(feature = " no-fileline" )]
2018-12-21 13:55:46 +01:00
# /// Use the `cherr!()` or `mstrerr!()` macro instead of calling this directly
2018-12-20 14:55:19 +01:00
# pub fn new(
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# _occurrence: Option< (u32, & 'static str)> ,
# ) -> Self {
# Self { kind, error_cause }
# }
#
2018-12-21 13:55:46 +01:00
# /// return the root cause of the error chain, if any exists
2018-12-20 14:55:19 +01:00
# pub fn root_cause(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.iter().last()
# }
#
# /// Find the first error cause of type U, if any exists
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// fn do_some_io() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# ///
# /// fn main() {
# /// if let Err(e) = func1() {
# /// if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# ///
# /// assert!(f1err.find_cause::< io::Error> ().is_some());
# ///
# /// assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// }
# /// # else {
# /// # panic!();
# /// # }
# /// }
# /// # else {
# /// # unreachable!();
# /// # }
# /// }
# /// ~~~
2018-12-20 14:55:19 +01:00
# pub fn find_cause< U: Error + 'static> (& self) -> Option< & U> {
2019-02-07 09:02:01 +01:00
# self.iter().filter_map(Error::downcast_ref::< U> ).next()
# }
#
# /// Find the first error cause of type `ChainError< U> `, if any exists
# ///
# /// Same as `find_cause`, but hides the `ChainError< U> ` implementation internals
# ///
# /// # Examples
# ///
# /// ~~~rust,ignore
# /// // Instead of writing
# /// err.find_cause::< ChainError< FooError> > ();
# ///
# /// // leave out the ChainError< FooError> implementation detail
# /// err.find_chain_cause::< FooError> ();
# /// ~~~
2018-12-20 14:55:19 +01:00
# pub fn find_chain_cause< U: Error + 'static> (& self) -> Option< & ChainError< U> > {
2019-02-07 09:02:01 +01:00
# self.iter()
# .filter_map(Error::downcast_ref::< ChainError< U> > )
# .next()
# }
#
# /// Find the first error cause of type `ChainError< U> ` or `U`, if any exists and return `U`
# ///
# /// Same as `find_cause` and `find_chain_cause`, but hides the `ChainError< U> ` implementation internals
# ///
# /// # Examples
# ///
# /// ~~~rust,ignore
# /// // Instead of writing
# /// err.find_cause::< ChainError< FooErrorKind> > ();
# /// // and/or
# /// err.find_chain_cause::< FooErrorKind> ();
# /// // and/or
# /// err.find_cause::< FooErrorKind> ();
# ///
# /// // leave out the ChainError< FooErrorKind> implementation detail
# /// err.find_chain_or_kind::< FooErrorKind> ();
# /// ~~~
# pub fn find_kind_or_cause< U: Error + 'static> (& self) -> Option< & U> {
# self.iter()
# .filter_map(|e| {
# e.downcast_ref::< ChainError< U> > ()
# .map(|e| e.kind())
# .or_else(|| e.downcast_ref::< U> ())
# })
# .next()
# }
#
# /// Return a reference to T of `ChainError< T> `
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// fn do_some_io() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// #[derive(Debug)]
# /// enum Func1ErrorKind {
# /// Func2,
# /// IO(String),
# /// }
# ///
# /// /// impl ::std::fmt::Display for Func1ErrorKind {…}
# /// # impl ::std::fmt::Display for Func1ErrorKind {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # Func1ErrorKind::Func2 => write!(f, " func1 error calling func2" ),
# /// # Func1ErrorKind::IO(filename) => write!(f, " Error reading '{}'" , filename),
# /// # }
# /// # }
# /// # }
# ///
# /// fn func1() -> ChainResult< (), Func1ErrorKind> {
# /// func2().map_err(|e| cherr!(e, Func1ErrorKind::Func2))?;
# /// do_some_io().map_err(|e| cherr!(e, Func1ErrorKind::IO(" bar.txt" .into())))?;
# /// Ok(())
# /// }
# ///
# /// fn main() {
# /// if let Err(e) = func1() {
# /// match e.kind() {
# /// Func1ErrorKind::Func2 => {},
# /// Func1ErrorKind::IO(filename) => panic!(),
# /// }
# /// }
# /// # else {
# /// # unreachable!();
# /// # }
# /// }
# /// ~~~
# pub fn kind(& self) -> & T {
# & self.kind
2018-12-21 13:55:46 +01:00
# }
#
2019-02-07 09:02:01 +01:00
# /// Returns an Iterator over all error causes/sources
# ///
# /// # Example
# ///
# ///
# pub fn iter(& self) -> impl Iterator< Item = & (dyn Error + 'static)> {
# ErrorIter {
# current: Some(self),
# }
2018-12-21 13:55:46 +01:00
# }
2019-02-07 09:02:01 +01:00
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# struct ErrorIter< 'a> {
# current: Option< & 'a (dyn Error + 'static)> ,
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# impl< 'a> Iterator for ErrorIter< 'a> {
# type Item = & 'a (dyn Error + 'static);
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# fn next(& mut self) -> Option< Self::Item> {
# let current = self.current;
# self.current = self.current.and_then(Error::source);
# current
2018-12-21 13:55:46 +01:00
# }
2019-02-07 09:02:01 +01:00
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# impl< T: 'static + Display + Debug> std::ops::Deref for ChainError< T> {
# type Target = T;
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# fn deref(& self) -> & Self::Target {
2018-12-20 14:55:19 +01:00
# & self.kind
# }
# }
#
2019-02-07 09:02:01 +01:00
# /// Convenience trait to hide the `ChainError< T> ` implementation internals
2018-12-20 14:55:19 +01:00
# pub trait ChainErrorDown {
2019-02-07 09:02:01 +01:00
# /// Test if of type `ChainError< T> `
2018-12-20 14:55:19 +01:00
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool;
2019-02-07 09:02:01 +01:00
# /// Downcast to a reference of `ChainError< T> `
2018-12-20 14:55:19 +01:00
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > ;
2019-02-07 09:02:01 +01:00
# /// Downcast to a mutable reference of `ChainError< T> `
2018-12-20 14:55:19 +01:00
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > ;
# }
#
# impl< U: 'static + Display + Debug> ChainErrorDown for ChainError< U> {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# TypeId::of::< T> () == TypeId::of::< U> ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# if self.is_chain::< T> () {
2019-02-07 09:02:01 +01:00
# #[allow(clippy::cast_ptr_alignment)]
# unsafe {
# Some(& *(self as *const dyn Error as *const & ChainError< T> ))
# }
2018-12-20 14:55:19 +01:00
# } else {
# None
# }
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# if self.is_chain::< T> () {
2019-02-07 09:02:01 +01:00
# #[allow(clippy::cast_ptr_alignment)]
# unsafe {
# Some(& mut *(self as *mut dyn Error as *mut & mut ChainError< T> ))
# }
2018-12-20 14:55:19 +01:00
# } else {
# None
# }
# }
# }
#
# impl ChainErrorDown for dyn Error + 'static {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl ChainErrorDown for dyn Error + 'static + Send {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl ChainErrorDown for dyn Error + 'static + Send + Sync {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl< T: 'static + Display + Debug> Error for ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.error_cause.as_ref().map(|e| e.as_ref())
2018-12-20 14:55:19 +01:00
# }
# }
#
# impl< T: 'static + Display + Debug> Error for & ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.error_cause.as_ref().map(|e| e.as_ref())
2018-12-20 14:55:19 +01:00
# }
# }
#
# impl< T: 'static + Display + Debug> Error for & mut ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.error_cause.as_ref().map(|e| e.as_ref())
2018-12-20 14:55:19 +01:00
# }
# }
#
# impl< T: 'static + Display + Debug> Display for ChainError< T> {
# fn fmt(& self, f: & mut Formatter) -> Result {
# write!(f, " {}" , self.kind)?;
#
# #[cfg(feature = " display-cause" )]
# {
# if let Some(e) = self.source() {
# writeln!(f, " \nCaused by:" )?;
# Display::fmt(& e, f)?;
# }
# }
# Ok(())
# }
# }
#
# impl< T: 'static + Display + Debug> Debug for ChainError< T> {
# fn fmt(& self, f: & mut Formatter) -> Result {
# #[cfg(not(feature = " no-fileline" ))]
# {
# if let Some(o) = self.occurrence {
# write!(f, " {}:{}: " , o.1, o.0)?;
# }
# }
#
2018-12-21 13:55:46 +01:00
# if self.is_chain::< String> () {
# Display::fmt(& self.kind, f)?;
# } else {
# Debug::fmt(& self.kind, f)?;
# }
2018-12-20 14:55:19 +01:00
#
# #[cfg(not(feature = " no-debug-cause" ))]
# {
# if let Some(e) = self.source() {
# writeln!(f, " \nCaused by:" )?;
# Debug::fmt(& e, f)?;
# }
# }
# Ok(())
# }
# }
#
2019-02-07 09:02:01 +01:00
# pub trait ChainErrorFrom< T> : Sized {
# fn chain_error_from(_: T, line_filename: Option< (u32, & 'static str)> ) -> ChainError< Self> ;
# }
#
# pub trait IntoChainError< T> : Sized {
# fn into_chain_error(self, line_filename: Option< (u32, & 'static str)> ) -> ChainError< T> ;
# }
#
# impl< T, U> IntoChainError< U> for T
# where
# U: ChainErrorFrom< T> ,
# {
# fn into_chain_error(self, line_filename: Option< (u32, & 'static str)> ) -> ChainError< U> {
# U::chain_error_from(self, line_filename)
# }
# }
#
# impl< T, U> ChainErrorFrom< T> for U
# where
# T: Into< U> ,
# U: 'static + Display + Debug,
# {
# fn chain_error_from(t: T, line_filename: Option< (u32, & 'static str)> ) -> ChainError< Self> {
# let e: U = t.into();
# ChainError::< _> ::new(e, None, line_filename)
# }
# }
#
2018-12-20 14:55:19 +01:00
# #[macro_export]
2019-02-07 09:02:01 +01:00
# macro_rules! minto_cherr {
# ( ) => {
# |e| e.into_chain_error(Some((line!(), file!())))
2018-12-20 14:55:19 +01:00
# };
# }
#
# #[macro_export]
2019-02-07 09:02:01 +01:00
# macro_rules! into_cherr {
# ( $t:expr ) => {
# $t.into_chain_error(Some((line!(), file!())))
2018-12-20 14:55:19 +01:00
# };
# }
#
2019-02-07 09:02:01 +01:00
# /// Creates a new `ChainError< T> `
# ///
# /// # Examples
# ///
# /// Create a new ChainError< FooError> , where `FooError` must implement `Display` and `Debug`.
# /// ~~~rust
# /// # use chainerror::*;
# /// #
# /// # #[derive(Debug)]
# /// enum FooError {
# /// Bar,
# /// Baz(& 'static str),
# /// }
# /// #
# /// # impl ::std::fmt::Display for FooError {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # FooError::Bar => write!(f, " Bar Error" ),
# /// # FooError::Baz(s) => write!(f, " Baz Error: '{}'" , s),
# /// # }
# /// # }
# /// # }
# ///
# /// // impl ::std::fmt::Display for FooError
# ///
# /// fn do_some_stuff() -> bool {
# /// false
# /// }
# ///
# /// fn func() -> ChainResult< (), FooError> {
# /// if ! do_some_stuff() {
# /// Err(cherr!(FooError::Baz(" Error" )))?;
# /// }
# /// Ok(())
# /// }
# /// #
# /// # pub fn main() {
# /// # match func().unwrap_err().kind() {
# /// # FooError::Baz(s) if s == & " Error" => {},
# /// # _ => panic!(),
# /// # }
# /// # }
# /// ~~~
# ///
# /// Additionally an error cause can be added.
# ///
# /// ~~~rust
# /// # use chainerror::*;
# /// # use std::io;
# /// # use std::error::Error;
# /// #
# /// # #[derive(Debug)]
# /// # enum FooError {
# /// # Bar,
# /// # Baz(& 'static str),
# /// # }
# /// #
# /// # impl ::std::fmt::Display for FooError {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # FooError::Bar => write!(f, " Bar Error" ),
# /// # FooError::Baz(s) => write!(f, " Baz Error: '{}'" , s),
# /// # }
# /// # }
# /// # }
# /// #
# /// fn do_some_stuff() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// fn func() -> ChainResult< (), FooError> {
# /// do_some_stuff().map_err(
# /// |e| cherr!(e, FooError::Baz(" Error" ))
# /// )?;
# /// Ok(())
# /// }
# /// #
# /// # pub fn main() {
# /// # match func().unwrap_err().kind() {
# /// # FooError::Baz(s) if s == & " Error" => {},
# /// # _ => panic!(),
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! cherr {
# ( $k:expr ) => ({
# ChainError::< _> ::new($k, None, Some((line!(), file!())))
# });
# ( None, $k:expr ) => ({
# ChainError::< _> ::new($k, None, Some((line!(), file!())))
# });
# ( None, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!(None, format!($fmt, $($arg)+ ))
# });
# ( None, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!(None, format!($fmt, $($arg)+ ))
# });
# ( $e:path, $k:expr ) => ({
# ChainError::< _> ::new($k, Some(Box::from($e)), Some((line!(), file!())))
# });
# ( $e:path, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!($e, format!($fmt, $($arg)+ ))
# });
#
# }
#
# /// Convenience macro for `|e| cherr!(e, format!(…))`
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(" func1 error" ))?;
# /// Ok(())
# /// }
# ///
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # #[cfg(not(windows))]
# /// # assert_eq!(
# /// # format!(" \n{:?}\n" , e), r#"
# /// # src/lib.rs:20: func1 error
# /// # Caused by:
# /// # src/lib.rs:15: Error reading 'foo.txt'
# /// # Caused by:
# /// # Kind(NotFound)
# /// # " #
# /// # );
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# ///
# /// `mstrerr!()` can also be used to map a new `ChainError< T> `, where T was defined with
# /// `derive_str_cherr!(T)`
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! mstrerr {
# ( $t:path, $msg:expr ) => ({
# |e| cherr!(e, $t ($msg.to_string()))
# });
# ( $t:path, $msg:expr, ) => ({
# |e| cherr!(e, $t ($msg.to_string()))
# });
# ( $t:path, $fmt:expr, $($arg:tt)+ ) => ({
# |e| cherr!(e, $t (format!($fmt, $($arg)+ )))
# });
# ($msg:expr) => ({
# |e| cherr!(e, $msg.to_string())
# });
# ($msg:expr, ) => ({
# |e| cherr!(e, $msg.to_string())
# });
# ($fmt:expr, $($arg:tt)+) => ({
# |e| cherr!(e, format!($fmt, $($arg)+ ))
# });
# }
#
# /// Convenience macro for `cherr!(T(format!(…)))` where `T(String)`
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::result::Result;
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> ChainResult< (), Func2Error> {
# /// let filename = " foo.txt" ;
# /// Err(strerr!(Func2Error, " Error reading '{}'" , filename))
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! strerr {
# ( $t:path, $msg:expr ) => ({
# cherr!($t ($msg.to_string()))
# });
# ( $t:path, $msg:expr, ) => ({
# cherr!($t ($msg.to_string()))
# });
# ( $t:path, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!($t (format!($fmt, $($arg)+ )))
# });
# ($msg:expr) => ({
# cherr!($msg.to_string())
# });
# ($msg:expr, ) => ({
# cherr!($msg.to_string())
# });
# ($fmt:expr, $($arg:tt)+) => ({
# cherr!(format!($fmt, $($arg)+ ))
# });
# }
#
# /// Convenience macro to create a " new type" T(String) and implement Display + Debug for T
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> ChainResult< (), Func2Error> {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
2018-12-20 14:55:19 +01:00
# #[macro_export]
# macro_rules! derive_str_cherr {
# ($e:ident) => {
2019-02-07 09:02:01 +01:00
# pub struct $e(pub String);
2018-12-20 14:55:19 +01:00
# impl ::std::fmt::Display for $e {
# fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# write!(f, " {}" , self.0)
# }
# }
# impl ::std::fmt::Debug for $e {
# fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# write!(f, " {}({})" , stringify!($e), self.0)
# }
# }
# impl ::std::error::Error for $e {}
# };
# }
# }
< / code > < / pre > < / pre >
2018-12-20 16:37:43 +01:00
< a class = "header" href = "#finding-an-error-cause" id = "finding-an-error-cause" > < h1 > Finding an Error cause< / h1 > < / a >
2018-12-21 13:55:46 +01:00
< p > To distinguish the errors occuring in various places, we can define named string errors with the
" new type" pattern.< / p >
< pre > < code class = "language-rust ignore" > derive_str_cherr!(Func2Error);
derive_str_cherr!(Func1Error);
< / code > < / pre >
< p > Instead of < code > ChainError< String> < / code > we now have < code > struct Func1Error(String)< / code > and < code > ChainError< Func1Error> < / code > .< / p >
< p > In the < code > main< / code > function you can see, how we can match the different errors.< / p >
< p > Also see:< / p >
< pre > < code class = "language-rust ignore" > if let Some(f2err) = f1err.find_chain_cause::< Func2Error> () {
< / code > < / pre >
< p > as a shortcut to< / p >
< pre > < code class = "language-rust ignore" > if let Some(f2err) = f1err.find_cause::< ChainError< Func2Error> > () {
< / code > < / pre >
< p > hiding the < code > ChainError< T> < / code > implementation detail.< / p >
2019-03-04 11:46:17 +01:00
< pre > < pre class = "playpen" > < code class = "language-rust" > use chainerror::*;
2018-12-20 14:55:19 +01:00
use std::error::Error;
use std::io;
use std::result::Result;
fn do_some_io() -> Result< (), Box< Error> > {
Err(io::Error::from(io::ErrorKind::NotFound))?;
Ok(())
}
derive_str_cherr!(Func2Error);
fn func2() -> Result< (), Box< Error> > {
let filename = " foo.txt" ;
do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
Ok(())
}
derive_str_cherr!(Func1Error);
fn func1() -> Result< (), Box< Error> > {
func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
Ok(())
}
fn main() -> Result< (), Box< Error> > {
if let Err(e) = func1() {
if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
eprintln!(" Func1Error: {}" , f1err);
if let Some(f2err) = f1err.find_cause::< ChainError< Func2Error> > () {
eprintln!(" Func2Error: {}" , f2err);
}
if let Some(f2err) = f1err.find_chain_cause::< Func2Error> () {
eprintln!(" Debug Func2Error:\n{:?}" , f2err);
}
}
}
Ok(())
}
2019-03-04 11:46:17 +01:00
2018-12-20 14:55:19 +01:00
# #[allow(dead_code)]
# mod chainerror {
2019-02-07 09:02:01 +01:00
# //! `chainerror` provides an error backtrace without doing a real backtrace, so even after you `strip` your
# //! binaries, you still have the error backtrace.
# //!
# //! `chainerror` has no dependencies!
# //!
# //! `chainerror` uses `.source()` of `std::error::Error` along with `line()!` and `file()!` to provide a nice debug error backtrace.
# //! It encapsulates all types, which have `Display + Debug` and can store the error cause internally.
# //!
# //! Along with the `ChainError< T> ` struct, `chainerror` comes with some useful helper macros to save a lot of typing.
# //!
# //! ## Features
# //!
# //! `no-fileline`
# //! : completely turn off storing filename and line
# //!
# //! `display-cause`
# //! : turn on printing a backtrace of the errors in `Display`
# //!
# //! `no-debug-cause`
# //! : turn off printing a backtrace of the errors in `Debug`
# //!
# //!
# //! # Tutorial
# //!
# //! Read the [Tutorial](https://haraldh.github.io/chainerror/tutorial1.html)
# //!
# //! # Examples
# //!
# //! ~~~rust
# //! use chainerror::*;
# //! use std::error::Error;
# //! use std::io;
# //! use std::result::Result;
# //!
# //! fn do_some_io() -> Result< (), Box< Error> > {
# //! Err(io::Error::from(io::ErrorKind::NotFound))?;
# //! Ok(())
# //! }
# //!
# //! fn func2() -> Result< (), Box< Error> > {
# //! let filename = " foo.txt" ;
# //! do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# //! Ok(())
# //! }
# //!
# //! fn func1() -> Result< (), Box< Error> > {
# //! func2().map_err(mstrerr!(" func1 error" ))?;
# //! Ok(())
# //! }
# //!
# //! fn main() {
# //! if let Err(e) = func1() {
# //! #[cfg(not(windows))]
# //! assert_eq!(
# //! format!(" \n{:?}\n" , e), r#"
# //! src/lib.rs:20: func1 error
# //! Caused by:
# //! src/lib.rs:15: Error reading 'foo.txt'
# //! Caused by:
# //! Kind(NotFound)
# //! " #
# //! );
# //! }
# //! # else {
# //! # unreachable!();
# //! # }
# //! }
# //! ~~~
# //!
# //!
# //! ~~~rust
# //! use chainerror::*;
# //! use std::error::Error;
# //! use std::io;
# //! use std::result::Result;
# //!
# //! fn do_some_io() -> Result< (), Box< Error> > {
# //! Err(io::Error::from(io::ErrorKind::NotFound))?;
# //! Ok(())
# //! }
# //!
# //! fn func3() -> Result< (), Box< Error> > {
# //! let filename = " foo.txt" ;
# //! do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# //! Ok(())
# //! }
# //!
# //! derive_str_cherr!(Func2Error);
# //!
# //! fn func2() -> ChainResult< (), Func2Error> {
# //! func3().map_err(mstrerr!(Func2Error, " func2 error: calling func3" ))?;
# //! Ok(())
# //! }
# //!
# //! enum Func1Error {
# //! Func2,
# //! IO(String),
# //! }
# //!
# //! impl ::std::fmt::Display for Func1Error {
# //! fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# //! match self {
# //! Func1Error::Func2 => write!(f, " func1 error calling func2" ),
# //! Func1Error::IO(filename) => write!(f, " Error reading '{}'" , filename),
# //! }
# //! }
# //! }
# //!
# //! impl ::std::fmt::Debug for Func1Error {
# //! fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# //! write!(f, " {}" , self)
# //! }
# //! }
# //!
# //! fn func1() -> ChainResult< (), Func1Error> {
# //! func2().map_err(|e| cherr!(e, Func1Error::Func2))?;
# //! let filename = String::from(" bar.txt" );
# //! do_some_io().map_err(|e| cherr!(e, Func1Error::IO(filename)))?;
# //! Ok(())
# //! }
# //!
# //! fn main() {
# //! if let Err(e) = func1() {
# //! assert!(
# //! match e.kind() {
# //! Func1Error::Func2 => {
# //! eprintln!(" Main Error Report: func1 error calling func2" );
# //! true
# //! }
# //! Func1Error::IO(filename) => {
# //! eprintln!(" Main Error Report: func1 error reading '{}'" , filename);
# //! false
# //! }
# //! }
# //! );
# //!
# //! assert!(e.find_chain_cause::< Func2Error> ().is_some());
# //!
# //! if let Some(e) = e.find_chain_cause::< Func2Error> () {
# //! eprintln!(" \nError reported by Func2Error: {}" , e)
# //! }
# //!
# //!
# //! assert!(e.root_cause().is_some());
# //!
# //! if let Some(e) = e.root_cause() {
# //! let ioerror = e.downcast_ref::< io::Error> ().unwrap();
# //! eprintln!(" \nThe root cause was: std::io::Error: {:#?}" , ioerror);
# //! }
# //!
# //! #[cfg(not(windows))]
# //! assert_eq!(
# //! format!(" \n{:?}\n" , e), r#"
# //! src/lib.rs:47: func1 error calling func2
# //! Caused by:
# //! src/lib.rs:22: Func2Error(func2 error: calling func3)
# //! Caused by:
# //! src/lib.rs:15: Error reading 'foo.txt'
# //! Caused by:
# //! Kind(NotFound)
# //! " #
# //! );
# //! }
# //! # else {
# //! # unreachable!();
# //! # }
# //! }
# //! ~~~
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# use std::any::TypeId;
# use std::error::Error;
# use std::fmt::{Debug, Display, Formatter, Result};
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# /// chains an inner error kind `T` with a causing error
# pub struct ChainError< T> {
# #[cfg(not(feature = " no-fileline" ))]
# occurrence: Option< (u32, & 'static str)> ,
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# }
2018-12-20 14:55:19 +01:00
#
2018-12-21 13:55:46 +01:00
# /// convenience type alias
# pub type ChainResult< O, E> = std::result::Result< O, ChainError< E> > ;
2018-12-20 14:55:19 +01:00
#
# impl< T: 'static + Display + Debug> ChainError< T> {
# #[cfg(not(feature = " no-fileline" ))]
2018-12-21 13:55:46 +01:00
# /// Use the `cherr!()` or `mstrerr!()` macro instead of calling this directly
2018-12-20 14:55:19 +01:00
# pub fn new(
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# occurrence: Option< (u32, & 'static str)> ,
# ) -> Self {
# Self {
# occurrence,
# kind,
# error_cause,
# }
# }
#
# #[cfg(feature = " no-fileline" )]
2018-12-21 13:55:46 +01:00
# /// Use the `cherr!()` or `mstrerr!()` macro instead of calling this directly
2018-12-20 14:55:19 +01:00
# pub fn new(
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# _occurrence: Option< (u32, & 'static str)> ,
# ) -> Self {
# Self { kind, error_cause }
# }
#
2018-12-21 13:55:46 +01:00
# /// return the root cause of the error chain, if any exists
2018-12-20 14:55:19 +01:00
# pub fn root_cause(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.iter().last()
# }
#
# /// Find the first error cause of type U, if any exists
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// fn do_some_io() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# ///
# /// fn main() {
# /// if let Err(e) = func1() {
# /// if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# ///
# /// assert!(f1err.find_cause::< io::Error> ().is_some());
# ///
# /// assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// }
# /// # else {
# /// # panic!();
# /// # }
# /// }
# /// # else {
# /// # unreachable!();
# /// # }
# /// }
# /// ~~~
2018-12-20 14:55:19 +01:00
# pub fn find_cause< U: Error + 'static> (& self) -> Option< & U> {
2019-02-07 09:02:01 +01:00
# self.iter().filter_map(Error::downcast_ref::< U> ).next()
# }
#
# /// Find the first error cause of type `ChainError< U> `, if any exists
# ///
# /// Same as `find_cause`, but hides the `ChainError< U> ` implementation internals
# ///
# /// # Examples
# ///
# /// ~~~rust,ignore
# /// // Instead of writing
# /// err.find_cause::< ChainError< FooError> > ();
# ///
# /// // leave out the ChainError< FooError> implementation detail
# /// err.find_chain_cause::< FooError> ();
# /// ~~~
2018-12-20 14:55:19 +01:00
# pub fn find_chain_cause< U: Error + 'static> (& self) -> Option< & ChainError< U> > {
2019-02-07 09:02:01 +01:00
# self.iter()
# .filter_map(Error::downcast_ref::< ChainError< U> > )
# .next()
# }
#
# /// Find the first error cause of type `ChainError< U> ` or `U`, if any exists and return `U`
# ///
# /// Same as `find_cause` and `find_chain_cause`, but hides the `ChainError< U> ` implementation internals
# ///
# /// # Examples
# ///
# /// ~~~rust,ignore
# /// // Instead of writing
# /// err.find_cause::< ChainError< FooErrorKind> > ();
# /// // and/or
# /// err.find_chain_cause::< FooErrorKind> ();
# /// // and/or
# /// err.find_cause::< FooErrorKind> ();
# ///
# /// // leave out the ChainError< FooErrorKind> implementation detail
# /// err.find_chain_or_kind::< FooErrorKind> ();
# /// ~~~
# pub fn find_kind_or_cause< U: Error + 'static> (& self) -> Option< & U> {
# self.iter()
# .filter_map(|e| {
# e.downcast_ref::< ChainError< U> > ()
# .map(|e| e.kind())
# .or_else(|| e.downcast_ref::< U> ())
# })
# .next()
# }
#
# /// Return a reference to T of `ChainError< T> `
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// fn do_some_io() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// #[derive(Debug)]
# /// enum Func1ErrorKind {
# /// Func2,
# /// IO(String),
# /// }
# ///
# /// /// impl ::std::fmt::Display for Func1ErrorKind {…}
# /// # impl ::std::fmt::Display for Func1ErrorKind {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # Func1ErrorKind::Func2 => write!(f, " func1 error calling func2" ),
# /// # Func1ErrorKind::IO(filename) => write!(f, " Error reading '{}'" , filename),
# /// # }
# /// # }
# /// # }
# ///
# /// fn func1() -> ChainResult< (), Func1ErrorKind> {
# /// func2().map_err(|e| cherr!(e, Func1ErrorKind::Func2))?;
# /// do_some_io().map_err(|e| cherr!(e, Func1ErrorKind::IO(" bar.txt" .into())))?;
# /// Ok(())
# /// }
# ///
# /// fn main() {
# /// if let Err(e) = func1() {
# /// match e.kind() {
# /// Func1ErrorKind::Func2 => {},
# /// Func1ErrorKind::IO(filename) => panic!(),
# /// }
# /// }
# /// # else {
# /// # unreachable!();
# /// # }
# /// }
# /// ~~~
# pub fn kind(& self) -> & T {
# & self.kind
2018-12-21 13:55:46 +01:00
# }
#
2019-02-07 09:02:01 +01:00
# /// Returns an Iterator over all error causes/sources
# ///
# /// # Example
# ///
# ///
# pub fn iter(& self) -> impl Iterator< Item = & (dyn Error + 'static)> {
# ErrorIter {
# current: Some(self),
# }
2018-12-21 13:55:46 +01:00
# }
2019-02-07 09:02:01 +01:00
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# struct ErrorIter< 'a> {
# current: Option< & 'a (dyn Error + 'static)> ,
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# impl< 'a> Iterator for ErrorIter< 'a> {
# type Item = & 'a (dyn Error + 'static);
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# fn next(& mut self) -> Option< Self::Item> {
# let current = self.current;
# self.current = self.current.and_then(Error::source);
# current
2018-12-21 13:55:46 +01:00
# }
2019-02-07 09:02:01 +01:00
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# impl< T: 'static + Display + Debug> std::ops::Deref for ChainError< T> {
# type Target = T;
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# fn deref(& self) -> & Self::Target {
2018-12-20 14:55:19 +01:00
# & self.kind
# }
# }
#
2019-02-07 09:02:01 +01:00
# /// Convenience trait to hide the `ChainError< T> ` implementation internals
2018-12-20 14:55:19 +01:00
# pub trait ChainErrorDown {
2019-02-07 09:02:01 +01:00
# /// Test if of type `ChainError< T> `
2018-12-20 14:55:19 +01:00
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool;
2019-02-07 09:02:01 +01:00
# /// Downcast to a reference of `ChainError< T> `
2018-12-20 14:55:19 +01:00
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > ;
2019-02-07 09:02:01 +01:00
# /// Downcast to a mutable reference of `ChainError< T> `
2018-12-20 14:55:19 +01:00
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > ;
# }
#
# impl< U: 'static + Display + Debug> ChainErrorDown for ChainError< U> {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# TypeId::of::< T> () == TypeId::of::< U> ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# if self.is_chain::< T> () {
2019-02-07 09:02:01 +01:00
# #[allow(clippy::cast_ptr_alignment)]
# unsafe {
# Some(& *(self as *const dyn Error as *const & ChainError< T> ))
# }
2018-12-20 14:55:19 +01:00
# } else {
# None
# }
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# if self.is_chain::< T> () {
2019-02-07 09:02:01 +01:00
# #[allow(clippy::cast_ptr_alignment)]
# unsafe {
# Some(& mut *(self as *mut dyn Error as *mut & mut ChainError< T> ))
# }
2018-12-20 14:55:19 +01:00
# } else {
# None
# }
# }
# }
#
# impl ChainErrorDown for dyn Error + 'static {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl ChainErrorDown for dyn Error + 'static + Send {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl ChainErrorDown for dyn Error + 'static + Send + Sync {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl< T: 'static + Display + Debug> Error for ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.error_cause.as_ref().map(|e| e.as_ref())
2018-12-20 14:55:19 +01:00
# }
# }
#
# impl< T: 'static + Display + Debug> Error for & ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.error_cause.as_ref().map(|e| e.as_ref())
2018-12-20 14:55:19 +01:00
# }
# }
#
# impl< T: 'static + Display + Debug> Error for & mut ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.error_cause.as_ref().map(|e| e.as_ref())
2018-12-20 14:55:19 +01:00
# }
# }
#
# impl< T: 'static + Display + Debug> Display for ChainError< T> {
# fn fmt(& self, f: & mut Formatter) -> Result {
# write!(f, " {}" , self.kind)?;
#
# #[cfg(feature = " display-cause" )]
# {
# if let Some(e) = self.source() {
# writeln!(f, " \nCaused by:" )?;
# Display::fmt(& e, f)?;
# }
# }
# Ok(())
# }
# }
#
# impl< T: 'static + Display + Debug> Debug for ChainError< T> {
# fn fmt(& self, f: & mut Formatter) -> Result {
# #[cfg(not(feature = " no-fileline" ))]
# {
# if let Some(o) = self.occurrence {
# write!(f, " {}:{}: " , o.1, o.0)?;
# }
# }
#
2018-12-21 13:55:46 +01:00
# if self.is_chain::< String> () {
# Display::fmt(& self.kind, f)?;
# } else {
# Debug::fmt(& self.kind, f)?;
# }
2018-12-20 14:55:19 +01:00
#
# #[cfg(not(feature = " no-debug-cause" ))]
# {
# if let Some(e) = self.source() {
# writeln!(f, " \nCaused by:" )?;
# Debug::fmt(& e, f)?;
# }
# }
# Ok(())
# }
# }
#
2019-02-07 09:02:01 +01:00
# pub trait ChainErrorFrom< T> : Sized {
# fn chain_error_from(_: T, line_filename: Option< (u32, & 'static str)> ) -> ChainError< Self> ;
# }
#
# pub trait IntoChainError< T> : Sized {
# fn into_chain_error(self, line_filename: Option< (u32, & 'static str)> ) -> ChainError< T> ;
# }
#
# impl< T, U> IntoChainError< U> for T
# where
# U: ChainErrorFrom< T> ,
# {
# fn into_chain_error(self, line_filename: Option< (u32, & 'static str)> ) -> ChainError< U> {
# U::chain_error_from(self, line_filename)
# }
# }
#
# impl< T, U> ChainErrorFrom< T> for U
# where
# T: Into< U> ,
# U: 'static + Display + Debug,
# {
# fn chain_error_from(t: T, line_filename: Option< (u32, & 'static str)> ) -> ChainError< Self> {
# let e: U = t.into();
# ChainError::< _> ::new(e, None, line_filename)
# }
# }
#
2018-12-20 14:55:19 +01:00
# #[macro_export]
2019-02-07 09:02:01 +01:00
# macro_rules! minto_cherr {
# ( ) => {
# |e| e.into_chain_error(Some((line!(), file!())))
2018-12-20 14:55:19 +01:00
# };
# }
#
# #[macro_export]
2019-02-07 09:02:01 +01:00
# macro_rules! into_cherr {
# ( $t:expr ) => {
# $t.into_chain_error(Some((line!(), file!())))
2018-12-20 14:55:19 +01:00
# };
# }
#
2019-02-07 09:02:01 +01:00
# /// Creates a new `ChainError< T> `
# ///
# /// # Examples
# ///
# /// Create a new ChainError< FooError> , where `FooError` must implement `Display` and `Debug`.
# /// ~~~rust
# /// # use chainerror::*;
# /// #
# /// # #[derive(Debug)]
# /// enum FooError {
# /// Bar,
# /// Baz(& 'static str),
# /// }
# /// #
# /// # impl ::std::fmt::Display for FooError {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # FooError::Bar => write!(f, " Bar Error" ),
# /// # FooError::Baz(s) => write!(f, " Baz Error: '{}'" , s),
# /// # }
# /// # }
# /// # }
# ///
# /// // impl ::std::fmt::Display for FooError
# ///
# /// fn do_some_stuff() -> bool {
# /// false
# /// }
# ///
# /// fn func() -> ChainResult< (), FooError> {
# /// if ! do_some_stuff() {
# /// Err(cherr!(FooError::Baz(" Error" )))?;
# /// }
# /// Ok(())
# /// }
# /// #
# /// # pub fn main() {
# /// # match func().unwrap_err().kind() {
# /// # FooError::Baz(s) if s == & " Error" => {},
# /// # _ => panic!(),
# /// # }
# /// # }
# /// ~~~
# ///
# /// Additionally an error cause can be added.
# ///
# /// ~~~rust
# /// # use chainerror::*;
# /// # use std::io;
# /// # use std::error::Error;
# /// #
# /// # #[derive(Debug)]
# /// # enum FooError {
# /// # Bar,
# /// # Baz(& 'static str),
# /// # }
# /// #
# /// # impl ::std::fmt::Display for FooError {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # FooError::Bar => write!(f, " Bar Error" ),
# /// # FooError::Baz(s) => write!(f, " Baz Error: '{}'" , s),
# /// # }
# /// # }
# /// # }
# /// #
# /// fn do_some_stuff() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// fn func() -> ChainResult< (), FooError> {
# /// do_some_stuff().map_err(
# /// |e| cherr!(e, FooError::Baz(" Error" ))
# /// )?;
# /// Ok(())
# /// }
# /// #
# /// # pub fn main() {
# /// # match func().unwrap_err().kind() {
# /// # FooError::Baz(s) if s == & " Error" => {},
# /// # _ => panic!(),
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! cherr {
# ( $k:expr ) => ({
# ChainError::< _> ::new($k, None, Some((line!(), file!())))
# });
# ( None, $k:expr ) => ({
# ChainError::< _> ::new($k, None, Some((line!(), file!())))
# });
# ( None, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!(None, format!($fmt, $($arg)+ ))
# });
# ( None, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!(None, format!($fmt, $($arg)+ ))
# });
# ( $e:path, $k:expr ) => ({
# ChainError::< _> ::new($k, Some(Box::from($e)), Some((line!(), file!())))
# });
# ( $e:path, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!($e, format!($fmt, $($arg)+ ))
# });
#
# }
#
# /// Convenience macro for `|e| cherr!(e, format!(…))`
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(" func1 error" ))?;
# /// Ok(())
# /// }
# ///
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # #[cfg(not(windows))]
# /// # assert_eq!(
# /// # format!(" \n{:?}\n" , e), r#"
# /// # src/lib.rs:20: func1 error
# /// # Caused by:
# /// # src/lib.rs:15: Error reading 'foo.txt'
# /// # Caused by:
# /// # Kind(NotFound)
# /// # " #
# /// # );
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# ///
# /// `mstrerr!()` can also be used to map a new `ChainError< T> `, where T was defined with
# /// `derive_str_cherr!(T)`
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! mstrerr {
# ( $t:path, $msg:expr ) => ({
# |e| cherr!(e, $t ($msg.to_string()))
# });
# ( $t:path, $msg:expr, ) => ({
# |e| cherr!(e, $t ($msg.to_string()))
# });
# ( $t:path, $fmt:expr, $($arg:tt)+ ) => ({
# |e| cherr!(e, $t (format!($fmt, $($arg)+ )))
# });
# ($msg:expr) => ({
# |e| cherr!(e, $msg.to_string())
# });
# ($msg:expr, ) => ({
# |e| cherr!(e, $msg.to_string())
# });
# ($fmt:expr, $($arg:tt)+) => ({
# |e| cherr!(e, format!($fmt, $($arg)+ ))
# });
# }
#
# /// Convenience macro for `cherr!(T(format!(…)))` where `T(String)`
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::result::Result;
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> ChainResult< (), Func2Error> {
# /// let filename = " foo.txt" ;
# /// Err(strerr!(Func2Error, " Error reading '{}'" , filename))
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! strerr {
# ( $t:path, $msg:expr ) => ({
# cherr!($t ($msg.to_string()))
# });
# ( $t:path, $msg:expr, ) => ({
# cherr!($t ($msg.to_string()))
# });
# ( $t:path, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!($t (format!($fmt, $($arg)+ )))
# });
# ($msg:expr) => ({
# cherr!($msg.to_string())
# });
# ($msg:expr, ) => ({
# cherr!($msg.to_string())
# });
# ($fmt:expr, $($arg:tt)+) => ({
# cherr!(format!($fmt, $($arg)+ ))
# });
# }
#
# /// Convenience macro to create a " new type" T(String) and implement Display + Debug for T
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> ChainResult< (), Func2Error> {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
2018-12-20 14:55:19 +01:00
# #[macro_export]
# macro_rules! derive_str_cherr {
# ($e:ident) => {
2019-02-07 09:02:01 +01:00
# pub struct $e(pub String);
2018-12-20 14:55:19 +01:00
# impl ::std::fmt::Display for $e {
# fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# write!(f, " {}" , self.0)
# }
# }
# impl ::std::fmt::Debug for $e {
# fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# write!(f, " {}({})" , stringify!($e), self.0)
# }
# }
# impl ::std::error::Error for $e {}
# };
# }
# }
< / code > < / pre > < / pre >
2018-12-20 16:37:43 +01:00
< a class = "header" href = "#selective-error-handling" id = "selective-error-handling" > < h1 > Selective Error Handling< / h1 > < / a >
2018-12-21 13:55:46 +01:00
< p > What about functions returning different Error types?< / p >
< p > In this example < code > func1()< / code > can return either < code > Func1ErrorFunc2< / code > or < code > Func1ErrorIO< / code > .< / p >
< p > We might want to < code > match< / code > on < code > func1()< / code > with something like:< / p >
< pre > < code class = "language-rust ignore" > fn main() -> Result< (), Box< Error> > {
match func1() {
Err(e) if let Some(s) = e.downcast_chain_ref::< Func1ErrorIO> () =>
eprintln!(" Func1ErrorIO:\n{:?}" , s),
Err(e) if let Some(s) = e.downcast_chain_ref::< Func1ErrorFunc2> () =>
eprintln!(" Func1ErrorFunc2:\n{:?}" , s),
Ok(_) => {},
}
Ok(())
}
< / code > < / pre >
< p > but this is not valid rust code, so we end up doing it the hard way.
In the next chapter, we will see, how to solve this more elegantly.< / p >
2019-03-04 11:46:17 +01:00
< pre > < pre class = "playpen" > < code class = "language-rust" > use chainerror::*;
2018-12-20 14:55:19 +01:00
use std::error::Error;
use std::io;
use std::result::Result;
fn do_some_io() -> Result< (), Box< Error> > {
Err(io::Error::from(io::ErrorKind::NotFound))?;
Ok(())
}
derive_str_cherr!(Func2Error);
fn func2() -> Result< (), Box< Error> > {
let filename = " foo.txt" ;
do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
Ok(())
}
derive_str_cherr!(Func1ErrorFunc2);
derive_str_cherr!(Func1ErrorIO);
fn func1() -> Result< (), Box< Error> > {
func2().map_err(mstrerr!(Func1ErrorFunc2, " func1 error calling func2" ))?;
let filename = " bar.txt" ;
do_some_io().map_err(mstrerr!(Func1ErrorIO, " Error reading '{}'" , filename))?;
Ok(())
}
fn main() -> Result< (), Box< Error> > {
if let Err(e) = func1() {
if let Some(s) = e.downcast_ref::< ChainError< Func1ErrorIO> > () {
eprintln!(" Func1ErrorIO:\n{:?}" , s);
}
2018-12-21 13:55:46 +01:00
if let Some(s) = e.downcast_chain_ref::< Func1ErrorFunc2> () {
2018-12-20 14:55:19 +01:00
eprintln!(" Func1ErrorFunc2:\n{:?}" , s);
}
}
Ok(())
}
2019-03-04 11:46:17 +01:00
2018-12-20 14:55:19 +01:00
# #[allow(dead_code)]
# mod chainerror {
2019-02-07 09:02:01 +01:00
# //! `chainerror` provides an error backtrace without doing a real backtrace, so even after you `strip` your
# //! binaries, you still have the error backtrace.
# //!
# //! `chainerror` has no dependencies!
# //!
# //! `chainerror` uses `.source()` of `std::error::Error` along with `line()!` and `file()!` to provide a nice debug error backtrace.
# //! It encapsulates all types, which have `Display + Debug` and can store the error cause internally.
# //!
# //! Along with the `ChainError< T> ` struct, `chainerror` comes with some useful helper macros to save a lot of typing.
# //!
# //! ## Features
# //!
# //! `no-fileline`
# //! : completely turn off storing filename and line
# //!
# //! `display-cause`
# //! : turn on printing a backtrace of the errors in `Display`
# //!
# //! `no-debug-cause`
# //! : turn off printing a backtrace of the errors in `Debug`
# //!
# //!
# //! # Tutorial
# //!
# //! Read the [Tutorial](https://haraldh.github.io/chainerror/tutorial1.html)
# //!
# //! # Examples
# //!
# //! ~~~rust
# //! use chainerror::*;
# //! use std::error::Error;
# //! use std::io;
# //! use std::result::Result;
# //!
# //! fn do_some_io() -> Result< (), Box< Error> > {
# //! Err(io::Error::from(io::ErrorKind::NotFound))?;
# //! Ok(())
# //! }
# //!
# //! fn func2() -> Result< (), Box< Error> > {
# //! let filename = " foo.txt" ;
# //! do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# //! Ok(())
# //! }
# //!
# //! fn func1() -> Result< (), Box< Error> > {
# //! func2().map_err(mstrerr!(" func1 error" ))?;
# //! Ok(())
# //! }
# //!
# //! fn main() {
# //! if let Err(e) = func1() {
# //! #[cfg(not(windows))]
# //! assert_eq!(
# //! format!(" \n{:?}\n" , e), r#"
# //! src/lib.rs:20: func1 error
# //! Caused by:
# //! src/lib.rs:15: Error reading 'foo.txt'
# //! Caused by:
# //! Kind(NotFound)
# //! " #
# //! );
# //! }
# //! # else {
# //! # unreachable!();
# //! # }
# //! }
# //! ~~~
# //!
# //!
# //! ~~~rust
# //! use chainerror::*;
# //! use std::error::Error;
# //! use std::io;
# //! use std::result::Result;
# //!
# //! fn do_some_io() -> Result< (), Box< Error> > {
# //! Err(io::Error::from(io::ErrorKind::NotFound))?;
# //! Ok(())
# //! }
# //!
# //! fn func3() -> Result< (), Box< Error> > {
# //! let filename = " foo.txt" ;
# //! do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# //! Ok(())
# //! }
# //!
# //! derive_str_cherr!(Func2Error);
# //!
# //! fn func2() -> ChainResult< (), Func2Error> {
# //! func3().map_err(mstrerr!(Func2Error, " func2 error: calling func3" ))?;
# //! Ok(())
# //! }
# //!
# //! enum Func1Error {
# //! Func2,
# //! IO(String),
# //! }
# //!
# //! impl ::std::fmt::Display for Func1Error {
# //! fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# //! match self {
# //! Func1Error::Func2 => write!(f, " func1 error calling func2" ),
# //! Func1Error::IO(filename) => write!(f, " Error reading '{}'" , filename),
# //! }
# //! }
# //! }
# //!
# //! impl ::std::fmt::Debug for Func1Error {
# //! fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# //! write!(f, " {}" , self)
# //! }
# //! }
# //!
# //! fn func1() -> ChainResult< (), Func1Error> {
# //! func2().map_err(|e| cherr!(e, Func1Error::Func2))?;
# //! let filename = String::from(" bar.txt" );
# //! do_some_io().map_err(|e| cherr!(e, Func1Error::IO(filename)))?;
# //! Ok(())
# //! }
# //!
# //! fn main() {
# //! if let Err(e) = func1() {
# //! assert!(
# //! match e.kind() {
# //! Func1Error::Func2 => {
# //! eprintln!(" Main Error Report: func1 error calling func2" );
# //! true
# //! }
# //! Func1Error::IO(filename) => {
# //! eprintln!(" Main Error Report: func1 error reading '{}'" , filename);
# //! false
# //! }
# //! }
# //! );
# //!
# //! assert!(e.find_chain_cause::< Func2Error> ().is_some());
# //!
# //! if let Some(e) = e.find_chain_cause::< Func2Error> () {
# //! eprintln!(" \nError reported by Func2Error: {}" , e)
# //! }
# //!
# //!
# //! assert!(e.root_cause().is_some());
# //!
# //! if let Some(e) = e.root_cause() {
# //! let ioerror = e.downcast_ref::< io::Error> ().unwrap();
# //! eprintln!(" \nThe root cause was: std::io::Error: {:#?}" , ioerror);
# //! }
# //!
# //! #[cfg(not(windows))]
# //! assert_eq!(
# //! format!(" \n{:?}\n" , e), r#"
# //! src/lib.rs:47: func1 error calling func2
# //! Caused by:
# //! src/lib.rs:22: Func2Error(func2 error: calling func3)
# //! Caused by:
# //! src/lib.rs:15: Error reading 'foo.txt'
# //! Caused by:
# //! Kind(NotFound)
# //! " #
# //! );
# //! }
# //! # else {
# //! # unreachable!();
# //! # }
# //! }
# //! ~~~
2018-12-21 13:55:46 +01:00
#
# use std::any::TypeId;
2018-12-20 14:55:19 +01:00
# use std::error::Error;
# use std::fmt::{Debug, Display, Formatter, Result};
#
2019-02-07 09:02:01 +01:00
# /// chains an inner error kind `T` with a causing error
2018-12-20 14:55:19 +01:00
# pub struct ChainError< T> {
# #[cfg(not(feature = " no-fileline" ))]
# occurrence: Option< (u32, & 'static str)> ,
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# }
#
2018-12-21 13:55:46 +01:00
# /// convenience type alias
# pub type ChainResult< O, E> = std::result::Result< O, ChainError< E> > ;
2018-12-20 14:55:19 +01:00
#
# impl< T: 'static + Display + Debug> ChainError< T> {
# #[cfg(not(feature = " no-fileline" ))]
2018-12-21 13:55:46 +01:00
# /// Use the `cherr!()` or `mstrerr!()` macro instead of calling this directly
2018-12-20 14:55:19 +01:00
# pub fn new(
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# occurrence: Option< (u32, & 'static str)> ,
# ) -> Self {
# Self {
# occurrence,
# kind,
# error_cause,
# }
# }
#
# #[cfg(feature = " no-fileline" )]
2018-12-21 13:55:46 +01:00
# /// Use the `cherr!()` or `mstrerr!()` macro instead of calling this directly
2018-12-20 14:55:19 +01:00
# pub fn new(
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# _occurrence: Option< (u32, & 'static str)> ,
# ) -> Self {
# Self { kind, error_cause }
# }
#
2018-12-21 13:55:46 +01:00
# /// return the root cause of the error chain, if any exists
2018-12-20 14:55:19 +01:00
# pub fn root_cause(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.iter().last()
# }
#
# /// Find the first error cause of type U, if any exists
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// fn do_some_io() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# ///
# /// fn main() {
# /// if let Err(e) = func1() {
# /// if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# ///
# /// assert!(f1err.find_cause::< io::Error> ().is_some());
# ///
# /// assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// }
# /// # else {
# /// # panic!();
# /// # }
# /// }
# /// # else {
# /// # unreachable!();
# /// # }
# /// }
# /// ~~~
# pub fn find_cause< U: Error + 'static> (& self) -> Option< & U> {
# self.iter().filter_map(Error::downcast_ref::< U> ).next()
# }
#
# /// Find the first error cause of type `ChainError< U> `, if any exists
# ///
# /// Same as `find_cause`, but hides the `ChainError< U> ` implementation internals
# ///
# /// # Examples
# ///
# /// ~~~rust,ignore
# /// // Instead of writing
# /// err.find_cause::< ChainError< FooError> > ();
# ///
# /// // leave out the ChainError< FooError> implementation detail
# /// err.find_chain_cause::< FooError> ();
# /// ~~~
# pub fn find_chain_cause< U: Error + 'static> (& self) -> Option< & ChainError< U> > {
# self.iter()
# .filter_map(Error::downcast_ref::< ChainError< U> > )
# .next()
# }
#
# /// Find the first error cause of type `ChainError< U> ` or `U`, if any exists and return `U`
# ///
# /// Same as `find_cause` and `find_chain_cause`, but hides the `ChainError< U> ` implementation internals
# ///
# /// # Examples
# ///
# /// ~~~rust,ignore
# /// // Instead of writing
# /// err.find_cause::< ChainError< FooErrorKind> > ();
# /// // and/or
# /// err.find_chain_cause::< FooErrorKind> ();
# /// // and/or
# /// err.find_cause::< FooErrorKind> ();
# ///
# /// // leave out the ChainError< FooErrorKind> implementation detail
# /// err.find_chain_or_kind::< FooErrorKind> ();
# /// ~~~
# pub fn find_kind_or_cause< U: Error + 'static> (& self) -> Option< & U> {
# self.iter()
# .filter_map(|e| {
# e.downcast_ref::< ChainError< U> > ()
# .map(|e| e.kind())
# .or_else(|| e.downcast_ref::< U> ())
# })
# .next()
# }
#
# /// Return a reference to T of `ChainError< T> `
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// fn do_some_io() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// #[derive(Debug)]
# /// enum Func1ErrorKind {
# /// Func2,
# /// IO(String),
# /// }
# ///
# /// /// impl ::std::fmt::Display for Func1ErrorKind {…}
# /// # impl ::std::fmt::Display for Func1ErrorKind {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # Func1ErrorKind::Func2 => write!(f, " func1 error calling func2" ),
# /// # Func1ErrorKind::IO(filename) => write!(f, " Error reading '{}'" , filename),
# /// # }
# /// # }
# /// # }
# ///
# /// fn func1() -> ChainResult< (), Func1ErrorKind> {
# /// func2().map_err(|e| cherr!(e, Func1ErrorKind::Func2))?;
# /// do_some_io().map_err(|e| cherr!(e, Func1ErrorKind::IO(" bar.txt" .into())))?;
# /// Ok(())
# /// }
# ///
# /// fn main() {
# /// if let Err(e) = func1() {
# /// match e.kind() {
# /// Func1ErrorKind::Func2 => {},
# /// Func1ErrorKind::IO(filename) => panic!(),
# /// }
# /// }
# /// # else {
# /// # unreachable!();
# /// # }
# /// }
# /// ~~~
# pub fn kind(& self) -> & T {
# & self.kind
# }
#
# /// Returns an Iterator over all error causes/sources
# ///
# /// # Example
# ///
# ///
# pub fn iter(& self) -> impl Iterator< Item = & (dyn Error + 'static)> {
# ErrorIter {
# current: Some(self),
2018-12-20 14:55:19 +01:00
# }
# }
2019-02-07 09:02:01 +01:00
# }
2018-12-20 14:55:19 +01:00
#
2019-02-07 09:02:01 +01:00
# struct ErrorIter< 'a> {
# current: Option< & 'a (dyn Error + 'static)> ,
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# impl< 'a> Iterator for ErrorIter< 'a> {
# type Item = & 'a (dyn Error + 'static);
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# fn next(& mut self) -> Option< Self::Item> {
# let current = self.current;
# self.current = self.current.and_then(Error::source);
# current
2018-12-21 13:55:46 +01:00
# }
2019-02-07 09:02:01 +01:00
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# impl< T: 'static + Display + Debug> std::ops::Deref for ChainError< T> {
# type Target = T;
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# fn deref(& self) -> & Self::Target {
# & self.kind
2018-12-21 13:55:46 +01:00
# }
2019-02-07 09:02:01 +01:00
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# /// Convenience trait to hide the `ChainError< T> ` implementation internals
# pub trait ChainErrorDown {
# /// Test if of type `ChainError< T> `
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool;
# /// Downcast to a reference of `ChainError< T> `
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > ;
# /// Downcast to a mutable reference of `ChainError< T> `
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > ;
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# impl< U: 'static + Display + Debug> ChainErrorDown for ChainError< U> {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# TypeId::of::< T> () == TypeId::of::< U> ()
2018-12-21 13:55:46 +01:00
# }
#
2019-02-07 09:02:01 +01:00
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# if self.is_chain::< T> () {
# #[allow(clippy::cast_ptr_alignment)]
# unsafe {
# Some(& *(self as *const dyn Error as *const & ChainError< T> ))
2018-12-21 13:55:46 +01:00
# }
2019-02-07 09:02:01 +01:00
# } else {
# None
2018-12-21 13:55:46 +01:00
# }
# }
2018-12-20 14:55:19 +01:00
#
2019-02-07 09:02:01 +01:00
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# if self.is_chain::< T> () {
# #[allow(clippy::cast_ptr_alignment)]
# unsafe {
# Some(& mut *(self as *mut dyn Error as *mut & mut ChainError< T> ))
2018-12-20 14:55:19 +01:00
# }
2019-02-07 09:02:01 +01:00
# } else {
# None
2018-12-20 14:55:19 +01:00
# }
# }
2019-02-07 09:02:01 +01:00
# }
2018-12-20 14:55:19 +01:00
#
2019-02-07 09:02:01 +01:00
# impl ChainErrorDown for dyn Error + 'static {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
2018-12-20 14:55:19 +01:00
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl ChainErrorDown for dyn Error + 'static + Send {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl ChainErrorDown for dyn Error + 'static + Send + Sync {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl< T: 'static + Display + Debug> Error for ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.error_cause.as_ref().map(|e| e.as_ref())
2018-12-20 14:55:19 +01:00
# }
# }
#
# impl< T: 'static + Display + Debug> Error for & ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.error_cause.as_ref().map(|e| e.as_ref())
2018-12-20 14:55:19 +01:00
# }
# }
#
# impl< T: 'static + Display + Debug> Error for & mut ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.error_cause.as_ref().map(|e| e.as_ref())
2018-12-20 14:55:19 +01:00
# }
# }
#
# impl< T: 'static + Display + Debug> Display for ChainError< T> {
# fn fmt(& self, f: & mut Formatter) -> Result {
# write!(f, " {}" , self.kind)?;
#
# #[cfg(feature = " display-cause" )]
# {
# if let Some(e) = self.source() {
# writeln!(f, " \nCaused by:" )?;
# Display::fmt(& e, f)?;
# }
# }
# Ok(())
# }
# }
#
# impl< T: 'static + Display + Debug> Debug for ChainError< T> {
# fn fmt(& self, f: & mut Formatter) -> Result {
# #[cfg(not(feature = " no-fileline" ))]
# {
# if let Some(o) = self.occurrence {
# write!(f, " {}:{}: " , o.1, o.0)?;
# }
# }
#
2018-12-21 13:55:46 +01:00
# if self.is_chain::< String> () {
# Display::fmt(& self.kind, f)?;
# } else {
# Debug::fmt(& self.kind, f)?;
# }
2018-12-20 14:55:19 +01:00
#
# #[cfg(not(feature = " no-debug-cause" ))]
# {
# if let Some(e) = self.source() {
# writeln!(f, " \nCaused by:" )?;
# Debug::fmt(& e, f)?;
# }
# }
# Ok(())
# }
# }
#
2019-02-07 09:02:01 +01:00
# pub trait ChainErrorFrom< T> : Sized {
# fn chain_error_from(_: T, line_filename: Option< (u32, & 'static str)> ) -> ChainError< Self> ;
# }
#
# pub trait IntoChainError< T> : Sized {
# fn into_chain_error(self, line_filename: Option< (u32, & 'static str)> ) -> ChainError< T> ;
# }
#
# impl< T, U> IntoChainError< U> for T
# where
# U: ChainErrorFrom< T> ,
# {
# fn into_chain_error(self, line_filename: Option< (u32, & 'static str)> ) -> ChainError< U> {
# U::chain_error_from(self, line_filename)
# }
# }
#
# impl< T, U> ChainErrorFrom< T> for U
# where
# T: Into< U> ,
# U: 'static + Display + Debug,
# {
# fn chain_error_from(t: T, line_filename: Option< (u32, & 'static str)> ) -> ChainError< Self> {
# let e: U = t.into();
# ChainError::< _> ::new(e, None, line_filename)
# }
# }
#
2018-12-20 14:55:19 +01:00
# #[macro_export]
2019-02-07 09:02:01 +01:00
# macro_rules! minto_cherr {
# ( ) => {
# |e| e.into_chain_error(Some((line!(), file!())))
2018-12-20 14:55:19 +01:00
# };
# }
#
# #[macro_export]
2019-02-07 09:02:01 +01:00
# macro_rules! into_cherr {
# ( $t:expr ) => {
# $t.into_chain_error(Some((line!(), file!())))
2018-12-20 14:55:19 +01:00
# };
# }
#
2019-02-07 09:02:01 +01:00
# /// Creates a new `ChainError< T> `
# ///
# /// # Examples
# ///
# /// Create a new ChainError< FooError> , where `FooError` must implement `Display` and `Debug`.
# /// ~~~rust
# /// # use chainerror::*;
# /// #
# /// # #[derive(Debug)]
# /// enum FooError {
# /// Bar,
# /// Baz(& 'static str),
# /// }
# /// #
# /// # impl ::std::fmt::Display for FooError {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # FooError::Bar => write!(f, " Bar Error" ),
# /// # FooError::Baz(s) => write!(f, " Baz Error: '{}'" , s),
# /// # }
# /// # }
# /// # }
# ///
# /// // impl ::std::fmt::Display for FooError
# ///
# /// fn do_some_stuff() -> bool {
# /// false
# /// }
# ///
# /// fn func() -> ChainResult< (), FooError> {
# /// if ! do_some_stuff() {
# /// Err(cherr!(FooError::Baz(" Error" )))?;
# /// }
# /// Ok(())
# /// }
# /// #
# /// # pub fn main() {
# /// # match func().unwrap_err().kind() {
# /// # FooError::Baz(s) if s == & " Error" => {},
# /// # _ => panic!(),
# /// # }
# /// # }
# /// ~~~
# ///
# /// Additionally an error cause can be added.
# ///
# /// ~~~rust
# /// # use chainerror::*;
# /// # use std::io;
# /// # use std::error::Error;
# /// #
# /// # #[derive(Debug)]
# /// # enum FooError {
# /// # Bar,
# /// # Baz(& 'static str),
# /// # }
# /// #
# /// # impl ::std::fmt::Display for FooError {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # FooError::Bar => write!(f, " Bar Error" ),
# /// # FooError::Baz(s) => write!(f, " Baz Error: '{}'" , s),
# /// # }
# /// # }
# /// # }
# /// #
# /// fn do_some_stuff() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// fn func() -> ChainResult< (), FooError> {
# /// do_some_stuff().map_err(
# /// |e| cherr!(e, FooError::Baz(" Error" ))
# /// )?;
# /// Ok(())
# /// }
# /// #
# /// # pub fn main() {
# /// # match func().unwrap_err().kind() {
# /// # FooError::Baz(s) if s == & " Error" => {},
# /// # _ => panic!(),
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! cherr {
# ( $k:expr ) => ({
# ChainError::< _> ::new($k, None, Some((line!(), file!())))
# });
# ( None, $k:expr ) => ({
# ChainError::< _> ::new($k, None, Some((line!(), file!())))
# });
# ( None, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!(None, format!($fmt, $($arg)+ ))
# });
# ( None, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!(None, format!($fmt, $($arg)+ ))
# });
# ( $e:path, $k:expr ) => ({
# ChainError::< _> ::new($k, Some(Box::from($e)), Some((line!(), file!())))
# });
# ( $e:path, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!($e, format!($fmt, $($arg)+ ))
# });
#
# }
#
# /// Convenience macro for `|e| cherr!(e, format!(…))`
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(" func1 error" ))?;
# /// Ok(())
# /// }
# ///
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # #[cfg(not(windows))]
# /// # assert_eq!(
# /// # format!(" \n{:?}\n" , e), r#"
# /// # src/lib.rs:20: func1 error
# /// # Caused by:
# /// # src/lib.rs:15: Error reading 'foo.txt'
# /// # Caused by:
# /// # Kind(NotFound)
# /// # " #
# /// # );
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# ///
# /// `mstrerr!()` can also be used to map a new `ChainError< T> `, where T was defined with
# /// `derive_str_cherr!(T)`
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! mstrerr {
# ( $t:path, $msg:expr ) => ({
# |e| cherr!(e, $t ($msg.to_string()))
# });
# ( $t:path, $msg:expr, ) => ({
# |e| cherr!(e, $t ($msg.to_string()))
# });
# ( $t:path, $fmt:expr, $($arg:tt)+ ) => ({
# |e| cherr!(e, $t (format!($fmt, $($arg)+ )))
# });
# ($msg:expr) => ({
# |e| cherr!(e, $msg.to_string())
# });
# ($msg:expr, ) => ({
# |e| cherr!(e, $msg.to_string())
# });
# ($fmt:expr, $($arg:tt)+) => ({
# |e| cherr!(e, format!($fmt, $($arg)+ ))
# });
# }
#
# /// Convenience macro for `cherr!(T(format!(…)))` where `T(String)`
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::result::Result;
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> ChainResult< (), Func2Error> {
# /// let filename = " foo.txt" ;
# /// Err(strerr!(Func2Error, " Error reading '{}'" , filename))
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! strerr {
# ( $t:path, $msg:expr ) => ({
# cherr!($t ($msg.to_string()))
# });
# ( $t:path, $msg:expr, ) => ({
# cherr!($t ($msg.to_string()))
# });
# ( $t:path, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!($t (format!($fmt, $($arg)+ )))
# });
# ($msg:expr) => ({
# cherr!($msg.to_string())
# });
# ($msg:expr, ) => ({
# cherr!($msg.to_string())
# });
# ($fmt:expr, $($arg:tt)+) => ({
# cherr!(format!($fmt, $($arg)+ ))
# });
# }
#
# /// Convenience macro to create a " new type" T(String) and implement Display + Debug for T
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> ChainResult< (), Func2Error> {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
2018-12-20 14:55:19 +01:00
# #[macro_export]
# macro_rules! derive_str_cherr {
# ($e:ident) => {
2019-02-07 09:02:01 +01:00
# pub struct $e(pub String);
2018-12-20 14:55:19 +01:00
# impl ::std::fmt::Display for $e {
# fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# write!(f, " {}" , self.0)
# }
# }
# impl ::std::fmt::Debug for $e {
# fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# write!(f, " {}({})" , stringify!($e), self.0)
# }
# }
# impl ::std::error::Error for $e {}
# };
# }
# }
< / code > < / pre > < / pre >
2018-12-20 16:37:43 +01:00
< a class = "header" href = "#errorkind-to-the-rescue" id = "errorkind-to-the-rescue" > < h1 > ErrorKind to the rescue< / h1 > < / a >
2018-12-21 13:55:46 +01:00
< p > To cope with different kind of errors, we introduce the kind of an error < code > Func1ErrorKind< / code > with an enum.< / p >
< p > Because we derive < code > Debug< / code > and implement < code > Display< / code > our < code > Func1ErrorKind< / code > enum, this enum can be used as
a < code > std::error::Error< / code > .< / p >
< p > Not using < code > String< / code > errors anymore, the < code > cherr!()< / code > macro seen in the beginning of
the tutorial has to be used again.< / p >
< p > Only returning < code > Func1ErrorKind< / code > in < code > func1()< / code > now let us get rid of < code > Result< (), Box< Error> > < / code > and we can
use < code > ChainResult< (), Func1ErrorKind> < / code > .< / p >
< p > In < code > main< / code > we can now directly use the methods of < code > ChainError< T> < / code > without downcasting the error first.< / p >
< p > Also a nice < code > match< / code > on < code > ChainError< T> .kind()< / code > is now possible, which returns < code > & T< / code > , meaning
< code > & Func1ErrorKind< / code > here.< / p >
2019-03-04 11:46:17 +01:00
< pre > < pre class = "playpen" > < code class = "language-rust" > use chainerror::*;
2018-12-20 14:55:19 +01:00
use std::error::Error;
use std::io;
use std::result::Result;
fn do_some_io() -> Result< (), Box< Error> > {
Err(io::Error::from(io::ErrorKind::NotFound))?;
Ok(())
}
derive_str_cherr!(Func2Error);
fn func2() -> Result< (), Box< Error> > {
let filename = " foo.txt" ;
do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
Ok(())
}
#[derive(Debug)]
2018-12-21 13:55:46 +01:00
enum Func1ErrorKind {
2018-12-20 14:55:19 +01:00
Func2,
IO(String),
}
2018-12-21 13:55:46 +01:00
impl ::std::fmt::Display for Func1ErrorKind {
2018-12-20 14:55:19 +01:00
fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
match self {
2018-12-21 13:55:46 +01:00
Func1ErrorKind::Func2 => write!(f, " func1 error calling func2" ),
Func1ErrorKind::IO(filename) => write!(f, " Error reading '{}'" , filename),
2018-12-20 14:55:19 +01:00
}
}
}
2019-02-07 09:02:01 +01:00
impl ::std::error::Error for Func1ErrorKind {}
2018-12-20 14:55:19 +01:00
2018-12-21 13:55:46 +01:00
fn func1() -> ChainResult< (), Func1ErrorKind> {
func2().map_err(|e| cherr!(e, Func1ErrorKind::Func2))?;
2018-12-20 14:55:19 +01:00
let filename = String::from(" bar.txt" );
2018-12-21 13:55:46 +01:00
do_some_io().map_err(|e| cherr!(e, Func1ErrorKind::IO(filename)))?;
2018-12-20 14:55:19 +01:00
Ok(())
}
fn main() -> Result< (), Box< Error> > {
if let Err(e) = func1() {
match e.kind() {
2018-12-21 13:55:46 +01:00
Func1ErrorKind::Func2 => eprintln!(" Main Error Report: func1 error calling func2" ),
Func1ErrorKind::IO(filename) => {
2018-12-20 14:55:19 +01:00
eprintln!(" Main Error Report: func1 error reading '{}'" , filename)
}
}
if let Some(e) = e.find_chain_cause::< Func2Error> () {
2018-12-21 13:55:46 +01:00
eprintln!(" \nError reported by Func2Error: {}" , e)
2018-12-20 14:55:19 +01:00
}
eprintln!(" \nDebug Error:\n{:?}" , e);
}
Ok(())
}
2019-03-04 11:46:17 +01:00
2018-12-20 14:55:19 +01:00
# #[allow(dead_code)]
# mod chainerror {
2019-02-07 09:02:01 +01:00
# //! `chainerror` provides an error backtrace without doing a real backtrace, so even after you `strip` your
# //! binaries, you still have the error backtrace.
# //!
# //! `chainerror` has no dependencies!
# //!
# //! `chainerror` uses `.source()` of `std::error::Error` along with `line()!` and `file()!` to provide a nice debug error backtrace.
# //! It encapsulates all types, which have `Display + Debug` and can store the error cause internally.
# //!
# //! Along with the `ChainError< T> ` struct, `chainerror` comes with some useful helper macros to save a lot of typing.
# //!
# //! ## Features
# //!
# //! `no-fileline`
# //! : completely turn off storing filename and line
# //!
# //! `display-cause`
# //! : turn on printing a backtrace of the errors in `Display`
# //!
# //! `no-debug-cause`
# //! : turn off printing a backtrace of the errors in `Debug`
# //!
# //!
# //! # Tutorial
# //!
# //! Read the [Tutorial](https://haraldh.github.io/chainerror/tutorial1.html)
# //!
# //! # Examples
# //!
# //! ~~~rust
# //! use chainerror::*;
# //! use std::error::Error;
# //! use std::io;
# //! use std::result::Result;
# //!
# //! fn do_some_io() -> Result< (), Box< Error> > {
# //! Err(io::Error::from(io::ErrorKind::NotFound))?;
# //! Ok(())
# //! }
# //!
# //! fn func2() -> Result< (), Box< Error> > {
# //! let filename = " foo.txt" ;
# //! do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# //! Ok(())
# //! }
# //!
# //! fn func1() -> Result< (), Box< Error> > {
# //! func2().map_err(mstrerr!(" func1 error" ))?;
# //! Ok(())
# //! }
# //!
# //! fn main() {
# //! if let Err(e) = func1() {
# //! #[cfg(not(windows))]
# //! assert_eq!(
# //! format!(" \n{:?}\n" , e), r#"
# //! src/lib.rs:20: func1 error
# //! Caused by:
# //! src/lib.rs:15: Error reading 'foo.txt'
# //! Caused by:
# //! Kind(NotFound)
# //! " #
# //! );
# //! }
# //! # else {
# //! # unreachable!();
# //! # }
# //! }
# //! ~~~
# //!
# //!
# //! ~~~rust
# //! use chainerror::*;
# //! use std::error::Error;
# //! use std::io;
# //! use std::result::Result;
# //!
# //! fn do_some_io() -> Result< (), Box< Error> > {
# //! Err(io::Error::from(io::ErrorKind::NotFound))?;
# //! Ok(())
# //! }
# //!
# //! fn func3() -> Result< (), Box< Error> > {
# //! let filename = " foo.txt" ;
# //! do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# //! Ok(())
# //! }
# //!
# //! derive_str_cherr!(Func2Error);
# //!
# //! fn func2() -> ChainResult< (), Func2Error> {
# //! func3().map_err(mstrerr!(Func2Error, " func2 error: calling func3" ))?;
# //! Ok(())
# //! }
# //!
# //! enum Func1Error {
# //! Func2,
# //! IO(String),
# //! }
# //!
# //! impl ::std::fmt::Display for Func1Error {
# //! fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# //! match self {
# //! Func1Error::Func2 => write!(f, " func1 error calling func2" ),
# //! Func1Error::IO(filename) => write!(f, " Error reading '{}'" , filename),
# //! }
# //! }
# //! }
# //!
# //! impl ::std::fmt::Debug for Func1Error {
# //! fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# //! write!(f, " {}" , self)
# //! }
# //! }
# //!
# //! fn func1() -> ChainResult< (), Func1Error> {
# //! func2().map_err(|e| cherr!(e, Func1Error::Func2))?;
# //! let filename = String::from(" bar.txt" );
# //! do_some_io().map_err(|e| cherr!(e, Func1Error::IO(filename)))?;
# //! Ok(())
# //! }
# //!
# //! fn main() {
# //! if let Err(e) = func1() {
# //! assert!(
# //! match e.kind() {
# //! Func1Error::Func2 => {
# //! eprintln!(" Main Error Report: func1 error calling func2" );
# //! true
# //! }
# //! Func1Error::IO(filename) => {
# //! eprintln!(" Main Error Report: func1 error reading '{}'" , filename);
# //! false
# //! }
# //! }
# //! );
# //!
# //! assert!(e.find_chain_cause::< Func2Error> ().is_some());
# //!
# //! if let Some(e) = e.find_chain_cause::< Func2Error> () {
# //! eprintln!(" \nError reported by Func2Error: {}" , e)
# //! }
# //!
# //!
# //! assert!(e.root_cause().is_some());
# //!
# //! if let Some(e) = e.root_cause() {
# //! let ioerror = e.downcast_ref::< io::Error> ().unwrap();
# //! eprintln!(" \nThe root cause was: std::io::Error: {:#?}" , ioerror);
# //! }
# //!
# //! #[cfg(not(windows))]
# //! assert_eq!(
# //! format!(" \n{:?}\n" , e), r#"
# //! src/lib.rs:47: func1 error calling func2
# //! Caused by:
# //! src/lib.rs:22: Func2Error(func2 error: calling func3)
# //! Caused by:
# //! src/lib.rs:15: Error reading 'foo.txt'
# //! Caused by:
# //! Kind(NotFound)
# //! " #
# //! );
# //! }
# //! # else {
# //! # unreachable!();
# //! # }
# //! }
# //! ~~~
2018-12-21 13:55:46 +01:00
#
# use std::any::TypeId;
2018-12-20 14:55:19 +01:00
# use std::error::Error;
# use std::fmt::{Debug, Display, Formatter, Result};
#
2019-02-07 09:02:01 +01:00
# /// chains an inner error kind `T` with a causing error
2018-12-20 14:55:19 +01:00
# pub struct ChainError< T> {
# #[cfg(not(feature = " no-fileline" ))]
# occurrence: Option< (u32, & 'static str)> ,
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# }
#
2018-12-21 13:55:46 +01:00
# /// convenience type alias
# pub type ChainResult< O, E> = std::result::Result< O, ChainError< E> > ;
2018-12-20 14:55:19 +01:00
#
# impl< T: 'static + Display + Debug> ChainError< T> {
# #[cfg(not(feature = " no-fileline" ))]
2018-12-21 13:55:46 +01:00
# /// Use the `cherr!()` or `mstrerr!()` macro instead of calling this directly
2018-12-20 14:55:19 +01:00
# pub fn new(
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# occurrence: Option< (u32, & 'static str)> ,
# ) -> Self {
# Self {
# occurrence,
# kind,
# error_cause,
# }
# }
#
# #[cfg(feature = " no-fileline" )]
2018-12-21 13:55:46 +01:00
# /// Use the `cherr!()` or `mstrerr!()` macro instead of calling this directly
2018-12-20 14:55:19 +01:00
# pub fn new(
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# _occurrence: Option< (u32, & 'static str)> ,
# ) -> Self {
# Self { kind, error_cause }
# }
#
2018-12-21 13:55:46 +01:00
# /// return the root cause of the error chain, if any exists
2018-12-20 14:55:19 +01:00
# pub fn root_cause(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.iter().last()
# }
#
# /// Find the first error cause of type U, if any exists
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// fn do_some_io() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# ///
# /// fn main() {
# /// if let Err(e) = func1() {
# /// if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# ///
# /// assert!(f1err.find_cause::< io::Error> ().is_some());
# ///
# /// assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// }
# /// # else {
# /// # panic!();
# /// # }
# /// }
# /// # else {
# /// # unreachable!();
# /// # }
# /// }
# /// ~~~
# pub fn find_cause< U: Error + 'static> (& self) -> Option< & U> {
# self.iter().filter_map(Error::downcast_ref::< U> ).next()
# }
#
# /// Find the first error cause of type `ChainError< U> `, if any exists
# ///
# /// Same as `find_cause`, but hides the `ChainError< U> ` implementation internals
# ///
# /// # Examples
# ///
# /// ~~~rust,ignore
# /// // Instead of writing
# /// err.find_cause::< ChainError< FooError> > ();
# ///
# /// // leave out the ChainError< FooError> implementation detail
# /// err.find_chain_cause::< FooError> ();
# /// ~~~
# pub fn find_chain_cause< U: Error + 'static> (& self) -> Option< & ChainError< U> > {
# self.iter()
# .filter_map(Error::downcast_ref::< ChainError< U> > )
# .next()
# }
#
# /// Find the first error cause of type `ChainError< U> ` or `U`, if any exists and return `U`
# ///
# /// Same as `find_cause` and `find_chain_cause`, but hides the `ChainError< U> ` implementation internals
# ///
# /// # Examples
# ///
# /// ~~~rust,ignore
# /// // Instead of writing
# /// err.find_cause::< ChainError< FooErrorKind> > ();
# /// // and/or
# /// err.find_chain_cause::< FooErrorKind> ();
# /// // and/or
# /// err.find_cause::< FooErrorKind> ();
# ///
# /// // leave out the ChainError< FooErrorKind> implementation detail
# /// err.find_chain_or_kind::< FooErrorKind> ();
# /// ~~~
# pub fn find_kind_or_cause< U: Error + 'static> (& self) -> Option< & U> {
# self.iter()
# .filter_map(|e| {
# e.downcast_ref::< ChainError< U> > ()
# .map(|e| e.kind())
# .or_else(|| e.downcast_ref::< U> ())
# })
# .next()
# }
#
# /// Return a reference to T of `ChainError< T> `
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// fn do_some_io() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// #[derive(Debug)]
# /// enum Func1ErrorKind {
# /// Func2,
# /// IO(String),
# /// }
# ///
# /// /// impl ::std::fmt::Display for Func1ErrorKind {…}
# /// # impl ::std::fmt::Display for Func1ErrorKind {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # Func1ErrorKind::Func2 => write!(f, " func1 error calling func2" ),
# /// # Func1ErrorKind::IO(filename) => write!(f, " Error reading '{}'" , filename),
# /// # }
# /// # }
# /// # }
# ///
# /// fn func1() -> ChainResult< (), Func1ErrorKind> {
# /// func2().map_err(|e| cherr!(e, Func1ErrorKind::Func2))?;
# /// do_some_io().map_err(|e| cherr!(e, Func1ErrorKind::IO(" bar.txt" .into())))?;
# /// Ok(())
# /// }
# ///
# /// fn main() {
# /// if let Err(e) = func1() {
# /// match e.kind() {
# /// Func1ErrorKind::Func2 => {},
# /// Func1ErrorKind::IO(filename) => panic!(),
# /// }
# /// }
# /// # else {
# /// # unreachable!();
# /// # }
# /// }
# /// ~~~
# pub fn kind(& self) -> & T {
# & self.kind
# }
#
# /// Returns an Iterator over all error causes/sources
# ///
# /// # Example
# ///
# ///
# pub fn iter(& self) -> impl Iterator< Item = & (dyn Error + 'static)> {
# ErrorIter {
# current: Some(self),
2018-12-20 14:55:19 +01:00
# }
# }
2019-02-07 09:02:01 +01:00
# }
2018-12-20 14:55:19 +01:00
#
2019-02-07 09:02:01 +01:00
# struct ErrorIter< 'a> {
# current: Option< & 'a (dyn Error + 'static)> ,
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# impl< 'a> Iterator for ErrorIter< 'a> {
# type Item = & 'a (dyn Error + 'static);
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# fn next(& mut self) -> Option< Self::Item> {
# let current = self.current;
# self.current = self.current.and_then(Error::source);
# current
2018-12-21 13:55:46 +01:00
# }
2019-02-07 09:02:01 +01:00
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# impl< T: 'static + Display + Debug> std::ops::Deref for ChainError< T> {
# type Target = T;
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# fn deref(& self) -> & Self::Target {
# & self.kind
2018-12-21 13:55:46 +01:00
# }
2019-02-07 09:02:01 +01:00
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# /// Convenience trait to hide the `ChainError< T> ` implementation internals
# pub trait ChainErrorDown {
# /// Test if of type `ChainError< T> `
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool;
# /// Downcast to a reference of `ChainError< T> `
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > ;
# /// Downcast to a mutable reference of `ChainError< T> `
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > ;
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# impl< U: 'static + Display + Debug> ChainErrorDown for ChainError< U> {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# TypeId::of::< T> () == TypeId::of::< U> ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# if self.is_chain::< T> () {
# #[allow(clippy::cast_ptr_alignment)]
# unsafe {
# Some(& *(self as *const dyn Error as *const & ChainError< T> ))
# }
# } else {
# None
# }
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# if self.is_chain::< T> () {
# #[allow(clippy::cast_ptr_alignment)]
# unsafe {
# Some(& mut *(self as *mut dyn Error as *mut & mut ChainError< T> ))
# }
# } else {
# None
# }
# }
# }
#
# impl ChainErrorDown for dyn Error + 'static {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl ChainErrorDown for dyn Error + 'static + Send {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl ChainErrorDown for dyn Error + 'static + Send + Sync {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
2018-12-21 13:55:46 +01:00
# }
#
2019-02-07 09:02:01 +01:00
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl< T: 'static + Display + Debug> Error for ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
# self.error_cause.as_ref().map(|e| e.as_ref())
# }
# }
#
# impl< T: 'static + Display + Debug> Error for & ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
# self.error_cause.as_ref().map(|e| e.as_ref())
# }
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# impl< T: 'static + Display + Debug> Error for & mut ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
# self.error_cause.as_ref().map(|e| e.as_ref())
# }
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# impl< T: 'static + Display + Debug> Display for ChainError< T> {
# fn fmt(& self, f: & mut Formatter) -> Result {
# write!(f, " {}" , self.kind)?;
#
# #[cfg(feature = " display-cause" )]
# {
# if let Some(e) = self.source() {
# writeln!(f, " \nCaused by:" )?;
# Display::fmt(& e, f)?;
2018-12-21 13:55:46 +01:00
# }
# }
2019-02-07 09:02:01 +01:00
# Ok(())
2018-12-21 13:55:46 +01:00
# }
2019-02-07 09:02:01 +01:00
# }
#
# impl< T: 'static + Display + Debug> Debug for ChainError< T> {
# fn fmt(& self, f: & mut Formatter) -> Result {
# #[cfg(not(feature = " no-fileline" ))]
# {
# if let Some(o) = self.occurrence {
# write!(f, " {}:{}: " , o.1, o.0)?;
2018-12-20 14:55:19 +01:00
# }
2019-02-07 09:02:01 +01:00
# }
#
# if self.is_chain::< String> () {
# Display::fmt(& self.kind, f)?;
# } else {
# Debug::fmt(& self.kind, f)?;
# }
2018-12-20 14:55:19 +01:00
#
2019-02-07 09:02:01 +01:00
# #[cfg(not(feature = " no-debug-cause" ))]
# {
# if let Some(e) = self.source() {
# writeln!(f, " \nCaused by:" )?;
# Debug::fmt(& e, f)?;
2018-12-20 14:55:19 +01:00
# }
# }
2019-02-07 09:02:01 +01:00
# Ok(())
2018-12-20 14:55:19 +01:00
# }
2019-02-07 09:02:01 +01:00
# }
2018-12-20 14:55:19 +01:00
#
2019-02-07 09:02:01 +01:00
# pub trait ChainErrorFrom< T> : Sized {
# fn chain_error_from(_: T, line_filename: Option< (u32, & 'static str)> ) -> ChainError< Self> ;
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# pub trait IntoChainError< T> : Sized {
# fn into_chain_error(self, line_filename: Option< (u32, & 'static str)> ) -> ChainError< T> ;
# }
#
# impl< T, U> IntoChainError< U> for T
# where
# U: ChainErrorFrom< T> ,
# {
# fn into_chain_error(self, line_filename: Option< (u32, & 'static str)> ) -> ChainError< U> {
# U::chain_error_from(self, line_filename)
# }
# }
#
# impl< T, U> ChainErrorFrom< T> for U
# where
# T: Into< U> ,
# U: 'static + Display + Debug,
# {
# fn chain_error_from(t: T, line_filename: Option< (u32, & 'static str)> ) -> ChainError< Self> {
# let e: U = t.into();
# ChainError::< _> ::new(e, None, line_filename)
# }
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# #[macro_export]
# macro_rules! minto_cherr {
# ( ) => {
# |e| e.into_chain_error(Some((line!(), file!())))
# };
# }
#
# #[macro_export]
# macro_rules! into_cherr {
# ( $t:expr ) => {
# $t.into_chain_error(Some((line!(), file!())))
# };
# }
#
# /// Creates a new `ChainError< T> `
# ///
# /// # Examples
# ///
# /// Create a new ChainError< FooError> , where `FooError` must implement `Display` and `Debug`.
# /// ~~~rust
# /// # use chainerror::*;
# /// #
# /// # #[derive(Debug)]
# /// enum FooError {
# /// Bar,
# /// Baz(& 'static str),
# /// }
# /// #
# /// # impl ::std::fmt::Display for FooError {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # FooError::Bar => write!(f, " Bar Error" ),
# /// # FooError::Baz(s) => write!(f, " Baz Error: '{}'" , s),
# /// # }
# /// # }
# /// # }
# ///
# /// // impl ::std::fmt::Display for FooError
# ///
# /// fn do_some_stuff() -> bool {
# /// false
# /// }
# ///
# /// fn func() -> ChainResult< (), FooError> {
# /// if ! do_some_stuff() {
# /// Err(cherr!(FooError::Baz(" Error" )))?;
# /// }
# /// Ok(())
# /// }
# /// #
# /// # pub fn main() {
# /// # match func().unwrap_err().kind() {
# /// # FooError::Baz(s) if s == & " Error" => {},
# /// # _ => panic!(),
# /// # }
# /// # }
# /// ~~~
# ///
# /// Additionally an error cause can be added.
# ///
# /// ~~~rust
# /// # use chainerror::*;
# /// # use std::io;
# /// # use std::error::Error;
# /// #
# /// # #[derive(Debug)]
# /// # enum FooError {
# /// # Bar,
# /// # Baz(& 'static str),
# /// # }
# /// #
# /// # impl ::std::fmt::Display for FooError {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # FooError::Bar => write!(f, " Bar Error" ),
# /// # FooError::Baz(s) => write!(f, " Baz Error: '{}'" , s),
# /// # }
# /// # }
# /// # }
# /// #
# /// fn do_some_stuff() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// fn func() -> ChainResult< (), FooError> {
# /// do_some_stuff().map_err(
# /// |e| cherr!(e, FooError::Baz(" Error" ))
# /// )?;
# /// Ok(())
# /// }
# /// #
# /// # pub fn main() {
# /// # match func().unwrap_err().kind() {
# /// # FooError::Baz(s) if s == & " Error" => {},
# /// # _ => panic!(),
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! cherr {
# ( $k:expr ) => ({
# ChainError::< _> ::new($k, None, Some((line!(), file!())))
# });
# ( None, $k:expr ) => ({
# ChainError::< _> ::new($k, None, Some((line!(), file!())))
# });
# ( None, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!(None, format!($fmt, $($arg)+ ))
# });
# ( None, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!(None, format!($fmt, $($arg)+ ))
# });
# ( $e:path, $k:expr ) => ({
# ChainError::< _> ::new($k, Some(Box::from($e)), Some((line!(), file!())))
# });
# ( $e:path, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!($e, format!($fmt, $($arg)+ ))
# });
#
# }
#
# /// Convenience macro for `|e| cherr!(e, format!(…))`
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(" func1 error" ))?;
# /// Ok(())
# /// }
# ///
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # #[cfg(not(windows))]
# /// # assert_eq!(
# /// # format!(" \n{:?}\n" , e), r#"
# /// # src/lib.rs:20: func1 error
# /// # Caused by:
# /// # src/lib.rs:15: Error reading 'foo.txt'
# /// # Caused by:
# /// # Kind(NotFound)
# /// # " #
# /// # );
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# ///
# /// `mstrerr!()` can also be used to map a new `ChainError< T> `, where T was defined with
# /// `derive_str_cherr!(T)`
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! mstrerr {
# ( $t:path, $msg:expr ) => ({
# |e| cherr!(e, $t ($msg.to_string()))
# });
# ( $t:path, $msg:expr, ) => ({
# |e| cherr!(e, $t ($msg.to_string()))
# });
# ( $t:path, $fmt:expr, $($arg:tt)+ ) => ({
# |e| cherr!(e, $t (format!($fmt, $($arg)+ )))
# });
# ($msg:expr) => ({
# |e| cherr!(e, $msg.to_string())
# });
# ($msg:expr, ) => ({
# |e| cherr!(e, $msg.to_string())
# });
# ($fmt:expr, $($arg:tt)+) => ({
# |e| cherr!(e, format!($fmt, $($arg)+ ))
# });
# }
#
# /// Convenience macro for `cherr!(T(format!(…)))` where `T(String)`
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::result::Result;
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> ChainResult< (), Func2Error> {
# /// let filename = " foo.txt" ;
# /// Err(strerr!(Func2Error, " Error reading '{}'" , filename))
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! strerr {
# ( $t:path, $msg:expr ) => ({
# cherr!($t ($msg.to_string()))
# });
# ( $t:path, $msg:expr, ) => ({
# cherr!($t ($msg.to_string()))
# });
# ( $t:path, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!($t (format!($fmt, $($arg)+ )))
# });
# ($msg:expr) => ({
# cherr!($msg.to_string())
# });
# ($msg:expr, ) => ({
# cherr!($msg.to_string())
# });
# ($fmt:expr, $($arg:tt)+) => ({
# cherr!(format!($fmt, $($arg)+ ))
# });
# }
#
# /// Convenience macro to create a " new type" T(String) and implement Display + Debug for T
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> ChainResult< (), Func2Error> {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! derive_str_cherr {
# ($e:ident) => {
# pub struct $e(pub String);
# impl ::std::fmt::Display for $e {
# fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# write!(f, " {}" , self.0)
# }
# }
# impl ::std::fmt::Debug for $e {
# fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# write!(f, " {}({})" , stringify!($e), self.0)
# }
# }
# impl ::std::error::Error for $e {}
# };
# }
# }
< / code > < / pre > < / pre >
< a class = "header" href = "#debug-for-the-errorkind" id = "debug-for-the-errorkind" > < h1 > Debug for the ErrorKind< / h1 > < / a >
< p > One small improvement at the end of the tutorial is to fix the debug output of
< code > Func1ErrorKind< / code > . As you probably noticed, the output doesn't say much of the enum.< / p >
< pre > < code > Debug Error:
src/main.rs:35: Func2
[…]
< / code > < / pre >
< p > As a lazy shortcut, we implement < code > Debug< / code > by calling < code > Display< / code > and end up with< / p >
< pre > < code > Debug Error:
src/main.rs:40: func1 error calling func2
[…}
< / code > < / pre >
< p > which gives us a lot more detail.< / p >
< p > To create your own Errors, you might find < a href = "https://crates.io" > crates< / a > which create enum < code > Display+Debug< / code > via derive macros.< / p >
< p > Also noteworthy is < a href = "https://crates.io/crates/custom_error" > custom_error< / a > to define your custom errors,
which can then be used with < code > chainerror< / code > .< / p >
2019-03-04 11:46:17 +01:00
< pre > < pre class = "playpen" > < code class = "language-rust" > use chainerror::*;
2019-02-07 09:02:01 +01:00
use std::error::Error;
use std::io;
use std::result::Result;
fn do_some_io() -> Result< (), Box< Error> > {
Err(io::Error::from(io::ErrorKind::NotFound))?;
Ok(())
}
derive_str_cherr!(Func2Error);
fn func2() -> Result< (), Box< Error> > {
let filename = " foo.txt" ;
do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
Ok(())
}
enum Func1ErrorKind {
Func2,
IO(String),
}
impl ::std::fmt::Display for Func1ErrorKind {
fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
match self {
Func1ErrorKind::Func2 => write!(f, " func1 error calling func2" ),
Func1ErrorKind::IO(filename) => write!(f, " Error reading '{}'" , filename),
}
}
}
impl ::std::fmt::Debug for Func1ErrorKind {
fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
write!(f, " {}" , self)
}
}
impl ::std::error::Error for Func1ErrorKind {}
fn func1() -> ChainResult< (), Func1ErrorKind> {
func2().map_err(|e| cherr!(e, Func1ErrorKind::Func2))?;
let filename = String::from(" bar.txt" );
do_some_io().map_err(|e| cherr!(e, Func1ErrorKind::IO(filename)))?;
Ok(())
}
fn main() -> Result< (), Box< Error> > {
if let Err(e) = func1() {
match e.kind() {
Func1ErrorKind::Func2 => eprintln!(" Main Error Report: func1 error calling func2" ),
Func1ErrorKind::IO(filename) => {
eprintln!(" Main Error Report: func1 error reading '{}'" , filename)
}
}
if let Some(e) = e.find_chain_cause::< Func2Error> () {
eprintln!(" \nError reported by Func2Error: {}" , e)
}
eprintln!(" \nDebug Error:\n{:?}" , e);
}
Ok(())
}
2019-03-04 11:46:17 +01:00
2019-02-07 09:02:01 +01:00
# #[allow(dead_code)]
# mod chainerror {
# //! `chainerror` provides an error backtrace without doing a real backtrace, so even after you `strip` your
# //! binaries, you still have the error backtrace.
# //!
# //! `chainerror` has no dependencies!
# //!
# //! `chainerror` uses `.source()` of `std::error::Error` along with `line()!` and `file()!` to provide a nice debug error backtrace.
# //! It encapsulates all types, which have `Display + Debug` and can store the error cause internally.
# //!
# //! Along with the `ChainError< T> ` struct, `chainerror` comes with some useful helper macros to save a lot of typing.
# //!
# //! ## Features
# //!
# //! `no-fileline`
# //! : completely turn off storing filename and line
# //!
# //! `display-cause`
# //! : turn on printing a backtrace of the errors in `Display`
# //!
# //! `no-debug-cause`
# //! : turn off printing a backtrace of the errors in `Debug`
# //!
# //!
# //! # Tutorial
# //!
# //! Read the [Tutorial](https://haraldh.github.io/chainerror/tutorial1.html)
# //!
# //! # Examples
# //!
# //! ~~~rust
# //! use chainerror::*;
# //! use std::error::Error;
# //! use std::io;
# //! use std::result::Result;
# //!
# //! fn do_some_io() -> Result< (), Box< Error> > {
# //! Err(io::Error::from(io::ErrorKind::NotFound))?;
# //! Ok(())
# //! }
# //!
# //! fn func2() -> Result< (), Box< Error> > {
# //! let filename = " foo.txt" ;
# //! do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# //! Ok(())
# //! }
# //!
# //! fn func1() -> Result< (), Box< Error> > {
# //! func2().map_err(mstrerr!(" func1 error" ))?;
# //! Ok(())
# //! }
# //!
# //! fn main() {
# //! if let Err(e) = func1() {
# //! #[cfg(not(windows))]
# //! assert_eq!(
# //! format!(" \n{:?}\n" , e), r#"
# //! src/lib.rs:20: func1 error
# //! Caused by:
# //! src/lib.rs:15: Error reading 'foo.txt'
# //! Caused by:
# //! Kind(NotFound)
# //! " #
# //! );
# //! }
# //! # else {
# //! # unreachable!();
# //! # }
# //! }
# //! ~~~
# //!
# //!
# //! ~~~rust
# //! use chainerror::*;
# //! use std::error::Error;
# //! use std::io;
# //! use std::result::Result;
# //!
# //! fn do_some_io() -> Result< (), Box< Error> > {
# //! Err(io::Error::from(io::ErrorKind::NotFound))?;
# //! Ok(())
# //! }
# //!
# //! fn func3() -> Result< (), Box< Error> > {
# //! let filename = " foo.txt" ;
# //! do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# //! Ok(())
# //! }
# //!
# //! derive_str_cherr!(Func2Error);
# //!
# //! fn func2() -> ChainResult< (), Func2Error> {
# //! func3().map_err(mstrerr!(Func2Error, " func2 error: calling func3" ))?;
# //! Ok(())
# //! }
# //!
# //! enum Func1Error {
# //! Func2,
# //! IO(String),
# //! }
# //!
# //! impl ::std::fmt::Display for Func1Error {
# //! fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# //! match self {
# //! Func1Error::Func2 => write!(f, " func1 error calling func2" ),
# //! Func1Error::IO(filename) => write!(f, " Error reading '{}'" , filename),
# //! }
# //! }
# //! }
# //!
# //! impl ::std::fmt::Debug for Func1Error {
# //! fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# //! write!(f, " {}" , self)
# //! }
# //! }
# //!
# //! fn func1() -> ChainResult< (), Func1Error> {
# //! func2().map_err(|e| cherr!(e, Func1Error::Func2))?;
# //! let filename = String::from(" bar.txt" );
# //! do_some_io().map_err(|e| cherr!(e, Func1Error::IO(filename)))?;
# //! Ok(())
# //! }
# //!
# //! fn main() {
# //! if let Err(e) = func1() {
# //! assert!(
# //! match e.kind() {
# //! Func1Error::Func2 => {
# //! eprintln!(" Main Error Report: func1 error calling func2" );
# //! true
# //! }
# //! Func1Error::IO(filename) => {
# //! eprintln!(" Main Error Report: func1 error reading '{}'" , filename);
# //! false
# //! }
# //! }
# //! );
# //!
# //! assert!(e.find_chain_cause::< Func2Error> ().is_some());
# //!
# //! if let Some(e) = e.find_chain_cause::< Func2Error> () {
# //! eprintln!(" \nError reported by Func2Error: {}" , e)
# //! }
# //!
# //!
# //! assert!(e.root_cause().is_some());
# //!
# //! if let Some(e) = e.root_cause() {
# //! let ioerror = e.downcast_ref::< io::Error> ().unwrap();
# //! eprintln!(" \nThe root cause was: std::io::Error: {:#?}" , ioerror);
# //! }
# //!
# //! #[cfg(not(windows))]
# //! assert_eq!(
# //! format!(" \n{:?}\n" , e), r#"
# //! src/lib.rs:47: func1 error calling func2
# //! Caused by:
# //! src/lib.rs:22: Func2Error(func2 error: calling func3)
# //! Caused by:
# //! src/lib.rs:15: Error reading 'foo.txt'
# //! Caused by:
# //! Kind(NotFound)
# //! " #
# //! );
# //! }
# //! # else {
# //! # unreachable!();
# //! # }
# //! }
# //! ~~~
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# use std::any::TypeId;
# use std::error::Error;
# use std::fmt::{Debug, Display, Formatter, Result};
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# /// chains an inner error kind `T` with a causing error
# pub struct ChainError< T> {
# #[cfg(not(feature = " no-fileline" ))]
# occurrence: Option< (u32, & 'static str)> ,
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# /// convenience type alias
# pub type ChainResult< O, E> = std::result::Result< O, ChainError< E> > ;
2018-12-20 14:55:19 +01:00
#
2019-02-07 09:02:01 +01:00
# impl< T: 'static + Display + Debug> ChainError< T> {
# #[cfg(not(feature = " no-fileline" ))]
# /// Use the `cherr!()` or `mstrerr!()` macro instead of calling this directly
# pub fn new(
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# occurrence: Option< (u32, & 'static str)> ,
# ) -> Self {
# Self {
# occurrence,
# kind,
# error_cause,
2018-12-20 14:55:19 +01:00
# }
# }
#
2019-02-07 09:02:01 +01:00
# #[cfg(feature = " no-fileline" )]
# /// Use the `cherr!()` or `mstrerr!()` macro instead of calling this directly
# pub fn new(
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# _occurrence: Option< (u32, & 'static str)> ,
# ) -> Self {
# Self { kind, error_cause }
2018-12-21 13:55:46 +01:00
# }
#
2019-02-07 09:02:01 +01:00
# /// return the root cause of the error chain, if any exists
# pub fn root_cause(& self) -> Option< & (dyn Error + 'static)> {
# self.iter().last()
# }
#
# /// Find the first error cause of type U, if any exists
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// fn do_some_io() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# ///
# /// fn main() {
# /// if let Err(e) = func1() {
# /// if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# ///
# /// assert!(f1err.find_cause::< io::Error> ().is_some());
# ///
# /// assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// }
# /// # else {
# /// # panic!();
# /// # }
# /// }
# /// # else {
# /// # unreachable!();
# /// # }
# /// }
# /// ~~~
# pub fn find_cause< U: Error + 'static> (& self) -> Option< & U> {
# self.iter().filter_map(Error::downcast_ref::< U> ).next()
# }
#
# /// Find the first error cause of type `ChainError< U> `, if any exists
# ///
# /// Same as `find_cause`, but hides the `ChainError< U> ` implementation internals
# ///
# /// # Examples
# ///
# /// ~~~rust,ignore
# /// // Instead of writing
# /// err.find_cause::< ChainError< FooError> > ();
# ///
# /// // leave out the ChainError< FooError> implementation detail
# /// err.find_chain_cause::< FooError> ();
# /// ~~~
# pub fn find_chain_cause< U: Error + 'static> (& self) -> Option< & ChainError< U> > {
# self.iter()
# .filter_map(Error::downcast_ref::< ChainError< U> > )
# .next()
# }
#
# /// Find the first error cause of type `ChainError< U> ` or `U`, if any exists and return `U`
# ///
# /// Same as `find_cause` and `find_chain_cause`, but hides the `ChainError< U> ` implementation internals
# ///
# /// # Examples
# ///
# /// ~~~rust,ignore
# /// // Instead of writing
# /// err.find_cause::< ChainError< FooErrorKind> > ();
# /// // and/or
# /// err.find_chain_cause::< FooErrorKind> ();
# /// // and/or
# /// err.find_cause::< FooErrorKind> ();
# ///
# /// // leave out the ChainError< FooErrorKind> implementation detail
# /// err.find_chain_or_kind::< FooErrorKind> ();
# /// ~~~
# pub fn find_kind_or_cause< U: Error + 'static> (& self) -> Option< & U> {
# self.iter()
# .filter_map(|e| {
# e.downcast_ref::< ChainError< U> > ()
# .map(|e| e.kind())
# .or_else(|| e.downcast_ref::< U> ())
# })
# .next()
# }
#
# /// Return a reference to T of `ChainError< T> `
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// fn do_some_io() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// #[derive(Debug)]
# /// enum Func1ErrorKind {
# /// Func2,
# /// IO(String),
# /// }
# ///
# /// /// impl ::std::fmt::Display for Func1ErrorKind {…}
# /// # impl ::std::fmt::Display for Func1ErrorKind {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # Func1ErrorKind::Func2 => write!(f, " func1 error calling func2" ),
# /// # Func1ErrorKind::IO(filename) => write!(f, " Error reading '{}'" , filename),
# /// # }
# /// # }
# /// # }
# ///
# /// fn func1() -> ChainResult< (), Func1ErrorKind> {
# /// func2().map_err(|e| cherr!(e, Func1ErrorKind::Func2))?;
# /// do_some_io().map_err(|e| cherr!(e, Func1ErrorKind::IO(" bar.txt" .into())))?;
# /// Ok(())
# /// }
# ///
# /// fn main() {
# /// if let Err(e) = func1() {
# /// match e.kind() {
# /// Func1ErrorKind::Func2 => {},
# /// Func1ErrorKind::IO(filename) => panic!(),
# /// }
# /// }
# /// # else {
# /// # unreachable!();
# /// # }
# /// }
# /// ~~~
# pub fn kind(& self) -> & T {
# & self.kind
2018-12-21 13:55:46 +01:00
# }
#
2019-02-07 09:02:01 +01:00
# /// Returns an Iterator over all error causes/sources
# ///
# /// # Example
# ///
# ///
# pub fn iter(& self) -> impl Iterator< Item = & (dyn Error + 'static)> {
# ErrorIter {
# current: Some(self),
# }
2018-12-21 13:55:46 +01:00
# }
2019-02-07 09:02:01 +01:00
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# struct ErrorIter< 'a> {
# current: Option< & 'a (dyn Error + 'static)> ,
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# impl< 'a> Iterator for ErrorIter< 'a> {
# type Item = & 'a (dyn Error + 'static);
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# fn next(& mut self) -> Option< Self::Item> {
# let current = self.current;
# self.current = self.current.and_then(Error::source);
# current
2018-12-21 13:55:46 +01:00
# }
2019-02-07 09:02:01 +01:00
# }
#
# impl< T: 'static + Display + Debug> std::ops::Deref for ChainError< T> {
# type Target = T;
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# fn deref(& self) -> & Self::Target {
2018-12-20 14:55:19 +01:00
# & self.kind
# }
# }
#
2019-02-07 09:02:01 +01:00
# /// Convenience trait to hide the `ChainError< T> ` implementation internals
2018-12-20 14:55:19 +01:00
# pub trait ChainErrorDown {
2019-02-07 09:02:01 +01:00
# /// Test if of type `ChainError< T> `
2018-12-20 14:55:19 +01:00
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool;
2019-02-07 09:02:01 +01:00
# /// Downcast to a reference of `ChainError< T> `
2018-12-20 14:55:19 +01:00
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > ;
2019-02-07 09:02:01 +01:00
# /// Downcast to a mutable reference of `ChainError< T> `
2018-12-20 14:55:19 +01:00
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > ;
# }
#
# impl< U: 'static + Display + Debug> ChainErrorDown for ChainError< U> {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# TypeId::of::< T> () == TypeId::of::< U> ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# if self.is_chain::< T> () {
2019-02-07 09:02:01 +01:00
# #[allow(clippy::cast_ptr_alignment)]
# unsafe {
# Some(& *(self as *const dyn Error as *const & ChainError< T> ))
# }
2018-12-20 14:55:19 +01:00
# } else {
# None
# }
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# if self.is_chain::< T> () {
2019-02-07 09:02:01 +01:00
# #[allow(clippy::cast_ptr_alignment)]
# unsafe {
# Some(& mut *(self as *mut dyn Error as *mut & mut ChainError< T> ))
# }
2018-12-20 14:55:19 +01:00
# } else {
# None
# }
# }
# }
#
# impl ChainErrorDown for dyn Error + 'static {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl ChainErrorDown for dyn Error + 'static + Send {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl ChainErrorDown for dyn Error + 'static + Send + Sync {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl< T: 'static + Display + Debug> Error for ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.error_cause.as_ref().map(|e| e.as_ref())
2018-12-20 14:55:19 +01:00
# }
# }
#
# impl< T: 'static + Display + Debug> Error for & ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.error_cause.as_ref().map(|e| e.as_ref())
2018-12-20 14:55:19 +01:00
# }
# }
#
# impl< T: 'static + Display + Debug> Error for & mut ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.error_cause.as_ref().map(|e| e.as_ref())
2018-12-20 14:55:19 +01:00
# }
# }
#
# impl< T: 'static + Display + Debug> Display for ChainError< T> {
# fn fmt(& self, f: & mut Formatter) -> Result {
# write!(f, " {}" , self.kind)?;
#
# #[cfg(feature = " display-cause" )]
# {
# if let Some(e) = self.source() {
# writeln!(f, " \nCaused by:" )?;
# Display::fmt(& e, f)?;
# }
# }
# Ok(())
# }
# }
#
# impl< T: 'static + Display + Debug> Debug for ChainError< T> {
# fn fmt(& self, f: & mut Formatter) -> Result {
# #[cfg(not(feature = " no-fileline" ))]
# {
# if let Some(o) = self.occurrence {
# write!(f, " {}:{}: " , o.1, o.0)?;
# }
# }
#
2018-12-21 13:55:46 +01:00
# if self.is_chain::< String> () {
# Display::fmt(& self.kind, f)?;
# } else {
# Debug::fmt(& self.kind, f)?;
# }
2018-12-20 14:55:19 +01:00
#
# #[cfg(not(feature = " no-debug-cause" ))]
# {
# if let Some(e) = self.source() {
# writeln!(f, " \nCaused by:" )?;
# Debug::fmt(& e, f)?;
# }
# }
# Ok(())
# }
# }
#
2019-02-07 09:02:01 +01:00
# pub trait ChainErrorFrom< T> : Sized {
# fn chain_error_from(_: T, line_filename: Option< (u32, & 'static str)> ) -> ChainError< Self> ;
# }
#
# pub trait IntoChainError< T> : Sized {
# fn into_chain_error(self, line_filename: Option< (u32, & 'static str)> ) -> ChainError< T> ;
# }
#
# impl< T, U> IntoChainError< U> for T
# where
# U: ChainErrorFrom< T> ,
# {
# fn into_chain_error(self, line_filename: Option< (u32, & 'static str)> ) -> ChainError< U> {
# U::chain_error_from(self, line_filename)
# }
# }
#
# impl< T, U> ChainErrorFrom< T> for U
# where
# T: Into< U> ,
# U: 'static + Display + Debug,
# {
# fn chain_error_from(t: T, line_filename: Option< (u32, & 'static str)> ) -> ChainError< Self> {
# let e: U = t.into();
# ChainError::< _> ::new(e, None, line_filename)
# }
# }
#
2018-12-20 14:55:19 +01:00
# #[macro_export]
2019-02-07 09:02:01 +01:00
# macro_rules! minto_cherr {
# ( ) => {
# |e| e.into_chain_error(Some((line!(), file!())))
2018-12-20 14:55:19 +01:00
# };
# }
#
# #[macro_export]
2019-02-07 09:02:01 +01:00
# macro_rules! into_cherr {
# ( $t:expr ) => {
# $t.into_chain_error(Some((line!(), file!())))
2018-12-20 14:55:19 +01:00
# };
# }
#
2019-02-07 09:02:01 +01:00
# /// Creates a new `ChainError< T> `
# ///
# /// # Examples
# ///
# /// Create a new ChainError< FooError> , where `FooError` must implement `Display` and `Debug`.
# /// ~~~rust
# /// # use chainerror::*;
# /// #
# /// # #[derive(Debug)]
# /// enum FooError {
# /// Bar,
# /// Baz(& 'static str),
# /// }
# /// #
# /// # impl ::std::fmt::Display for FooError {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # FooError::Bar => write!(f, " Bar Error" ),
# /// # FooError::Baz(s) => write!(f, " Baz Error: '{}'" , s),
# /// # }
# /// # }
# /// # }
# ///
# /// // impl ::std::fmt::Display for FooError
# ///
# /// fn do_some_stuff() -> bool {
# /// false
# /// }
# ///
# /// fn func() -> ChainResult< (), FooError> {
# /// if ! do_some_stuff() {
# /// Err(cherr!(FooError::Baz(" Error" )))?;
# /// }
# /// Ok(())
# /// }
# /// #
# /// # pub fn main() {
# /// # match func().unwrap_err().kind() {
# /// # FooError::Baz(s) if s == & " Error" => {},
# /// # _ => panic!(),
# /// # }
# /// # }
# /// ~~~
# ///
# /// Additionally an error cause can be added.
# ///
# /// ~~~rust
# /// # use chainerror::*;
# /// # use std::io;
# /// # use std::error::Error;
# /// #
# /// # #[derive(Debug)]
# /// # enum FooError {
# /// # Bar,
# /// # Baz(& 'static str),
# /// # }
# /// #
# /// # impl ::std::fmt::Display for FooError {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # FooError::Bar => write!(f, " Bar Error" ),
# /// # FooError::Baz(s) => write!(f, " Baz Error: '{}'" , s),
# /// # }
# /// # }
# /// # }
# /// #
# /// fn do_some_stuff() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// fn func() -> ChainResult< (), FooError> {
# /// do_some_stuff().map_err(
# /// |e| cherr!(e, FooError::Baz(" Error" ))
# /// )?;
# /// Ok(())
# /// }
# /// #
# /// # pub fn main() {
# /// # match func().unwrap_err().kind() {
# /// # FooError::Baz(s) if s == & " Error" => {},
# /// # _ => panic!(),
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! cherr {
# ( $k:expr ) => ({
# ChainError::< _> ::new($k, None, Some((line!(), file!())))
# });
# ( None, $k:expr ) => ({
# ChainError::< _> ::new($k, None, Some((line!(), file!())))
# });
# ( None, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!(None, format!($fmt, $($arg)+ ))
# });
# ( None, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!(None, format!($fmt, $($arg)+ ))
# });
# ( $e:path, $k:expr ) => ({
# ChainError::< _> ::new($k, Some(Box::from($e)), Some((line!(), file!())))
# });
# ( $e:path, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!($e, format!($fmt, $($arg)+ ))
# });
#
# }
#
# /// Convenience macro for `|e| cherr!(e, format!(…))`
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(" func1 error" ))?;
# /// Ok(())
# /// }
# ///
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # #[cfg(not(windows))]
# /// # assert_eq!(
# /// # format!(" \n{:?}\n" , e), r#"
# /// # src/lib.rs:20: func1 error
# /// # Caused by:
# /// # src/lib.rs:15: Error reading 'foo.txt'
# /// # Caused by:
# /// # Kind(NotFound)
# /// # " #
# /// # );
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# ///
# /// `mstrerr!()` can also be used to map a new `ChainError< T> `, where T was defined with
# /// `derive_str_cherr!(T)`
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! mstrerr {
# ( $t:path, $msg:expr ) => ({
# |e| cherr!(e, $t ($msg.to_string()))
# });
# ( $t:path, $msg:expr, ) => ({
# |e| cherr!(e, $t ($msg.to_string()))
# });
# ( $t:path, $fmt:expr, $($arg:tt)+ ) => ({
# |e| cherr!(e, $t (format!($fmt, $($arg)+ )))
# });
# ($msg:expr) => ({
# |e| cherr!(e, $msg.to_string())
# });
# ($msg:expr, ) => ({
# |e| cherr!(e, $msg.to_string())
# });
# ($fmt:expr, $($arg:tt)+) => ({
# |e| cherr!(e, format!($fmt, $($arg)+ ))
# });
# }
#
# /// Convenience macro for `cherr!(T(format!(…)))` where `T(String)`
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::result::Result;
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> ChainResult< (), Func2Error> {
# /// let filename = " foo.txt" ;
# /// Err(strerr!(Func2Error, " Error reading '{}'" , filename))
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! strerr {
# ( $t:path, $msg:expr ) => ({
# cherr!($t ($msg.to_string()))
# });
# ( $t:path, $msg:expr, ) => ({
# cherr!($t ($msg.to_string()))
# });
# ( $t:path, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!($t (format!($fmt, $($arg)+ )))
# });
# ($msg:expr) => ({
# cherr!($msg.to_string())
# });
# ($msg:expr, ) => ({
# cherr!($msg.to_string())
# });
# ($fmt:expr, $($arg:tt)+) => ({
# cherr!(format!($fmt, $($arg)+ ))
# });
# }
#
# /// Convenience macro to create a " new type" T(String) and implement Display + Debug for T
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> ChainResult< (), Func2Error> {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
2018-12-20 14:55:19 +01:00
# #[macro_export]
# macro_rules! derive_str_cherr {
# ($e:ident) => {
2019-02-07 09:02:01 +01:00
# pub struct $e(pub String);
2018-12-20 14:55:19 +01:00
# impl ::std::fmt::Display for $e {
# fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# write!(f, " {}" , self.0)
# }
# }
# impl ::std::fmt::Debug for $e {
# fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# write!(f, " {}({})" , stringify!($e), self.0)
# }
# }
# impl ::std::error::Error for $e {}
# };
# }
# }
< / code > < / pre > < / pre >
2019-02-07 09:02:01 +01:00
< a class = "header" href = "#deref-for-the-errorkind" id = "deref-for-the-errorkind" > < h1 > Deref for the ErrorKind< / h1 > < / a >
< p > Because ChainError< T > implements Deref to & T, we can also match on < code > *e< / code > instead of < code > e.kind()< / code >
or call a function with < code > & e< / code > < / p >
2019-03-04 11:46:17 +01:00
< pre > < pre class = "playpen" > < code class = "language-rust" > use chainerror::*;
2018-12-20 14:55:19 +01:00
use std::error::Error;
use std::io;
use std::result::Result;
fn do_some_io() -> Result< (), Box< Error> > {
Err(io::Error::from(io::ErrorKind::NotFound))?;
Ok(())
}
derive_str_cherr!(Func2Error);
fn func2() -> Result< (), Box< Error> > {
let filename = " foo.txt" ;
do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
Ok(())
}
2018-12-21 13:55:46 +01:00
enum Func1ErrorKind {
2018-12-20 14:55:19 +01:00
Func2,
IO(String),
}
2018-12-21 13:55:46 +01:00
impl ::std::fmt::Display for Func1ErrorKind {
2018-12-20 14:55:19 +01:00
fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
match self {
2018-12-21 13:55:46 +01:00
Func1ErrorKind::Func2 => write!(f, " func1 error calling func2" ),
Func1ErrorKind::IO(filename) => write!(f, " Error reading '{}'" , filename),
2018-12-20 14:55:19 +01:00
}
}
}
2018-12-21 13:55:46 +01:00
impl ::std::fmt::Debug for Func1ErrorKind {
2018-12-20 14:55:19 +01:00
fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
write!(f, " {}" , self)
}
}
2019-02-07 09:02:01 +01:00
impl ::std::error::Error for Func1ErrorKind {}
2018-12-21 13:55:46 +01:00
fn func1() -> ChainResult< (), Func1ErrorKind> {
func2().map_err(|e| cherr!(e, Func1ErrorKind::Func2))?;
2018-12-20 14:55:19 +01:00
let filename = String::from(" bar.txt" );
2018-12-21 13:55:46 +01:00
do_some_io().map_err(|e| cherr!(e, Func1ErrorKind::IO(filename)))?;
2018-12-20 14:55:19 +01:00
Ok(())
}
2019-02-07 09:02:01 +01:00
fn handle_func1errorkind(e: & Func1ErrorKind) {
match e {
Func1ErrorKind::Func2 => eprintln!(" Main Error Report: func1 error calling func2" ),
Func1ErrorKind::IO(ref filename) => {
eprintln!(" Main Error Report: func1 error reading '{}'" , filename)
}
}
}
2018-12-20 14:55:19 +01:00
fn main() -> Result< (), Box< Error> > {
if let Err(e) = func1() {
2019-02-07 09:02:01 +01:00
match *e {
2018-12-21 13:55:46 +01:00
Func1ErrorKind::Func2 => eprintln!(" Main Error Report: func1 error calling func2" ),
2019-02-07 09:02:01 +01:00
Func1ErrorKind::IO(ref filename) => {
2018-12-20 14:55:19 +01:00
eprintln!(" Main Error Report: func1 error reading '{}'" , filename)
}
}
2019-02-07 09:02:01 +01:00
handle_func1errorkind(& e);
2018-12-20 14:55:19 +01:00
if let Some(e) = e.find_chain_cause::< Func2Error> () {
2018-12-21 13:55:46 +01:00
eprintln!(" \nError reported by Func2Error: {}" , e)
2018-12-20 14:55:19 +01:00
}
eprintln!(" \nDebug Error:\n{:?}" , e);
}
Ok(())
}
2019-03-04 11:46:17 +01:00
2018-12-20 14:55:19 +01:00
# #[allow(dead_code)]
# mod chainerror {
2019-02-07 09:02:01 +01:00
# //! `chainerror` provides an error backtrace without doing a real backtrace, so even after you `strip` your
# //! binaries, you still have the error backtrace.
# //!
# //! `chainerror` has no dependencies!
# //!
# //! `chainerror` uses `.source()` of `std::error::Error` along with `line()!` and `file()!` to provide a nice debug error backtrace.
# //! It encapsulates all types, which have `Display + Debug` and can store the error cause internally.
# //!
# //! Along with the `ChainError< T> ` struct, `chainerror` comes with some useful helper macros to save a lot of typing.
# //!
# //! ## Features
# //!
# //! `no-fileline`
# //! : completely turn off storing filename and line
# //!
# //! `display-cause`
# //! : turn on printing a backtrace of the errors in `Display`
# //!
# //! `no-debug-cause`
# //! : turn off printing a backtrace of the errors in `Debug`
# //!
# //!
# //! # Tutorial
# //!
# //! Read the [Tutorial](https://haraldh.github.io/chainerror/tutorial1.html)
# //!
# //! # Examples
# //!
# //! ~~~rust
# //! use chainerror::*;
# //! use std::error::Error;
# //! use std::io;
# //! use std::result::Result;
# //!
# //! fn do_some_io() -> Result< (), Box< Error> > {
# //! Err(io::Error::from(io::ErrorKind::NotFound))?;
# //! Ok(())
# //! }
# //!
# //! fn func2() -> Result< (), Box< Error> > {
# //! let filename = " foo.txt" ;
# //! do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# //! Ok(())
# //! }
# //!
# //! fn func1() -> Result< (), Box< Error> > {
# //! func2().map_err(mstrerr!(" func1 error" ))?;
# //! Ok(())
# //! }
# //!
# //! fn main() {
# //! if let Err(e) = func1() {
# //! #[cfg(not(windows))]
# //! assert_eq!(
# //! format!(" \n{:?}\n" , e), r#"
# //! src/lib.rs:20: func1 error
# //! Caused by:
# //! src/lib.rs:15: Error reading 'foo.txt'
# //! Caused by:
# //! Kind(NotFound)
# //! " #
# //! );
# //! }
# //! # else {
# //! # unreachable!();
# //! # }
# //! }
# //! ~~~
# //!
# //!
# //! ~~~rust
# //! use chainerror::*;
# //! use std::error::Error;
# //! use std::io;
# //! use std::result::Result;
# //!
# //! fn do_some_io() -> Result< (), Box< Error> > {
# //! Err(io::Error::from(io::ErrorKind::NotFound))?;
# //! Ok(())
# //! }
# //!
# //! fn func3() -> Result< (), Box< Error> > {
# //! let filename = " foo.txt" ;
# //! do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# //! Ok(())
# //! }
# //!
# //! derive_str_cherr!(Func2Error);
# //!
# //! fn func2() -> ChainResult< (), Func2Error> {
# //! func3().map_err(mstrerr!(Func2Error, " func2 error: calling func3" ))?;
# //! Ok(())
# //! }
# //!
# //! enum Func1Error {
# //! Func2,
# //! IO(String),
# //! }
# //!
# //! impl ::std::fmt::Display for Func1Error {
# //! fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# //! match self {
# //! Func1Error::Func2 => write!(f, " func1 error calling func2" ),
# //! Func1Error::IO(filename) => write!(f, " Error reading '{}'" , filename),
# //! }
# //! }
# //! }
# //!
# //! impl ::std::fmt::Debug for Func1Error {
# //! fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# //! write!(f, " {}" , self)
# //! }
# //! }
# //!
# //! fn func1() -> ChainResult< (), Func1Error> {
# //! func2().map_err(|e| cherr!(e, Func1Error::Func2))?;
# //! let filename = String::from(" bar.txt" );
# //! do_some_io().map_err(|e| cherr!(e, Func1Error::IO(filename)))?;
# //! Ok(())
# //! }
# //!
# //! fn main() {
# //! if let Err(e) = func1() {
# //! assert!(
# //! match e.kind() {
# //! Func1Error::Func2 => {
# //! eprintln!(" Main Error Report: func1 error calling func2" );
# //! true
# //! }
# //! Func1Error::IO(filename) => {
# //! eprintln!(" Main Error Report: func1 error reading '{}'" , filename);
# //! false
# //! }
# //! }
# //! );
# //!
# //! assert!(e.find_chain_cause::< Func2Error> ().is_some());
# //!
# //! if let Some(e) = e.find_chain_cause::< Func2Error> () {
# //! eprintln!(" \nError reported by Func2Error: {}" , e)
# //! }
# //!
# //!
# //! assert!(e.root_cause().is_some());
# //!
# //! if let Some(e) = e.root_cause() {
# //! let ioerror = e.downcast_ref::< io::Error> ().unwrap();
# //! eprintln!(" \nThe root cause was: std::io::Error: {:#?}" , ioerror);
# //! }
# //!
# //! #[cfg(not(windows))]
# //! assert_eq!(
# //! format!(" \n{:?}\n" , e), r#"
# //! src/lib.rs:47: func1 error calling func2
# //! Caused by:
# //! src/lib.rs:22: Func2Error(func2 error: calling func3)
# //! Caused by:
# //! src/lib.rs:15: Error reading 'foo.txt'
# //! Caused by:
# //! Kind(NotFound)
# //! " #
# //! );
# //! }
# //! # else {
# //! # unreachable!();
# //! # }
# //! }
# //! ~~~
2018-12-21 13:55:46 +01:00
#
# use std::any::TypeId;
2018-12-20 14:55:19 +01:00
# use std::error::Error;
# use std::fmt::{Debug, Display, Formatter, Result};
#
2019-02-07 09:02:01 +01:00
# /// chains an inner error kind `T` with a causing error
2018-12-20 14:55:19 +01:00
# pub struct ChainError< T> {
# #[cfg(not(feature = " no-fileline" ))]
# occurrence: Option< (u32, & 'static str)> ,
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# }
#
2018-12-21 13:55:46 +01:00
# /// convenience type alias
# pub type ChainResult< O, E> = std::result::Result< O, ChainError< E> > ;
2018-12-20 14:55:19 +01:00
#
# impl< T: 'static + Display + Debug> ChainError< T> {
# #[cfg(not(feature = " no-fileline" ))]
2018-12-21 13:55:46 +01:00
# /// Use the `cherr!()` or `mstrerr!()` macro instead of calling this directly
2018-12-20 14:55:19 +01:00
# pub fn new(
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# occurrence: Option< (u32, & 'static str)> ,
# ) -> Self {
# Self {
# occurrence,
# kind,
# error_cause,
# }
# }
#
# #[cfg(feature = " no-fileline" )]
2018-12-21 13:55:46 +01:00
# /// Use the `cherr!()` or `mstrerr!()` macro instead of calling this directly
2018-12-20 14:55:19 +01:00
# pub fn new(
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# _occurrence: Option< (u32, & 'static str)> ,
# ) -> Self {
# Self { kind, error_cause }
# }
#
2018-12-21 13:55:46 +01:00
# /// return the root cause of the error chain, if any exists
2018-12-20 14:55:19 +01:00
# pub fn root_cause(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.iter().last()
# }
#
# /// Find the first error cause of type U, if any exists
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// fn do_some_io() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# ///
# /// fn main() {
# /// if let Err(e) = func1() {
# /// if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# ///
# /// assert!(f1err.find_cause::< io::Error> ().is_some());
# ///
# /// assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// }
# /// # else {
# /// # panic!();
# /// # }
# /// }
# /// # else {
# /// # unreachable!();
# /// # }
# /// }
# /// ~~~
2018-12-20 14:55:19 +01:00
# pub fn find_cause< U: Error + 'static> (& self) -> Option< & U> {
2019-02-07 09:02:01 +01:00
# self.iter().filter_map(Error::downcast_ref::< U> ).next()
# }
#
# /// Find the first error cause of type `ChainError< U> `, if any exists
# ///
# /// Same as `find_cause`, but hides the `ChainError< U> ` implementation internals
# ///
# /// # Examples
# ///
# /// ~~~rust,ignore
# /// // Instead of writing
# /// err.find_cause::< ChainError< FooError> > ();
# ///
# /// // leave out the ChainError< FooError> implementation detail
# /// err.find_chain_cause::< FooError> ();
# /// ~~~
2018-12-20 14:55:19 +01:00
# pub fn find_chain_cause< U: Error + 'static> (& self) -> Option< & ChainError< U> > {
2019-02-07 09:02:01 +01:00
# self.iter()
# .filter_map(Error::downcast_ref::< ChainError< U> > )
# .next()
# }
#
# /// Find the first error cause of type `ChainError< U> ` or `U`, if any exists and return `U`
# ///
# /// Same as `find_cause` and `find_chain_cause`, but hides the `ChainError< U> ` implementation internals
# ///
# /// # Examples
# ///
# /// ~~~rust,ignore
# /// // Instead of writing
# /// err.find_cause::< ChainError< FooErrorKind> > ();
# /// // and/or
# /// err.find_chain_cause::< FooErrorKind> ();
# /// // and/or
# /// err.find_cause::< FooErrorKind> ();
# ///
# /// // leave out the ChainError< FooErrorKind> implementation detail
# /// err.find_chain_or_kind::< FooErrorKind> ();
# /// ~~~
# pub fn find_kind_or_cause< U: Error + 'static> (& self) -> Option< & U> {
# self.iter()
# .filter_map(|e| {
# e.downcast_ref::< ChainError< U> > ()
# .map(|e| e.kind())
# .or_else(|| e.downcast_ref::< U> ())
# })
# .next()
# }
#
# /// Return a reference to T of `ChainError< T> `
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// fn do_some_io() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// #[derive(Debug)]
# /// enum Func1ErrorKind {
# /// Func2,
# /// IO(String),
# /// }
# ///
# /// /// impl ::std::fmt::Display for Func1ErrorKind {…}
# /// # impl ::std::fmt::Display for Func1ErrorKind {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # Func1ErrorKind::Func2 => write!(f, " func1 error calling func2" ),
# /// # Func1ErrorKind::IO(filename) => write!(f, " Error reading '{}'" , filename),
# /// # }
# /// # }
# /// # }
# ///
# /// fn func1() -> ChainResult< (), Func1ErrorKind> {
# /// func2().map_err(|e| cherr!(e, Func1ErrorKind::Func2))?;
# /// do_some_io().map_err(|e| cherr!(e, Func1ErrorKind::IO(" bar.txt" .into())))?;
# /// Ok(())
# /// }
# ///
# /// fn main() {
# /// if let Err(e) = func1() {
# /// match e.kind() {
# /// Func1ErrorKind::Func2 => {},
# /// Func1ErrorKind::IO(filename) => panic!(),
# /// }
# /// }
# /// # else {
# /// # unreachable!();
# /// # }
# /// }
# /// ~~~
# pub fn kind(& self) -> & T {
# & self.kind
2018-12-21 13:55:46 +01:00
# }
#
2019-02-07 09:02:01 +01:00
# /// Returns an Iterator over all error causes/sources
# ///
# /// # Example
# ///
# ///
# pub fn iter(& self) -> impl Iterator< Item = & (dyn Error + 'static)> {
# ErrorIter {
# current: Some(self),
# }
2018-12-21 13:55:46 +01:00
# }
2019-02-07 09:02:01 +01:00
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# struct ErrorIter< 'a> {
# current: Option< & 'a (dyn Error + 'static)> ,
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# impl< 'a> Iterator for ErrorIter< 'a> {
# type Item = & 'a (dyn Error + 'static);
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# fn next(& mut self) -> Option< Self::Item> {
# let current = self.current;
# self.current = self.current.and_then(Error::source);
# current
2018-12-21 13:55:46 +01:00
# }
2019-02-07 09:02:01 +01:00
# }
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# impl< T: 'static + Display + Debug> std::ops::Deref for ChainError< T> {
# type Target = T;
2018-12-21 13:55:46 +01:00
#
2019-02-07 09:02:01 +01:00
# fn deref(& self) -> & Self::Target {
2018-12-20 14:55:19 +01:00
# & self.kind
# }
# }
#
2019-02-07 09:02:01 +01:00
# /// Convenience trait to hide the `ChainError< T> ` implementation internals
2018-12-20 14:55:19 +01:00
# pub trait ChainErrorDown {
2019-02-07 09:02:01 +01:00
# /// Test if of type `ChainError< T> `
2018-12-20 14:55:19 +01:00
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool;
2019-02-07 09:02:01 +01:00
# /// Downcast to a reference of `ChainError< T> `
2018-12-20 14:55:19 +01:00
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > ;
2019-02-07 09:02:01 +01:00
# /// Downcast to a mutable reference of `ChainError< T> `
2018-12-20 14:55:19 +01:00
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > ;
# }
#
# impl< U: 'static + Display + Debug> ChainErrorDown for ChainError< U> {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# TypeId::of::< T> () == TypeId::of::< U> ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# if self.is_chain::< T> () {
2019-02-07 09:02:01 +01:00
# #[allow(clippy::cast_ptr_alignment)]
# unsafe {
# Some(& *(self as *const dyn Error as *const & ChainError< T> ))
# }
2018-12-20 14:55:19 +01:00
# } else {
# None
# }
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# if self.is_chain::< T> () {
2019-02-07 09:02:01 +01:00
# #[allow(clippy::cast_ptr_alignment)]
# unsafe {
# Some(& mut *(self as *mut dyn Error as *mut & mut ChainError< T> ))
# }
2018-12-20 14:55:19 +01:00
# } else {
# None
# }
# }
# }
#
# impl ChainErrorDown for dyn Error + 'static {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl ChainErrorDown for dyn Error + 'static + Send {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl ChainErrorDown for dyn Error + 'static + Send + Sync {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl< T: 'static + Display + Debug> Error for ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.error_cause.as_ref().map(|e| e.as_ref())
2018-12-20 14:55:19 +01:00
# }
# }
#
# impl< T: 'static + Display + Debug> Error for & ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.error_cause.as_ref().map(|e| e.as_ref())
2018-12-20 14:55:19 +01:00
# }
# }
#
# impl< T: 'static + Display + Debug> Error for & mut ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
2019-02-07 09:02:01 +01:00
# self.error_cause.as_ref().map(|e| e.as_ref())
2018-12-20 14:55:19 +01:00
# }
# }
#
# impl< T: 'static + Display + Debug> Display for ChainError< T> {
# fn fmt(& self, f: & mut Formatter) -> Result {
# write!(f, " {}" , self.kind)?;
#
# #[cfg(feature = " display-cause" )]
# {
# if let Some(e) = self.source() {
# writeln!(f, " \nCaused by:" )?;
# Display::fmt(& e, f)?;
# }
# }
# Ok(())
# }
# }
#
# impl< T: 'static + Display + Debug> Debug for ChainError< T> {
# fn fmt(& self, f: & mut Formatter) -> Result {
# #[cfg(not(feature = " no-fileline" ))]
# {
# if let Some(o) = self.occurrence {
# write!(f, " {}:{}: " , o.1, o.0)?;
# }
# }
#
2018-12-21 13:55:46 +01:00
# if self.is_chain::< String> () {
# Display::fmt(& self.kind, f)?;
# } else {
# Debug::fmt(& self.kind, f)?;
# }
2018-12-20 14:55:19 +01:00
#
# #[cfg(not(feature = " no-debug-cause" ))]
# {
# if let Some(e) = self.source() {
# writeln!(f, " \nCaused by:" )?;
# Debug::fmt(& e, f)?;
# }
# }
# Ok(())
# }
# }
#
2019-02-07 09:02:01 +01:00
# pub trait ChainErrorFrom< T> : Sized {
# fn chain_error_from(_: T, line_filename: Option< (u32, & 'static str)> ) -> ChainError< Self> ;
# }
#
# pub trait IntoChainError< T> : Sized {
# fn into_chain_error(self, line_filename: Option< (u32, & 'static str)> ) -> ChainError< T> ;
# }
#
# impl< T, U> IntoChainError< U> for T
# where
# U: ChainErrorFrom< T> ,
# {
# fn into_chain_error(self, line_filename: Option< (u32, & 'static str)> ) -> ChainError< U> {
# U::chain_error_from(self, line_filename)
# }
# }
#
# impl< T, U> ChainErrorFrom< T> for U
# where
# T: Into< U> ,
# U: 'static + Display + Debug,
# {
# fn chain_error_from(t: T, line_filename: Option< (u32, & 'static str)> ) -> ChainError< Self> {
# let e: U = t.into();
# ChainError::< _> ::new(e, None, line_filename)
# }
# }
#
2018-12-20 14:55:19 +01:00
# #[macro_export]
2019-02-07 09:02:01 +01:00
# macro_rules! minto_cherr {
# ( ) => {
# |e| e.into_chain_error(Some((line!(), file!())))
2018-12-20 14:55:19 +01:00
# };
# }
#
# #[macro_export]
2019-02-07 09:02:01 +01:00
# macro_rules! into_cherr {
# ( $t:expr ) => {
# $t.into_chain_error(Some((line!(), file!())))
2018-12-20 14:55:19 +01:00
# };
# }
#
2019-02-07 09:02:01 +01:00
# /// Creates a new `ChainError< T> `
# ///
# /// # Examples
# ///
# /// Create a new ChainError< FooError> , where `FooError` must implement `Display` and `Debug`.
# /// ~~~rust
# /// # use chainerror::*;
# /// #
# /// # #[derive(Debug)]
# /// enum FooError {
# /// Bar,
# /// Baz(& 'static str),
# /// }
# /// #
# /// # impl ::std::fmt::Display for FooError {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # FooError::Bar => write!(f, " Bar Error" ),
# /// # FooError::Baz(s) => write!(f, " Baz Error: '{}'" , s),
# /// # }
# /// # }
# /// # }
# ///
# /// // impl ::std::fmt::Display for FooError
# ///
# /// fn do_some_stuff() -> bool {
# /// false
# /// }
# ///
# /// fn func() -> ChainResult< (), FooError> {
# /// if ! do_some_stuff() {
# /// Err(cherr!(FooError::Baz(" Error" )))?;
# /// }
# /// Ok(())
# /// }
# /// #
# /// # pub fn main() {
# /// # match func().unwrap_err().kind() {
# /// # FooError::Baz(s) if s == & " Error" => {},
# /// # _ => panic!(),
# /// # }
# /// # }
# /// ~~~
# ///
# /// Additionally an error cause can be added.
# ///
# /// ~~~rust
# /// # use chainerror::*;
# /// # use std::io;
# /// # use std::error::Error;
# /// #
# /// # #[derive(Debug)]
# /// # enum FooError {
# /// # Bar,
# /// # Baz(& 'static str),
# /// # }
# /// #
# /// # impl ::std::fmt::Display for FooError {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # FooError::Bar => write!(f, " Bar Error" ),
# /// # FooError::Baz(s) => write!(f, " Baz Error: '{}'" , s),
# /// # }
# /// # }
# /// # }
# /// #
# /// fn do_some_stuff() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// fn func() -> ChainResult< (), FooError> {
# /// do_some_stuff().map_err(
# /// |e| cherr!(e, FooError::Baz(" Error" ))
# /// )?;
# /// Ok(())
# /// }
# /// #
# /// # pub fn main() {
# /// # match func().unwrap_err().kind() {
# /// # FooError::Baz(s) if s == & " Error" => {},
# /// # _ => panic!(),
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! cherr {
# ( $k:expr ) => ({
# ChainError::< _> ::new($k, None, Some((line!(), file!())))
# });
# ( None, $k:expr ) => ({
# ChainError::< _> ::new($k, None, Some((line!(), file!())))
# });
# ( None, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!(None, format!($fmt, $($arg)+ ))
# });
# ( None, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!(None, format!($fmt, $($arg)+ ))
# });
# ( $e:path, $k:expr ) => ({
# ChainError::< _> ::new($k, Some(Box::from($e)), Some((line!(), file!())))
# });
# ( $e:path, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!($e, format!($fmt, $($arg)+ ))
# });
#
# }
#
# /// Convenience macro for `|e| cherr!(e, format!(…))`
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(" func1 error" ))?;
# /// Ok(())
# /// }
# ///
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # #[cfg(not(windows))]
# /// # assert_eq!(
# /// # format!(" \n{:?}\n" , e), r#"
# /// # src/lib.rs:20: func1 error
# /// # Caused by:
# /// # src/lib.rs:15: Error reading 'foo.txt'
# /// # Caused by:
# /// # Kind(NotFound)
# /// # " #
# /// # );
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# ///
# /// `mstrerr!()` can also be used to map a new `ChainError< T> `, where T was defined with
# /// `derive_str_cherr!(T)`
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! mstrerr {
# ( $t:path, $msg:expr ) => ({
# |e| cherr!(e, $t ($msg.to_string()))
# });
# ( $t:path, $msg:expr, ) => ({
# |e| cherr!(e, $t ($msg.to_string()))
# });
# ( $t:path, $fmt:expr, $($arg:tt)+ ) => ({
# |e| cherr!(e, $t (format!($fmt, $($arg)+ )))
# });
# ($msg:expr) => ({
# |e| cherr!(e, $msg.to_string())
# });
# ($msg:expr, ) => ({
# |e| cherr!(e, $msg.to_string())
# });
# ($fmt:expr, $($arg:tt)+) => ({
# |e| cherr!(e, format!($fmt, $($arg)+ ))
# });
# }
#
# /// Convenience macro for `cherr!(T(format!(…)))` where `T(String)`
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::result::Result;
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> ChainResult< (), Func2Error> {
# /// let filename = " foo.txt" ;
# /// Err(strerr!(Func2Error, " Error reading '{}'" , filename))
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! strerr {
# ( $t:path, $msg:expr ) => ({
# cherr!($t ($msg.to_string()))
# });
# ( $t:path, $msg:expr, ) => ({
# cherr!($t ($msg.to_string()))
# });
# ( $t:path, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!($t (format!($fmt, $($arg)+ )))
# });
# ($msg:expr) => ({
# cherr!($msg.to_string())
# });
# ($msg:expr, ) => ({
# cherr!($msg.to_string())
# });
# ($fmt:expr, $($arg:tt)+) => ({
# cherr!(format!($fmt, $($arg)+ ))
# });
# }
#
# /// Convenience macro to create a " new type" T(String) and implement Display + Debug for T
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> ChainResult< (), Func2Error> {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
2018-12-20 14:55:19 +01:00
# #[macro_export]
# macro_rules! derive_str_cherr {
# ($e:ident) => {
2019-02-07 09:02:01 +01:00
# pub struct $e(pub String);
2018-12-20 14:55:19 +01:00
# impl ::std::fmt::Display for $e {
# fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# write!(f, " {}" , self.0)
# }
# }
# impl ::std::fmt::Debug for $e {
# fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# write!(f, " {}({})" , stringify!($e), self.0)
# }
# }
# impl ::std::error::Error for $e {}
# };
# }
# }
< / code > < / pre > < / pre >
2019-03-04 11:46:17 +01:00
< a class = "header" href = "#writing-a-library" id = "writing-a-library" > < h1 > Writing a library< / h1 > < / a >
< p > I would advise to only expose an < code > mycrate::ErrorKind< / code > and type alias < code > mycrate::Error< / code > to < code > ChainError< mycrate::ErrorKind> < / code >
so you can tell your library users to use the < code > .kind()< / code > method as < code > std::io::Error< / code > does.< / p >
< p > If you later decide to make your own < code > Error< / code > implementation, your library users don't
have to change much or anything.< / p >
< pre > < pre class = "playpen" > < code class = "language-rust" > # #[allow(dead_code)]
# #[macro_use]
# pub mod chainerror {
# //! `chainerror` provides an error backtrace without doing a real backtrace, so even after you `strip` your
# //! binaries, you still have the error backtrace.
# //!
# //! `chainerror` has no dependencies!
# //!
# //! `chainerror` uses `.source()` of `std::error::Error` along with `line()!` and `file()!` to provide a nice debug error backtrace.
# //! It encapsulates all types, which have `Display + Debug` and can store the error cause internally.
# //!
# //! Along with the `ChainError< T> ` struct, `chainerror` comes with some useful helper macros to save a lot of typing.
# //!
# //! ## Features
# //!
# //! `no-fileline`
# //! : completely turn off storing filename and line
# //!
# //! `display-cause`
# //! : turn on printing a backtrace of the errors in `Display`
# //!
# //! `no-debug-cause`
# //! : turn off printing a backtrace of the errors in `Debug`
# //!
# //!
# //! # Tutorial
# //!
# //! Read the [Tutorial](https://haraldh.github.io/chainerror/tutorial1.html)
# //!
# //! # Examples
# //!
# //! ~~~rust
# //! use chainerror::*;
# //! use std::error::Error;
# //! use std::io;
# //! use std::result::Result;
# //!
# //! fn do_some_io() -> Result< (), Box< Error> > {
# //! Err(io::Error::from(io::ErrorKind::NotFound))?;
# //! Ok(())
# //! }
# //!
# //! fn func2() -> Result< (), Box< Error> > {
# //! let filename = " foo.txt" ;
# //! do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# //! Ok(())
# //! }
# //!
# //! fn func1() -> Result< (), Box< Error> > {
# //! func2().map_err(mstrerr!(" func1 error" ))?;
# //! Ok(())
# //! }
# //!
# //! fn main() {
# //! if let Err(e) = func1() {
# //! #[cfg(not(windows))]
# //! assert_eq!(
# //! format!(" \n{:?}\n" , e), r#"
# //! src/lib.rs:20: func1 error
# //! Caused by:
# //! src/lib.rs:15: Error reading 'foo.txt'
# //! Caused by:
# //! Kind(NotFound)
# //! " #
# //! );
# //! }
# //! # else {
# //! # unreachable!();
# //! # }
# //! }
# //! ~~~
# //!
# //!
# //! ~~~rust
# //! use chainerror::*;
# //! use std::error::Error;
# //! use std::io;
# //! use std::result::Result;
# //!
# //! fn do_some_io() -> Result< (), Box< Error> > {
# //! Err(io::Error::from(io::ErrorKind::NotFound))?;
# //! Ok(())
# //! }
# //!
# //! fn func3() -> Result< (), Box< Error> > {
# //! let filename = " foo.txt" ;
# //! do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# //! Ok(())
# //! }
# //!
# //! derive_str_cherr!(Func2Error);
# //!
# //! fn func2() -> ChainResult< (), Func2Error> {
# //! func3().map_err(mstrerr!(Func2Error, " func2 error: calling func3" ))?;
# //! Ok(())
# //! }
# //!
# //! enum Func1Error {
# //! Func2,
# //! IO(String),
# //! }
# //!
# //! impl ::std::fmt::Display for Func1Error {
# //! fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# //! match self {
# //! Func1Error::Func2 => write!(f, " func1 error calling func2" ),
# //! Func1Error::IO(filename) => write!(f, " Error reading '{}'" , filename),
# //! }
# //! }
# //! }
# //!
# //! impl ::std::fmt::Debug for Func1Error {
# //! fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# //! write!(f, " {}" , self)
# //! }
# //! }
# //!
# //! fn func1() -> ChainResult< (), Func1Error> {
# //! func2().map_err(|e| cherr!(e, Func1Error::Func2))?;
# //! let filename = String::from(" bar.txt" );
# //! do_some_io().map_err(|e| cherr!(e, Func1Error::IO(filename)))?;
# //! Ok(())
# //! }
# //!
# //! fn main() {
# //! if let Err(e) = func1() {
# //! assert!(
# //! match e.kind() {
# //! Func1Error::Func2 => {
# //! eprintln!(" Main Error Report: func1 error calling func2" );
# //! true
# //! }
# //! Func1Error::IO(filename) => {
# //! eprintln!(" Main Error Report: func1 error reading '{}'" , filename);
# //! false
# //! }
# //! }
# //! );
# //!
# //! assert!(e.find_chain_cause::< Func2Error> ().is_some());
# //!
# //! if let Some(e) = e.find_chain_cause::< Func2Error> () {
# //! eprintln!(" \nError reported by Func2Error: {}" , e)
# //! }
# //!
# //!
# //! assert!(e.root_cause().is_some());
# //!
# //! if let Some(e) = e.root_cause() {
# //! let ioerror = e.downcast_ref::< io::Error> ().unwrap();
# //! eprintln!(" \nThe root cause was: std::io::Error: {:#?}" , ioerror);
# //! }
# //!
# //! #[cfg(not(windows))]
# //! assert_eq!(
# //! format!(" \n{:?}\n" , e), r#"
# //! src/lib.rs:47: func1 error calling func2
# //! Caused by:
# //! src/lib.rs:22: Func2Error(func2 error: calling func3)
# //! Caused by:
# //! src/lib.rs:15: Error reading 'foo.txt'
# //! Caused by:
# //! Kind(NotFound)
# //! " #
# //! );
# //! }
# //! # else {
# //! # unreachable!();
# //! # }
# //! }
# //! ~~~
#
# use std::any::TypeId;
# use std::error::Error;
# use std::fmt::{Debug, Display, Formatter, Result};
#
# /// chains an inner error kind `T` with a causing error
# pub struct ChainError< T> {
# #[cfg(not(feature = " no-fileline" ))]
# occurrence: Option< (u32, & 'static str)> ,
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# }
#
# /// convenience type alias
# pub type ChainResult< O, E> = std::result::Result< O, ChainError< E> > ;
#
# impl< T: 'static + Display + Debug> ChainError< T> {
# #[cfg(not(feature = " no-fileline" ))]
# /// Use the `cherr!()` or `mstrerr!()` macro instead of calling this directly
# pub fn new(
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# occurrence: Option< (u32, & 'static str)> ,
# ) -> Self {
# Self {
# occurrence,
# kind,
# error_cause,
# }
# }
#
# #[cfg(feature = " no-fileline" )]
# /// Use the `cherr!()` or `mstrerr!()` macro instead of calling this directly
# pub fn new(
# kind: T,
# error_cause: Option< Box< dyn Error + 'static> > ,
# _occurrence: Option< (u32, & 'static str)> ,
# ) -> Self {
# Self { kind, error_cause }
# }
#
# /// return the root cause of the error chain, if any exists
# pub fn root_cause(& self) -> Option< & (dyn Error + 'static)> {
# self.iter().last()
# }
#
# /// Find the first error cause of type U, if any exists
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// fn do_some_io() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# ///
# /// fn main() {
# /// if let Err(e) = func1() {
# /// if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# ///
# /// assert!(f1err.find_cause::< io::Error> ().is_some());
# ///
# /// assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// }
# /// # else {
# /// # panic!();
# /// # }
# /// }
# /// # else {
# /// # unreachable!();
# /// # }
# /// }
# /// ~~~
# pub fn find_cause< U: Error + 'static> (& self) -> Option< & U> {
# self.iter().filter_map(Error::downcast_ref::< U> ).next()
# }
#
# /// Find the first error cause of type `ChainError< U> `, if any exists
# ///
# /// Same as `find_cause`, but hides the `ChainError< U> ` implementation internals
# ///
# /// # Examples
# ///
# /// ~~~rust,ignore
# /// // Instead of writing
# /// err.find_cause::< ChainError< FooError> > ();
# ///
# /// // leave out the ChainError< FooError> implementation detail
# /// err.find_chain_cause::< FooError> ();
# /// ~~~
# pub fn find_chain_cause< U: Error + 'static> (& self) -> Option< & ChainError< U> > {
# self.iter()
# .filter_map(Error::downcast_ref::< ChainError< U> > )
# .next()
# }
#
# /// Find the first error cause of type `ChainError< U> ` or `U`, if any exists and return `U`
# ///
# /// Same as `find_cause` and `find_chain_cause`, but hides the `ChainError< U> ` implementation internals
# ///
# /// # Examples
# ///
# /// ~~~rust,ignore
# /// // Instead of writing
# /// err.find_cause::< ChainError< FooErrorKind> > ();
# /// // and/or
# /// err.find_chain_cause::< FooErrorKind> ();
# /// // and/or
# /// err.find_cause::< FooErrorKind> ();
# ///
# /// // leave out the ChainError< FooErrorKind> implementation detail
# /// err.find_chain_or_kind::< FooErrorKind> ();
# /// ~~~
# pub fn find_kind_or_cause< U: Error + 'static> (& self) -> Option< & U> {
# self.iter()
# .filter_map(|e| {
# e.downcast_ref::< ChainError< U> > ()
# .map(|e| e.kind())
# .or_else(|| e.downcast_ref::< U> ())
# })
# .next()
# }
#
# /// Return a reference to T of `ChainError< T> `
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// fn do_some_io() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// #[derive(Debug)]
# /// enum Func1ErrorKind {
# /// Func2,
# /// IO(String),
# /// }
# ///
# /// /// impl ::std::fmt::Display for Func1ErrorKind {…}
# /// # impl ::std::fmt::Display for Func1ErrorKind {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # Func1ErrorKind::Func2 => write!(f, " func1 error calling func2" ),
# /// # Func1ErrorKind::IO(filename) => write!(f, " Error reading '{}'" , filename),
# /// # }
# /// # }
# /// # }
# ///
# /// fn func1() -> ChainResult< (), Func1ErrorKind> {
# /// func2().map_err(|e| cherr!(e, Func1ErrorKind::Func2))?;
# /// do_some_io().map_err(|e| cherr!(e, Func1ErrorKind::IO(" bar.txt" .into())))?;
# /// Ok(())
# /// }
# ///
# /// fn main() {
# /// if let Err(e) = func1() {
# /// match e.kind() {
# /// Func1ErrorKind::Func2 => {},
# /// Func1ErrorKind::IO(filename) => panic!(),
# /// }
# /// }
# /// # else {
# /// # unreachable!();
# /// # }
# /// }
# /// ~~~
# pub fn kind(& self) -> & T {
# & self.kind
# }
#
# /// Returns an Iterator over all error causes/sources
# ///
# /// # Example
# ///
# ///
# pub fn iter(& self) -> impl Iterator< Item = & (dyn Error + 'static)> {
# ErrorIter {
# current: Some(self),
# }
# }
# }
#
# struct ErrorIter< 'a> {
# current: Option< & 'a (dyn Error + 'static)> ,
# }
#
# impl< 'a> Iterator for ErrorIter< 'a> {
# type Item = & 'a (dyn Error + 'static);
#
# fn next(& mut self) -> Option< Self::Item> {
# let current = self.current;
# self.current = self.current.and_then(Error::source);
# current
# }
# }
#
# impl< T: 'static + Display + Debug> std::ops::Deref for ChainError< T> {
# type Target = T;
#
# fn deref(& self) -> & Self::Target {
# & self.kind
# }
# }
#
# /// Convenience trait to hide the `ChainError< T> ` implementation internals
# pub trait ChainErrorDown {
# /// Test if of type `ChainError< T> `
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool;
# /// Downcast to a reference of `ChainError< T> `
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > ;
# /// Downcast to a mutable reference of `ChainError< T> `
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > ;
# }
#
# impl< U: 'static + Display + Debug> ChainErrorDown for ChainError< U> {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# TypeId::of::< T> () == TypeId::of::< U> ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# if self.is_chain::< T> () {
# #[allow(clippy::cast_ptr_alignment)]
# unsafe {
# Some(& *(self as *const dyn Error as *const & ChainError< T> ))
# }
# } else {
# None
# }
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# if self.is_chain::< T> () {
# #[allow(clippy::cast_ptr_alignment)]
# unsafe {
# Some(& mut *(self as *mut dyn Error as *mut & mut ChainError< T> ))
# }
# } else {
# None
# }
# }
# }
#
# impl ChainErrorDown for dyn Error + 'static {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl ChainErrorDown for dyn Error + 'static + Send {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl ChainErrorDown for dyn Error + 'static + Send + Sync {
# fn is_chain< T: 'static + Display + Debug> (& self) -> bool {
# self.is::< ChainError< T> > ()
# }
#
# fn downcast_chain_ref< T: 'static + Display + Debug> (& self) -> Option< & ChainError< T> > {
# self.downcast_ref::< ChainError< T> > ()
# }
#
# fn downcast_chain_mut< T: 'static + Display + Debug> (& mut self) -> Option< & mut ChainError< T> > {
# self.downcast_mut::< ChainError< T> > ()
# }
# }
#
# impl< T: 'static + Display + Debug> Error for ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
# self.error_cause.as_ref().map(|e| e.as_ref())
# }
# }
#
# impl< T: 'static + Display + Debug> Error for & ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
# self.error_cause.as_ref().map(|e| e.as_ref())
# }
# }
#
# impl< T: 'static + Display + Debug> Error for & mut ChainError< T> {
# fn source(& self) -> Option< & (dyn Error + 'static)> {
# self.error_cause.as_ref().map(|e| e.as_ref())
# }
# }
#
# impl< T: 'static + Display + Debug> Display for ChainError< T> {
# fn fmt(& self, f: & mut Formatter) -> Result {
# write!(f, " {}" , self.kind)?;
#
# #[cfg(feature = " display-cause" )]
# {
# if let Some(e) = self.source() {
# writeln!(f, " \nCaused by:" )?;
# Display::fmt(& e, f)?;
# }
# }
# Ok(())
# }
# }
#
# impl< T: 'static + Display + Debug> Debug for ChainError< T> {
# fn fmt(& self, f: & mut Formatter) -> Result {
# #[cfg(not(feature = " no-fileline" ))]
# {
# if let Some(o) = self.occurrence {
# write!(f, " {}:{}: " , o.1, o.0)?;
# }
# }
#
# if self.is_chain::< String> () {
# Display::fmt(& self.kind, f)?;
# } else {
# Debug::fmt(& self.kind, f)?;
# }
#
# #[cfg(not(feature = " no-debug-cause" ))]
# {
# if let Some(e) = self.source() {
# writeln!(f, " \nCaused by:" )?;
# Debug::fmt(& e, f)?;
# }
# }
# Ok(())
# }
# }
#
# pub trait ChainErrorFrom< T> : Sized {
# fn chain_error_from(_: T, line_filename: Option< (u32, & 'static str)> ) -> ChainError< Self> ;
# }
#
# pub trait IntoChainError< T> : Sized {
# fn into_chain_error(self, line_filename: Option< (u32, & 'static str)> ) -> ChainError< T> ;
# }
#
# impl< T, U> IntoChainError< U> for T
# where
# U: ChainErrorFrom< T> ,
# {
# fn into_chain_error(self, line_filename: Option< (u32, & 'static str)> ) -> ChainError< U> {
# U::chain_error_from(self, line_filename)
# }
# }
#
# impl< T, U> ChainErrorFrom< T> for U
# where
# T: Into< U> ,
# U: 'static + Display + Debug,
# {
# fn chain_error_from(t: T, line_filename: Option< (u32, & 'static str)> ) -> ChainError< Self> {
# let e: U = t.into();
# ChainError::< _> ::new(e, None, line_filename)
# }
# }
#
# #[macro_export]
# macro_rules! minto_cherr {
# ( ) => {
# |e| e.into_chain_error(Some((line!(), file!())))
# };
# }
#
# #[macro_export]
# macro_rules! into_cherr {
# ( $t:expr ) => {
# $t.into_chain_error(Some((line!(), file!())))
# };
# }
#
# /// Creates a new `ChainError< T> `
# ///
# /// # Examples
# ///
# /// Create a new ChainError< FooError> , where `FooError` must implement `Display` and `Debug`.
# /// ~~~rust
# /// # use chainerror::*;
# /// #
# /// # #[derive(Debug)]
# /// enum FooError {
# /// Bar,
# /// Baz(& 'static str),
# /// }
# /// #
# /// # impl ::std::fmt::Display for FooError {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # FooError::Bar => write!(f, " Bar Error" ),
# /// # FooError::Baz(s) => write!(f, " Baz Error: '{}'" , s),
# /// # }
# /// # }
# /// # }
# ///
# /// // impl ::std::fmt::Display for FooError
# ///
# /// fn do_some_stuff() -> bool {
# /// false
# /// }
# ///
# /// fn func() -> ChainResult< (), FooError> {
# /// if ! do_some_stuff() {
# /// Err(cherr!(FooError::Baz(" Error" )))?;
# /// }
# /// Ok(())
# /// }
# /// #
# /// # pub fn main() {
# /// # match func().unwrap_err().kind() {
# /// # FooError::Baz(s) if s == & " Error" => {},
# /// # _ => panic!(),
# /// # }
# /// # }
# /// ~~~
# ///
# /// Additionally an error cause can be added.
# ///
# /// ~~~rust
# /// # use chainerror::*;
# /// # use std::io;
# /// # use std::error::Error;
# /// #
# /// # #[derive(Debug)]
# /// # enum FooError {
# /// # Bar,
# /// # Baz(& 'static str),
# /// # }
# /// #
# /// # impl ::std::fmt::Display for FooError {
# /// # fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# /// # match self {
# /// # FooError::Bar => write!(f, " Bar Error" ),
# /// # FooError::Baz(s) => write!(f, " Baz Error: '{}'" , s),
# /// # }
# /// # }
# /// # }
# /// #
# /// fn do_some_stuff() -> Result< (), Box< Error> > {
# /// Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// Ok(())
# /// }
# ///
# /// fn func() -> ChainResult< (), FooError> {
# /// do_some_stuff().map_err(
# /// |e| cherr!(e, FooError::Baz(" Error" ))
# /// )?;
# /// Ok(())
# /// }
# /// #
# /// # pub fn main() {
# /// # match func().unwrap_err().kind() {
# /// # FooError::Baz(s) if s == & " Error" => {},
# /// # _ => panic!(),
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! cherr {
# ( $k:expr ) => ({
# ChainError::< _> ::new($k, None, Some((line!(), file!())))
# });
# ( None, $k:expr ) => ({
# ChainError::< _> ::new($k, None, Some((line!(), file!())))
# });
# ( None, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!(None, format!($fmt, $($arg)+ ))
# });
# ( None, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!(None, format!($fmt, $($arg)+ ))
# });
# ( $e:path, $k:expr ) => ({
# ChainError::< _> ::new($k, Some(Box::from($e)), Some((line!(), file!())))
# });
# ( $e:path, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!($e, format!($fmt, $($arg)+ ))
# });
#
# }
#
# /// Convenience macro for `|e| cherr!(e, format!(…))`
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(" Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(" func1 error" ))?;
# /// Ok(())
# /// }
# ///
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # #[cfg(not(windows))]
# /// # assert_eq!(
# /// # format!(" \n{:?}\n" , e), r#"
# /// # src/lib.rs:20: func1 error
# /// # Caused by:
# /// # src/lib.rs:15: Error reading 'foo.txt'
# /// # Caused by:
# /// # Kind(NotFound)
# /// # " #
# /// # );
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# ///
# /// `mstrerr!()` can also be used to map a new `ChainError< T> `, where T was defined with
# /// `derive_str_cherr!(T)`
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> Result< (), Box< Error> > {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! mstrerr {
# ( $t:path, $msg:expr ) => ({
# |e| cherr!(e, $t ($msg.to_string()))
# });
# ( $t:path, $msg:expr, ) => ({
# |e| cherr!(e, $t ($msg.to_string()))
# });
# ( $t:path, $fmt:expr, $($arg:tt)+ ) => ({
# |e| cherr!(e, $t (format!($fmt, $($arg)+ )))
# });
# ($msg:expr) => ({
# |e| cherr!(e, $msg.to_string())
# });
# ($msg:expr, ) => ({
# |e| cherr!(e, $msg.to_string())
# });
# ($fmt:expr, $($arg:tt)+) => ({
# |e| cherr!(e, format!($fmt, $($arg)+ ))
# });
# }
#
# /// Convenience macro for `cherr!(T(format!(…)))` where `T(String)`
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::result::Result;
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> ChainResult< (), Func2Error> {
# /// let filename = " foo.txt" ;
# /// Err(strerr!(Func2Error, " Error reading '{}'" , filename))
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! strerr {
# ( $t:path, $msg:expr ) => ({
# cherr!($t ($msg.to_string()))
# });
# ( $t:path, $msg:expr, ) => ({
# cherr!($t ($msg.to_string()))
# });
# ( $t:path, $fmt:expr, $($arg:tt)+ ) => ({
# cherr!($t (format!($fmt, $($arg)+ )))
# });
# ($msg:expr) => ({
# cherr!($msg.to_string())
# });
# ($msg:expr, ) => ({
# cherr!($msg.to_string())
# });
# ($fmt:expr, $($arg:tt)+) => ({
# cherr!(format!($fmt, $($arg)+ ))
# });
# }
#
# /// Convenience macro to create a " new type" T(String) and implement Display + Debug for T
# ///
# /// # Examples
# ///
# /// ~~~rust
# /// # use crate::chainerror::*;
# /// # use std::error::Error;
# /// # use std::io;
# /// # use std::result::Result;
# /// #
# /// # fn do_some_io() -> Result< (), Box< Error> > {
# /// # Err(io::Error::from(io::ErrorKind::NotFound))?;
# /// # Ok(())
# /// # }
# /// #
# /// derive_str_cherr!(Func2Error);
# ///
# /// fn func2() -> ChainResult< (), Func2Error> {
# /// let filename = " foo.txt" ;
# /// do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
# /// Ok(())
# /// }
# ///
# /// derive_str_cherr!(Func1Error);
# ///
# /// fn func1() -> Result< (), Box< Error> > {
# /// func2().map_err(mstrerr!(Func1Error, " func1 error" ))?;
# /// Ok(())
# /// }
# /// #
# /// # fn main() {
# /// # if let Err(e) = func1() {
# /// # if let Some(f1err) = e.downcast_chain_ref::< Func1Error> () {
# /// # assert!(f1err.find_cause::< ChainError< Func2Error> > ().is_some());
# /// # assert!(f1err.find_chain_cause::< Func2Error> ().is_some());
# /// # } else {
# /// # panic!();
# /// # }
# /// # } else {
# /// # unreachable!();
# /// # }
# /// # }
# /// ~~~
# #[macro_export]
# macro_rules! derive_str_cherr {
# ($e:ident) => {
# pub struct $e(pub String);
# impl ::std::fmt::Display for $e {
# fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# write!(f, " {}" , self.0)
# }
# }
# impl ::std::fmt::Debug for $e {
# fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
# write!(f, " {}({})" , stringify!($e), self.0)
# }
# }
# impl ::std::error::Error for $e {}
# };
# }
# }
pub mod mycrate {
use crate::chainerror::*; // omit the `crate::` part
use std::io;
fn do_some_io() -> std::result::Result< (), Box< std::error::Error> > {
Err(io::Error::from(io::ErrorKind::NotFound))?;
Ok(())
}
derive_str_cherr!(Func2Error);
fn func2() -> std::result::Result< (), Box< std::error::Error> > {
let filename = " foo.txt" ;
do_some_io().map_err(mstrerr!(Func2Error, " Error reading '{}'" , filename))?;
Ok(())
}
#[derive(Debug)]
pub enum ErrorKind {
Func2,
IO(String),
}
pub type Error = ChainError< ErrorKind> ;
pub type Result< T> = std::result::Result< T, Error> ;
impl ::std::fmt::Display for ErrorKind {
fn fmt(& self, f: & mut ::std::fmt::Formatter) -> ::std::fmt::Result {
match self {
ErrorKind::Func2 => write!(f, " func1 error calling func2" ),
ErrorKind::IO(filename) => write!(f, " Error reading '{}'" , filename),
}
}
}
pub fn func1() -> Result< ()> {
func2().map_err(|e| cherr!(e, ErrorKind::Func2))?;
let filename = String::from(" bar.txt" );
do_some_io().map_err(|e| cherr!(e, ErrorKind::IO(filename)))?;
Ok(())
}
}
fn main() -> Result< (), Box< std::error::Error> > {
use mycrate::func1;
use mycrate::ErrorKind;
use std::error::Error;
use std::io;
if let Err(e) = func1() {
match e.kind() {
ErrorKind::Func2 => eprintln!(" Main Error Report: func1 error calling func2" ),
ErrorKind::IO(ref filename) => {
eprintln!(" Main Error Report: func1 error reading '{}'" , filename)
}
}
eprintln!();
let mut s : & Error = & e;
while let Some(c) = s.source() {
if let Some(ioerror) = c.downcast_ref::< io::Error> () {
eprintln!(" caused by: std::io::Error: {}" , ioerror);
match ioerror.kind() {
io::ErrorKind::NotFound => eprintln!(" of kind: std::io::ErrorKind::NotFound" ),
_ => {}
}
} else {
eprintln!(" caused by: {}" , c);
}
s = c;
}
eprintln!(" \nDebug Error:\n{:?}" , e);
}
Ok(())
}
< / code > < / pre > < / pre >
2018-12-21 13:55:46 +01:00
< a class = "header" href = "#the-end" id = "the-end" > < h1 > The End< / h1 > < / a >
< p > That's it for now…< / p >
< p > Happy error handling!< / p >
2018-12-21 14:07:02 +01:00
< p > To report issues, submit pull request or for the source code, examples and the book source, visit
the < a href = "https://github.com/haraldh/chainerror" > Git Repo< / a > .< / p >
2018-12-20 14:55:19 +01:00
< / main >
< nav class = "nav-wrapper" aria-label = "Page navigation" >
<!-- Mobile navigation buttons -->
< div style = "clear: both" > < / div >
< / nav >
< / div >
< / div >
< nav class = "nav-wide-wrapper" aria-label = "Page navigation" >
< / nav >
< / div >
< script src = "elasticlunr.min.js" type = "text/javascript" charset = "utf-8" > < / script >
< script src = "mark.min.js" type = "text/javascript" charset = "utf-8" > < / script >
< script src = "searcher.js" type = "text/javascript" charset = "utf-8" > < / script >
< script src = "clipboard.min.js" type = "text/javascript" charset = "utf-8" > < / script >
< script src = "highlight.js" type = "text/javascript" charset = "utf-8" > < / script >
< script src = "book.js" type = "text/javascript" charset = "utf-8" > < / script >
<!-- Custom JS scripts -->
< script type = "text/javascript" >
window.addEventListener('load', function() {
window.setTimeout(window.print, 100);
});
< / script >
< / body >
< / html >
