mirror of
https://github.com/haraldh/chainerror.git
synced 2025-01-31 00:56:41 +01:00
532 lines
21 KiB
HTML
532 lines
21 KiB
HTML
<!DOCTYPE HTML>
|
|
<html lang="en" class="sidebar-visible no-js">
|
|
<head>
|
|
<!-- Book generated using mdBook -->
|
|
<meta charset="UTF-8">
|
|
<title>Chapter 6 - chainerror</title>
|
|
<meta content="text/html; charset=utf-8" http-equiv="Content-Type">
|
|
<meta name="description" content="">
|
|
<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">
|
|
<ol class="chapter"><li><a href="tutorial1.html"><strong aria-hidden="true">1.</strong> Chapter 1</a></li><li><a href="tutorial2.html"><strong aria-hidden="true">2.</strong> Chapter 2</a></li><li><a href="tutorial3.html"><strong aria-hidden="true">3.</strong> Chapter 3</a></li><li><a href="tutorial4.html"><strong aria-hidden="true">4.</strong> Chapter 4</a></li><li><a href="tutorial5.html"><strong aria-hidden="true">5.</strong> Chapter 5</a></li><li><a href="tutorial6.html" class="active"><strong aria-hidden="true">6.</strong> Chapter 6</a></li><li><a href="tutorial7.html"><strong aria-hidden="true">7.</strong> Chapter 7</a></li><li><a href="tutorial8.html"><strong aria-hidden="true">8.</strong> Chapter 8</a></li><li><a href="tutorial9.html"><strong aria-hidden="true">9.</strong> Chapter 9</a></li><li><a href="tutorial10.html"><strong aria-hidden="true">10.</strong> Chapter 10</a></li><li><a href="tutorial11.html"><strong aria-hidden="true">11.</strong> Chapter 11</a></li></ol>
|
|
</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>
|
|
<a class="header" href="#downcast-the-errors" id="downcast-the-errors"><h2>Downcast the Errors</h2></a>
|
|
<p>[TBD]</p>
|
|
<pre><pre class="playpen"><code class="language-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() -> 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(())
|
|
}
|
|
# #[allow(dead_code)]
|
|
# mod chainerror {
|
|
# use std::error::Error;
|
|
# use std::fmt::{Debug, Display, Formatter, Result};
|
|
# use std::result::Result as StdResult;
|
|
#
|
|
# pub struct ChainError<T> {
|
|
# #[cfg(not(feature = "no-fileline"))]
|
|
# occurrence: Option<(u32, &'static str)>,
|
|
# kind: T,
|
|
# error_cause: Option<Box<dyn Error + 'static>>,
|
|
# }
|
|
#
|
|
# pub type ChainResult<O, E> = StdResult<O, ChainError<E>>;
|
|
#
|
|
# impl<T: 'static + Display + Debug> ChainError<T> {
|
|
# #[cfg(not(feature = "no-fileline"))]
|
|
# 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")]
|
|
# pub fn new(
|
|
# kind: T,
|
|
# error_cause: Option<Box<dyn Error + 'static>>,
|
|
# _occurrence: Option<(u32, &'static str)>,
|
|
# ) -> Self {
|
|
# Self { kind, error_cause }
|
|
# }
|
|
#
|
|
# pub fn root_cause(&self) -> Option<&(dyn Error + 'static)> {
|
|
# let mut cause = self as &(dyn Error + 'static);
|
|
# while let Some(c) = cause.source() {
|
|
# cause = c;
|
|
# }
|
|
# Some(cause)
|
|
# }
|
|
#
|
|
# pub fn find_cause<U: Error + 'static>(&self) -> Option<&U> {
|
|
# let mut cause = self as &(dyn Error + 'static);
|
|
# loop {
|
|
# if cause.is::<U>() {
|
|
# return cause.downcast_ref::<U>();
|
|
# }
|
|
#
|
|
# match cause.source() {
|
|
# Some(c) => cause = c,
|
|
# None => return None,
|
|
# }
|
|
# }
|
|
# }
|
|
#
|
|
# pub fn find_chain_cause<U: Error + 'static>(&self) -> Option<&ChainError<U>> {
|
|
# let mut cause = self as &(dyn Error + 'static);
|
|
# loop {
|
|
# if cause.is::<ChainError<U>>() {
|
|
# return cause.downcast_ref::<ChainError<U>>();
|
|
# }
|
|
#
|
|
# match cause.source() {
|
|
# Some(c) => cause = c,
|
|
# None => return None,
|
|
# }
|
|
# }
|
|
# }
|
|
#
|
|
# pub fn kind<'a>(&'a self) -> &'a T {
|
|
# &self.kind
|
|
# }
|
|
# }
|
|
#
|
|
# pub trait ChainErrorDown {
|
|
# 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>>;
|
|
# }
|
|
#
|
|
# use std::any::TypeId;
|
|
#
|
|
# 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>() {
|
|
# 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>() {
|
|
# 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)> {
|
|
# if let Some(ref e) = self.error_cause {
|
|
# Some(e.as_ref())
|
|
# } else {
|
|
# None
|
|
# }
|
|
# }
|
|
# }
|
|
#
|
|
# impl<T: 'static + Display + Debug> Error for &ChainError<T> {
|
|
# fn source(&self) -> Option<&(dyn Error + 'static)> {
|
|
# if let Some(ref e) = self.error_cause {
|
|
# Some(e.as_ref())
|
|
# } else {
|
|
# None
|
|
# }
|
|
# }
|
|
# }
|
|
#
|
|
# impl<T: 'static + Display + Debug> Error for &mut ChainError<T> {
|
|
# fn source(&self) -> Option<&(dyn Error + 'static)> {
|
|
# if let Some(ref e) = self.error_cause {
|
|
# Some(e.as_ref())
|
|
# } else {
|
|
# None
|
|
# }
|
|
# }
|
|
# }
|
|
#
|
|
# 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)?;
|
|
# }
|
|
# }
|
|
#
|
|
# 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(())
|
|
# }
|
|
# }
|
|
#
|
|
# #[macro_export]
|
|
# macro_rules! cherr {
|
|
# ( $k:expr ) => {
|
|
# ChainError::<_>::new($k, None, Some((line!(), file!())))
|
|
# };
|
|
# ( $e:expr, $k:expr ) => {
|
|
# ChainError::<_>::new($k, Some(Box::from($e)), Some((line!(), file!())))
|
|
# };
|
|
# }
|
|
#
|
|
# #[macro_export]
|
|
# macro_rules! mstrerr {
|
|
# ( $t:ident, $v:expr $(, $more:expr)* ) => {
|
|
# |e| cherr!(e, $t (format!($v, $( $more , )* )))
|
|
# };
|
|
# ( $t:path, $v:expr $(, $more:expr)* ) => {
|
|
# |e| cherr!(e, $t (format!($v, $( $more , )* )))
|
|
# };
|
|
# ( $v:expr $(, $more:expr)* ) => {
|
|
# |e| cherr!(e, format!($v, $( $more , )* ))
|
|
# };
|
|
# }
|
|
#
|
|
# #[macro_export]
|
|
# macro_rules! derive_str_cherr {
|
|
# ($e:ident) => {
|
|
# struct $e(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 {}
|
|
# };
|
|
# }
|
|
#
|
|
# #[macro_export]
|
|
# macro_rules! try_cherr_ref {
|
|
# ( $e:expr, $t:ident ) => {
|
|
# $e.downcast_ref::<ChainError<$t>>()
|
|
# };
|
|
# ( $e:expr, $t:path ) => {
|
|
# $e.downcast_ref::<ChainError<$t>>()
|
|
# };
|
|
# }
|
|
#
|
|
# #[macro_export]
|
|
# macro_rules! try_cherr_mut {
|
|
# ( $e:expr, $t:ident ) => {
|
|
# $e.downcast_mut::<ChainError<$t>>()
|
|
# };
|
|
# ( $e:expr, $t:path ) => {
|
|
# $e.downcast_mut::<ChainError<$t>>()
|
|
# };
|
|
# }
|
|
# }
|
|
</code></pre></pre>
|
|
|
|
</main>
|
|
|
|
<nav class="nav-wrapper" aria-label="Page navigation">
|
|
<!-- Mobile navigation buttons -->
|
|
|
|
<a rel="prev" href="tutorial5.html" class="mobile-nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
|
|
<i class="fa fa-angle-left"></i>
|
|
</a>
|
|
|
|
|
|
|
|
<a rel="next" href="tutorial7.html" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
|
|
<i class="fa fa-angle-right"></i>
|
|
</a>
|
|
|
|
|
|
<div style="clear: both"></div>
|
|
</nav>
|
|
</div>
|
|
</div>
|
|
|
|
<nav class="nav-wide-wrapper" aria-label="Page navigation">
|
|
|
|
<a href="tutorial5.html" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
|
|
<i class="fa fa-angle-left"></i>
|
|
</a>
|
|
|
|
|
|
|
|
<a href="tutorial7.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
|
|
<i class="fa fa-angle-right"></i>
|
|
</a>
|
|
|
|
</nav>
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<script src="ace.js" type="text/javascript" charset="utf-8"></script>
|
|
<script src="editor.js" type="text/javascript" charset="utf-8"></script>
|
|
<script src="mode-rust.js" type="text/javascript" charset="utf-8"></script>
|
|
<script src="theme-dawn.js" type="text/javascript" charset="utf-8"></script>
|
|
<script src="theme-tomorrow_night.js" type="text/javascript" charset="utf-8"></script>
|
|
|
|
|
|
|
|
<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 -->
|
|
|
|
|
|
|
|
|
|
</body>
|
|
</html>
|