mirror of
https://github.com/haraldh/chainerror.git
synced 2024-10-05 20:15:11 +02:00
441 lines
18 KiB
HTML
441 lines
18 KiB
HTML
<!DOCTYPE HTML>
|
|
<html lang="en" class="sidebar-visible no-js light">
|
|
<head>
|
|
<!-- Book generated using mdBook -->
|
|
<meta charset="UTF-8">
|
|
<title>Going back to std - chainerror</title>
|
|
|
|
|
|
<meta content="text/html; charset=utf-8" http-equiv="Content-Type">
|
|
<meta name="description" content="A tutorial for the chainerror rust crate.">
|
|
<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>
|
|
<!-- Provide site root to javascript -->
|
|
<script type="text/javascript">
|
|
var path_to_root = "";
|
|
var default_theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? "light" : "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; }
|
|
var html = document.querySelector('html');
|
|
html.classList.remove('no-js')
|
|
html.classList.remove('light')
|
|
html.classList.add(theme);
|
|
html.classList.add('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">
|
|
<div id="sidebar-scrollbox" class="sidebar-scrollbox">
|
|
<ol class="chapter"><li class="expanded affix "><a href="index.html">chainerror</a></li><li class="expanded "><a href="tutorial1.html"><strong aria-hidden="true">1.</strong> Simple String Errors</a></li><li class="expanded "><a href="tutorial2.html"><strong aria-hidden="true">2.</strong> Simple Chained String Errors</a></li><li class="expanded "><a href="tutorial3.html"><strong aria-hidden="true">3.</strong> Mapping Errors</a></li><li class="expanded "><a href="tutorial4.html"><strong aria-hidden="true">4.</strong> Saving coding chars</a></li><li class="expanded "><a href="tutorial5.html"><strong aria-hidden="true">5.</strong> The source() of Errors</a></li><li class="expanded "><a href="tutorial6.html"><strong aria-hidden="true">6.</strong> Downcast the Errors</a></li><li class="expanded "><a href="tutorial7.html"><strong aria-hidden="true">7.</strong> The root cause of all Errors</a></li><li class="expanded "><a href="tutorial8.html"><strong aria-hidden="true">8.</strong> Finding an Error cause</a></li><li class="expanded "><a href="tutorial9.html"><strong aria-hidden="true">9.</strong> Selective Error Handling</a></li><li class="expanded "><a href="tutorial10.html"><strong aria-hidden="true">10.</strong> ErrorKind to the rescue</a></li><li class="expanded "><a href="tutorial11.html"><strong aria-hidden="true">11.</strong> Debug for the ErrorKind</a></li><li class="expanded "><a href="tutorial12.html"><strong aria-hidden="true">12.</strong> Deref for the ErrorKind</a></li><li class="expanded "><a href="tutorial13.html"><strong aria-hidden="true">13.</strong> Writing a library</a></li><li class="expanded "><a href="tutorial14.html" class="active"><strong aria-hidden="true">14.</strong> Going back to std</a></li><li class="expanded affix "><a href="end.html">The End</a></li></ol>
|
|
</div>
|
|
<div id="sidebar-resize-handle" class="sidebar-resize-handle"></div>
|
|
</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>
|
|
<h1><a class="header" href="#going-back-to-std" id="going-back-to-std">Going back to std</a></h1>
|
|
<p>Not using <code>chainerror</code> and going full <code>std</code> would look like this:</p>
|
|
<p>Btw, the code size is bigger than using <code>chainerror</code> :-)</p>
|
|
<pre><pre class="playpen"><code class="language-rust">pub mod mycrate {
|
|
use std::error::Error as StdError;
|
|
|
|
use func2mod::{do_some_io, func2};
|
|
|
|
pub mod func2mod {
|
|
use std::error::Error as StdError;
|
|
use std::io;
|
|
|
|
pub enum ErrorKind {
|
|
IO(String),
|
|
}
|
|
|
|
impl std::fmt::Display for ErrorKind {
|
|
fn fmt(&self, f: &mut ::std::fmt::Formatter) -> std::fmt::Result {
|
|
match self {
|
|
ErrorKind::IO(s) => std::fmt::Display::fmt(s, f),
|
|
}
|
|
}
|
|
}
|
|
|
|
impl std::fmt::Debug for ErrorKind {
|
|
fn fmt(&self, f: &mut ::std::fmt::Formatter) -> std::fmt::Result {
|
|
match self {
|
|
ErrorKind::IO(s) => std::fmt::Display::fmt(s, f),
|
|
}
|
|
}
|
|
}
|
|
|
|
macro_rules! mcherr {
|
|
( $k:expr ) => {{
|
|
|e| {
|
|
Error(
|
|
$k,
|
|
Some(Box::from(e)),
|
|
Some(concat!(file!(), ":", line!(), ": ")),
|
|
)
|
|
}
|
|
}};
|
|
}
|
|
|
|
pub struct Error(
|
|
ErrorKind,
|
|
Option<Box<dyn std::error::Error + 'static>>,
|
|
Option<&'static str>,
|
|
);
|
|
|
|
impl Error {
|
|
pub fn kind(&self) -> &ErrorKind {
|
|
&self.0
|
|
}
|
|
}
|
|
|
|
impl From<ErrorKind> for Error {
|
|
fn from(e: ErrorKind) -> Self {
|
|
Error(e, None, None)
|
|
}
|
|
}
|
|
|
|
impl std::error::Error for Error {
|
|
fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
|
|
self.1.as_ref().map(|e| e.as_ref())
|
|
}
|
|
}
|
|
|
|
impl std::fmt::Display for Error {
|
|
fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
|
|
std::fmt::Display::fmt(&self.0, f)
|
|
}
|
|
}
|
|
|
|
impl std::fmt::Debug for Error {
|
|
fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
|
|
if let Some(ref o) = self.2 {
|
|
std::fmt::Display::fmt(o, f)?;
|
|
}
|
|
|
|
std::fmt::Debug::fmt(&self.0, f)?;
|
|
|
|
if let Some(e) = self.source() {
|
|
std::fmt::Display::fmt("\nCaused by:\n", f)?;
|
|
std::fmt::Debug::fmt(&e, f)?;
|
|
}
|
|
Ok(())
|
|
}
|
|
}
|
|
|
|
pub fn do_some_io() -> std::result::Result<(), Box<dyn std::error::Error>> {
|
|
Err(io::Error::from(io::ErrorKind::NotFound))?;
|
|
Ok(())
|
|
}
|
|
|
|
pub fn func2() -> std::result::Result<(), Error> {
|
|
let filename = "foo.txt";
|
|
do_some_io().map_err(mcherr!(ErrorKind::IO(format!(
|
|
"Error reading '{}'",
|
|
filename
|
|
))))?;
|
|
Ok(())
|
|
}
|
|
}
|
|
|
|
#[derive(Debug)]
|
|
pub enum ErrorKind {
|
|
Func2,
|
|
IO(String),
|
|
}
|
|
|
|
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),
|
|
}
|
|
}
|
|
}
|
|
|
|
macro_rules! mcherr {
|
|
( $k:expr ) => {{
|
|
|e| {
|
|
Error(
|
|
$k,
|
|
Some(Box::from(e)),
|
|
Some(concat!(file!(), ":", line!(), ": ")),
|
|
)
|
|
}
|
|
}};
|
|
}
|
|
|
|
pub struct Error(
|
|
ErrorKind,
|
|
Option<Box<dyn std::error::Error + 'static>>,
|
|
Option<&'static str>,
|
|
);
|
|
|
|
impl Error {
|
|
pub fn kind(&self) -> &ErrorKind {
|
|
&self.0
|
|
}
|
|
}
|
|
|
|
impl From<ErrorKind> for Error {
|
|
fn from(e: ErrorKind) -> Self {
|
|
Error(e, None, None)
|
|
}
|
|
}
|
|
|
|
impl std::error::Error for Error {
|
|
fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
|
|
self.1.as_ref().map(|e| e.as_ref())
|
|
}
|
|
}
|
|
|
|
impl std::fmt::Display for Error {
|
|
fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
|
|
std::fmt::Display::fmt(&self.0, f)
|
|
}
|
|
}
|
|
|
|
impl std::fmt::Debug for Error {
|
|
fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
|
|
if let Some(ref o) = self.2 {
|
|
std::fmt::Display::fmt(o, f)?;
|
|
}
|
|
|
|
std::fmt::Debug::fmt(&self.0, f)?;
|
|
if let Some(e) = self.source() {
|
|
std::fmt::Display::fmt("\nCaused by:\n", f)?;
|
|
std::fmt::Debug::fmt(&e, f)?;
|
|
}
|
|
Ok(())
|
|
}
|
|
}
|
|
|
|
pub type Result<T> = std::result::Result<T, Error>;
|
|
|
|
pub fn func1() -> Result<()> {
|
|
func2().map_err(mcherr!(ErrorKind::Func2))?;
|
|
let filename = String::from("bar.txt");
|
|
do_some_io().map_err(mcherr!(ErrorKind::IO(filename)))?;
|
|
Ok(())
|
|
}
|
|
}
|
|
|
|
fn main() -> Result<(), Box<std::error::Error + Send + Sync>> {
|
|
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>
|
|
|
|
</main>
|
|
|
|
<nav class="nav-wrapper" aria-label="Page navigation">
|
|
<!-- Mobile navigation buttons -->
|
|
|
|
<a rel="prev" href="tutorial13.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="end.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="tutorial13.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="end.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 type="text/javascript">
|
|
window.playpen_copyable = true;
|
|
</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>
|