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3474 lines
118 KiB
HTML
3474 lines
118 KiB
HTML
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<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"><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>
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<h1 class="menu-title">chainerror</h1>
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<div id="content" class="content">
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<main>
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<a class="header" href="#simple-string-errors" id="simple-string-errors"><h1>Simple String Errors</h1></a>
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<p>The most simplest of doing error handling in rust is by returning <code>String</code> as a <code>Box<Error></code>.</p>
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<p>As you can see by running the example (the "Play" button in upper right of the code block), this only
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prints out the last <code>Error</code>.</p>
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<p>If the rust <code>main</code> function returns an Err(), this Err() will be displayed with <code>std::fmt::Debug</code>.</p>
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<pre><pre class="playpen"><code class="language-rust">use std::error::Error;
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use std::result::Result;
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fn do_some_io() -> Result<(), Box<Error>> {
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Err("do_some_io error")?;
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Ok(())
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}
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fn func2() -> Result<(), Box<Error>> {
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if let Err(_) = do_some_io() {
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Err("func2 error")?;
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}
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Ok(())
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}
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fn func1() -> Result<(), Box<Error>> {
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if let Err(_) = func2() {
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Err("func1 error")?;
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}
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Ok(())
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}
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fn main() -> Result<(), Box<Error>> {
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func1()
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}
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</code></pre></pre>
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<a class="header" href="#simple-chained-string-errors" id="simple-chained-string-errors"><h1>Simple Chained String Errors</h1></a>
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<p>Now with the help of the <code>chainerror</code> crate, we can have a nicer output.</p>
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<p>Press the play button in the upper right corner and see the nice debug output.</p>
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<pre><pre class="playpen"><code class="language-rust">use crate::chainerror::*;
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use std::error::Error;
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use std::result::Result;
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fn do_some_io() -> Result<(), Box<Error>> {
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Err("do_some_io error")?;
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Ok(())
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}
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fn func2() -> Result<(), Box<Error>> {
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if let Err(e) = do_some_io() {
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Err(cherr!(e, "func2 error"))?;
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}
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Ok(())
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}
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fn func1() -> Result<(), Box<Error>> {
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if let Err(e) = func2() {
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Err(cherr!(e, "func1 error"))?;
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}
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Ok(())
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}
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fn main() -> Result<(), Box<Error>> {
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func1()
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}
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# #[allow(dead_code)]
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# mod chainerror {
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# use std::error::Error;
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# use std::fmt::{Debug, Display, Formatter, Result};
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# use std::result::Result as StdResult;
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#
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# pub struct ChainError<T> {
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# #[cfg(not(feature = "no-fileline"))]
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# occurrence: Option<(u32, &'static str)>,
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# kind: T,
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# error_cause: Option<Box<dyn Error + 'static>>,
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# }
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#
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# pub type ChainResult<O, E> = StdResult<O, ChainError<E>>;
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#
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# impl<T: 'static + Display + Debug> ChainError<T> {
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# #[cfg(not(feature = "no-fileline"))]
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# pub fn new(
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# kind: T,
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# error_cause: Option<Box<dyn Error + 'static>>,
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# occurrence: Option<(u32, &'static str)>,
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# ) -> Self {
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# Self {
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# occurrence,
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# kind,
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# error_cause,
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# }
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# }
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#
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# #[cfg(feature = "no-fileline")]
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# pub fn new(
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# kind: T,
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# error_cause: Option<Box<dyn Error + 'static>>,
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# _occurrence: Option<(u32, &'static str)>,
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# ) -> Self {
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# Self { kind, error_cause }
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# }
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#
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# pub fn root_cause(&self) -> Option<&(dyn Error + 'static)> {
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# let mut cause = self as &(dyn Error + 'static);
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# while let Some(c) = cause.source() {
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# cause = c;
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# }
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# Some(cause)
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# }
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#
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# pub fn find_cause<U: Error + 'static>(&self) -> Option<&U> {
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# let mut cause = self as &(dyn Error + 'static);
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# loop {
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# if cause.is::<U>() {
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# return cause.downcast_ref::<U>();
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# }
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#
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# match cause.source() {
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# Some(c) => cause = c,
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# None => return None,
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# }
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# }
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# }
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#
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# pub fn find_chain_cause<U: Error + 'static>(&self) -> Option<&ChainError<U>> {
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# let mut cause = self as &(dyn Error + 'static);
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# loop {
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# if cause.is::<ChainError<U>>() {
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# return cause.downcast_ref::<ChainError<U>>();
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# }
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#
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# match cause.source() {
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# Some(c) => cause = c,
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# None => return None,
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# }
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# }
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# }
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#
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# pub fn kind<'a>(&'a self) -> &'a T {
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# &self.kind
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# }
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# }
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#
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# pub trait ChainErrorDown {
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# fn is_chain<T: 'static + Display + Debug>(&self) -> bool;
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# fn downcast_chain_ref<T: 'static + Display + Debug>(&self) -> Option<&ChainError<T>>;
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# fn downcast_chain_mut<T: 'static + Display + Debug>(&mut self) -> Option<&mut ChainError<T>>;
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# }
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#
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# use std::any::TypeId;
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#
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# impl<U: 'static + Display + Debug> ChainErrorDown for ChainError<U> {
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# fn is_chain<T: 'static + Display + Debug>(&self) -> bool {
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# TypeId::of::<T>() == TypeId::of::<U>()
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# }
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#
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# fn downcast_chain_ref<T: 'static + Display + Debug>(&self) -> Option<&ChainError<T>> {
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# if self.is_chain::<T>() {
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# unsafe { Some(&*(self as *const dyn Error as *const &ChainError<T>)) }
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# } else {
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# None
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# }
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# }
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#
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# fn downcast_chain_mut<T: 'static + Display + Debug>(&mut self) -> Option<&mut ChainError<T>> {
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# if self.is_chain::<T>() {
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# unsafe { Some(&mut *(self as *mut dyn Error as *mut &mut ChainError<T>)) }
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# } else {
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# None
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# }
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# }
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# }
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#
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# impl ChainErrorDown for dyn Error + 'static {
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# fn is_chain<T: 'static + Display + Debug>(&self) -> bool {
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# self.is::<ChainError<T>>()
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# }
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#
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# fn downcast_chain_ref<T: 'static + Display + Debug>(&self) -> Option<&ChainError<T>> {
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# self.downcast_ref::<ChainError<T>>()
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# }
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#
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# fn downcast_chain_mut<T: 'static + Display + Debug>(&mut self) -> Option<&mut ChainError<T>> {
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# self.downcast_mut::<ChainError<T>>()
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# }
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# }
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#
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# impl ChainErrorDown for dyn Error + 'static + Send {
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# fn is_chain<T: 'static + Display + Debug>(&self) -> bool {
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# self.is::<ChainError<T>>()
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# }
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#
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# fn downcast_chain_ref<T: 'static + Display + Debug>(&self) -> Option<&ChainError<T>> {
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# self.downcast_ref::<ChainError<T>>()
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# }
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#
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# fn downcast_chain_mut<T: 'static + Display + Debug>(&mut self) -> Option<&mut ChainError<T>> {
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# self.downcast_mut::<ChainError<T>>()
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# }
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# }
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#
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# impl ChainErrorDown for dyn Error + 'static + Send + Sync {
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# fn is_chain<T: 'static + Display + Debug>(&self) -> bool {
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# self.is::<ChainError<T>>()
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# }
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#
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# fn downcast_chain_ref<T: 'static + Display + Debug>(&self) -> Option<&ChainError<T>> {
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# self.downcast_ref::<ChainError<T>>()
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# }
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#
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# fn downcast_chain_mut<T: 'static + Display + Debug>(&mut self) -> Option<&mut ChainError<T>> {
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# self.downcast_mut::<ChainError<T>>()
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# }
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# }
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#
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# impl<T: 'static + Display + Debug> Error for ChainError<T> {
|
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# fn source(&self) -> Option<&(dyn Error + 'static)> {
|
|
# if let Some(ref e) = self.error_cause {
|
|
# Some(e.as_ref())
|
|
# } else {
|
|
# None
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|
# }
|
|
# }
|
|
# }
|
|
#
|
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# 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
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|
# }
|
|
# }
|
|
# }
|
|
#
|
|
# 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
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|
# }
|
|
# }
|
|
# }
|
|
#
|
|
# 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>
|
|
<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>
|
|
<p>The macro <code>cherr!(cause, newerror)</code> stores <code>cause</code> as the source/cause of <code>newerror</code> and returns
|
|
<code>newerror</code>, along with the filename (<code>file!()</code>) and line number (<code>line!()</code>).</p>
|
|
<p><code>Err(e)?</code> then returns the error <code>e</code> applying <code>e.into()</code>, so that we
|
|
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>
|
|
<p><code>ChainError<T></code> is in our case <code>ChainError<String></code>.</p>
|
|
<a class="header" href="#mapping-errors" id="mapping-errors"><h1>Mapping Errors</h1></a>
|
|
<p>Now let's get more rust idiomatic by using <code>.map_err()</code>.</p>
|
|
<pre><pre class="playpen"><code class="language-rust">use crate::chainerror::*;
|
|
use std::error::Error;
|
|
use std::result::Result;
|
|
|
|
fn do_some_io() -> Result<(), Box<Error>> {
|
|
Err("do_some_io error")?;
|
|
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(())
|
|
}
|
|
# #[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>
|
|
<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>
|
|
<a class="header" href="#saving-coding-chars" id="saving-coding-chars"><h1>Saving coding chars</h1></a>
|
|
<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>
|
|
<pre><pre class="playpen"><code class="language-rust">use crate::chainerror::*;
|
|
use std::error::Error;
|
|
use std::result::Result;
|
|
|
|
fn do_some_io() -> Result<(), Box<Error>> {
|
|
Err("do_some_io error")?;
|
|
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!("{:?}", e);
|
|
}
|
|
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>
|
|
<a class="header" href="#the-source-of-errors" id="the-source-of-errors"><h1>The source() of Errors</h1></a>
|
|
<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>
|
|
<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>> {
|
|
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(())
|
|
}
|
|
# #[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>
|
|
<p>Note, that we changed the output of the error in <code>main()</code> from <code>Debug</code> to <code>Display</code>, so we don't see
|
|
the error backtrace with filename and line number.</p>
|
|
<p>To enable the <code>Display</code> backtrace, you have to enable the feature <code>display-cause</code> for <code>chainerror</code>.</p>
|
|
<a class="header" href="#downcast-the-errors" id="downcast-the-errors"><h1>Downcast the Errors</h1></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>
|
|
<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>
|
|
<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);
|
|
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(())
|
|
}
|
|
# #[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>
|
|
<a class="header" href="#finding-an-error-cause" id="finding-an-error-cause"><h1>Finding an Error cause</h1></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(())
|
|
}
|
|
|
|
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(())
|
|
}
|
|
# #[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>
|
|
<a class="header" href="#selective-error-handling" id="selective-error-handling"><h1>Selective Error Handling</h1></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(())
|
|
}
|
|
|
|
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);
|
|
}
|
|
|
|
if let Some(s) = try_cherr_ref!(e, Func1ErrorFunc2) {
|
|
eprintln!("Func1ErrorFunc2:\n{:?}", s);
|
|
}
|
|
}
|
|
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>
|
|
<a class="header" href="#errorkind-to-the-rescue" id="errorkind-to-the-rescue"><h1>ErrorKind to the rescue</h1></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(())
|
|
}
|
|
|
|
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 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),
|
|
}
|
|
}
|
|
}
|
|
|
|
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() -> Result<(), Box<Error>> {
|
|
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!("Error reported by Func2Error: {}", e)
|
|
}
|
|
|
|
eprintln!("\nDebug Error:\n{:?}", e);
|
|
}
|
|
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>
|
|
<a class="header" href="#debug-for-the-errorkind" id="debug-for-the-errorkind"><h1>Debug for the ErrorKind</h1></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(())
|
|
}
|
|
|
|
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 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() -> Result<(), Box<Error>> {
|
|
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!("Error reported by Func2Error: {}", e)
|
|
}
|
|
|
|
eprintln!("\nDebug Error:\n{:?}", e);
|
|
}
|
|
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>
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