| <!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="The error type for I/O operations of the `Read`, `Write`, `Seek`, and associated traits."><meta name="keywords" content="rust, rustlang, rust-lang, Error"><title>Error in futures::io - Rust</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin 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class="sidebar-menu-toggle">☰</button><a class="sidebar-logo" href="../../futures/index.html"><div class="logo-container"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></div></a><h2></h2></nav><nav class="sidebar"><a class="sidebar-logo" href="../../futures/index.html"><div class="logo-container"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></div></a><h2 class="location"><a href="#">Error</a></h2><div class="sidebar-elems"><section><h3><a href="#implementations">Methods</a></h3><ul class="block"><li><a href="#method.downcast">downcast</a></li><li><a href="#method.from_raw_os_error">from_raw_os_error</a></li><li><a href="#method.from_sgx_error">from_sgx_error</a></li><li><a href="#method.get_mut">get_mut</a></li><li><a href="#method.get_ref">get_ref</a></li><li><a href="#method.into_inner">into_inner</a></li><li><a href="#method.kind">kind</a></li><li><a href="#method.last_os_error">last_os_error</a></li><li><a href="#method.new">new</a></li><li><a href="#method.other">other</a></li><li><a href="#method.raw_os_error">raw_os_error</a></li><li><a href="#method.raw_sgx_error">raw_sgx_error</a></li></ul><h3><a href="#trait-implementations">Trait Implementations</a></h3><ul class="block"><li><a href="#impl-Debug-for-Error">Debug</a></li><li><a href="#impl-Display-for-Error">Display</a></li><li><a href="#impl-Error-for-Error">Error</a></li><li><a href="#impl-From%3CErrorKind%3E-for-Error">From<ErrorKind></a></li><li><a href="#impl-From%3CIntoInnerError%3CW%3E%3E-for-Error">From<IntoInnerError<W>></a></li><li><a href="#impl-From%3CNulError%3E-for-Error">From<NulError></a></li><li><a href="#impl-From%3COCallError%3E-for-Error">From<OCallError></a></li><li><a href="#impl-From%3CSgxStatus%3E-for-Error">From<SgxStatus></a></li></ul><h3><a href="#synthetic-implementations">Auto Trait Implementations</a></h3><ul class="block"><li><a href="#impl-RefUnwindSafe-for-Error">!RefUnwindSafe</a></li><li><a href="#impl-Send-for-Error">Send</a></li><li><a href="#impl-Sync-for-Error">Sync</a></li><li><a href="#impl-Unpin-for-Error">Unpin</a></li><li><a href="#impl-UnwindSafe-for-Error">!UnwindSafe</a></li></ul><h3><a href="#blanket-implementations">Blanket Implementations</a></h3><ul class="block"><li><a href="#impl-Any-for-Error">Any</a></li><li><a href="#impl-Borrow%3CT%3E-for-Error">Borrow<T></a></li><li><a href="#impl-BorrowMut%3CT%3E-for-Error">BorrowMut<T></a></li><li><a href="#impl-From%3CT%3E-for-Error">From<T></a></li><li><a href="#impl-Into%3CU%3E-for-Error">Into<U></a></li><li><a href="#impl-Provider-for-Error">Provider</a></li><li><a href="#impl-ToString-for-Error">ToString</a></li><li><a href="#impl-TryFrom%3CU%3E-for-Error">TryFrom<U></a></li><li><a href="#impl-TryInto%3CU%3E-for-Error">TryInto<U></a></li></ul></section><h2><a href="index.html">In futures::io</a></h2></div></nav><main><div class="width-limiter"><nav class="sub"><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="main-heading"><h1 class="fqn">Struct <a href="../index.html">futures</a>::<wbr><a href="index.html">io</a>::<wbr><a class="struct" href="#">Error</a><button id="copy-path" onclick="copy_path(this)" title="Copy item path to clipboard"><img src="../../clipboard.svg" width="19" height="18" alt="Copy item path"></button></h1><span class="out-of-band"><a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class="inner">−</span>]</a></span></div><div class="item-decl"><pre class="rust struct"><code>pub struct Error { /* private fields */ }</code></pre></div><details class="rustdoc-toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>The error type for I/O operations of the <a href="crate::io::Read"><code>Read</code></a>, <a href="crate::io::Write"><code>Write</code></a>, <a href="crate::io::Seek"><code>Seek</code></a>, and |
| associated traits.</p> |
| <p>Errors mostly originate from the underlying OS, but custom instances of |
| <code>Error</code> can be created with crafted error messages and a particular value of |
| <a href="enum.ErrorKind.html" title="ErrorKind"><code>ErrorKind</code></a>.</p> |
| </div></details><h2 id="implementations" class="small-section-header">Implementations<a href="#implementations" class="anchor"></a></h2><div id="implementations-list"><details class="rustdoc-toggle implementors-toggle" open><summary><section id="impl-Error" class="impl has-srclink"><a href="#impl-Error" class="anchor"></a><h3 class="code-header">impl <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a></h3></section></summary><div class="impl-items"><details class="rustdoc-toggle method-toggle" open><summary><section id="method.new" class="method has-srclink"><h4 class="code-header">pub fn <a href="#method.new" class="fnname">new</a><E>(kind: <a class="enum" href="enum.ErrorKind.html" title="enum futures::io::ErrorKind">ErrorKind</a>, error: E) -> <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a><span class="where fmt-newline">where<br> E: Into<Box<dyn Error + Sync + Send + 'static, Global>>,</span></h4></section></summary><div class="docblock"><p>Creates a new I/O error from a known kind of error as well as an |
| arbitrary error payload.</p> |
| <p>This function is used to generically create I/O errors which do not |
| originate from the OS itself. The <code>error</code> argument is an arbitrary |
| payload which will be contained in this <a href="struct.Error.html" title="Error"><code>Error</code></a>.</p> |
| <p>Note that this function allocates memory on the heap. |
| If no extra payload is required, use the <code>From</code> conversion from |
| <code>ErrorKind</code>.</p> |
| <h5 id="examples"><a href="#examples">Examples</a></h5> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>std::io::{Error, ErrorKind}; |
| |
| <span class="comment">// errors can be created from strings |
| </span><span class="kw">let </span>custom_error = Error::new(ErrorKind::Other, <span class="string">"oh no!"</span>); |
| |
| <span class="comment">// errors can also be created from other errors |
| </span><span class="kw">let </span>custom_error2 = Error::new(ErrorKind::Interrupted, custom_error); |
| |
| <span class="comment">// creating an error without payload (and without memory allocation) |
| </span><span class="kw">let </span>eof_error = Error::from(ErrorKind::UnexpectedEof);</code></pre></div> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.other" class="method has-srclink"><h4 class="code-header">pub fn <a href="#method.other" class="fnname">other</a><E>(error: E) -> <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a><span class="where fmt-newline">where<br> E: Into<Box<dyn Error + Sync + Send + 'static, Global>>,</span></h4></section></summary><div class="docblock"><p>Creates a new I/O error from an arbitrary error payload.</p> |
| <p>This function is used to generically create I/O errors which do not |
| originate from the OS itself. It is a shortcut for <a href="struct.Error.html#method.new" title="Error::new"><code>Error::new</code></a> |
| with <a href="enum.ErrorKind.html#variant.Other" title="ErrorKind::Other"><code>ErrorKind::Other</code></a>.</p> |
| <h5 id="examples-1"><a href="#examples-1">Examples</a></h5> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="attribute">#![feature(io_error_other)] |
| |
| </span><span class="kw">use </span>std::io::Error; |
| |
| <span class="comment">// errors can be created from strings |
| </span><span class="kw">let </span>custom_error = Error::other(<span class="string">"oh no!"</span>); |
| |
| <span class="comment">// errors can also be created from other errors |
| </span><span class="kw">let </span>custom_error2 = Error::other(custom_error);</code></pre></div> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.last_os_error" class="method has-srclink"><h4 class="code-header">pub fn <a href="#method.last_os_error" class="fnname">last_os_error</a>() -> <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a></h4></section></summary><div class="docblock"><p>Returns an error representing the last OS error which occurred.</p> |
| <p>This function reads the value of <code>errno</code> for the target platform (e.g. |
| <code>GetLastError</code> on Windows) and will return a corresponding instance of |
| <a href="struct.Error.html" title="Error"><code>Error</code></a> for the error code.</p> |
| <p>This should be called immediately after a call to a platform function, |
| otherwise the state of the error value is indeterminate. In particular, |
| other standard library functions may call platform functions that may |
| (or may not) reset the error value even if they succeed.</p> |
| <h5 id="examples-2"><a href="#examples-2">Examples</a></h5> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>std::io::Error; |
| |
| <span class="kw">let </span>os_error = Error::last_os_error(); |
| <span class="macro">println!</span>(<span class="string">"last OS error: {os_error:?}"</span>);</code></pre></div> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.from_raw_os_error" class="method has-srclink"><h4 class="code-header">pub fn <a href="#method.from_raw_os_error" class="fnname">from_raw_os_error</a>(code: i32) -> <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a></h4></section></summary><div class="docblock"><p>Creates a new instance of an <a href="struct.Error.html" title="Error"><code>Error</code></a> from a particular OS error code.</p> |
| <h5 id="examples-3"><a href="#examples-3">Examples</a></h5> |
| <p>On Linux:</p> |
| |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>std::io; |
| |
| <span class="kw">let </span>error = io::Error::from_raw_os_error(<span class="number">22</span>); |
| <span class="macro">assert_eq!</span>(error.kind(), io::ErrorKind::InvalidInput);</code></pre></div> |
| <p>On Windows:</p> |
| |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>std::io; |
| |
| <span class="kw">let </span>error = io::Error::from_raw_os_error(<span class="number">10022</span>); |
| <span class="macro">assert_eq!</span>(error.kind(), io::ErrorKind::InvalidInput);</code></pre></div> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.raw_os_error" class="method has-srclink"><h4 class="code-header">pub fn <a href="#method.raw_os_error" class="fnname">raw_os_error</a>(&self) -> Option<i32></h4></section></summary><div class="docblock"><p>Returns the OS error that this error represents (if any).</p> |
| <p>If this <a href="struct.Error.html" title="Error"><code>Error</code></a> was constructed via <a href="struct.Error.html#method.last_os_error"><code>last_os_error</code></a> or |
| <a href="struct.Error.html#method.from_raw_os_error"><code>from_raw_os_error</code></a>, then this function will return [<code>Some</code>], otherwise |
| it will return [<code>None</code>].</p> |
| <h5 id="examples-4"><a href="#examples-4">Examples</a></h5> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>std::io::{Error, ErrorKind}; |
| |
| <span class="kw">fn </span>print_os_error(err: <span class="kw-2">&</span>Error) { |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(raw_os_err) = err.raw_os_error() { |
| <span class="macro">println!</span>(<span class="string">"raw OS error: {raw_os_err:?}"</span>); |
| } <span class="kw">else </span>{ |
| <span class="macro">println!</span>(<span class="string">"Not an OS error"</span>); |
| } |
| } |
| |
| <span class="kw">fn </span>main() { |
| <span class="comment">// Will print "raw OS error: ...". |
| </span>print_os_error(<span class="kw-2">&</span>Error::last_os_error()); |
| <span class="comment">// Will print "Not an OS error". |
| </span>print_os_error(<span class="kw-2">&</span>Error::new(ErrorKind::Other, <span class="string">"oh no!"</span>)); |
| }</code></pre></div> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.from_sgx_error" class="method has-srclink"><h4 class="code-header">pub fn <a href="#method.from_sgx_error" class="fnname">from_sgx_error</a>(status: <a class="enum" href="../../sgx_types/error/enum.SgxStatus.html" title="enum sgx_types::error::SgxStatus">SgxStatus</a>) -> <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a></h4></section></summary><div class="docblock"><p>Creates a new instance of an <code>Error</code> from a particular SGX error status.</p> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.raw_sgx_error" class="method has-srclink"><h4 class="code-header">pub fn <a href="#method.raw_sgx_error" class="fnname">raw_sgx_error</a>(&self) -> Option<<a class="enum" href="../../sgx_types/error/enum.SgxStatus.html" title="enum sgx_types::error::SgxStatus">SgxStatus</a>></h4></section></summary><div class="docblock"><p>Returns the SGX error that this error represents (if any).</p> |
| <p>If this <code>Error</code> was constructed via <code>from_sgx_error</code> or |
| then this function will return <code>Some</code>, otherwise |
| it will return <code>None</code>.</p> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.get_ref" class="method has-srclink"><h4 class="code-header">pub fn <a href="#method.get_ref" class="fnname">get_ref</a>(&self) -> Option<&(dyn Error + Sync + Send + 'static)></h4></section></summary><div class="docblock"><p>Returns a reference to the inner error wrapped by this error (if any).</p> |
| <p>If this <a href="struct.Error.html" title="Error"><code>Error</code></a> was constructed via <a href="struct.Error.html#method.new"><code>new</code></a> then this function will |
| return [<code>Some</code>], otherwise it will return [<code>None</code>].</p> |
| <h5 id="examples-5"><a href="#examples-5">Examples</a></h5> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>std::io::{Error, ErrorKind}; |
| |
| <span class="kw">fn </span>print_error(err: <span class="kw-2">&</span>Error) { |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(inner_err) = err.get_ref() { |
| <span class="macro">println!</span>(<span class="string">"Inner error: {inner_err:?}"</span>); |
| } <span class="kw">else </span>{ |
| <span class="macro">println!</span>(<span class="string">"No inner error"</span>); |
| } |
| } |
| |
| <span class="kw">fn </span>main() { |
| <span class="comment">// Will print "No inner error". |
| </span>print_error(<span class="kw-2">&</span>Error::last_os_error()); |
| <span class="comment">// Will print "Inner error: ...". |
| </span>print_error(<span class="kw-2">&</span>Error::new(ErrorKind::Other, <span class="string">"oh no!"</span>)); |
| }</code></pre></div> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.get_mut" class="method has-srclink"><h4 class="code-header">pub fn <a href="#method.get_mut" class="fnname">get_mut</a>(&mut self) -> Option<&mut (dyn Error + Sync + Send + 'static)></h4></section></summary><div class="docblock"><p>Returns a mutable reference to the inner error wrapped by this error |
| (if any).</p> |
| <p>If this <a href="struct.Error.html" title="Error"><code>Error</code></a> was constructed via <a href="struct.Error.html#method.new"><code>new</code></a> then this function will |
| return [<code>Some</code>], otherwise it will return [<code>None</code>].</p> |
| <h5 id="examples-6"><a href="#examples-6">Examples</a></h5> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>std::io::{Error, ErrorKind}; |
| <span class="kw">use </span>std::{error, fmt}; |
| <span class="kw">use </span>std::fmt::Display; |
| |
| <span class="attribute">#[derive(Debug)] |
| </span><span class="kw">struct </span>MyError { |
| v: String, |
| } |
| |
| <span class="kw">impl </span>MyError { |
| <span class="kw">fn </span>new() -> MyError { |
| MyError { |
| v: <span class="string">"oh no!"</span>.to_string() |
| } |
| } |
| |
| <span class="kw">fn </span>change_message(<span class="kw-2">&mut </span><span class="self">self</span>, new_message: <span class="kw-2">&</span>str) { |
| <span class="self">self</span>.v = new_message.to_string(); |
| } |
| } |
| |
| <span class="kw">impl </span>error::Error <span class="kw">for </span>MyError {} |
| |
| <span class="kw">impl </span>Display <span class="kw">for </span>MyError { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| <span class="macro">write!</span>(f, <span class="string">"MyError: {}"</span>, <span class="kw-2">&</span><span class="self">self</span>.v) |
| } |
| } |
| |
| <span class="kw">fn </span>change_error(<span class="kw-2">mut </span>err: Error) -> Error { |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(inner_err) = err.get_mut() { |
| inner_err.downcast_mut::<MyError>().unwrap().change_message(<span class="string">"I've been changed!"</span>); |
| } |
| err |
| } |
| |
| <span class="kw">fn </span>print_error(err: <span class="kw-2">&</span>Error) { |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(inner_err) = err.get_ref() { |
| <span class="macro">println!</span>(<span class="string">"Inner error: {inner_err}"</span>); |
| } <span class="kw">else </span>{ |
| <span class="macro">println!</span>(<span class="string">"No inner error"</span>); |
| } |
| } |
| |
| <span class="kw">fn </span>main() { |
| <span class="comment">// Will print "No inner error". |
| </span>print_error(<span class="kw-2">&</span>change_error(Error::last_os_error())); |
| <span class="comment">// Will print "Inner error: ...". |
| </span>print_error(<span class="kw-2">&</span>change_error(Error::new(ErrorKind::Other, MyError::new()))); |
| }</code></pre></div> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.into_inner" class="method has-srclink"><h4 class="code-header">pub fn <a href="#method.into_inner" class="fnname">into_inner</a>(<br> self<br>) -> Option<Box<dyn Error + Sync + Send + 'static, Global>></h4></section></summary><div class="docblock"><p>Consumes the <code>Error</code>, returning its inner error (if any).</p> |
| <p>If this <a href="struct.Error.html" title="Error"><code>Error</code></a> was constructed via <a href="struct.Error.html#method.new"><code>new</code></a> then this function will |
| return [<code>Some</code>], otherwise it will return [<code>None</code>].</p> |
| <h5 id="examples-7"><a href="#examples-7">Examples</a></h5> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>std::io::{Error, ErrorKind}; |
| |
| <span class="kw">fn </span>print_error(err: Error) { |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(inner_err) = err.into_inner() { |
| <span class="macro">println!</span>(<span class="string">"Inner error: {inner_err}"</span>); |
| } <span class="kw">else </span>{ |
| <span class="macro">println!</span>(<span class="string">"No inner error"</span>); |
| } |
| } |
| |
| <span class="kw">fn </span>main() { |
| <span class="comment">// Will print "No inner error". |
| </span>print_error(Error::last_os_error()); |
| <span class="comment">// Will print "Inner error: ...". |
| </span>print_error(Error::new(ErrorKind::Other, <span class="string">"oh no!"</span>)); |
| }</code></pre></div> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.downcast" class="method has-srclink"><h4 class="code-header">pub fn <a href="#method.downcast" class="fnname">downcast</a><E>(self) -> Result<Box<E, Global>, <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a>><span class="where fmt-newline">where<br> E: 'static + Error + Send + Sync,</span></h4></section></summary><div class="docblock"><p>Attempt to downgrade the inner error to <code>E</code> if any.</p> |
| <p>If this <a href="struct.Error.html" title="Error"><code>Error</code></a> was constructed via <a href="struct.Error.html#method.new"><code>new</code></a> then this function will |
| attempt to perform downgrade on it, otherwise it will return [<code>Err</code>].</p> |
| <p>If downgrade succeeds, it will return [<code>Ok</code>], otherwise it will also |
| return [<code>Err</code>].</p> |
| <h5 id="examples-8"><a href="#examples-8">Examples</a></h5> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="attribute">#![feature(io_error_downcast)] |
| |
| </span><span class="kw">use </span>std::fmt; |
| <span class="kw">use </span>std::io; |
| <span class="kw">use </span>std::error::Error; |
| |
| <span class="attribute">#[derive(Debug)] |
| </span><span class="kw">enum </span>E { |
| Io(io::Error), |
| SomeOtherVariant, |
| } |
| |
| <span class="kw">impl </span>fmt::Display <span class="kw">for </span>E { |
| <span class="comment">// ... |
| </span>} |
| <span class="kw">impl </span>Error <span class="kw">for </span>E {} |
| |
| <span class="kw">impl </span>From<io::Error> <span class="kw">for </span>E { |
| <span class="kw">fn </span>from(err: io::Error) -> E { |
| err.downcast::<E>() |
| .map(|b| <span class="kw-2">*</span>b) |
| .unwrap_or_else(E::Io) |
| } |
| }</code></pre></div> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.kind" class="method has-srclink"><h4 class="code-header">pub fn <a href="#method.kind" class="fnname">kind</a>(&self) -> <a class="enum" href="enum.ErrorKind.html" title="enum futures::io::ErrorKind">ErrorKind</a></h4></section></summary><div class="docblock"><p>Returns the corresponding <a href="enum.ErrorKind.html" title="ErrorKind"><code>ErrorKind</code></a> for this error.</p> |
| <h5 id="examples-9"><a href="#examples-9">Examples</a></h5> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>std::io::{Error, ErrorKind}; |
| |
| <span class="kw">fn </span>print_error(err: Error) { |
| <span class="macro">println!</span>(<span class="string">"{:?}"</span>, err.kind()); |
| } |
| |
| <span class="kw">fn </span>main() { |
| <span class="comment">// Will print "Uncategorized". |
| </span>print_error(Error::last_os_error()); |
| <span class="comment">// Will print "AddrInUse". |
| </span>print_error(Error::new(ErrorKind::AddrInUse, <span class="string">"oh no!"</span>)); |
| }</code></pre></div> |
| </div></details></div></details></div><h2 id="trait-implementations" class="small-section-header">Trait Implementations<a href="#trait-implementations" class="anchor"></a></h2><div id="trait-implementations-list"><details class="rustdoc-toggle implementors-toggle" open><summary><section id="impl-Debug-for-Error" class="impl has-srclink"><a href="#impl-Debug-for-Error" class="anchor"></a><h3 class="code-header">impl Debug for <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a></h3></section></summary><div class="impl-items"><details class="rustdoc-toggle method-toggle" open><summary><section id="method.fmt-1" class="method trait-impl has-srclink"><a href="#method.fmt-1" class="anchor"></a><h4 class="code-header">fn <a class="fnname">fmt</a>(&self, f: &mut Formatter<'_>) -> Result<(), Error></h4></section></summary><div class='docblock'>Formats the value using the given formatter. <a>Read more</a></div></details></div></details><details class="rustdoc-toggle implementors-toggle" open><summary><section id="impl-Display-for-Error" class="impl has-srclink"><a href="#impl-Display-for-Error" class="anchor"></a><h3 class="code-header">impl Display for <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a></h3></section></summary><div class="impl-items"><details class="rustdoc-toggle method-toggle" open><summary><section id="method.fmt" class="method trait-impl has-srclink"><a href="#method.fmt" class="anchor"></a><h4 class="code-header">fn <a class="fnname">fmt</a>(&self, fmt: &mut Formatter<'_>) -> Result<(), Error></h4></section></summary><div class='docblock'>Formats the value using the given formatter. <a>Read more</a></div></details></div></details><details class="rustdoc-toggle implementors-toggle" open><summary><section id="impl-Error-for-Error" class="impl has-srclink"><a href="#impl-Error-for-Error" class="anchor"></a><h3 class="code-header">impl Error for <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a></h3></section></summary><div class="impl-items"><details class="rustdoc-toggle method-toggle" open><summary><section id="method.description" class="method trait-impl has-srclink"><a href="#method.description" class="anchor"></a><h4 class="code-header">fn <a class="fnname">description</a>(&self) -> &str</h4></section></summary><span class="item-info"><div class="stab deprecated"><span class="emoji">👎</span><span>Deprecated since 1.42.0: use the Display impl or to_string()</span></div></span><div class='docblock'> <a>Read more</a></div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.cause" class="method trait-impl has-srclink"><a href="#method.cause" class="anchor"></a><h4 class="code-header">fn <a class="fnname">cause</a>(&self) -> Option<&dyn Error></h4></section></summary><span class="item-info"><div class="stab deprecated"><span class="emoji">👎</span><span>Deprecated since 1.33.0: replaced by Error::source, which can support downcasting</span></div></span></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.source" class="method trait-impl has-srclink"><a href="#method.source" class="anchor"></a><h4 class="code-header">fn <a class="fnname">source</a>(&self) -> Option<&(dyn Error + 'static)></h4></section></summary><div class='docblock'>The lower-level source of this error, if any. <a>Read more</a></div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.provide" class="method trait-impl has-srclink"><a href="#method.provide" class="anchor"></a><h4 class="code-header">fn <a class="fnname">provide</a>(&'a self, demand: &mut Demand<'a>)</h4></section></summary><span class="item-info"><div class="stab unstable"><span class="emoji">🔬</span><span>This is a nightly-only experimental API. (<code>error_generic_member_access</code>)</span></div></span><div class='docblock'>Provides type based access to context intended for error reports. <a>Read more</a></div></details></div></details><details class="rustdoc-toggle implementors-toggle" open><summary><section id="impl-From%3CErrorKind%3E-for-Error" class="impl has-srclink"><a href="#impl-From%3CErrorKind%3E-for-Error" class="anchor"></a><h3 class="code-header">impl From<<a class="enum" href="enum.ErrorKind.html" title="enum futures::io::ErrorKind">ErrorKind</a>> for <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a></h3></section></summary><div class="docblock"><p>Intended for use for errors not exposed to the user, where allocating onto |
| the heap (for normal construction via Error::new) is too costly.</p> |
| </div><div class="impl-items"><details class="rustdoc-toggle method-toggle" open><summary><section id="method.from-2" class="method trait-impl has-srclink"><a href="#method.from-2" class="anchor"></a><h4 class="code-header">fn <a class="fnname">from</a>(kind: <a class="enum" href="enum.ErrorKind.html" title="enum futures::io::ErrorKind">ErrorKind</a>) -> <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a></h4></section></summary><div class="docblock"><p>Converts an <a href="enum.ErrorKind.html" title="ErrorKind"><code>ErrorKind</code></a> into an <a href="struct.Error.html" title="Error"><code>Error</code></a>.</p> |
| <p>This conversion creates a new error with a simple representation of error kind.</p> |
| <h5 id="examples-10"><a href="#examples-10">Examples</a></h5> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>std::io::{Error, ErrorKind}; |
| |
| <span class="kw">let </span>not_found = ErrorKind::NotFound; |
| <span class="kw">let </span>error = Error::from(not_found); |
| <span class="macro">assert_eq!</span>(<span class="string">"entity not found"</span>, <span class="macro">format!</span>(<span class="string">"{error}"</span>));</code></pre></div> |
| </div></details></div></details><details class="rustdoc-toggle implementors-toggle" open><summary><section id="impl-From%3CIntoInnerError%3CW%3E%3E-for-Error" class="impl has-srclink"><a href="#impl-From%3CIntoInnerError%3CW%3E%3E-for-Error" class="anchor"></a><h3 class="code-header">impl<W> From<IntoInnerError<W>> for <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a></h3></section></summary><div class="impl-items"><details class="rustdoc-toggle method-toggle" open><summary><section id="method.from-4" class="method trait-impl has-srclink"><a href="#method.from-4" class="anchor"></a><h4 class="code-header">fn <a class="fnname">from</a>(iie: IntoInnerError<W>) -> <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a></h4></section></summary><div class='docblock'>Converts to this type from the input type.</div></details></div></details><details class="rustdoc-toggle implementors-toggle" open><summary><section id="impl-From%3CNulError%3E-for-Error" class="impl has-srclink"><a href="#impl-From%3CNulError%3E-for-Error" class="anchor"></a><h3 class="code-header">impl From<NulError> for <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a></h3></section></summary><div class="impl-items"><details class="rustdoc-toggle method-toggle" open><summary><section id="method.from-3" class="method trait-impl has-srclink"><a href="#method.from-3" class="anchor"></a><h4 class="code-header">fn <a class="fnname">from</a>(NulError) -> <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a></h4></section></summary><div class="docblock"><p>Converts a [<code>alloc::ffi::NulError</code>] into a <a href="struct.Error.html" title="Error"><code>Error</code></a>.</p> |
| </div></details></div></details><details class="rustdoc-toggle implementors-toggle" open><summary><section id="impl-From%3COCallError%3E-for-Error" class="impl has-srclink"><a href="#impl-From%3COCallError%3E-for-Error" class="anchor"></a><h3 class="code-header">impl From<OCallError> for <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a></h3></section></summary><div class="impl-items"><details class="rustdoc-toggle method-toggle" open><summary><section id="method.from" class="method trait-impl has-srclink"><a href="#method.from" class="anchor"></a><h4 class="code-header">fn <a class="fnname">from</a>(e: OCallError) -> <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a></h4></section></summary><div class='docblock'>Converts to this type from the input type.</div></details></div></details><details class="rustdoc-toggle implementors-toggle" open><summary><section id="impl-From%3CSgxStatus%3E-for-Error" class="impl has-srclink"><a href="#impl-From%3CSgxStatus%3E-for-Error" class="anchor"></a><h3 class="code-header">impl From<<a class="enum" href="../../sgx_types/error/enum.SgxStatus.html" title="enum sgx_types::error::SgxStatus">SgxStatus</a>> for <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a></h3></section></summary><div class="impl-items"><details class="rustdoc-toggle method-toggle" open><summary><section id="method.from-1" class="method trait-impl has-srclink"><a href="#method.from-1" class="anchor"></a><h4 class="code-header">fn <a class="fnname">from</a>(status: <a class="enum" href="../../sgx_types/error/enum.SgxStatus.html" title="enum sgx_types::error::SgxStatus">SgxStatus</a>) -> <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a></h4></section></summary><div class='docblock'>Converts to this type from the input type.</div></details></div></details></div><h2 id="synthetic-implementations" class="small-section-header">Auto Trait Implementations<a href="#synthetic-implementations" class="anchor"></a></h2><div id="synthetic-implementations-list"><section id="impl-RefUnwindSafe-for-Error" class="impl has-srclink"><a href="#impl-RefUnwindSafe-for-Error" class="anchor"></a><h3 class="code-header">impl !RefUnwindSafe for <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a></h3></section><section id="impl-Send-for-Error" class="impl has-srclink"><a href="#impl-Send-for-Error" class="anchor"></a><h3 class="code-header">impl Send for <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a></h3></section><section id="impl-Sync-for-Error" class="impl has-srclink"><a href="#impl-Sync-for-Error" class="anchor"></a><h3 class="code-header">impl Sync for <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a></h3></section><section id="impl-Unpin-for-Error" class="impl has-srclink"><a href="#impl-Unpin-for-Error" class="anchor"></a><h3 class="code-header">impl Unpin for <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a></h3></section><section id="impl-UnwindSafe-for-Error" class="impl has-srclink"><a href="#impl-UnwindSafe-for-Error" class="anchor"></a><h3 class="code-header">impl !UnwindSafe for <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a></h3></section></div><h2 id="blanket-implementations" class="small-section-header">Blanket Implementations<a href="#blanket-implementations" class="anchor"></a></h2><div id="blanket-implementations-list"><details class="rustdoc-toggle implementors-toggle"><summary><section id="impl-Any-for-Error" class="impl has-srclink"><a href="#impl-Any-for-Error" class="anchor"></a><h3 class="code-header">impl<T> Any for T<span class="where fmt-newline">where<br> T: 'static + ?Sized,</span></h3></section></summary><div class="impl-items"><details class="rustdoc-toggle method-toggle" open><summary><section id="method.type_id" class="method trait-impl has-srclink"><a href="#method.type_id" class="anchor"></a><h4 class="code-header">fn <a class="fnname">type_id</a>(&self) -> TypeId</h4></section></summary><div class='docblock'>Gets the <code>TypeId</code> of <code>self</code>. <a>Read more</a></div></details></div></details><details class="rustdoc-toggle implementors-toggle"><summary><section id="impl-Borrow%3CT%3E-for-Error" class="impl has-srclink"><a href="#impl-Borrow%3CT%3E-for-Error" class="anchor"></a><h3 class="code-header">impl<T> Borrow<T> for T<span class="where fmt-newline">where<br> T: ?Sized,</span></h3></section></summary><div class="impl-items"><details class="rustdoc-toggle method-toggle" open><summary><section id="method.borrow" class="method trait-impl has-srclink"><span class="since rightside" title="const unstable">const: <a href="https://github.com/rust-lang/rust/issues/91522" title="Tracking issue for const_borrow">unstable</a></span><a href="#method.borrow" class="anchor"></a><h4 class="code-header">fn <a class="fnname">borrow</a>(&self) -> &T</h4></section></summary><div class='docblock'>Immutably borrows from an owned value. <a>Read more</a></div></details></div></details><details class="rustdoc-toggle implementors-toggle"><summary><section id="impl-BorrowMut%3CT%3E-for-Error" class="impl has-srclink"><a href="#impl-BorrowMut%3CT%3E-for-Error" class="anchor"></a><h3 class="code-header">impl<T> BorrowMut<T> for T<span class="where fmt-newline">where<br> T: ?Sized,</span></h3></section></summary><div class="impl-items"><details class="rustdoc-toggle method-toggle" open><summary><section id="method.borrow_mut" class="method trait-impl has-srclink"><span class="since rightside" title="const unstable">const: <a href="https://github.com/rust-lang/rust/issues/91522" title="Tracking issue for const_borrow">unstable</a></span><a href="#method.borrow_mut" class="anchor"></a><h4 class="code-header">fn <a class="fnname">borrow_mut</a>(&mut self) -> &mut T</h4></section></summary><div class='docblock'>Mutably borrows from an owned value. <a>Read more</a></div></details></div></details><details class="rustdoc-toggle implementors-toggle"><summary><section id="impl-From%3CT%3E-for-Error" class="impl has-srclink"><a href="#impl-From%3CT%3E-for-Error" class="anchor"></a><h3 class="code-header">impl<T> From<T> for T</h3></section></summary><div class="impl-items"><details class="rustdoc-toggle method-toggle" open><summary><section id="method.from-5" class="method trait-impl has-srclink"><span class="since rightside" title="const unstable">const: <a href="https://github.com/rust-lang/rust/issues/88674" title="Tracking issue for const_convert">unstable</a></span><a href="#method.from-5" class="anchor"></a><h4 class="code-header">fn <a class="fnname">from</a>(t: T) -> T</h4></section></summary><div class="docblock"><p>Returns the argument unchanged.</p> |
| </div></details></div></details><details class="rustdoc-toggle implementors-toggle"><summary><section id="impl-Into%3CU%3E-for-Error" class="impl has-srclink"><a href="#impl-Into%3CU%3E-for-Error" class="anchor"></a><h3 class="code-header">impl<T, U> Into<U> for T<span class="where fmt-newline">where<br> U: From<T>,</span></h3></section></summary><div class="impl-items"><details class="rustdoc-toggle method-toggle" open><summary><section id="method.into" class="method trait-impl has-srclink"><span class="since rightside" title="const unstable">const: <a href="https://github.com/rust-lang/rust/issues/88674" title="Tracking issue for const_convert">unstable</a></span><a href="#method.into" class="anchor"></a><h4 class="code-header">fn <a class="fnname">into</a>(self) -> U</h4></section></summary><div class="docblock"><p>Calls <code>U::from(self)</code>.</p> |
| <p>That is, this conversion is whatever the implementation of |
| <code>[From]<T> for U</code> chooses to do.</p> |
| </div></details></div></details><details class="rustdoc-toggle implementors-toggle"><summary><section id="impl-Provider-for-Error" class="impl has-srclink"><a href="#impl-Provider-for-Error" class="anchor"></a><h3 class="code-header">impl<E> Provider for E<span class="where fmt-newline">where<br> E: Error + ?Sized,</span></h3></section></summary><div class="impl-items"><details class="rustdoc-toggle method-toggle" open><summary><section id="method.provide-1" class="method trait-impl has-srclink"><a href="#method.provide-1" class="anchor"></a><h4 class="code-header">fn <a class="fnname">provide</a>(&'a self, demand: &mut Demand<'a>)</h4></section></summary><span class="item-info"><div class="stab unstable"><span class="emoji">🔬</span><span>This is a nightly-only experimental API. (<code>provide_any</code>)</span></div></span><div class='docblock'>Data providers should implement this method to provide <em>all</em> values they are able to |
| provide by using <code>demand</code>. <a>Read more</a></div></details></div></details><details class="rustdoc-toggle implementors-toggle"><summary><section id="impl-ToString-for-Error" class="impl has-srclink"><a href="#impl-ToString-for-Error" class="anchor"></a><h3 class="code-header">impl<T> ToString for T<span class="where fmt-newline">where<br> T: Display + ?Sized,</span></h3></section></summary><div class="impl-items"><details class="rustdoc-toggle method-toggle" open><summary><section id="method.to_string" class="method trait-impl has-srclink"><a href="#method.to_string" class="anchor"></a><h4 class="code-header">default fn <a class="fnname">to_string</a>(&self) -> String</h4></section></summary><div class='docblock'>Converts the given value to a <code>String</code>. <a>Read more</a></div></details></div></details><details class="rustdoc-toggle implementors-toggle"><summary><section id="impl-TryFrom%3CU%3E-for-Error" class="impl has-srclink"><a href="#impl-TryFrom%3CU%3E-for-Error" class="anchor"></a><h3 class="code-header">impl<T, U> TryFrom<U> for T<span class="where fmt-newline">where<br> U: Into<T>,</span></h3></section></summary><div class="impl-items"><details class="rustdoc-toggle" open><summary><section id="associatedtype.Error-1" class="associatedtype trait-impl has-srclink"><a href="#associatedtype.Error-1" class="anchor"></a><h4 class="code-header">type <a class="associatedtype">Error</a> = Infallible</h4></section></summary><div class='docblock'>The type returned in the event of a conversion error.</div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.try_from" class="method trait-impl has-srclink"><span class="since rightside" title="const unstable">const: <a href="https://github.com/rust-lang/rust/issues/88674" title="Tracking issue for const_convert">unstable</a></span><a href="#method.try_from" class="anchor"></a><h4 class="code-header">fn <a class="fnname">try_from</a>(value: U) -> Result<T, <T as TryFrom<U>>::Error></h4></section></summary><div class='docblock'>Performs the conversion.</div></details></div></details><details class="rustdoc-toggle implementors-toggle"><summary><section id="impl-TryInto%3CU%3E-for-Error" class="impl has-srclink"><a href="#impl-TryInto%3CU%3E-for-Error" class="anchor"></a><h3 class="code-header">impl<T, U> TryInto<U> for T<span class="where fmt-newline">where<br> U: TryFrom<T>,</span></h3></section></summary><div class="impl-items"><details class="rustdoc-toggle" open><summary><section id="associatedtype.Error" class="associatedtype trait-impl has-srclink"><a href="#associatedtype.Error" class="anchor"></a><h4 class="code-header">type <a class="associatedtype">Error</a> = <U as TryFrom<T>>::Error</h4></section></summary><div class='docblock'>The type returned in the event of a conversion error.</div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.try_into" class="method trait-impl has-srclink"><span class="since rightside" title="const unstable">const: <a href="https://github.com/rust-lang/rust/issues/88674" title="Tracking issue for const_convert">unstable</a></span><a href="#method.try_into" class="anchor"></a><h4 class="code-header">fn <a class="fnname">try_into</a>(self) -> Result<U, <U as TryFrom<T>>::Error></h4></section></summary><div class='docblock'>Performs the conversion.</div></details></div></details></div></section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="futures" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
