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<p class='location'>Trait Write</p><div class="block items"><ul><li><a href="#required-methods">Required Methods</a></li><li><a href="#provided-methods">Provided Methods</a></li><li><a href="#implementors">Implementors</a></li></ul></div><p class='location'><a href='../index.html'>collections</a>::<wbr><a href='index.html'>fmt</a></p><script>window.sidebarCurrent = {name: 'Write', ty: 'trait', relpath: ''};</script><script defer src="sidebar-items.js"></script>
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<h1 class='fqn'><span class='in-band'>Trait <a href='../index.html'>collections</a>::<wbr><a href='index.html'>fmt</a>::<wbr><a class="trait" href=''>Write</a></span><span class='out-of-band'><span class='since' title='Stable since Rust version 1.0.0'>1.0.0</span><span id='render-detail'>
<a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">
[<span class='inner'>−</span>]
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</span><a class='srclink' href='../../src/core/fmt/mod.rs.html#101-209' title='goto source code'>[src]</a></span></h1>
<pre class='rust trait'>pub trait Write {
fn <a href='#tymethod.write_str' class='fnname'>write_str</a>(&mut self, s: &str) -> <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><(), <a class="struct" href="../../collections/fmt/struct.Error.html" title="struct collections::fmt::Error">Error</a>>;
fn <a href='#method.write_char' class='fnname'>write_char</a>(&mut self, c: char) -> <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><(), <a class="struct" href="../../collections/fmt/struct.Error.html" title="struct collections::fmt::Error">Error</a>> { ... }
fn <a href='#method.write_fmt' class='fnname'>write_fmt</a>(&mut self, args: <a class="struct" href="../../collections/fmt/struct.Arguments.html" title="struct collections::fmt::Arguments">Arguments</a>) -> <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><(), <a class="struct" href="../../collections/fmt/struct.Error.html" title="struct collections::fmt::Error">Error</a>> { ... }
}</pre><div class='docblock'><p>A collection of methods that are required to format a message into a stream.</p>
<p>This trait is the type which this modules requires when formatting
information. This is similar to the standard library's <a href="../../std/io/trait.Write.html"><code>io::Write</code></a> trait,
but it is only intended for use in libcore.</p>
<p>This trait should generally not be implemented by consumers of the standard
library. The <a href="../../std/macro.write.html"><code>write!</code></a> macro accepts an instance of <a href="../../std/io/trait.Write.html"><code>io::Write</code></a>, and the
<a href="../../std/io/trait.Write.html"><code>io::Write</code></a> trait is favored over implementing this trait.</p>
</div>
<h2 id='required-methods'>Required Methods</h2>
<div class='methods'>
<h3 id='tymethod.write_str' class='method'><span id='write_str.v' class='invisible'><code>fn <a href='#tymethod.write_str' class='fnname'>write_str</a>(&mut self, s: &str) -> <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><(), <a class="struct" href="../../collections/fmt/struct.Error.html" title="struct collections::fmt::Error">Error</a>></code></span></h3><div class='docblock'><p>Writes a slice of bytes into this writer, returning whether the write
succeeded.</p>
<p>This method can only succeed if the entire byte slice was successfully
written, and this method will not return until all data has been
written or an error occurs.</p>
<h1 id='errors' class='section-header'><a href='#errors'>Errors</a></h1>
<p>This function will return an instance of <a href="struct.Error.html"><code>Error</code></a> on error.</p>
<h1 id='examples' class='section-header'><a href='#examples'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">fmt</span>::{<span class="ident">Error</span>, <span class="ident">Write</span>};
<span class="kw">fn</span> <span class="ident">writer</span><span class="op"><</span><span class="ident">W</span>: <span class="ident">Write</span><span class="op">></span>(<span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">W</span>, <span class="ident">s</span>: <span class="kw-2">&</span><span class="ident">str</span>) <span class="op">-></span> <span class="prelude-ty">Result</span><span class="op"><</span>(), <span class="ident">Error</span><span class="op">></span> {
<span class="ident">f</span>.<span class="ident">write_str</span>(<span class="ident">s</span>)
}
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">buf</span> <span class="op">=</span> <span class="ident">String</span>::<span class="ident">new</span>();
<span class="ident">writer</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">buf</span>, <span class="string">"hola"</span>).<span class="ident">unwrap</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">&</span><span class="ident">buf</span>, <span class="string">"hola"</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Ause%20std%3A%3Afmt%3A%3A%7BError%2C%20Write%7D%3B%0A%0Afn%20writer%3CW%3A%20Write%3E(f%3A%20%26mut%20W%2C%20s%3A%20%26str)%20-%3E%20Result%3C()%2C%20Error%3E%20%7B%0A%20%20%20%20f.write_str(s)%0A%7D%0A%0Alet%20mut%20buf%20%3D%20String%3A%3Anew()%3B%0Awriter(%26mut%20buf%2C%20%22hola%22).unwrap()%3B%0Aassert_eq!(%26buf%2C%20%22hola%22)%3B%0A%7D">Run</a></pre>
</div></div>
<h2 id='provided-methods'>Provided Methods</h2>
<div class='methods'>
<h3 id='method.write_char' class='method'><span id='write_char.v' class='invisible'><code>fn <a href='#method.write_char' class='fnname'>write_char</a>(&mut self, c: char) -> <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><(), <a class="struct" href="../../collections/fmt/struct.Error.html" title="struct collections::fmt::Error">Error</a>></code><div class='since' title='Stable since Rust version 1.1.0'>1.1.0</div></span></h3><div class='docblock'><p>Writes a <a href="../../std/primitive.char.html"><code>char</code></a> into this writer, returning whether the write succeeded.</p>
<p>A single <a href="../../std/primitive.char.html"><code>char</code></a> may be encoded as more than one byte.
This method can only succeed if the entire byte sequence was successfully
written, and this method will not return until all data has been
written or an error occurs.</p>
<h1 id='errors-1' class='section-header'><a href='#errors-1'>Errors</a></h1>
<p>This function will return an instance of <a href="struct.Error.html"><code>Error</code></a> on error.</p>
<h1 id='examples-1' class='section-header'><a href='#examples-1'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">fmt</span>::{<span class="ident">Error</span>, <span class="ident">Write</span>};
<span class="kw">fn</span> <span class="ident">writer</span><span class="op"><</span><span class="ident">W</span>: <span class="ident">Write</span><span class="op">></span>(<span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">W</span>, <span class="ident">c</span>: <span class="ident">char</span>) <span class="op">-></span> <span class="prelude-ty">Result</span><span class="op"><</span>(), <span class="ident">Error</span><span class="op">></span> {
<span class="ident">f</span>.<span class="ident">write_char</span>(<span class="ident">c</span>)
}
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">buf</span> <span class="op">=</span> <span class="ident">String</span>::<span class="ident">new</span>();
<span class="ident">writer</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">buf</span>, <span class="string">'a'</span>).<span class="ident">unwrap</span>();
<span class="ident">writer</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">buf</span>, <span class="string">'b'</span>).<span class="ident">unwrap</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">&</span><span class="ident">buf</span>, <span class="string">"ab"</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Ause%20std%3A%3Afmt%3A%3A%7BError%2C%20Write%7D%3B%0A%0Afn%20writer%3CW%3A%20Write%3E(f%3A%20%26mut%20W%2C%20c%3A%20char)%20-%3E%20Result%3C()%2C%20Error%3E%20%7B%0A%20%20%20%20f.write_char(c)%0A%7D%0A%0Alet%20mut%20buf%20%3D%20String%3A%3Anew()%3B%0Awriter(%26mut%20buf%2C%20'a').unwrap()%3B%0Awriter(%26mut%20buf%2C%20'b').unwrap()%3B%0Aassert_eq!(%26buf%2C%20%22ab%22)%3B%0A%7D">Run</a></pre>
</div><h3 id='method.write_fmt' class='method'><span id='write_fmt.v' class='invisible'><code>fn <a href='#method.write_fmt' class='fnname'>write_fmt</a>(&mut self, args: <a class="struct" href="../../collections/fmt/struct.Arguments.html" title="struct collections::fmt::Arguments">Arguments</a>) -> <a class="enum" href="../../core/result/enum.Result.html" title="enum core::result::Result">Result</a><(), <a class="struct" href="../../collections/fmt/struct.Error.html" title="struct collections::fmt::Error">Error</a>></code></span></h3><div class='docblock'><p>Glue for usage of the <a href="../../std/macro.write.html"><code>write!</code></a> macro with implementors of this trait.</p>
<p>This method should generally not be invoked manually, but rather through
the <a href="../../std/macro.write.html"><code>write!</code></a> macro itself.</p>
<h1 id='examples-2' class='section-header'><a href='#examples-2'>Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">fmt</span>::{<span class="ident">Error</span>, <span class="ident">Write</span>};
<span class="kw">fn</span> <span class="ident">writer</span><span class="op"><</span><span class="ident">W</span>: <span class="ident">Write</span><span class="op">></span>(<span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">W</span>, <span class="ident">s</span>: <span class="kw-2">&</span><span class="ident">str</span>) <span class="op">-></span> <span class="prelude-ty">Result</span><span class="op"><</span>(), <span class="ident">Error</span><span class="op">></span> {
<span class="ident">f</span>.<span class="ident">write_fmt</span>(<span class="macro">format_args</span><span class="macro">!</span>(<span class="string">"{}"</span>, <span class="ident">s</span>))
}
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">buf</span> <span class="op">=</span> <span class="ident">String</span>::<span class="ident">new</span>();
<span class="ident">writer</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">buf</span>, <span class="string">"world"</span>).<span class="ident">unwrap</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">&</span><span class="ident">buf</span>, <span class="string">"world"</span>);<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=fn%20main()%20%7B%0Ause%20std%3A%3Afmt%3A%3A%7BError%2C%20Write%7D%3B%0A%0Afn%20writer%3CW%3A%20Write%3E(f%3A%20%26mut%20W%2C%20s%3A%20%26str)%20-%3E%20Result%3C()%2C%20Error%3E%20%7B%0A%20%20%20%20f.write_fmt(format_args!(%22%7B%7D%22%2C%20s))%0A%7D%0A%0Alet%20mut%20buf%20%3D%20String%3A%3Anew()%3B%0Awriter(%26mut%20buf%2C%20%22world%22).unwrap()%3B%0Aassert_eq!(%26buf%2C%20%22world%22)%3B%0A%7D">Run</a></pre>
</div></div>
<h2 id='implementors'>Implementors</h2>
<ul class='item-list' id='implementors-list'>
<li><code>impl<'a, W> Write for &'a mut W <span class="where fmt-newline">where<br> W: <a class="trait" href="../../collections/fmt/trait.Write.html" title="trait collections::fmt::Write">Write</a> + ?<a class="trait" href="../../core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>, </span></code></li>
<li><code>impl<'a> Write for <a class="struct" href="../../collections/fmt/struct.Formatter.html" title="struct collections::fmt::Formatter">Formatter</a><'a></code></li>
<li><code>impl Write for <a class="struct" href="../../collections/string/struct.String.html" title="struct collections::string::String">String</a></code></li>
</ul><script type="text/javascript" async
src="../../implementors/core/fmt/trait.Write.js">
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