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<h1 class='fqn'><span class='in-band'>Trait <a href='../index.html'>core</a>::<wbr><a href='index.html'>ops</a>::<wbr><a class='trait' href=''>DerefMut</a></span><span class='out-of-band'><span id='render-detail'>
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                [<span class='inner'>&#x2212;</span>]
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        </span><a id='src-20998' class='srclink' href='../../src/core/ops.rs.html#1717-1721' title='goto source code'>[src]</a></span></h1>
<pre class='rust trait'>pub trait DerefMut: <a class='trait' href='../../core/ops/trait.Deref.html' title='core::ops::Deref'>Deref</a> {
    fn <a href='#tymethod.deref_mut' class='fnname'>deref_mut</a>(&amp;mut self) -&gt; &amp;mut Self::<a class='trait' href='../../core/ops/trait.DerefMut.html' title='core::ops::DerefMut'>Target</a>;
}</pre><div class='docblock'><p>The <code>DerefMut</code> trait is used to specify the functionality of dereferencing
mutably like <code>*v = 1;</code></p>

<p><code>DerefMut</code> also enables <a href="../../book/deref-coercions.html">&#39;<code>Deref</code> coercions&#39;</a>.</p>

<h1 id='examples' class='section-header'><a href='#examples'>Examples</a></h1>
<p>A struct with a single field which is modifiable via dereferencing the
struct.</p>
<span class='rusttest'>use std::ops::{Deref, DerefMut};

struct DerefMutExample&lt;T&gt; {
    value: T
}

impl&lt;T&gt; Deref for DerefMutExample&lt;T&gt; {
    type Target = T;

    fn deref&lt;&#39;a&gt;(&amp;&#39;a self) -&gt; &amp;&#39;a T {
        &amp;self.value
    }
}

impl&lt;T&gt; DerefMut for DerefMutExample&lt;T&gt; {
    fn deref_mut&lt;&#39;a&gt;(&amp;&#39;a mut self) -&gt; &amp;&#39;a mut T {
        &amp;mut self.value
    }
}

fn main() {
    let mut x = DerefMutExample { value: &#39;a&#39; };
    *x = &#39;b&#39;;
    assert_eq!(&#39;b&#39;, *x);
}
</span><pre class='rust rust-example-rendered'>
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>ops</span>::{<span class='ident'>Deref</span>, <span class='ident'>DerefMut</span>};

<span class='kw'>struct</span> <span class='ident'>DerefMutExample</span><span class='op'>&lt;</span><span class='ident'>T</span><span class='op'>&gt;</span> {
    <span class='ident'>value</span>: <span class='ident'>T</span>
}

<span class='kw'>impl</span><span class='op'>&lt;</span><span class='ident'>T</span><span class='op'>&gt;</span> <span class='ident'>Deref</span> <span class='kw'>for</span> <span class='ident'>DerefMutExample</span><span class='op'>&lt;</span><span class='ident'>T</span><span class='op'>&gt;</span> {
    <span class='kw'>type</span> <span class='ident'>Target</span> <span class='op'>=</span> <span class='ident'>T</span>;

    <span class='kw'>fn</span> <span class='ident'>deref</span><span class='op'>&lt;</span><span class='lifetime'>&#39;a</span><span class='op'>&gt;</span>(<span class='kw-2'>&amp;</span><span class='lifetime'>&#39;a</span> <span class='self'>self</span>) <span class='op'>-&gt;</span> <span class='kw-2'>&amp;</span><span class='lifetime'>&#39;a</span> <span class='ident'>T</span> {
        <span class='kw-2'>&amp;</span><span class='self'>self</span>.<span class='ident'>value</span>
    }
}

<span class='kw'>impl</span><span class='op'>&lt;</span><span class='ident'>T</span><span class='op'>&gt;</span> <span class='ident'>DerefMut</span> <span class='kw'>for</span> <span class='ident'>DerefMutExample</span><span class='op'>&lt;</span><span class='ident'>T</span><span class='op'>&gt;</span> {
    <span class='kw'>fn</span> <span class='ident'>deref_mut</span><span class='op'>&lt;</span><span class='lifetime'>&#39;a</span><span class='op'>&gt;</span>(<span class='kw-2'>&amp;</span><span class='lifetime'>&#39;a</span> <span class='kw-2'>mut</span> <span class='self'>self</span>) <span class='op'>-&gt;</span> <span class='kw-2'>&amp;</span><span class='lifetime'>&#39;a</span> <span class='kw-2'>mut</span> <span class='ident'>T</span> {
        <span class='kw-2'>&amp;</span><span class='kw-2'>mut</span> <span class='self'>self</span>.<span class='ident'>value</span>
    }
}

<span class='kw'>fn</span> <span class='ident'>main</span>() {
    <span class='kw'>let</span> <span class='kw-2'>mut</span> <span class='ident'>x</span> <span class='op'>=</span> <span class='ident'>DerefMutExample</span> { <span class='ident'>value</span>: <span class='string'>&#39;a&#39;</span> };
    <span class='op'>*</span><span class='ident'>x</span> <span class='op'>=</span> <span class='string'>&#39;b&#39;</span>;
    <span class='macro'>assert_eq</span><span class='macro'>!</span>(<span class='string'>&#39;b&#39;</span>, <span class='op'>*</span><span class='ident'>x</span>);
}</pre>
</div>
            <h2 id='required-methods'>Required Methods</h2>
            <div class='methods'>
        <h3 id='tymethod.deref_mut' class='method stab '><code>fn <a href='#tymethod.deref_mut' class='fnname'>deref_mut</a>(&amp;mut self) -&gt; &amp;mut Self::<a class='trait' href='../../core/ops/trait.DerefMut.html' title='core::ops::DerefMut'>Target</a></code></h3><div class='docblock'><p>The method called to mutably dereference a value</p>
</div></div>
        <h2 id='implementors'>Implementors</h2>
        <ul class='item-list' id='implementors-list'>
    <li><code>impl&lt;'a, T: ?<a class='trait' href='../../core/marker/trait.Sized.html' title='core::marker::Sized'>Sized</a>&gt; <a class='trait' href='../../core/ops/trait.DerefMut.html' title='core::ops::DerefMut'>DerefMut</a> for &amp;'a mut T</code></li>
<li><code>impl&lt;'b, T: ?<a class='trait' href='../../core/marker/trait.Sized.html' title='core::marker::Sized'>Sized</a>&gt; <a class='trait' href='../../core/ops/trait.DerefMut.html' title='core::ops::DerefMut'>DerefMut</a> for <a class='struct' href='../../core/cell/struct.RefMut.html' title='core::cell::RefMut'>RefMut</a>&lt;'b, T&gt;</code></li>
</ul><script type="text/javascript" async
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