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<h1 class="title">Deref coercions</h1>
<p><small>There is a new edition of the book and this is an old link.</small></p>
<blockquote>
<p>Implementing the <code>Deref</code> trait allows us to customize the behavior of the <em>dereference operator</em> <code>*</code>.
By implementing <code>Deref</code> in such a way that a smart pointer can be treated like a regular reference, we can write code that operates on references and use that code with smart pointers too.</p>
</blockquote>
<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="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">Deref</span> <span class="kw">for</span> <span class="ident">MyBox</span><span class="op"><</span><span class="ident">T</span><span class="op">></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="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="kw-2">&</span><span class="ident">T</span> {
<span class="kw-2">&</span><span class="self">self</span>.<span class="number">0</span>
}
}<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=%23!%5Ballow(unused)%5D%0Afn%20main()%20%7B%0Ause%20std%3A%3Aops%3A%3ADeref%3B%0A%0Astruct%20MyBox%3CT%3E(T)%3B%0Aimpl%3CT%3E%20Deref%20for%20MyBox%3CT%3E%20%7B%0A%20%20%20%20type%20Target%20%3D%20T%3B%0A%0A%20%20%20%20fn%20deref(%26self)%20-%3E%20%26T%20%7B%0A%20%20%20%20%20%20%20%20%26self.0%0A%20%20%20%20%7D%0A%7D%0A%7D">Run</a></pre>
<hr />
<p>Here are the relevant sections in the new and old books:</p>
<ul>
<li><strong><a href="second-edition/ch15-02-deref.html">In the second edition: Ch 15.02 — Treating Smart Pointers like Regular References with the <code>Deref</code> Trait</a></strong></li>
<li><small><a href="first-edition/deref-coercions.html">In the first edition: Ch 3.33 — Deref coercions</a></small></li>
</ul>
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