<!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">
<title>Unsized Types</title>
<link rel="stylesheet" type="text/css" href="../rust.css">
<link rel="shortcut icon" href="https://www.rust-lang.org/favicon.ico">
</head>
<body class="rustdoc">
<!--[if lte IE 8]>
<div class="warning">
This old browser is unsupported and will most likely display funky
things.
</div>
<![endif]-->
<div id="versioninfo">
<img src="https://www.rust-lang.org/logos/rust-logo-32x32-blk.png" width="32" height="32" alt="Rust logo"><br>
<span class="white-sticker"><a href="https://www.rust-lang.org">Rust</a> 1.28.0</span><br>
<a href="https://github.com/rust-lang/rust/commit/"
class="hash white-sticker"></a>
</div>
<h1 class="title">Unsized Types</h1>
<p><small>There is a new edition of the book and this is an old link.</small></p>
<blockquote>
<p>Sometimes referred to as ‘DSTs’ or ‘unsized types’, these types let us talk about types whose size we can only know at runtime.
The <code>Sized</code> trait is automatically implemented for everything the compiler knows the size of at compile time.
A trait bound on <code>?Sized</code> is the opposite of a trait bound on <code>Sized</code>; that is, we would read this as “<code>T</code> may or may not be <code>Sized</code>”.</p>
</blockquote>
<div class='information'><div class='tooltip ignore'>ⓘ<span class='tooltiptext'>This example is not tested</span></div></div><pre class="rust rust-example-rendered ignore">
<span class="kw">fn</span> <span class="ident">generic</span><span class="op"><</span><span class="ident">T</span>: <span class="question-mark">?</span><span class="ident">Sized</span><span class="op">></span>(<span class="ident">t</span>: <span class="kw-2">&</span><span class="ident">T</span>) {
<span class="comment">// ...snip...</span>
}<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=%23!%5Ballow(unused)%5D%0Afn%20main()%20%7B%0Afn%20generic%3CT%3A%20%3FSized%3E(t%3A%20%26T)%20%7B%0A%20%20%20%20%2F%2F%20...snip...%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/ch19-04-advanced-types.html#dynamically-sized-types-and-the-sized-trait">In the second edition: Ch 19.04 — Advanced Types, section Dynamically Sized Types</a></strong></li>
<li><small><a href="first-edition/unsized-types.html">In the first edition: Ch 3.31 — Unsized Types</a></small></li>
</ul>
<footer><p>
Copyright © 2011 The Rust Project Developers. Licensed under the
<a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>
or the <a href="https://opensource.org/licenses/MIT">MIT license</a>, at your option.
</p><p>
This file may not be copied, modified, or distributed except according to those terms.
</p></footer>
</body>
</html>
distrib
>
Mageia
>
6
>
armv7hl
>
media
>
core-updates
>
by-pkgid
>
4e2dbb669434a7691662cb2f0ad38972
>
files
>
887
