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        <p class='location'>Struct Scope</p><div class="sidebar-elems"><div class="block items"><a class="sidebar-title" href="#methods">Methods</a><div class="sidebar-links"><a href="#method.defer">defer</a><a href="#method.spawn">spawn</a><a href="#method.builder">builder</a></div><a class="sidebar-title" href="#implementations">Trait Implementations</a><div class="sidebar-links"><a href="#impl-Debug">Debug</a><a href="#impl-Drop">Drop</a></div></div><p class='location'><a href='index.html'>crossbeam</a></p><script>window.sidebarCurrent = {name: 'Scope', ty: 'struct', relpath: ''};</script><script defer src="sidebar-items.js"></script></div>
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<h1 class='fqn'><span class='in-band'>Struct <a href='index.html'>crossbeam</a>::<wbr><a class="struct" href=''>Scope</a></span><span class='out-of-band'><span id='render-detail'>
                   <a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">
                       [<span class='inner'>&#x2212;</span>]
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               </span><a class='srclink' href='../src/crossbeam/scoped.rs.html#13-15' title='goto source code'>[src]</a></span></h1>
<pre class='rust struct'>pub struct Scope&lt;'a&gt; { /* fields omitted */ }</pre>
                    <h2 id='methods' class='small-section-header'>
                      Methods<a href='#methods' class='anchor'></a>
                    </h2>
                <h3 id='impl' class='impl'><span class='in-band'><code>impl&lt;'a&gt; <a class="struct" href="../crossbeam/struct.Scope.html" title="struct crossbeam::Scope">Scope</a>&lt;'a&gt;</code><a href='#impl' class='anchor'></a></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../src/crossbeam/scoped.rs.html#80-244' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.defer' class="method"><span id='defer.v' class='invisible'><code>pub fn <a href='#method.defer' class='fnname'>defer</a>&lt;F&gt;(&amp;self, f: F) <span class="where fmt-newline">where<br>&nbsp;&nbsp;&nbsp;&nbsp;F: <a class="trait" href="https://doc.rust-lang.org/nightly/core/ops/function/trait.FnOnce.html" title="trait core::ops::function::FnOnce">FnOnce</a>() + 'a,&nbsp;</span></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../src/crossbeam/scoped.rs.html#107-113' title='goto source code'>[src]</a></span></h4>
<div class='docblock'><p>Schedule code to be executed when exiting the scope.</p>
<p>This is akin to having a destructor on the stack, except that it is
<em>guaranteed</em> to be run.</p>
</div><h4 id='method.spawn' class="method"><span id='spawn.v' class='invisible'><code>pub fn <a href='#method.spawn' class='fnname'>spawn</a>&lt;F, T&gt;(&amp;self, f: F) -&gt; <a class="struct" href="../crossbeam/struct.ScopedJoinHandle.html" title="struct crossbeam::ScopedJoinHandle">ScopedJoinHandle</a>&lt;T&gt; <span class="where fmt-newline">where<br>&nbsp;&nbsp;&nbsp;&nbsp;F: <a class="trait" href="https://doc.rust-lang.org/nightly/core/ops/function/trait.FnOnce.html" title="trait core::ops::function::FnOnce">FnOnce</a>() -&gt; T + <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Send.html" title="trait core::marker::Send">Send</a> + 'a,<br>&nbsp;&nbsp;&nbsp;&nbsp;T: <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Send.html" title="trait core::marker::Send">Send</a> + 'a,&nbsp;</span></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../src/crossbeam/scoped.rs.html#230-234' title='goto source code'>[src]</a></span></h4>
<div class='docblock'><p>Create a scoped thread.</p>
<p><code>spawn</code> is similar to the <a href="http://doc.rust-lang.org/std/thread/fn.spawn.html"><code>spawn</code></a> function in Rust's standard library. The
difference is that this thread is scoped, meaning that it's guaranteed to terminate
before the current stack frame goes away, allowing you to reference the parent stack frame
directly. This is ensured by having the parent thread join on the child thread before the
scope exits.</p>
<h1 id="examples" class="section-header"><a href="#examples">Examples</a></h1>
<p>A basic scoped thread:</p>

<pre class="rust rust-example-rendered">
<span class="ident">crossbeam</span>::<span class="ident">scope</span>(<span class="op">|</span><span class="ident">scope</span><span class="op">|</span> {
    <span class="ident">scope</span>.<span class="ident">spawn</span>(<span class="op">||</span> {
        <span class="macro">println</span><span class="macro">!</span>(<span class="string">&quot;Hello from a scoped thread!&quot;</span>);
    });
});</pre>
<p>When writing concurrent Rust programs, you'll sometimes see a pattern like this, using
<a href="http://doc.rust-lang.org/std/thread/fn.spawn.html"><code>std::thread::spawn</code></a>:</p>

<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">let</span> <span class="ident">array</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">guards</span> <span class="op">=</span> <span class="macro">vec</span><span class="macro">!</span>[];

<span class="kw">for</span> <span class="ident">i</span> <span class="kw">in</span> <span class="kw-2">&amp;</span><span class="ident">array</span> {
    <span class="kw">let</span> <span class="ident">guard</span> <span class="op">=</span> <span class="ident">std</span>::<span class="ident">thread</span>::<span class="ident">spawn</span>(<span class="kw">move</span> <span class="op">||</span> {
        <span class="macro">println</span><span class="macro">!</span>(<span class="string">&quot;element: {}&quot;</span>, <span class="ident">i</span>);
    });

    <span class="ident">guards</span>.<span class="ident">push</span>(<span class="ident">guard</span>);
}

<span class="kw">for</span> <span class="ident">guard</span> <span class="kw">in</span> <span class="ident">guards</span> {
    <span class="ident">guard</span>.<span class="ident">join</span>().<span class="ident">unwrap</span>();
}</pre>
<p>The basic pattern is:</p>
<ol>
<li>Iterate over some collection.</li>
<li>Spin up a thread to operate on each part of the collection.</li>
<li>Join all the threads.</li>
</ol>
<p>However, this code actually gives an error:</p>
<pre><code class="language-text">error: `array` does not live long enough
for i in &amp;array {
          ^~~~~
in expansion of for loop expansion
note: expansion site
note: reference must be valid for the static lifetime...
note: ...but borrowed value is only valid for the block suffix following statement 0 at ...
    let array = [1, 2, 3];
    let mut guards = vec![];

    for i in &amp;array {
        let guard = std::thread::spawn(move || {
            println!(&quot;element: {}&quot;, i);
...
error: aborting due to previous error
</code></pre>
<p>Because <a href="http://doc.rust-lang.org/std/thread/fn.spawn.html"><code>std::thread::spawn</code></a> doesn't know about this scope, it requires a
<code>'static</code> lifetime. One way of giving it a proper lifetime is to use an <a href="http://doc.rust-lang.org/stable/std/sync/struct.Arc.html"><code>Arc</code></a>:</p>

<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">sync</span>::<span class="ident">Arc</span>;

<span class="kw">let</span> <span class="ident">array</span> <span class="op">=</span> <span class="ident">Arc</span>::<span class="ident">new</span>([<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>]);
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">guards</span> <span class="op">=</span> <span class="macro">vec</span><span class="macro">!</span>[];

<span class="kw">for</span> <span class="ident">i</span> <span class="kw">in</span> <span class="number">0</span>..<span class="ident">array</span>.<span class="ident">len</span>() {
    <span class="kw">let</span> <span class="ident">a</span> <span class="op">=</span> <span class="ident">array</span>.<span class="ident">clone</span>();

    <span class="kw">let</span> <span class="ident">guard</span> <span class="op">=</span> <span class="ident">std</span>::<span class="ident">thread</span>::<span class="ident">spawn</span>(<span class="kw">move</span> <span class="op">||</span> {
        <span class="macro">println</span><span class="macro">!</span>(<span class="string">&quot;element: {}&quot;</span>, <span class="ident">a</span>[<span class="ident">i</span>]);
    });

    <span class="ident">guards</span>.<span class="ident">push</span>(<span class="ident">guard</span>);
}

<span class="kw">for</span> <span class="ident">guard</span> <span class="kw">in</span> <span class="ident">guards</span> {
    <span class="ident">guard</span>.<span class="ident">join</span>().<span class="ident">unwrap</span>();
}</pre>
<p>But this introduces unnecessary allocation, as <code>Arc&lt;T&gt;</code> puts its data on the heap, and we
also end up dealing with reference counts. We know that we're joining the threads before
our function returns, so just taking a reference <em>should</em> be safe. Rust can't know that,
though.</p>
<p>Enter scoped threads. Here's our original example, using <code>spawn</code> from crossbeam rather
than from <code>std::thread</code>:</p>

<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">array</span> <span class="op">=</span> [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>];

<span class="ident">crossbeam</span>::<span class="ident">scope</span>(<span class="op">|</span><span class="ident">scope</span><span class="op">|</span> {
    <span class="kw">for</span> <span class="ident">i</span> <span class="kw">in</span> <span class="kw-2">&amp;</span><span class="ident">array</span> {
        <span class="ident">scope</span>.<span class="ident">spawn</span>(<span class="kw">move</span> <span class="op">||</span> {
            <span class="macro">println</span><span class="macro">!</span>(<span class="string">&quot;element: {}&quot;</span>, <span class="ident">i</span>);
        });
    }
});</pre>
<p>Much more straightforward.</p>
</div><h4 id='method.builder' class="method"><span id='builder.v' class='invisible'><code>pub fn <a href='#method.builder' class='fnname'>builder</a>&lt;'s&gt;(&amp;'s self) -&gt; ScopedThreadBuilder&lt;'s, 'a&gt;</code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../src/crossbeam/scoped.rs.html#238-243' title='goto source code'>[src]</a></span></h4>
<div class='docblock'><p>Generates the base configuration for spawning a scoped thread, from which configuration
methods can be chained.</p>
</div></div>
            <h2 id='implementations' class='small-section-header'>
              Trait Implementations<a href='#implementations' class='anchor'></a>
            </h2>
        <h3 id='impl-Debug' class='impl'><span class='in-band'><code>impl&lt;'a&gt; <a class="trait" href="https://doc.rust-lang.org/nightly/core/fmt/trait.Debug.html" title="trait core::fmt::Debug">Debug</a> for <a class="struct" href="../crossbeam/struct.Scope.html" title="struct crossbeam::Scope">Scope</a>&lt;'a&gt;</code><a href='#impl-Debug' class='anchor'></a></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../src/crossbeam/scoped.rs.html#68-72' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.fmt' class="method"><span id='fmt.v' class='invisible'><code>fn <a href='https://doc.rust-lang.org/nightly/core/fmt/trait.Debug.html#tymethod.fmt' class='fnname'>fmt</a>(&amp;self, f: &amp;mut <a class="struct" href="https://doc.rust-lang.org/nightly/core/fmt/struct.Formatter.html" title="struct core::fmt::Formatter">Formatter</a>) -&gt; <a class="type" href="https://doc.rust-lang.org/nightly/core/fmt/type.Result.html" title="type core::fmt::Result">Result</a></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../src/crossbeam/scoped.rs.html#69-71' title='goto source code'>[src]</a></span></h4>
<div class='docblock'><p>Formats the value using the given formatter. <a href="https://doc.rust-lang.org/nightly/core/fmt/trait.Debug.html#tymethod.fmt">Read more</a></p>
</div></div><h3 id='impl-Drop' class='impl'><span class='in-band'><code>impl&lt;'a&gt; <a class="trait" href="https://doc.rust-lang.org/nightly/core/ops/drop/trait.Drop.html" title="trait core::ops::drop::Drop">Drop</a> for <a class="struct" href="../crossbeam/struct.Scope.html" title="struct crossbeam::Scope">Scope</a>&lt;'a&gt;</code><a href='#impl-Drop' class='anchor'></a></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../src/crossbeam/scoped.rs.html#310-314' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.drop' class="method"><span id='drop.v' class='invisible'><code>fn <a href='https://doc.rust-lang.org/nightly/core/ops/drop/trait.Drop.html#tymethod.drop' class='fnname'>drop</a>(&amp;mut self)</code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../src/crossbeam/scoped.rs.html#311-313' title='goto source code'>[src]</a></span></h4>
<div class='docblock'><p>Executes the destructor for this type. <a href="https://doc.rust-lang.org/nightly/core/ops/drop/trait.Drop.html#tymethod.drop">Read more</a></p>
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