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<p class='location'>Struct LocalKey</p><div class="sidebar-elems"><div class="block items"><a class="sidebar-title" href="#methods">Methods</a><div class="sidebar-links"><a href="#method.with">with</a></div><a class="sidebar-title" href="#implementations">Trait Implementations</a><div class="sidebar-links"><a href="#impl-Debug">Debug</a></div></div><p class='location'><a href='../index.html'>futures</a>::<wbr><a href='index.html'>task</a></p><script>window.sidebarCurrent = {name: 'LocalKey', 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'>futures</a>::<wbr><a href='index.html'>task</a>::<wbr><a class="struct" href=''>LocalKey</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'>−</span>]
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</span><a class='srclink' href='../../src/futures/task_impl/std/data.rs.html#59-66' title='goto source code'>[src]</a></span></h1>
<pre class='rust struct'>pub struct LocalKey<T> { /* fields omitted */ }</pre><div class='docblock'><p>A key for task-local data stored in a future's task.</p>
<p>This type is generated by the <code>task_local!</code> macro and performs very
similarly to the <code>thread_local!</code> macro and <code>std::thread::LocalKey</code> types.
Data associated with a <code>LocalKey<T></code> is stored inside of a future's task,
and the data is destroyed when the future is completed and the task is
destroyed.</p>
<p>Task-local data can migrate between threads and hence requires a <code>Send</code>
bound. Additionally, task-local data also requires the <code>'static</code> bound to
ensure it lives long enough. When a key is accessed for the first time the
task's data is initialized with the provided initialization expression to
the macro.</p>
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<h2 id='methods' class='small-section-header'>
Methods<a href='#methods' class='anchor'></a>
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<h3 id='impl' class='impl'><span class='in-band'><code>impl<T: <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Send.html" title="trait core::marker::Send">Send</a> + 'static> <a class="struct" href="../../futures/task/struct.LocalKey.html" title="struct futures::task::LocalKey">LocalKey</a><T></code><a href='#impl' class='anchor'></a></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/futures/task_impl/std/data.rs.html#93-131' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.with' class="method"><span id='with.v' class='invisible'><code>pub fn <a href='#method.with' class='fnname'>with</a><F, R>(&'static self, f: F) -> R <span class="where fmt-newline">where<br> 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 class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&</a>T) -> R, </span></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/futures/task_impl/std/data.rs.html#114-130' title='goto source code'>[src]</a></span></h4>
<div class='docblock'><p>Access this task-local key, running the provided closure with a
reference to the value.</p>
<p>This function will access this task-local key to retrieve the data
associated with the current task and this key. If this is the first time
this key has been accessed on this task, then the key will be
initialized with the initialization expression provided at the time the
<code>task_local!</code> macro was called.</p>
<p>The provided closure will be provided a shared reference to the
underlying data associated with this task-local-key. The data itself is
stored inside of the current task.</p>
<h1 id="panics" class="section-header"><a href="#panics">Panics</a></h1>
<p>This function can possibly panic for a number of reasons:</p>
<ul>
<li>If there is not a current task.</li>
<li>If the initialization expression is run and it panics</li>
<li>If the closure provided panics</li>
</ul>
</div></div>
<h2 id='implementations' class='small-section-header'>
Trait Implementations<a href='#implementations' class='anchor'></a>
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<h3 id='impl-Debug' class='impl'><span class='in-band'><code>impl<T: <a class="trait" href="https://doc.rust-lang.org/nightly/core/fmt/trait.Debug.html" title="trait core::fmt::Debug">Debug</a>> <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="../../futures/task/struct.LocalKey.html" title="struct futures::task::LocalKey">LocalKey</a><T></code><a href='#impl-Debug' class='anchor'></a></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/futures/task_impl/std/data.rs.html#58' 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>(&self, __arg_0: &mut <a class="struct" href="https://doc.rust-lang.org/nightly/core/fmt/struct.Formatter.html" title="struct core::fmt::Formatter">Formatter</a>) -> <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/futures/task_impl/std/data.rs.html#58' 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>
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