<!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"> <meta name="description" content="API documentation for the Rust `thread_local` macro in crate `std`."> <meta name="keywords" content="rust, rustlang, rust-lang, thread_local"> <title>std::thread_local - Rust</title> <link rel="stylesheet" type="text/css" href="../normalize.css"> <link rel="stylesheet" type="text/css" href="../rustdoc.css" id="mainThemeStyle"> <link rel="stylesheet" type="text/css" href="../dark.css"> <link rel="stylesheet" type="text/css" href="../main.css" id="themeStyle"> <script src="../storage.js"></script> <link rel="shortcut icon" href="https://doc.rust-lang.org/favicon.ico"> </head> <body class="rustdoc macro"> <!--[if lte IE 8]> <div class="warning"> This old browser is unsupported and will most likely display funky things. </div> <![endif]--> <nav class="sidebar"> <div class="sidebar-menu">☰</div> <a href='../std/index.html'><img src='https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png' alt='logo' width='100'></a> <p class='location'><a href='index.html'>std</a></p><script>window.sidebarCurrent = {name: 'thread_local', ty: 'macro', relpath: ''};</script><script defer src="sidebar-items.js"></script> </nav> <div class="theme-picker"> <button id="theme-picker" aria-label="Pick another theme!"> <img src="../brush.svg" width="18" alt="Pick another theme!"> </button> <div id="theme-choices"></div> </div> <script src="../theme.js"></script> <nav class="sub"> <form class="search-form js-only"> <div class="search-container"> <input class="search-input" name="search" autocomplete="off" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"> </div> </form> </nav> <section id='main' class="content"> <h1 class='fqn'><span class='in-band'>Macro <a href='index.html'>std</a>::<wbr><a class="macro" href=''>thread_local</a></span><span class='out-of-band'><span class='since' title='Stable since Rust version 1.0.0'>1.0.0</span><span id='render-detail'> <a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs"> [<span class='inner'>−</span>] </a> </span><a class='srclink' href='../src/std/thread/local.rs.html#142-156' title='goto source code'>[src]</a></span></h1> <pre class="rust macro"> <span class="macro">macro_rules</span><span class="macro">!</span> <span class="ident">thread_local</span> { () <span class="op">=></span> { ... }; ($(<span class="attribute">#[<span class="macro-nonterminal">$</span><span class="macro-nonterminal">attr</span>:<span class="ident">meta</span>]</span>)<span class="op">*</span> <span class="macro-nonterminal">$</span><span class="macro-nonterminal">vis</span>:<span class="ident">vis</span> <span class="kw">static</span> <span class="macro-nonterminal">$</span><span class="macro-nonterminal">name</span>:<span class="ident">ident</span>: <span class="macro-nonterminal">$</span><span class="macro-nonterminal">t</span>:<span class="ident">ty</span> <span class="op">=</span> <span class="macro-nonterminal">$</span><span class="macro-nonterminal">init</span>:<span class="ident">expr</span>; $(<span class="macro-nonterminal">$</span><span class="macro-nonterminal">rest</span>:<span class="ident">tt</span>)<span class="kw-2">*</span>) <span class="op">=></span> { ... }; ($(<span class="attribute">#[<span class="macro-nonterminal">$</span><span class="macro-nonterminal">attr</span>:<span class="ident">meta</span>]</span>)<span class="op">*</span> <span class="macro-nonterminal">$</span><span class="macro-nonterminal">vis</span>:<span class="ident">vis</span> <span class="kw">static</span> <span class="macro-nonterminal">$</span><span class="macro-nonterminal">name</span>:<span class="ident">ident</span>: <span class="macro-nonterminal">$</span><span class="macro-nonterminal">t</span>:<span class="ident">ty</span> <span class="op">=</span> <span class="macro-nonterminal">$</span><span class="macro-nonterminal">init</span>:<span class="ident">expr</span>) <span class="op">=></span> { ... }; }</pre> <div class='docblock'><p>Declare a new thread local storage key of type <a href="../std/thread/struct.LocalKey.html"><code>std::thread::LocalKey</code></a>.</p> <h1 id="syntax" class="section-header"><a href="#syntax">Syntax</a></h1> <p>The macro wraps any number of static declarations and makes them thread local. Publicity and attributes for each static are allowed. Example:</p> <pre class="rust rust-example-rendered"> <span class="kw">use</span> <span class="ident">std</span>::<span class="ident">cell</span>::<span class="ident">RefCell</span>; <span class="macro">thread_local</span><span class="macro">!</span> { <span class="kw">pub</span> <span class="kw">static</span> <span class="ident">FOO</span>: <span class="ident">RefCell</span><span class="op"><</span><span class="ident">u32</span><span class="op">></span> <span class="op">=</span> <span class="ident">RefCell</span>::<span class="ident">new</span>(<span class="number">1</span>); <span class="attribute">#[<span class="ident">allow</span>(<span class="ident">unused</span>)]</span> <span class="kw">static</span> <span class="ident">BAR</span>: <span class="ident">RefCell</span><span class="op"><</span><span class="ident">f32</span><span class="op">></span> <span class="op">=</span> <span class="ident">RefCell</span>::<span class="ident">new</span>(<span class="number">1.0</span>); }<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=%23!%5Ballow(unused)%5D%0Ause%20std%3A%3Acell%3A%3ARefCell%3B%0Athread_local!%20%7B%0A%20%20%20%20pub%20static%20FOO%3A%20RefCell%3Cu32%3E%20%3D%20RefCell%3A%3Anew(1)%3B%0A%0A%20%20%20%20%23%5Ballow(unused)%5D%0A%20%20%20%20static%20BAR%3A%20RefCell%3Cf32%3E%20%3D%20RefCell%3A%3Anew(1.0)%3B%0A%7D%0Afn%20main()%20%7B%7D%0A">Run</a></pre> <p>See <a href="../std/thread/struct.LocalKey.html">LocalKey documentation</a> for more information.</p> </div></section> <section id='search' class="content hidden"></section> <section class="footer"></section> <aside id="help" class="hidden"> <div> <h1 class="hidden">Help</h1> <div class="shortcuts"> <h2>Keyboard Shortcuts</h2> <dl> <dt><kbd>?</kbd></dt> <dd>Show this help dialog</dd> <dt><kbd>S</kbd></dt> <dd>Focus the search field</dd> <dt><kbd>↑</kbd></dt> <dd>Move up in search results</dd> <dt><kbd>↓</kbd></dt> <dd>Move down in search results</dd> <dt><kbd>↹</kbd></dt> <dd>Switch tab</dd> <dt><kbd>⏎</kbd></dt> <dd>Go to active search result</dd> <dt><kbd>+</kbd></dt> <dd>Expand all sections</dd> <dt><kbd>-</kbd></dt> <dd>Collapse all sections</dd> </dl> </div> <div class="infos"> <h2>Search Tricks</h2> <p> Prefix searches with a type followed by a colon (e.g. <code>fn:</code>) to restrict the search to a given type. </p> <p> Accepted types are: <code>fn</code>, <code>mod</code>, <code>struct</code>, <code>enum</code>, <code>trait</code>, <code>type</code>, <code>macro</code>, and <code>const</code>. </p> <p> Search functions by type signature (e.g. <code>vec -> usize</code> or <code>* -> vec</code>) </p> </div> </div> </aside> <script> window.rootPath = "../"; window.currentCrate = "std"; </script> <script src="../main.js"></script> <script defer src="../search-index.js"></script> </body> </html>