mirror of
https://github.com/fluencelabs/wasmer
synced 2025-05-02 05:42:13 +00:00
51 lines
8.2 KiB
HTML
51 lines
8.2 KiB
HTML
<!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 `ctor` attr in crate `ctor`."><meta name="keywords" content="rust, rustlang, rust-lang, ctor"><title>ctor::ctor - 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="../light.css" id="themeStyle"><script src="../storage.js"></script><noscript><link rel="stylesheet" href="../noscript.css"></noscript><link rel="shortcut icon" href="../favicon.ico"><style type="text/css">#crate-search{background-image:url("../down-arrow.svg");}</style></head><body class="rustdoc attr"><!--[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='../ctor/index.html'><div class='logo-container'><img src='../rust-logo.png' alt='logo'></div></a><div class="sidebar-elems"><p class='location'><a href='index.html'>ctor</a></p><script>window.sidebarCurrent = {name: 'ctor', ty: 'attr', relpath: ''};</script><script defer src="sidebar-items.js"></script></div></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"><div><select id="crate-search"><option value="All crates">All crates</option></select><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"></div><a id="settings-menu" href="../settings.html"><img src="../wheel.svg" width="18" alt="Change settings"></a></div></form></nav><section id="main" class="content"><h1 class='fqn'><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>]</a></span><a class='srclink' href='../src/ctor/lib.rs.html#109-227' title='goto source code'>[src]</a></span><span class='in-band'>Attribute Macro <a href='index.html'>ctor</a>::<wbr><a class="attr" href=''>ctor</a></span></h1><pre class='rust attr'>#[ctor]</pre><div class='docblock'><p>Marks a function or static variable as a library/executable constructor.
|
||
This uses OS-specific linker sections to call a specific function at
|
||
load time.</p>
|
||
<p>Multiple startup functions/statics are supported, but the invocation order is not
|
||
guaranteed.</p>
|
||
<h1 id="examples" class="section-header"><a href="#examples">Examples</a></h1>
|
||
<p>Print a startup message:</p>
|
||
|
||
<div class="example-wrap"><pre class="rust rust-example-rendered">
|
||
<span class="attribute">#[<span class="ident">ctor</span>]</span>
|
||
<span class="kw">fn</span> <span class="ident">foo</span>() {
|
||
<span class="macro">println</span><span class="macro">!</span>(<span class="string">"Hello, world!"</span>);
|
||
}
|
||
|
||
<span class="macro">println</span><span class="macro">!</span>(<span class="string">"main()"</span>);</pre></div>
|
||
<p>Make changes to <code>static</code> variables:</p>
|
||
|
||
<div class="example-wrap"><pre class="rust rust-example-rendered">
|
||
<span class="kw">static</span> <span class="ident">INITED</span>: <span class="ident">AtomicBool</span> <span class="op">=</span> <span class="ident">AtomicBool</span>::<span class="ident">new</span>(<span class="bool-val">false</span>);
|
||
|
||
<span class="attribute">#[<span class="ident">ctor</span>]</span>
|
||
<span class="kw">fn</span> <span class="ident">foo</span>() {
|
||
<span class="ident">INITED</span>.<span class="ident">store</span>(<span class="bool-val">true</span>, <span class="ident">Ordering</span>::<span class="ident">SeqCst</span>);
|
||
}</pre></div>
|
||
<p>Initialize a <code>HashMap</code> at startup time:</p>
|
||
|
||
<div class="example-wrap"><pre class="rust rust-example-rendered">
|
||
<span class="attribute">#[<span class="ident">ctor</span>]</span>
|
||
<span class="kw">static</span> <span class="ident">STATIC_CTOR</span>: <span class="ident">HashMap</span><span class="op"><</span><span class="ident">u32</span>, <span class="ident">String</span><span class="op">></span> <span class="op">=</span> {
|
||
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">m</span> <span class="op">=</span> <span class="ident">HashMap</span>::<span class="ident">new</span>();
|
||
<span class="kw">for</span> <span class="ident">i</span> <span class="kw">in</span> <span class="number">0</span>..<span class="number">100</span> {
|
||
<span class="ident">m</span>.<span class="ident">insert</span>(<span class="ident">i</span>, <span class="macro">format</span><span class="macro">!</span>(<span class="string">"x*100={}"</span>, <span class="ident">i</span><span class="kw-2">*</span><span class="number">100</span>));
|
||
}
|
||
<span class="ident">m</span>
|
||
};
|
||
</pre></div>
|
||
<h1 id="details" class="section-header"><a href="#details">Details</a></h1>
|
||
<p>The <code>#[ctor]</code> macro makes use of linker sections to ensure that a
|
||
function is run at startup time.</p>
|
||
<p>The above example translates into the following Rust code (approximately):</p>
|
||
|
||
<div class="example-wrap"><pre class="rust rust-example-rendered">
|
||
<span class="attribute">#[<span class="ident">used</span>]</span>
|
||
<span class="attribute">#[<span class="ident">cfg_attr</span>(<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"linux"</span>, <span class="ident">link_section</span> <span class="op">=</span> <span class="string">".ctors"</span>)]</span>
|
||
<span class="attribute">#[<span class="ident">cfg_attr</span>(<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"macos"</span>, <span class="ident">link_section</span> <span class="op">=</span> <span class="string">"__DATA,__mod_init_func"</span>)]</span>
|
||
<span class="attribute">#[<span class="ident">cfg_attr</span>(<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"windows"</span>, <span class="ident">link_section</span> <span class="op">=</span> <span class="string">".CRT$XCU"</span>)]</span>
|
||
<span class="kw">static</span> <span class="ident">FOO</span>: <span class="kw">extern</span> <span class="kw">fn</span>() <span class="op">=</span> {
|
||
<span class="kw">extern</span> <span class="kw">fn</span> <span class="ident">foo</span>() { <span class="comment">/* ... */</span> };
|
||
<span class="ident">foo</span>
|
||
};</pre></div>
|
||
</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><p>Search multiple things at once by splitting your query with comma (e.g., <code>str,u8</code> or <code>String,struct:Vec,test</code>)</p></div></div></aside><script>window.rootPath = "../";window.currentCrate = "ctor";</script><script src="../aliases.js"></script><script src="../main.js"></script><script defer src="../search-index.js"></script></body></html> |