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<!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="Construct a variance marker; equivalent to `Default::default`."><title>variance in stdx::variance - Rust</title><script>if(window.location.protocol!=="file:")document.head.insertAdjacentHTML("beforeend","SourceSerif4-Regular-6b053e98.ttf.woff2,FiraSans-Italic-81dc35de.woff2,FiraSans-Regular-0fe48ade.woff2,FiraSans-MediumItalic-ccf7e434.woff2,FiraSans-Medium-e1aa3f0a.woff2,SourceCodePro-Regular-8badfe75.ttf.woff2,SourceCodePro-Semibold-aa29a496.ttf.woff2".split(",").map(f=>`<link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/${f}">`).join(""))</script><link rel="stylesheet" href="../../static.files/normalize-9960930a.css"><link rel="stylesheet" href="../../static.files/rustdoc-84e720fa.css"><meta name="rustdoc-vars" data-root-path="../../" data-static-root-path="../../static.files/" data-current-crate="stdx" data-themes="" data-resource-suffix="" data-rustdoc-version="1.89.0 (29483883e 2025-08-04)" data-channel="1.89.0" data-search-js="search-92309212.js" data-settings-js="settings-5514c975.js" ><script src="../../static.files/storage-4e99c027.js"></script><script defer src="sidebar-items.js"></script><script defer src="../../static.files/main-fd3af306.js"></script><noscript><link rel="stylesheet" href="../../static.files/noscript-32bb7600.css"></noscript><link rel="alternate icon" type="image/png" href="../../static.files/favicon-32x32-6580c154.png"><link rel="icon" type="image/svg+xml" href="../../static.files/favicon-044be391.svg"></head><body class="rustdoc fn"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="mobile-topbar"><button class="sidebar-menu-toggle" title="show sidebar"></button></nav><nav class="sidebar"><div class="sidebar-crate"><h2><a href="../../stdx/index.html">stdx</a><span class="version">0.0.0</span></h2></div><div class="sidebar-elems"><section id="rustdoc-toc"><h2 class="location"><a href="#">variance</a></h2><h3><a href="#">Sections</a></h3><ul class="block top-toc"><li><a href="#example" title="Example">Example</a></li></ul></section><div id="rustdoc-modnav"><h2><a href="index.html">In stdx::<wbr>variance</a></h2></div></div></nav><div class="sidebar-resizer" title="Drag to resize sidebar"></div><main><div class="width-limiter"><rustdoc-search></rustdoc-search><section id="main-content" class="content"><div class="main-heading"><div class="rustdoc-breadcrumbs"><a href="../index.html">stdx</a>::<wbr><a href="index.html">variance</a></div><h1>Function <span class="fn">variance</span><button id="copy-path" title="Copy item path to clipboard">Copy item path</button></h1><rustdoc-toolbar></rustdoc-toolbar><span class="sub-heading"><a class="src" href="../../src/stdx/variance.rs.html#265-270">Source</a> </span></div><pre class="rust item-decl"><code>pub const fn variance<T>() -> T<div class="where">where
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T: <a class="trait" href="trait.Variance.html" title="trait stdx::variance::Variance">Variance</a>,</div></code></pre><details class="toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>Construct a variance marker; equivalent to <a href="https://doc.rust-lang.org/1.89.0/core/default/trait.Default.html#tymethod.default" title="associated function core::default::Default::default"><code>Default::default</code></a>.</p>
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<p>This type can be any of the following. You generally should not need to explicitly name the
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type, however.</p>
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<ul>
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<li><a href="struct.PhantomCovariant.html" title="struct stdx::variance::PhantomCovariant"><code>PhantomCovariant</code></a></li>
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<li><a href="struct.PhantomContravariant.html" title="struct stdx::variance::PhantomContravariant"><code>PhantomContravariant</code></a></li>
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<li><a href="struct.PhantomInvariant.html" title="struct stdx::variance::PhantomInvariant"><code>PhantomInvariant</code></a></li>
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<li><a href="struct.PhantomCovariantLifetime.html" title="struct stdx::variance::PhantomCovariantLifetime"><code>PhantomCovariantLifetime</code></a></li>
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<li><a href="struct.PhantomContravariantLifetime.html" title="struct stdx::variance::PhantomContravariantLifetime"><code>PhantomContravariantLifetime</code></a></li>
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<li><a href="struct.PhantomInvariantLifetime.html" title="struct stdx::variance::PhantomInvariantLifetime"><code>PhantomInvariantLifetime</code></a></li>
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</ul>
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<h2 id="example"><a class="doc-anchor" href="#example">§</a>Example</h2>
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<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="attr">#![feature(phantom_variance_markers)]
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</span><span class="kw">use </span>core::marker::{PhantomCovariant, variance};
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<span class="kw">struct </span>BoundFn<F, P, R>
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<span class="kw">where
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</span>F: Fn(P) -> R,
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{
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function: F,
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parameter: P,
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return_value: PhantomCovariant<R>,
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}
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<span class="kw">let </span>bound_fn = BoundFn {
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function: core::convert::identity,
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parameter: <span class="number">5u8</span>,
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return_value: variance(),
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};</code></pre></div>
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</div></details></section></div></main></body></html> |