<!DOCTYPE html><htmllang="en"><head><metacharset="utf-8"><metaname="viewport"content="width=device-width, initial-scale=1.0"><metaname="generator"content="rustdoc"><metaname="description"content="A value which is initialized on the first access."><title>Lazy in once_cell::sync - Rust</title><linkrel="preload"as="font"type="font/woff2"crossoriginhref="../../static.files/SourceSerif4-Regular-46f98efaafac5295.ttf.woff2"><linkrel="preload"as="font"type="font/woff2"crossoriginhref="../../static.files/FiraSans-Regular-018c141bf0843ffd.woff2"><linkrel="preload"as="font"type="font/woff2"crossoriginhref="../../static.files/FiraSans-Medium-8f9a781e4970d388.woff2"><linkrel="preload"as="font"type="font/woff2"crossoriginhref="../../static.files/SourceCodePro-Regular-562dcc5011b6de7d.ttf.woff2"><linkrel="preload"as="font"type="font/woff2"crossoriginhref="../../static.files/SourceCodePro-Semibold-d899c5a5c4aeb14a.ttf.woff2"><linkrel="stylesheet"href="../../static.files/normalize-76eba96aa4d2e634.css"><linkrel="stylesheet"href="../../static.files/rustdoc-5bc39a1768837dd0.css"><metaname="rustdoc-vars"data-root-path="../../"data-static-root-path="../../static.files/"data-current-crate="once_cell"data-themes=""data-resource-suffix=""data-rustdoc-version="1.77.2 (25ef9e3d8 2024-04-09)"data-channel="1.77.2"data-search-js="search-dd67cee4cfa65049.js"data-settings-js="settings-4313503d2e1961c2.js"><scriptsrc="../../static.files/storage-4c98445ec4002617.js"></script><scriptdefersrc="sidebar-items.js"></script><scriptdefersrc="../../static.files/main-48f368f3872407c8.js"></script><noscript><linkrel="stylesheet"href="../../static.files/noscript-04d5337699b92874.css"></noscript><linkrel="alternate icon"type="image/png"href="../../static.files/favicon-16x16-8b506e7a72182f1c.png"><linkrel="alternate icon"type="image/png"href="../../static.files/favicon-32x32-422f7d1d52889060.png"><linkrel="icon"type="image/svg+xml"href="../../static.files/favicon-2c020d218678b618.svg"></head><bodyclass="rustdoc struct"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><navclass="mobile-topbar"><buttonclass="sidebar-menu-toggle"title="show sidebar"></button></nav><navclass="sidebar"><divclass="sidebar-crate"><h2><ahref="../../once_cell/index.html">once_cell</a><spanclass="version">1.19.0</span></h2></div><h2class="location"><ahref="#">Lazy</a></h2><divclass="sidebar-elems"><section><h3><ahref="#implementations">Methods</a></h3><ulclass="block method"><li><ahref="#method.force">force</a></li><li><ahref="#method.force_mut">force_mut</a></li><li><ahref="#method.get">get</a></li><li><ahref="#method.get_mut">get_mut</a></li><li><ahref="#method.into_value">into_value</a></li><li><ahref="#method.new">new</a></li></ul><h3><ahref="#trait-implementations">Trait Implementations</a></h3><ulclass="block trait-implementation"><li><ahref="#impl-Debug-for-Lazy%3CT,+F%3E">Debug</a></li><li><ahref="#impl-Default-for-Lazy%3CT%3E">Default</a></li><li><ahref="#impl-Deref-for-Lazy%3CT,+F%3E">Deref</a></li><li><ahref="#impl-DerefMut-for-Lazy%3CT,+F%3E">DerefMut</a></li><li><ahref="#impl-RefUnwindSafe-for-Lazy%3CT,+F%3E">RefUnwindSafe</a></li><li><ahref="#impl-Sync-for-Lazy%3CT,+F%3E">Sync</a></li></ul><h3><ahref="#synthetic-implementations">Auto Trait Implementations</a></h3><ulclass="block synthetic-implementation"><li><ahref="#impl-Send-for-Lazy%3CT,+F%3E">Send</a></li><li><ahref="#impl-Unpin-for-Lazy%3CT,+F%3E">Unpin</a></li><li><ahref="#impl-UnwindSafe-for-Lazy%3CT,+F%3E">UnwindSafe</a></li></ul><h3><ahref="#blanket-implementations">Blanket Implementations</a></h3><ulclass="block blanket-implementation"><li><ahref="#impl-Any-for-T">Any</a></li><li><ahref="#impl-Borrow%3CT%3E-for-T">Borrow<T></a></li><li><ahref="#impl-BorrowMut%3CT%3E-for-T">BorrowMut<T></a></li><li><ahref="#impl-From%3CT%3E-for-T">From<T></a></li><li><ahref="#impl-Into%3CU%3E-for-T">Into<U></a></li><li><ahref="#
<main><divclass="width-limiter"><navclass="sub"><formclass="search-form"><span></span><divid="sidebar-button"tabindex="-1"><ahref="../../once_cell/all.html"title="show sidebar"></a></div><inputclass="search-input"name="search"aria-label="Run search in the documentation"autocomplete="off"spellcheck="false"placeholder="Click or press ‘S’ to search, ‘?’ for more options…"type="search"><divid="help-button"tabindex="-1"><ahref="../../help.html"title="help">?</a></div><divid="settings-menu"tabindex="-1"><ahref="../../settings.html"title="settings"><imgwidth="22"height="22"alt="Change settings"src="../../static.files/wheel-7b819b6101059cd0.svg"></a></div></form></nav><sectionid="main-content"class="content"><divclass="main-heading"><h1>Struct <ahref="../index.html">once_cell</a>::<wbr><ahref="index.html">sync</a>::<wbr><aclass="struct"href="#">Lazy</a><buttonid="copy-path"title="Copy item path to clipboard"><imgsrc="../../static.files/clipboard-7571035ce49a181d.svg"width="19"height="18"alt="Copy item path"></button></h1><spanclass="out-of-band"><aclass="src"href="../../src/once_cell/lib.rs.html#1255-1258">source</a> · <buttonid="toggle-all-docs"title="collapse all docs">[<span>−</span>]</button></span></div><preclass="rust item-decl"><code>pub struct Lazy<T, F = <aclass="primitive"href="https://doc.rust-lang.org/1.77.2/std/primitive.fn.html">fn</a>() -> T> { <spanclass="comment">/* private fields */</span> }</code></pre><detailsclass="toggle top-doc"open><summaryclass="hideme"><span>Expand description</span></summary><divclass="docblock"><p>A value which is initialized on the first access.</p>
</div></details><h2id="implementations"class="section-header">Implementations<ahref="#implementations"class="anchor">§</a></h2><divid="implementations-list"><detailsclass="toggle implementors-toggle"open><summary><sectionid="impl-Lazy%3CT,+F%3E"class="impl"><aclass="src rightside"href="../../src/once_cell/lib.rs.html#1275-1292">source</a><ahref="#impl-Lazy%3CT,+F%3E"class="anchor">§</a><h3class="code-header">impl<T, F><aclass="struct"href="struct.Lazy.html"title="struct once_cell::sync::Lazy">Lazy</a><T, F></h3></section></summary><divclass="impl-items"><detailsclass="toggle method-toggle"open><summary><sectionid="method.new"class="method"><aclass="src rightside"href="../../src/once_cell/lib.rs.html#1278-1280">source</a><h4class="code-header">pub const fn <ahref="#method.new"class="fn">new</a>(f: F) -><aclass="struct"href="struct.Lazy.html"title="struct once_cell::sync::Lazy">Lazy</a><T, F></h4></section></summary><divclass="docblock"><p>Creates a new lazy value with the given initializing
</div></details></div></details><detailsclass="toggle implementors-toggle"open><summary><sectionid="impl-Lazy%3CT,+F%3E-1"class="impl"><aclass="src rightside"href="../../src/once_cell/lib.rs.html#1294-1371">source</a><ahref="#impl-Lazy%3CT,+F%3E-1"class="anchor">§</a><h3class="code-header">impl<T, F: <aclass="trait"href="https://doc.rust-lang.org/1.77.2/core/ops/function/trait.FnOnce.html"title="trait core::ops::function::FnOnce">FnOnce</a>() -> T><aclass="struct"href="struct.Lazy.html"title="struct once_cell::sync::Lazy">Lazy</a><T, F></h3></section></summary><divclass="impl-items"><detailsclass="toggle method-toggle"open><summary><sectionid="method.force"class="method"><aclass="src rightside"href="../../src/once_cell/lib.rs.html#1308-1313">source</a><h4class="code-header">pub fn <ahref="#method.force"class="fn">force</a>(this: &<aclass="struct"href="struct.Lazy.html"title="struct once_cell::sync::Lazy">Lazy</a><T, F>) -><aclass="primitive"href="https://doc.rust-lang.org/1.77.2/std/primitive.reference.html">&T</a></h4></section></summary><divclass="docblock"><p>Forces the evaluation of this lazy value and
</div></details><detailsclass="toggle method-toggle"open><summary><sectionid="method.force_mut"class="method"><aclass="src rightside"href="../../src/once_cell/lib.rs.html#1327-1336">source</a><h4class="code-header">pub fn <ahref="#method.force_mut"class="fn">force_mut</a>(this: &mut <aclass="struct"href="struct.Lazy.html"title="struct once_cell::sync::Lazy">Lazy</a><T, F>) -><aclass="primitive"href="https://doc.rust-lang.org/1.77.2/std/primitive.reference.html">&mut T</a></h4></section></summary><divclass="docblock"><p>Forces the evaluation of this lazy value and
</div></details><detailsclass="toggle method-toggle"open><summary><sectionid="method.get"class="method"><aclass="src rightside"href="../../src/once_cell/lib.rs.html#1351-1353">source</a><h4class="code-header">pub fn <ahref="#method.get"class="fn">get</a>(this: &<aclass="struct"href="struct.Lazy.html"title="struct once_cell::sync::Lazy">Lazy</a><T, F>) -><aclass="enum"href="https://doc.rust-lang.org/1.77.2/core/option/enum.Option.html"title="enum core::option::Option">Option</a><<aclass="primitive"href="https://doc.rust-lang.org/1.77.2/std/primitive.reference.html">&T</a>></h4></section></summary><divclass="docblock"><p>Gets the reference to the result of this lazy value if
</div></details><detailsclass="toggle method-toggle"open><summary><sectionid="method.get_mut"class="method"><aclass="src rightside"href="../../src/once_cell/lib.rs.html#1368-1370">source</a><h4class="code-header">pub fn <ahref="#method.get_mut"class="fn">get_mut</a>(this: &mut <aclass="struct"href="struct.Lazy.html"title="struct once_cell::sync::Lazy">Lazy</a><T, F>) -><aclass="enum"href="https://doc.rust-lang.org/1.77.2/core/option/enum.Option.html"title="enum core::option::Option">Option</a><<aclass="primitive"href="https://doc.rust-lang.org/1.77.2/std/primitive.reference.html">&mut T</a>></h4></section></summary><divclass="docblock"><p>Gets the reference to the result of this lazy value if
</div></details></div></details></div><h2id="trait-implementations"class="section-header">Trait Implementations<ahref="#trait-implementations"class="anchor">§</a></h2><divid="trait-implementations-list"><detailsclass="toggle implementors-toggle"open><summary><sectionid="impl-Debug-for-Lazy%3CT,+F%3E"class="impl"><aclass="src rightside"href="../../src/once_cell/lib.rs.html#1260-1264">source</a><ahref="#impl-Debug-for-Lazy%3CT,+F%3E"class="anchor">§</a><h3class="code-header">impl<T: <aclass="trait"href="https://doc.rust-lang.org/1.77.2/core/fmt/trait.Debug.html"title="trait core::fmt::Debug">Debug</a>, F><aclass="trait"href="https://doc.rust-lang.org/1.77.2/core/fmt/trait.Debug.html"title="trait core::fmt::Debug">Debug</a> for <aclass="struct"href="struct.Lazy.html"title="struct once_cell::sync::Lazy">Lazy</a><T, F></h3></section></summary><divclass="impl-items"><detailsclass="toggle method-toggle"open><summary><sectionid="method.fmt"class="method trait-impl"><aclass="src rightside"href="../../src/once_cell/lib.rs.html#1261-1263">source</a><ahref="#method.fmt"class="anchor">§</a><h4class="code-header">fn <ahref="https://doc.rust-lang.org/1.77.2/core/fmt/trait.Debug.html#tymethod.fmt"class="fn">fmt</a>(&self, f: &mut <aclass="struct"href="https://doc.rust-lang.org/1.77.2/core/fmt/struct.Formatter.html"title="struct core::fmt::Formatter">Formatter</a><'_>) -><aclass="type"href="https://doc.rust-lang.org/1.77.2/core/fmt/type.Result.html"title="type core::fmt::Result">Result</a></h4></section></summary><divclass='docblock'>Formats the value using the given formatter. <ahref="https://doc.rust-lang.org/1.77.2/core/fmt/trait.Debug.html#tymethod.fmt">Read more</a></div></details></div></details><detailsclass="toggle implementors-toggle"open><summary><sectionid="impl-Default-for-Lazy%3CT%3E"class="impl"><aclass="src rightside"href="../../src/once_cell/lib.rs.html#1386-1391">source</a><ahref="#impl-Default-for-Lazy%3CT%3E"class="anchor">§</a><h3class="code-header">impl<T: <aclass="trait"href="https://doc.rust-lang.org/1.77.2/core/default/trait.Default.html"title="trait core::default::Default">Default</a>><aclass="trait"href="https://doc.rust-lang.org/1.77.2/core/default/trait.Default.html"title="trait core::default::Default">Default</a> for <aclass="struct"href="struct.Lazy.html"title="struct once_cell::sync::Lazy">Lazy</a><T></h3></section></summary><divclass="impl-items"><detailsclass="toggle method-toggle"open><summary><sectionid="method.default"class="method trait-impl"><aclass="src rightside"href="../../src/once_cell/lib.rs.html#1388-1390">source</a><ahref="#method.default"class="anchor">§</a><h4class="code-header">fn <ahref="https://doc.rust-lang.org/1.77.2/core/default/trait.Default.html#tymethod.default"class="fn">default</a>() -><aclass="struct"href="struct.Lazy.html"title="struct once_cell::sync::Lazy">Lazy</a><T></h4></section></summary><divclass="docblock"><p>Creates a new lazy value using <code>Default</code> as the initializing function.</p>
</div></details></div></details><detailsclass="toggle implementors-toggle"open><summary><sectionid="impl-Deref-for-Lazy%3CT,+F%3E"class="impl"><aclass="src rightside"href="../../src/once_cell/lib.rs.html#1373-1378">source</a><ahref="#impl-Deref-for-Lazy%3CT,+F%3E"class="anchor">§</a><h3class="code-header">impl<T, F: <aclass="trait"href="https://doc.rust-lang.org/1.77.2/core/ops/function/trait.FnOnce.html"title="trait core::ops::function::FnOnce">FnOnce</a>() -> T><aclass="trait"href="https://doc.rust-lang.org/1.77.2/core/ops/deref/trait.Deref.html"title="trait core::ops::deref::Deref">Deref</a> for <aclass="struct"href="struct.Lazy.html"title="struct once_cell::sync::Lazy">Lazy</a><T, F></h3></section></summary><divclass="impl-items"><detailsclass="toggle"open><summary><sectionid="associatedtype.Target"class="associatedtype trait-impl"><ahref="#associatedtype.Target"class="anchor">§</a><h4class="code-header">type <ahref="https://doc.rust-lang.org/1.77.2/core/ops/deref/trait.Deref.html#associatedtype.Target"class="associatedtype">Target</a> = T</h4></section></summary><divclass='docblock'>The resulting type after dereferencing.</div></details><detailsclass="toggle method-toggle"open><summary><sectionid="method.deref"class="method trait-impl"><aclass="src rightside"href="../../src/once_cell/lib.rs.html#1375-1377">source</a><ahref="#method.deref"class="anchor">§</a><h4class="code-header">fn <ahref="https://doc.rust-lang.org/1.77.2/core/ops/deref/trait.Deref.html#tymethod.deref"class="fn">deref</a>(&self) -><aclass="primitive"href="https://doc.rust-lang.org/1.77.2/std/primitive.reference.html">&T</a></h4></section></summary><divclass='docblock'>Dereferences the value.</div></details></div></details><detailsclass="toggle implementors-toggle"open><summary><sectionid="impl-DerefMut-for-Lazy%3CT,+F%3E"class="impl"><aclass="src rightside"href="../../src/once_cell/lib.rs.html#1380-1384">source</a><ahref="#impl-DerefMut-for-Lazy%3CT,+F%3E"class="anchor">§</a><h3class="code-header">impl<T, F: <aclass="trait"href="https://doc.rust-lang.org/1.77.2/core/ops/function/trait.FnOnce.html"title="trait core::ops::function::FnOnce">FnOnce</a>() -> T><aclass="trait"href="https://doc.rust-lang.org/1.77.2/core/ops/deref/trait.DerefMut.html"title="trait core::ops::deref::DerefMut">DerefMut</a> for <aclass="struct"href="struct.Lazy.html"title="struct once_cell::sync::Lazy">Lazy</a><T, F></h3></section></summary><divclass="impl-items"><detailsclass="toggle method-toggle"open><summary><sectionid="method.deref_mut"class="method trait-impl"><aclass="src rightside"href="../../src/once_cell/lib.rs.html#1381-1383">source</a><ahref="#method.deref_mut"class="anchor">§</a><h4class="code-header">fn <ahref="https://doc.rust-lang.org/1.77.2/core/ops/deref/trait.DerefMut.html#tymethod.deref_mut"class="fn">deref_mut</a>(&mut self) -><aclass="primitive"href="https://doc.rust-lang.org/1.77.2/std/primitive.reference.html">&mut T</a></h4></section></summary><divclass='docblock'>Mutably dereferences the value.</div></details></div></details><sectionid="impl-RefUnwindSafe-for-Lazy%3CT,+F%3E"class="impl"><aclass="src rightside"href="../../src/once_cell/lib.rs.html#1273">source</a><ahref="#impl-RefUnwindSafe-for-Lazy%3CT,+F%3E"class="anchor">§</a><h3class="code-header">impl<T, F: <aclass="trait"href="https://doc.rust-lang.org/1.77.2/core/panic/unwind_safe/trait.RefUnwindSafe.html"title="trait core::panic::unwind_safe::RefUnwindSafe">RefUnwindSafe</a>><aclass="trait"href="https://doc.rust-lang.org/1.77.2/core/panic/unwind_safe/trait.RefUnwindSafe.html"title="trait core::panic::unwind_safe::RefUnwindSafe">RefUnwindSafe</a> for <aclass="struct"href="struct.Lazy.html"title="struct once_cell::sync::Lazy">Lazy</a><T, F><divclass="where">where
<code><ahref="https://doc.rust-lang.org/1.77.2/core/convert/trait.From.html"title="trait core::convert::From">From</a><T> for U</code> chooses to do.</p>
</div></details></div></details><detailsclass="toggle implementors-toggle"><summary><sectionid="impl-TryFrom%3CU%3E-for-T"class="impl"><aclass="src rightside"href="https://doc.rust-lang.org/1.77.2/src/core/convert/mod.rs.html#804-806">source</a><ahref="#impl-TryFrom%3CU%3E-for-T"class="anchor">§</a><h3class="code-header">impl<T, U><aclass="trait"href="https://doc.rust-lang.org/1.77.2/core/convert/trait.TryFrom.html"title="trait core::convert::TryFrom">TryFrom</a><U> for T<divclass="where">where
U: <aclass="trait"href="https://doc.rust-lang.org/1.77.2/core/convert/trait.Into.html"title="trait core::convert::Into">Into</a><T>,</div></h3></section></summary><divclass="impl-items"><detailsclass="toggle"open><summary><sectionid="associatedtype.Error-1"class="associatedtype trait-impl"><ahref="#associatedtype.Error-1"class="anchor">§</a><h4class="code-header">type <ahref="https://doc.rust-lang.org/1.77.2/core/convert/trait.TryFrom.html#associatedtype.Error"class="associatedtype">Error</a> = <aclass="enum"href="https://doc.rust-lang.org/1.77.2/core/convert/enum.Infallible.html"title="enum core::convert::Infallible">Infallible</a></h4></section></summary><divclass='docblock'>The type returned in the event of a conversion error.</div></details><detailsclass="toggle method-toggle"open><summary><sectionid="method.try_from"class="method trait-impl"><aclass="src rightside"href="https://doc.rust-lang.org/1.77.2/src/core/convert/mod.rs.html#811">source</a><ahref="#method.try_from"class="anchor">§</a><h4class="code-header">fn <ahref="https://doc.rust-lang.org/1.77.2/core/convert/trait.TryFrom.html#tymethod.try_from"class="fn">try_from</a>(value: U) -><aclass="enum"href="https://doc.rust-lang.org/1.77.2/core/result/enum.Result.html"title="enum core::result::Result">Result</a><T, <T as <aclass="trait"href="https://doc.rust-lang.org/1.77.2/core/convert/trait.TryFrom.html"title="trait core::convert::TryFrom">TryFrom</a><U>>::<aclass="associatedtype"href="https://doc.rust-lang.org/1.77.2/core/convert/trait.TryFrom.html#associatedtype.Error"title="type core::convert::TryFrom::Error">Error</a>></h4></section></summary><divclass='docblock'>Performs the conversion.</div></details></div></details><detailsclass="toggle implementors-toggle"><summary><sectionid="impl-TryInto%3CU%3E-for-T"class="impl"><aclass="src rightside"href="https://doc.rust-lang.org/1.77.2/src/core/convert/mod.rs.html#789-791">source</a><ahref="#impl-TryInto%3CU%3E-for-T"class="anchor">§</a><h3class="code-header">impl<T, U><aclass="trait"href="https://doc.rust-lang.org/1.77.2/core/convert/trait.TryInto.html"title="trait core::convert::TryInto">TryInto</a><U> for T<divclass="where">where
U: <aclass="trait"href="https://doc.rust-lang.org/1.77.2/core/convert/trait.TryFrom.html"title="trait core::convert::TryFrom">TryFrom</a><T>,</div></h3></section></summary><divclass="impl-items"><detailsclass="toggle"open><summary><sectionid="associatedtype.Error"class="associatedtype trait-impl"><ahref="#associatedtype.Error"class="anchor">§</a><h4class="code-header">type <ahref="https://doc.rust-lang.org/1.77.2/core/convert/trait.TryInto.html#associatedtype.Error"class="associatedtype">Error</a> = <U as <aclass="trait"href="https://doc.rust-lang.org/1.77.2/core/convert/trait.TryFrom.html"title="trait core::convert::TryFrom">TryFrom</a><T>>::<aclass="associatedtype"href="https://doc.rust-lang.org/1.77.2/core/convert/trait.TryFrom.html#associatedtype.Error"title="type core::convert::TryFrom::Error">Error</a></h4></section></summary><divclass='docblock'>The type returned in the event of a conversion error.</div></details><detailsclass="toggle method-toggle"open><summary><sectionid="method.try_into"class="method trait-impl"><aclass="src rightside"href="https://doc.rust-lang.org/1.77.2/src/core/convert/mod.rs.html#796">source</a><ahref="#method.try_into"class="anchor">§</a><h4class="code-header">fn <ahref="https://doc.rust-lang.org/1.77.2/core/convert/trait.TryInto.html#tymethod.try_into"class="fn">try_into</a>(self) -><aclass="enum"href="https://doc.rust-lang.org/1.77.2/core/result/enum.Result.html"title="enum core::result::Result">Result</a><U, <U as <aclass="trait"href="https://doc.rust-lang.org/1.77.2/core/convert/trait.TryFrom.html"title="trait core::convert::TryFrom">TryFrom</a><T>>::<aclass="associatedtype"href="https://doc.rust-lang.org/1.77.2/core/convert/trait.TryFrom.html#associatedtype.Error"title="type core::convert::TryFrom::Error">Error</a>></h4></section></summary><divclass='docblock'>Performs the conversion.</div></details></div></details></div></section></div></main></body></html>
