| <!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="A lightweight version of pin-project written with declarative macros."><meta name="keywords" content="rust, rustlang, rust-lang, pin_project_lite"><title>pin_project_lite - Rust</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../normalize.css"><link rel="stylesheet" href="../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../ayu.css" disabled><link rel="stylesheet" href="../dark.css" disabled><link rel="stylesheet" href="../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../storage.js"></script><script defer src="../crates.js"></script><script defer src="../main.js"></script><noscript><link rel="stylesheet" href="../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../favicon.svg"></head><body class="rustdoc mod crate"><!--[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">☰</button><a class="sidebar-logo" href="../pin_project_lite/index.html"><div class="logo-container"><img class="rust-logo" src="../rust-logo.svg" alt="logo"></div></a><h2></h2></nav><nav class="sidebar"><a class="sidebar-logo" href="../pin_project_lite/index.html"><div class="logo-container"><img class="rust-logo" src="../rust-logo.svg" alt="logo"></div></a><h2 class="location"><a href="#">Crate pin_project_lite</a></h2><div class="sidebar-elems"><ul class="block"><li class="version">Version 0.2.9</li><li><a id="all-types" href="all.html">All Items</a></li></ul><section><ul class="block"><li><a href="#macros">Macros</a></li></ul></section></div></nav><main><div class="width-limiter"><nav class="sub"><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="main-heading"><h1 class="fqn">Crate <a class="mod" href="#">pin_project_lite</a><button id="copy-path" onclick="copy_path(this)" title="Copy item path to clipboard"><img src="../clipboard.svg" width="19" height="18" alt="Copy item path"></button></h1><span class="out-of-band"><a class="srclink" href="../src/pin_project_lite/lib.rs.html#1-1559">source</a> · <a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class="inner">−</span>]</a></span></div><details class="rustdoc-toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>A lightweight version of <a href="https://github.com/taiki-e/pin-project">pin-project</a> written with declarative macros.</p> |
| <h2 id="examples"><a href="#examples">Examples</a></h2> |
| <p><a href="macro.pin_project.html" title="pin_project!"><code>pin_project!</code></a> macro creates a projection type covering all the fields of struct.</p> |
| |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>std::pin::Pin; |
| |
| <span class="kw">use </span>pin_project_lite::pin_project; |
| |
| <span class="macro">pin_project! </span>{ |
| <span class="kw">struct </span>Struct<T, U> { |
| <span class="attribute">#[pin] |
| </span>pinned: T, |
| unpinned: U, |
| } |
| } |
| |
| <span class="kw">impl</span><T, U> Struct<T, U> { |
| <span class="kw">fn </span>method(<span class="self">self</span>: Pin<<span class="kw-2">&mut </span><span class="self">Self</span>>) { |
| <span class="kw">let </span>this = <span class="self">self</span>.project(); |
| <span class="kw">let _</span>: Pin<<span class="kw-2">&mut </span>T> = this.pinned; <span class="comment">// Pinned reference to the field |
| </span><span class="kw">let _</span>: <span class="kw-2">&mut </span>U = this.unpinned; <span class="comment">// Normal reference to the field |
| </span>} |
| }</code></pre></div> |
| <p>To use <a href="macro.pin_project.html" title="pin_project!"><code>pin_project!</code></a> on enums, you need to name the projection type |
| returned from the method.</p> |
| |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>std::pin::Pin; |
| |
| <span class="kw">use </span>pin_project_lite::pin_project; |
| |
| <span class="macro">pin_project! </span>{ |
| <span class="attribute">#[project = EnumProj] |
| </span><span class="kw">enum </span>Enum<T, U> { |
| Variant { <span class="attribute">#[pin] </span>pinned: T, unpinned: U }, |
| } |
| } |
| |
| <span class="kw">impl</span><T, U> Enum<T, U> { |
| <span class="kw">fn </span>method(<span class="self">self</span>: Pin<<span class="kw-2">&mut </span><span class="self">Self</span>>) { |
| <span class="kw">match </span><span class="self">self</span>.project() { |
| EnumProj::Variant { pinned, unpinned } => { |
| <span class="kw">let _</span>: Pin<<span class="kw-2">&mut </span>T> = pinned; |
| <span class="kw">let _</span>: <span class="kw-2">&mut </span>U = unpinned; |
| } |
| } |
| } |
| }</code></pre></div> |
| <h2 id="pin-project-vs-pin-project-lite"><a href="#pin-project-vs-pin-project-lite">pin-project vs pin-project-lite</a></h2> |
| <p>Here are some similarities and differences compared to <a href="https://github.com/taiki-e/pin-project">pin-project</a>.</p> |
| <h3 id="similar-safety"><a href="#similar-safety">Similar: Safety</a></h3> |
| <p>pin-project-lite guarantees safety in much the same way as <a href="https://github.com/taiki-e/pin-project">pin-project</a>. |
| Both are completely safe unless you write other unsafe code.</p> |
| <h3 id="different-minimal-design"><a href="#different-minimal-design">Different: Minimal design</a></h3> |
| <p>This library does not tackle as expansive of a range of use cases as |
| <a href="https://github.com/taiki-e/pin-project">pin-project</a> does. If your use case is not already covered, please use |
| <a href="https://github.com/taiki-e/pin-project">pin-project</a>.</p> |
| <h3 id="different-no-proc-macro-related-dependencies"><a href="#different-no-proc-macro-related-dependencies">Different: No proc-macro related dependencies</a></h3> |
| <p>This is the <strong>only</strong> reason to use this crate. However, <strong>if you already |
| have proc-macro related dependencies in your crate’s dependency graph, there |
| is no benefit from using this crate.</strong> (Note: There is almost no difference |
| in the amount of code generated between <a href="https://github.com/taiki-e/pin-project">pin-project</a> and pin-project-lite.)</p> |
| <h3 id="different-no-useful-error-messages"><a href="#different-no-useful-error-messages">Different: No useful error messages</a></h3> |
| <p>This macro does not handle any invalid input. So error messages are not to |
| be useful in most cases. If you do need useful error messages, then upon |
| error you can pass the same input to <a href="https://github.com/taiki-e/pin-project">pin-project</a> to receive a helpful |
| description of the compile error.</p> |
| <h3 id="different-no-support-for-custom-unpin-implementation"><a href="#different-no-support-for-custom-unpin-implementation">Different: No support for custom Unpin implementation</a></h3> |
| <p>pin-project supports this by <a href="https://docs.rs/pin-project/1/pin_project/attr.pin_project.html#unsafeunpin"><code>UnsafeUnpin</code></a> and <a href="https://docs.rs/pin-project/1/pin_project/attr.pin_project.html#unpin"><code>!Unpin</code></a>.</p> |
| <h3 id="different-no-support-for-tuple-structs-and-tuple-variants"><a href="#different-no-support-for-tuple-structs-and-tuple-variants">Different: No support for tuple structs and tuple variants</a></h3> |
| <p>pin-project supports this.</p> |
| </div></details><h2 id="macros" class="small-section-header"><a href="#macros">Macros</a></h2><div class="item-table"><div class="item-row"><div class="item-left module-item"><a class="macro" href="macro.pin_project.html" title="pin_project_lite::pin_project macro">pin_project</a></div><div class="item-right docblock-short">A macro that creates a projection type covering all the fields of struct.</div></div></div></section></div></main><div id="rustdoc-vars" data-root-path="../" data-current-crate="pin_project_lite" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
