|
|
<!DOCTYPE HTML>
|
|
|
<html lang="zh-CN" class="light" dir="ltr">
|
|
|
<head>
|
|
|
<!-- Book generated using mdBook -->
|
|
|
<meta charset="UTF-8">
|
|
|
<title>泛型 Generics - Rust语言圣经(Rust Course)</title>
|
|
|
|
|
|
|
|
|
<!-- Custom HTML head -->
|
|
|
|
|
|
<meta name="description" content="">
|
|
|
<meta name="viewport" content="width=device-width, initial-scale=1">
|
|
|
<meta name="theme-color" content="#ffffff">
|
|
|
|
|
|
<link rel="icon" href="../../favicon.svg">
|
|
|
<link rel="shortcut icon" href="../../favicon.png">
|
|
|
<link rel="stylesheet" href="../../css/variables.css">
|
|
|
<link rel="stylesheet" href="../../css/general.css">
|
|
|
<link rel="stylesheet" href="../../css/chrome.css">
|
|
|
<link rel="stylesheet" href="../../css/print.css" media="print">
|
|
|
|
|
|
<!-- Fonts -->
|
|
|
<link rel="stylesheet" href="../../FontAwesome/css/font-awesome.css">
|
|
|
<link rel="stylesheet" href="../../fonts/fonts.css">
|
|
|
|
|
|
<!-- Highlight.js Stylesheets -->
|
|
|
<link rel="stylesheet" href="../../highlight.css">
|
|
|
<link rel="stylesheet" href="../../tomorrow-night.css">
|
|
|
<link rel="stylesheet" href="../../ayu-highlight.css">
|
|
|
|
|
|
<!-- Custom theme stylesheets -->
|
|
|
<link rel="stylesheet" href="../../theme/style.css">
|
|
|
|
|
|
</head>
|
|
|
<body class="sidebar-visible no-js">
|
|
|
<div id="body-container">
|
|
|
<!-- Provide site root to javascript -->
|
|
|
<script>
|
|
|
var path_to_root = "../../";
|
|
|
var default_theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? "navy" : "light";
|
|
|
</script>
|
|
|
|
|
|
<!-- Work around some values being stored in localStorage wrapped in quotes -->
|
|
|
<script>
|
|
|
try {
|
|
|
var theme = localStorage.getItem('mdbook-theme');
|
|
|
var sidebar = localStorage.getItem('mdbook-sidebar');
|
|
|
|
|
|
if (theme.startsWith('"') && theme.endsWith('"')) {
|
|
|
localStorage.setItem('mdbook-theme', theme.slice(1, theme.length - 1));
|
|
|
}
|
|
|
|
|
|
if (sidebar.startsWith('"') && sidebar.endsWith('"')) {
|
|
|
localStorage.setItem('mdbook-sidebar', sidebar.slice(1, sidebar.length - 1));
|
|
|
}
|
|
|
} catch (e) { }
|
|
|
</script>
|
|
|
|
|
|
<!-- Set the theme before any content is loaded, prevents flash -->
|
|
|
<script>
|
|
|
var theme;
|
|
|
try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { }
|
|
|
if (theme === null || theme === undefined) { theme = default_theme; }
|
|
|
var html = document.querySelector('html');
|
|
|
html.classList.remove('light')
|
|
|
html.classList.add(theme);
|
|
|
var body = document.querySelector('body');
|
|
|
body.classList.remove('no-js')
|
|
|
body.classList.add('js');
|
|
|
</script>
|
|
|
|
|
|
<input type="checkbox" id="sidebar-toggle-anchor" class="hidden">
|
|
|
|
|
|
<!-- Hide / unhide sidebar before it is displayed -->
|
|
|
<script>
|
|
|
var body = document.querySelector('body');
|
|
|
var sidebar = null;
|
|
|
var sidebar_toggle = document.getElementById("sidebar-toggle-anchor");
|
|
|
if (document.body.clientWidth >= 1080) {
|
|
|
try { sidebar = localStorage.getItem('mdbook-sidebar'); } catch(e) { }
|
|
|
sidebar = sidebar || 'visible';
|
|
|
} else {
|
|
|
sidebar = 'hidden';
|
|
|
}
|
|
|
sidebar_toggle.checked = sidebar === 'visible';
|
|
|
body.classList.remove('sidebar-visible');
|
|
|
body.classList.add("sidebar-" + sidebar);
|
|
|
</script>
|
|
|
|
|
|
<nav id="sidebar" class="sidebar" aria-label="Table of contents">
|
|
|
<div class="sidebar-scrollbox">
|
|
|
<ol class="chapter"><li class="chapter-item affix "><a href="../../about-book.html">关于本书</a></li><li class="chapter-item affix "><a href="../../into-rust.html">进入 Rust 编程世界</a></li><li class="chapter-item affix "><a href="../../first-try/sth-you-should-not-do.html">避免从入门到放弃</a></li><li class="chapter-item affix "><a href="../../community.html">社区和锈书</a></li><li class="spacer"></li><li class="chapter-item affix "><a href="../../some-thoughts.html">Xobserve: 一切皆可观测</a></li><li class="chapter-item affix "><a href="../../beat-ai.html">BeatAI: 工程师 AI 入门圣经</a></li><li class="chapter-item affix "><li class="part-title">Rust 语言基础学习</li><li class="spacer"></li><li class="chapter-item "><a href="../../first-try/intro.html"><strong aria-hidden="true">1.</strong> 寻找牛刀，以便小试</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../first-try/installation.html"><strong aria-hidden="true">1.1.</strong> 安装 Rust 环境</a></li><li class="chapter-item "><a href="../../first-try/editor.html"><strong aria-hidden="true">1.2.</strong> 墙推 VSCode!</a></li><li class="chapter-item "><a href="../../first-try/cargo.html"><strong aria-hidden="true">1.3.</strong> 认识 Cargo</a></li><li class="chapter-item "><a href="../../first-try/hello-world.html"><strong aria-hidden="true">1.4.</strong> 不仅仅是 Hello world</a></li><li class="chapter-item "><a href="../../first-try/slowly-downloading.html"><strong aria-hidden="true">1.5.</strong> 下载依赖太慢了？</a></li></ol></li><li class="chapter-item expanded "><a href="../../basic/intro.html"><strong aria-hidden="true">2.</strong> Rust 基础入门</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../basic/variable.html"><strong aria-hidden="true">2.1.</strong> 变量绑定与解构</a></li><li class="chapter-item "><a href="../../basic/base-type/index.html"><strong aria-hidden="true">2.2.</strong> 基本类型</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../basic/base-type/numbers.html"><strong aria-hidden="true">2.2.1.</strong> 数值类型</a></li><li class="chapter-item "><a href="../../basic/base-type/char-bool.html"><strong aria-hidden="true">2.2.2.</strong> 字符、布尔、单元类型</a></li><li class="chapter-item "><a href="../../basic/base-type/statement-expression.html"><strong aria-hidden="true">2.2.3.</strong> 语句与表达式</a></li><li class="chapter-item "><a href="../../basic/base-type/function.html"><strong aria-hidden="true">2.2.4.</strong> 函数</a></li></ol></li><li class="chapter-item "><a href="../../basic/ownership/index.html"><strong aria-hidden="true">2.3.</strong> 所有权和借用</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../basic/ownership/ownership.html"><strong aria-hidden="true">2.3.1.</strong> 所有权</a></li><li class="chapter-item "><a href="../../basic/ownership/borrowing.html"><strong aria-hidden="true">2.3.2.</strong> 引用与借用</a></li></ol></li><li class="chapter-item "><a href="../../basic/compound-type/intro.html"><strong aria-hidden="true">2.4.</strong> 复合类型</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../basic/compound-type/string-slice.html"><strong aria-hidden="true">2.4.1.</strong> 字符串与切片</a></li><li class="chapter-item "><a href="../../basic/compound-type/tuple.html"><strong aria-hidden="true">2.4.2.</strong> 元组</a></li><li class="chapter-item "><a href="../../basic/compound-type/struct.html"><strong aria-hidden="true">2.4.3.</strong> 结构体</a></li><li class="chapter-item "><a href="../../basic/compound-type/enum.html"><strong aria-hidden="true">2.4.4.</strong> 枚举</a></li><li class="chapter-item "><a href="../../basic/compound-type/array.html"><strong aria-hidden="true">2.4.5.</strong> 数组</a></li></ol></li><li class="chapter-item "><a href="../../basic/flow-control.html"><strong aria-hidden="true">2.5.</strong> 流程控制</a></li><li class="chapter-item "><a href="../../basic/match-pattern/intro.html"><strong aria-hidden="true">2.6.</strong> 模式匹配</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../basic/match-pattern/match-if-let.html"><strong aria-hidden="true">2.6.1.</strong> match 和 if let</a></li><li class="chapter-item "><a href="../../basic/match-pattern/option.html"><strong aria-hidden="true">2.6.2.</strong> 解构 Option</a></li><li class="chapter-item "><a href="../../basic/match-pattern/pattern-match.html"><strong aria-hidden="true">2.6.3.</strong> 模式适用场景</a></li><li class="chapter-item "><a href="../../basic/match-pattern/all-patterns.html"><strong aria-hidden="true">2.6.4.</strong> 全模式列表</a></li></ol></li><li class="chapter-item "><a href="../../basic/method.html"><strong aria-hidden="true">2.7.</strong> 方法 Method</a></li><li class="chapter-item expanded "><a href="../../basic/trait/intro.html"><strong aria-hidden="true">2.8.</strong> 泛型和特征</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item expanded "><a href="../../basic/trait/generic.html" class="active"><strong aria-hidden="true">2.8.1.</strong> 泛型 Generics</a></li><li class="chapter-item "><a href="../../basic/trait/trait.html"><strong aria-hidden="true">2.8.2.</strong> 特征 Trait</a></li><li class="chapter-item "><a href="../../basic/trait/trait-object.html"><strong aria-hidden="true">2.8.3.</strong> 特征对象</a></li><li class="chapter-item "><a href="../../basic/trait/advance-trait.html"><strong aria-hidden="true">2.8.4.</strong> 进一步深入特征</a></li></ol></li><li class="chapter-item "><a href="../../basic/collections/intro.html"><strong aria-hidden="true">2.9.</strong> 集合类型</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../basic/collections/vector.html"><strong aria-hidden="true">2.9.1.</strong> 动态数组 Vector</a></li><li class="chapter-item "><a href="../../basic/collections/hashmap.html"><strong aria-hidden="true">2.9.2.</strong> KV 存储 HashMap</a></li></ol></li><li class="chapter-item "><a href="../../basic/lifetime.html"><strong aria-hidden="true">2.10.</strong> 认识生命周期</a></li><li class="chapter-item "><a href="../../basic/result-error/intro.html"><strong aria-hidden="true">2.11.</strong> 返回值和错误处理</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../basic/result-error/panic.html"><strong aria-hidden="true">2.11.1.</strong> panic! 深入剖析</a></li><li class="chapter-item "><a href="../../basic/result-error/result.html"><strong aria-hidden="true">2.11.2.</strong> 返回值 Result 和?</a></li></ol></li><li class="chapter-item "><a href="../../basic/crate-module/intro.html"><strong aria-hidden="true">2.12.</strong> 包和模块</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../basic/crate-module/crate.html"><strong aria-hidden="true">2.12.1.</strong> 包 Crate</a></li><li class="chapter-item "><a href="../../basic/crate-module/module.html"><strong aria-hidden="true">2.12.2.</strong> 模块 Module</a></li><li class="chapter-item "><a href="../../basic/crate-module/use.html"><strong aria-hidden="true">2.12.3.</strong> 使用 use 引入模块及受限可见性</a></li></ol></li><li class="chapter-item "><a href="../../basic/comment.html"><strong aria-hidden="true">2.13.</strong> 注释和文档</a></li><li class="chapter-item "><a href="../../basic/formatted-output.html"><strong aria-hidden="true">2.14.</strong> 格式化输出</a></li></ol></li><li class="chapter-item "><a href="../../basic-practice/intro.html"><strong aria-hidden="true">3.</strong> 入门实战：文件搜索工具</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../basic-practice/base-features.html"><strong aria-hidden="true">3.1.</strong> 基本功能</a></li><li class="chapter-item "><a href="../../basic-practice/refactoring.html"><strong aria-hidden="true">3.2.</strong> 增加模块化和错误处理</a></li><li class="chapter-item "><a href="../../basic-practice/tests.html"><strong aria-hidden="true">3.3.</strong> 测试驱动开发</a></li><li class="chapter-item "><a href="../../basic-practice/envs.html"><strong aria-hidden="true">3.4.</strong> 使用环境变量</a></li><li class="chapter-item "><a href="../../basic-practice/stderr.html"><strong aria-hidden="true">3.5.</strong> 重定向错误信息的输出</a></li><li class="chapter-item "><a href="../../basic-practice/iterators.html"><strong aria-hidden="true">3.6.</strong> 使用迭代器来改进程序(可选)</a></li></ol></li><li class="chapter-item "><li class="part-title">Rust 语言进阶学习</li><li class="spacer"></li><li class="chapter-item "><a href="../../advance/intro.html"><strong aria-hidden="true">4.</strong> Rust 高级进阶</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../advance/lifetime/intro.html"><strong aria-hidden="true">4.1.</strong> 生命周期</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../advance/lifetime/advance.html"><strong aria-hidden="true">4.1.1.</strong> 深入生命周期</a></li><li class="chapter-item "><a href="../../advance/lifetime/static.html"><strong aria-hidden="true">4.1.2.</strong> &'static 和 T: 'static</a></li></ol></li><li class="chapter-item "><a href="../../advance/functional-programing/intro.html"><strong aria-hidden="true">4.2.</strong> 函数式编程: 闭包、迭代器</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../advance/functional-programing/closure.html"><strong aria-hidden="true">4.2.1.</strong> 闭包 Closure</a></li><li class="chapter-item "><a href="../../advance/functional-programing/iterator.html"><strong aria-hidden="true">4.2.2.</strong> 迭代器 Iterator</a></li></ol></li><li class="chapter-item "><a href="../../advance/into-types/intro.html"><strong aria-hidden="true">4.3.</strong> 深入类型</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../advance/into-types/converse.html"><strong aria-hidden="true">4.3.1.</strong> 类型转换</a></li><li class="chapter-item "><a href="../../advance/into-types/custom-type.html"><strong aria-hidden="true">4.3.2.</strong> newtype 和 类型别名</a></li><li class="chapter-item "><a href="../../advance/into-types/sized.html"><strong aria-hidden="true">4.3.3.</strong> Sized 和不定长类型 DST</a></li><li class="chapter-item "><a href="../../advance/into-types/enum-int.html"><strong aria-hidden="true">4.3.4.</strong> 枚举和整数</a></li></ol></li><li class="chapter-item "><a href="../../advance/smart-pointer/intro.html"><strong aria-hidden="true">4.4.</strong> 智能指针</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../advance/smart-pointer/box.html"><strong aria-hidden="true">4.4.1.</strong> Box堆对象分配</a></li><li class="chapter-item "><a href="../../advance/smart-pointer/deref.html"><strong aria-hidden="true">4.4.2.</strong> Deref 解引用</a></li><li class="chapter-item "><a href="../../advance/smart-pointer/drop.html"><strong aria-hidden="true">4.4.3.</strong> Drop 释放资源</a></li><li class="chapter-item "><a href="../../advance/smart-pointer/rc-arc.html"><strong aria-hidden="true">4.4.4.</strong> Rc 与 Arc 实现 1vN 所有权机制</a></li><li class="chapter-item "><a href="../../advance/smart-pointer/cell-refcell.html"><strong aria-hidden="true">4.4.5.</strong> Cell 与 RefCell 内部可变性</a></li></ol></li><li class="chapter-item "><a href="../../advance/circle-self-ref/intro.html"><strong aria-hidden="true">4.5.</strong> 循环引用与自引用</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../advance/circle-self-ref/circle-reference.html"><strong aria-hidden="true">4.5.1.</strong> Weak 与循环引用</a></li><li class="chapter-item "><a href="../../advance/circle-self-ref/self-referential.html"><strong aria-hidden="true">4.5.2.</strong> 结构体中的自引用</a></li></ol></li><li class="chapter-item "><a href="../../advance/concurrency-with-threads/intro.html"><strong aria-hidden="true">4.6.</strong> 多线程并发编程</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../advance/concurrency-with-threads/concurrency-parallelism.html"><strong aria-hidden="true">4.6.1.</strong> 并发和并行</a></li><li class="chapter-item "><a href="../../advance/concurrency-with-threads/thread.html"><strong aria-hidden="true">4.6.2.</strong> 使用多线程</a></li><li class="chapter-item "><a href="../../advance/concurrency-with-threads/message-passing.html"><strong aria-hidden="true">4.6.3.</strong> 线程同步：消息传递</a></li><li class="chapter-item "><a href="../../advance/concurrency-with-threads/sync1.html"><strong aria-hidden="true">4.6.4.</strong> 线程同步：锁、Condvar 和信号量</a></li><li class="chapter-item "><a href="../../advance/concurrency-with-threads/sync2.html"><strong aria-hidden="true">4.6.5.</strong> 线程同步：Atomic 原子操作与内存顺序</a></li><li class="chapter-item "><a href="../../advance/concurrency-with-threads/send-sync.html"><strong aria-hidden="true">4.6.6.</strong> 基于 Send 和 Sync 的线程安全</a></li></ol></li><li class="chapter-item "><a href="../../advance/global-variable.html"><strong aria-hidden="true">4.7.</strong> 全局变量</a></li><li class="chapter-item "><a href="../../advance/errors.html"><strong aria-hidden="true">4.8.</strong> 错误处理</a></li><li class="chapter-item "><a href="../../advance/unsafe/intro.html"><strong aria-hidden="true">4.9.</strong> Unsafe Rust</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../advance/unsafe/superpowers.html"><strong aria-hidden="true">4.9.1.</strong> 五种兵器</a></li><li class="chapter-item "><a href="../../advance/unsafe/inline-asm.html"><strong aria-hidden="true">4.9.2.</strong> 内联汇编</a></li></ol></li><li class="chapter-item "><a href="../../advance/macro.html"><strong aria-hidden="true">4.10.</strong> Macro 宏编程</a></li><li class="chapter-item "><a href="../../advance/async/intro.html"><strong aria-hidden="true">4.11.</strong> async/await 异步编程</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../advance/async/getting-started.html"><strong aria-hidden="true">4.11.1.</strong> async 编程入门</a></li><li class="chapter-item "><a href="../../advance/async/future-excuting.html"><strong aria-hidden="true">4.11.2.</strong> 底层探秘: Future 执行与任务调度</a></li><li class="chapter-item "><a href="../../advance/async/pin-unpin.html"><strong aria-hidden="true">4.11.3.</strong> 定海神针 Pin 和 Unpin</a></li><li class="chapter-item "><a href="../../advance/async/async-await.html"><strong aria-hidden="true">4.11.4.</strong> async/await 和 Stream 流处理</a></li><li class="chapter-item "><a href="../../advance/async/multi-futures-simultaneous.html"><strong aria-hidden="true">4.11.5.</strong> 同时运行多个 Future</a></li><li class="chapter-item "><a href="../../advance/async/pain-points-and-workarounds.html"><strong aria-hidden="true">4.11.6.</strong> 一些疑难问题的解决办法</a></li><li class="chapter-item "><a href="../../advance/async/web-server.html"><strong aria-hidden="true">4.11.7.</strong> 实践应用：Async Web 服务器</a></li></ol></li></ol></li><li class="chapter-item "><a href="../../advance-practice1/intro.html"><strong aria-hidden="true">5.</strong> 进阶实战1: 实现一个 web 服务器</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../advance-practice1/web-server.html"><strong aria-hidden="true">5.1.</strong> 单线程版本</a></li><li class="chapter-item "><a href="../../advance-practice1/multi-threads.html"><strong aria-hidden="true">5.2.</strong> 多线程版本</a></li><li class="chapter-item "><a href="../../advance-practice1/graceful-shutdown.html"><strong aria-hidden="true">5.3.</strong> 优雅关闭和资源清理</a></li></ol></li><li class="chapter-item "><a href="../../advance-practice/intro.html"><strong aria-hidden="true">6.</strong> 进阶实战2: 实现一个简单 Redis</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../advance-practice/overview.html"><strong aria-hidden="true">6.1.</strong> tokio 概览</a></li><li class="chapter-item "><a href="../../advance-practice/getting-startted.html"><strong aria-hidden="true">6.2.</strong> 使用初印象</a></li><li class="chapter-item "><a href="../../advance-practice/spawning.html"><strong aria-hidden="true">6.3.</strong> 创建异步任务</a></li><li class="chapter-item "><a href="../../advance-practice/shared-state.html"><strong aria-hidden="true">6.4.</strong> 共享状态</a></li><li class="chapter-item "><a href="../../advance-practice/channels.html"><strong aria-hidden="true">6.5.</strong> 消息传递</a></li><li class="chapter-item "><a href="../../advance-practice/io.html"><strong aria-hidden="true">6.6.</strong> I/O</a></li><li class="chapter-item "><a href="../../advance-practice/frame.html"><strong aria-hidden="true">6.7.</strong> 解析数据帧</a></li><li class="chapter-item "><a href="../../advance-practice/async.html"><strong aria-hidden="true">6.8.</strong> 深入 async</a></li><li class="chapter-item "><a href="../../advance-practice/select.html"><strong aria-hidden="true">6.9.</strong> select</a></li><li class="chapter-item "><a href="../../advance-practice/stream.html"><strong aria-hidden="true">6.10.</strong> 类似迭代器的 Stream</a></li><li class="chapter-item "><a href="../../advance-practice/graceful-shutdown.html"><strong aria-hidden="true">6.11.</strong> 优雅的关闭</a></li><li class="chapter-item "><a href="../../advance-practice/bridging-with-sync.html"><strong aria-hidden="true">6.12.</strong> 异步跟同步共存</a></li></ol></li><li class="chapter-item "><a href="../../difficulties/intro.html"><strong aria-hidden="true">7.</strong> Rust 难点攻关</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../difficulties/slice.html"><strong aria-hidden="true">7.1.</strong> 切片和切片引用</a></li><li class="chapter-item "><a href="../../difficulties/eq.html"><strong aria-hidden="true">7.2.</strong> Eq 和 PartialEq</a></li><li class="chapter-item "><a href="../../difficulties/string.html"><strong aria-hidden="true">7.3.</strong> String、&str 和 str TODO</a></li><li class="chapter-item "><a href="../../difficulties/lifetime.html"><strong aria-hidden="true">7.4.</strong> 作用域、生命周期和 NLL TODO</a></li><li class="chapter-item "><a href="../../difficulties/move-copy.html"><strong aria-hidden="true">7.5.</strong> move、Copy 和 Clone TODO</a></li><li class="chapter-item "><a href="../../advance/difficulties/pointer.html"><strong aria-hidden="true">7.6.</strong> 裸指针、引用和智能指针 TODO</a></li></ol></li><li class="chapter-item "><li class="part-title">常用工具链</li><li class="spacer"></li><li class="chapter-item "><a href="../../test/intro.html"><strong aria-hidden="true">8.</strong> 自动化测试</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../test/write-tests.html"><strong aria-hidden="true">8.1.</strong> 编写测试及控制执行</a></li><li class="chapter-item "><a href="../../test/unit-integration-test.html"><strong aria-hidden="true">8.2.</strong> 单元测试和集成测试</a></li><li class="chapter-item "><a href="../../test/assertion.html"><strong aria-hidden="true">8.3.</strong> 断言 assertion</a></li><li class="chapter-item "><a href="../../test/ci.html"><strong aria-hidden="true">8.4.</strong> 用 GitHub Actions 进行持续集成</a></li><li class="chapter-item "><a href="../../test/benchmark.html"><strong aria-hidden="true">8.5.</strong> 基准测试 benchmark</a></li></ol></li><li class="chapter-item "><a href="../../cargo/intro.html"><strong aria-hidden="true">9.</strong> Cargo 使用指南</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../cargo/getting-started.html"><strong aria-hidden="true">9.1.</strong> 上手使用</a></li><li class="chapter-item "><a href="../../cargo/guide/intro.html"><strong aria-hidden="true">9.2.</strong> 基础指南</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../cargo/guide/why-exist.html"><strong aria-hidden="true">9.2.1.</strong> 为何会有 Cargo</a></li><li class="chapter-item "><a href="../../cargo/guide/download-package.html"><strong aria-hidden="true">9.2.2.</strong> 下载并构建 Package</a></li><li class="chapter-item "><a href="../../cargo/guide/dependencies.html"><strong aria-hidden="true">9.2.3.</strong> 添加依赖</a></li><li class="chapter-item "><a href="../../cargo/guide/package-layout.html"><strong aria-hidden="true">9.2.4.</strong> Package 目录结构</a></li><li class="chapter-item "><a href="../../cargo/guide/cargo-toml-lock.html"><strong aria-hidden="true">9.2.5.</strong> Cargo.toml vs Cargo.lock</a></li><li class="chapter-item "><a href="../../cargo/guide/tests-ci.html"><strong aria-hidden="true">9.2.6.</strong> 测试和 CI</a></li><li class="chapter-item "><a href="../../cargo/guide/cargo-cache.html"><strong aria-hidden="true">9.2.7.</strong> Cargo 缓存</a></li><li class="chapter-item "><a href="../../cargo/guide/build-cache.html"><strong aria-hidden="true">9.2.8.</strong> Build 缓存</a></li></ol></li><li class="chapter-item "><a href="../../cargo/reference/intro.html"><strong aria-hidden="true">9.3.</strong> 进阶指南</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../cargo/reference/specify-deps.html"><strong aria-hidden="true">9.3.1.</strong> 指定依赖项</a></li><li class="chapter-item "><a href="../../cargo/reference/deps-overriding.html"><strong aria-hidden="true">9.3.2.</strong> 依赖覆盖</a></li><li class="chapter-item "><a href="../../cargo/reference/manifest.html"><strong aria-hidden="true">9.3.3.</strong> Cargo.toml 清单详解</a></li><li class="chapter-item "><a href="../../cargo/reference/cargo-target.html"><strong aria-hidden="true">9.3.4.</strong> Cargo Target</a></li><li class="chapter-item "><a href="../../cargo/reference/workspaces.html"><strong aria-hidden="true">9.3.5.</strong> 工作空间 Workspace</a></li><li class="chapter-item "><a href="../../cargo/reference/features/intro.html"><strong aria-hidden="true">9.3.6.</strong> 条件编译 Features</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../cargo/reference/features/examples.html"><strong aria-hidden="true">9.3.6.1.</strong> Features 示例</a></li></ol></li><li class="chapter-item "><a href="../../cargo/reference/profiles.html"><strong aria-hidden="true">9.3.7.</strong> 发布配置 Profile</a></li><li class="chapter-item "><a href="../../cargo/reference/configuration.html"><strong aria-hidden="true">9.3.8.</strong> 通过 config.toml 对 Cargo 进行配置</a></li><li class="chapter-item "><a href="../../cargo/reference/publishing-on-crates.io.html"><strong aria-hidden="true">9.3.9.</strong> 发布到 crates.io</a></li><li class="chapter-item "><a href="../../cargo/reference/build-script/intro.html"><strong aria-hidden="true">9.3.10.</strong> 构建脚本 build.rs</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../cargo/reference/build-script/examples.html"><strong aria-hidden="true">9.3.10.1.</strong> 构建脚本示例</a></li></ol></li></ol></li></ol></li><li class="chapter-item "><li class="part-title">开发实践</li><li class="spacer"></li><li class="chapter-item "><a href="../../usecases/intro.html"><strong aria-hidden="true">10.</strong> 企业落地实践</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../usecases/aws-rust.html"><strong aria-hidden="true">10.1.</strong> AWS 为何这么喜欢 Rust?</a></li></ol></li><li class="chapter-item "><a href="../../logs/intro.html"><strong aria-hidden="true">11.</strong> 日志和监控</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../logs/about-log.html"><strong aria-hidden="true">11.1.</strong> 日志详解</a></li><li class="chapter-item "><a href="../../logs/log.html"><strong aria-hidden="true">11.2.</strong> 日志门面 log</a></li><li class="chapter-item "><a href="../../logs/tracing.html"><strong aria-hidden="true">11.3.</strong> 使用 tracing 记录日志</a></li><li class="chapter-item "><a href="../../logs/tracing-logger.html"><strong aria-hidden="true">11.4.</strong> 自定义 tracing 的输出格式</a></li><li class="chapter-item "><a href="../../logs/observe/intro.html"><strong aria-hidden="true">11.5.</strong> 监控</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../logs/observe/about-observe.html"><strong aria-hidden="true">11.5.1.</strong> 可观测性</a></li><li class="chapter-item "><a href="../../logs/observe/trace.html"><strong aria-hidden="true">11.5.2.</strong> 分布式追踪</a></li></ol></li></ol></li><li class="chapter-item "><a href="../../practice/intro.html"><strong aria-hidden="true">12.</strong> Rust 最佳实践</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../practice/third-party-libs.html"><strong aria-hidden="true">12.1.</strong> 日常开发三方库精选</a></li><li class="chapter-item "><a href="../../practice/naming.html"><strong aria-hidden="true">12.2.</strong> 命名规范</a></li><li class="chapter-item "><a href="../../practice/interview.html"><strong aria-hidden="true">12.3.</strong> 面试经验</a></li><li class="chapter-item "><a href="../../practice/best-pratice.html"><strong aria-hidden="true">12.4.</strong> 代码开发实践 todo</a></li></ol></li><li class="chapter-item "><a href="../../too-many-lists/intro.html"><strong aria-hidden="true">13.</strong> 手把手带你实现链表</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../too-many-lists/do-we-need-it.html"><strong aria-hidden="true">13.1.</strong> 我们到底需不需要链表</a></li><li class="chapter-item "><a href="../../too-many-lists/bad-stack/intro.html"><strong aria-hidden="true">13.2.</strong> 不太优秀的单向链表：栈</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../too-many-lists/bad-stack/layout.html"><strong aria-hidden="true">13.2.1.</strong> 数据布局</a></li><li class="chapter-item "><a href="../../too-many-lists/bad-stack/basic-operations.html"><strong aria-hidden="true">13.2.2.</strong> 基本操作</a></li><li class="chapter-item "><a href="../../too-many-lists/bad-stack/final-code.html"><strong aria-hidden="true">13.2.3.</strong> 最后实现</a></li></ol></li><li class="chapter-item "><a href="../../too-many-lists/ok-stack/intro.html"><strong aria-hidden="true">13.3.</strong> 还可以的单向链表</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../too-many-lists/ok-stack/type-optimizing.html"><strong aria-hidden="true">13.3.1.</strong> 优化类型定义</a></li><li class="chapter-item "><a href="../../too-many-lists/ok-stack/peek.html"><strong aria-hidden="true">13.3.2.</strong> 定义 Peek 函数</a></li><li class="chapter-item "><a href="../../too-many-lists/ok-stack/iter.html"><strong aria-hidden="true">13.3.3.</strong> IntoIter 和 Iter</a></li><li class="chapter-item "><a href="../../too-many-lists/ok-stack/itermut.html"><strong aria-hidden="true">13.3.4.</strong> IterMut 以及完整代码</a></li></ol></li><li class="chapter-item "><a href="../../too-many-lists/persistent-stack/intro.html"><strong aria-hidden="true">13.4.</strong> 持久化单向链表</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../too-many-lists/persistent-stack/layout.html"><strong aria-hidden="true">13.4.1.</strong> 数据布局和基本操作</a></li><li class="chapter-item "><a href="../../too-many-lists/persistent-stack/drop-arc.html"><strong aria-hidden="true">13.4.2.</strong> Drop、Arc 及完整代码</a></li></ol></li><li class="chapter-item "><a href="../../too-many-lists/deque/intro.html"><strong aria-hidden="true">13.5.</strong> 不咋样的双端队列</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../too-many-lists/deque/layout.html"><strong aria-hidden="true">13.5.1.</strong> 数据布局和基本操作</a></li><li class="chapter-item "><a href="../../too-many-lists/deque/peek.html"><strong aria-hidden="true">13.5.2.</strong> Peek</a></li><li class="chapter-item "><a href="../../too-many-lists/deque/symmetric.html"><strong aria-hidden="true">13.5.3.</strong> 基本操作的对称镜像</a></li><li class="chapter-item "><a href="../../too-many-lists/deque/iterator.html"><strong aria-hidden="true">13.5.4.</strong> 迭代器</a></li><li class="chapter-item "><a href="../../too-many-lists/deque/final-code.html"><strong aria-hidden="true">13.5.5.</strong> 最终代码</a></li></ol></li><li class="chapter-item "><a href="../../too-many-lists/unsafe-queue/intro.html"><strong aria-hidden="true">13.6.</strong> 不错的 unsafe 队列</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../too-many-lists/unsafe-queue/layout.html"><strong aria-hidden="true">13.6.1.</strong> 数据布局</a></li><li class="chapter-item "><a href="../../too-many-lists/unsafe-queue/basics.html"><strong aria-hidden="true">13.6.2.</strong> 基本操作</a></li><li class="chapter-item "><a href="../../too-many-lists/unsafe-queue/miri.html"><strong aria-hidden="true">13.6.3.</strong> Miri</a></li><li class="chapter-item "><a href="../../too-many-lists/unsafe-queue/stacked-borrow.html"><strong aria-hidden="true">13.6.4.</strong> 栈借用</a></li><li class="chapter-item "><a href="../../too-many-lists/unsafe-queue/testing-stacked-borrow.html"><strong aria-hidden="true">13.6.5.</strong> 测试栈借用</a></li><li class="chapter-item "><a href="../../too-many-lists/unsafe-queue/layout2.html"><strong aria-hidden="true">13.6.6.</strong> 数据布局 2</a></li><li class="chapter-item "><a href="../../too-many-lists/unsafe-queue/extra-junk.html"><strong aria-hidden="true">13.6.7.</strong> 额外的操作</a></li><li class="chapter-item "><a href="../../too-many-lists/unsafe-queue/final-code.html"><strong aria-hidden="true">13.6.8.</strong> 最终代码</a></li></ol></li><li class="chapter-item "><a href="../../too-many-lists/production-unsafe-deque/intro.html"><strong aria-hidden="true">13.7.</strong> 生产级的双向 unsafe 队列</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../too-many-lists/production-unsafe-deque/layout.html"><strong aria-hidden="true">13.7.1.</strong> 数据布局</a></li><li class="chapter-item "><a href="../../too-many-lists/production-unsafe-deque/variance-and-phantomData.html"><strong aria-hidden="true">13.7.2.</strong> 型变与子类型</a></li><li class="chapter-item "><a href="../../too-many-lists/production-unsafe-deque/basics.html"><strong aria-hidden="true">13.7.3.</strong> 基础结构</a></li><li class="chapter-item "><a href="../../too-many-lists/production-unsafe-deque/drop-and-panic-safety.html"><strong aria-hidden="true">13.7.4.</strong> 恐慌与安全</a></li><li class="chapter-item "><a href="../../too-many-lists/production-unsafe-deque/boring-combinatorics.html"><strong aria-hidden="true">13.7.5.</strong> 无聊的组合</a></li><li class="chapter-item "><a href="../../too-many-lists/production-unsafe-deque/filling-in-random-bits.html"><strong aria-hidden="true">13.7.6.</strong> 其它特征</a></li><li class="chapter-item "><a href="../../too-many-lists/production-unsafe-deque/testing.html"><strong aria-hidden="true">13.7.7.</strong> 测试</a></li><li class="chapter-item "><a href="../../too-many-lists/production-unsafe-deque/send-sync-and-compile-tests.html"><strong aria-hidden="true">13.7.8.</strong> Send,Sync和编译测试</a></li><li class="chapter-item "><a href="../../too-many-lists/production-unsafe-deque/implementing-cursors.html"><strong aria-hidden="true">13.7.9.</strong> 实现游标</a></li><li class="chapter-item "><a href="../../too-many-lists/production-unsafe-deque/testing-cursors.html"><strong aria-hidden="true">13.7.10.</strong> 测试游标</a></li><li class="chapter-item "><a href="../../too-many-lists/production-unsafe-deque/final-code.html"><strong aria-hidden="true">13.7.11.</strong> 最终代码</a></li></ol></li><li class="chapter-item "><a href="../../too-many-lists/advanced-lists/intro.html"><strong aria-hidden="true">13.8.</strong> 使用高级技巧实现链表</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../too-many-lists/advanced-lists/double-singly.html"><strong aria-hidden="true">13.8.1.</strong> 双单向链表</a></li><li class="chapter-item "><a href="../../too-many-lists/advanced-lists/stack-allocated.html"><strong aria-hidden="true">13.8.2.</strong> 栈上的链表</a></li></ol></li></ol></li><li class="chapter-item "><li class="part-title">攻克编译错误</li><li class="spacer"></li><li class="chapter-item "><a href="../../compiler/intro.html"><strong aria-hidden="true">14.</strong> 征服编译错误</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../compiler/fight-with-compiler/intro.html"><strong aria-hidden="true">14.1.</strong> 对抗编译检查</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../compiler/fight-with-compiler/lifetime/intro.html"><strong aria-hidden="true">14.1.1.</strong> 生命周期</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../compiler/fight-with-compiler/lifetime/too-long1.html"><strong aria-hidden="true">14.1.1.1.</strong> 生命周期过大-01</a></li><li class="chapter-item "><a href="../../compiler/fight-with-compiler/lifetime/too-long2.html"><strong aria-hidden="true">14.1.1.2.</strong> 生命周期过大-02</a></li><li class="chapter-item "><a href="../../compiler/fight-with-compiler/lifetime/loop.html"><strong aria-hidden="true">14.1.1.3.</strong> 循环中的生命周期</a></li><li class="chapter-item "><a href="../../compiler/fight-with-compiler/lifetime/closure-with-static.html"><strong aria-hidden="true">14.1.1.4.</strong> 闭包碰到特征对象-01</a></li></ol></li><li class="chapter-item "><a href="../../compiler/fight-with-compiler/borrowing/intro.html"><strong aria-hidden="true">14.1.2.</strong> 重复借用</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../compiler/fight-with-compiler/borrowing/ref-exist-in-out-fn.html"><strong aria-hidden="true">14.1.2.1.</strong> 同时在函数内外使用引用</a></li><li class="chapter-item "><a href="../../compiler/fight-with-compiler/borrowing/borrow-distinct-fields-of-struct.html"><strong aria-hidden="true">14.1.2.2.</strong> 智能指针引起的重复借用错误</a></li></ol></li><li class="chapter-item "><a href="../../compiler/fight-with-compiler/unconstrained.html"><strong aria-hidden="true">14.1.3.</strong> 类型未限制(todo)</a></li><li class="chapter-item "><a href="../../compiler/fight-with-compiler/phantom-data.html"><strong aria-hidden="true">14.1.4.</strong> 幽灵数据(todo)</a></li></ol></li><li class="chapter-item "><a href="../../compiler/pitfalls/index.html"><strong aria-hidden="true">14.2.</strong> Rust 常见陷阱</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../compiler/pitfalls/use-vec-in-for.html"><strong aria-hidden="true">14.2.1.</strong> for 循环中使用外部数组</a></li><li class="chapter-item "><a href="../../compiler/pitfalls/stack-overflow.html"><strong aria-hidden="true">14.2.2.</strong> 线程类型导致的栈溢出</a></li><li class="chapter-item "><a href="../../compiler/pitfalls/arithmetic-overflow.html"><strong aria-hidden="true">14.2.3.</strong> 算术溢出导致的 panic</a></li><li class="chapter-item "><a href="../../compiler/pitfalls/closure-with-lifetime.html"><strong aria-hidden="true">14.2.4.</strong> 闭包中奇怪的生命周期</a></li><li class="chapter-item "><a href="../../compiler/pitfalls/the-disabled-mutability.html"><strong aria-hidden="true">14.2.5.</strong> 可变变量不可变？</a></li><li class="chapter-item "><a href="../../compiler/pitfalls/multiple-mutable-references.html"><strong aria-hidden="true">14.2.6.</strong> 可变借用失败引发的深入思考</a></li><li class="chapter-item "><a href="../../compiler/pitfalls/lazy-iterators.html"><strong aria-hidden="true">14.2.7.</strong> 不太勤快的迭代器</a></li><li class="chapter-item "><a href="../../compiler/pitfalls/weird-ranges.html"><strong aria-hidden="true">14.2.8.</strong> 奇怪的序列 x..y</a></li><li class="chapter-item "><a href="../../compiler/pitfalls/iterator-everywhere.html"><strong aria-hidden="true">14.2.9.</strong> 无处不在的迭代器</a></li><li class="chapter-item "><a href="../../compiler/pitfalls/main-with-channel-blocked.html"><strong aria-hidden="true">14.2.10.</strong> 线程间传递消息导致主线程无法结束</a></li><li class="chapter-item "><a href="../../compiler/pitfalls/utf8-performance.html"><strong aria-hidden="true">14.2.11.</strong> 警惕 UTF-8 引发的性能隐患</a></li></ol></li></ol></li><li class="chapter-item "><li class="part-title">性能优化</li><li class="spacer"></li><li class="chapter-item "><a href="../../profiling/intro.html"><strong aria-hidden="true">15.</strong> Rust 性能优化 todo</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../profiling/memory/intro.html"><strong aria-hidden="true">15.1.</strong> 深入内存 todo</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../profiling/memory/pointer-ref.html"><strong aria-hidden="true">15.1.1.</strong> 指针和引用 todo</a></li><li class="chapter-item "><a href="../../profiling/memory/uninit.html"><strong aria-hidden="true">15.1.2.</strong> 未初始化内存 todo</a></li><li class="chapter-item "><a href="../../profiling/memory/allocation.html"><strong aria-hidden="true">15.1.3.</strong> 内存分配 todo</a></li><li class="chapter-item "><a href="../../profiling/memory/layout.html"><strong aria-hidden="true">15.1.4.</strong> 内存布局 todo</a></li><li class="chapter-item "><a href="../../profiling/memory/virtual.html"><strong aria-hidden="true">15.1.5.</strong> 虚拟内存 todo</a></li></ol></li><li class="chapter-item "><a href="../../profiling/performance/intro.html"><strong aria-hidden="true">15.2.</strong> 性能调优 doing</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../profiling/performance/string.html"><strong aria-hidden="true">15.2.1.</strong> 字符串操作性能</a></li><li class="chapter-item "><a href="../../profiling/performance/deep-into-move.html"><strong aria-hidden="true">15.2.2.</strong> 深入理解 move</a></li><li class="chapter-item "><a href="../../profiling/performance/early-optimise.html"><strong aria-hidden="true">15.2.3.</strong> 糟糕的提前优化 todo</a></li><li class="chapter-item "><a href="../../profiling/performance/clone-copy.html"><strong aria-hidden="true">15.2.4.</strong> Clone 和 Copy todo</a></li><li class="chapter-item "><a href="../../profiling/performance/runtime-check.html"><strong aria-hidden="true">15.2.5.</strong> 减少 Runtime check(todo)</a></li><li class="chapter-item "><a href="../../profiling/performance/cpu-cache.html"><strong aria-hidden="true">15.2.6.</strong> CPU 缓存性能优化 todo</a></li><li class="chapter-item "><a href="../../profiling/performance/calculate.html"><strong aria-hidden="true">15.2.7.</strong> 计算性能优化 todo</a></li><li class="chapter-item "><a href="../../profiling/performance/heap-stack.html"><strong aria-hidden="true">15.2.8.</strong> 堆和栈 todo</a></li><li class="chapter-item "><a href="../../profiling/performance/allocator.html"><strong aria-hidden="true">15.2.9.</strong> 内存 allocator todo</a></li><li class="chapter-item "><a href="../../profiling/performance/tools.html"><strong aria-hidden="true">15.2.10.</strong> 常用性能测试工具 todo</a></li><li class="chapter-item "><a href="../../profiling/performance/enum.html"><strong aria-hidden="true">15.2.11.</strong> Enum 内存优化 todo</a></li></ol></li><li class="chapter-item "><a href="../../profiling/compiler/intro.html"><strong aria-hidden="true">15.3.</strong> 编译优化 todo</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../profiling/compiler/llvm.html"><strong aria-hidden="true">15.3.1.</strong> LLVM todo</a></li><li class="chapter-item "><a href="../../profiling/compiler/attributes.html"><strong aria-hidden="true">15.3.2.</strong> 常见属性标记 todo</a></li><li class="chapter-item "><a href="../../profiling/compiler/speed-up.html"><strong aria-hidden="true">15.3.3.</strong> 提升编译速度 todo</a></li><li class="chapter-item "><a href="../../profiling/compiler/optimization/intro.html"><strong aria-hidden="true">15.3.4.</strong> 编译器优化 todo</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../profiling/compiler/optimization/option.html"><strong aria-hidden="true">15.3.4.1.</strong> Option 枚举 todo</a></li></ol></li></ol></li></ol></li><li class="chapter-item "><li class="part-title">附录</li><li class="spacer"></li><li class="chapter-item "><div><strong aria-hidden="true">16.</strong> Appendix</div><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../appendix/keywords.html"><strong aria-hidden="true">16.1.</strong> 关键字</a></li><li class="chapter-item "><a href="../../appendix/operators.html"><strong aria-hidden="true">16.2.</strong> 运算符与符号</a></li><li class="chapter-item "><a href="../../appendix/expressions.html"><strong aria-hidden="true">16.3.</strong> 表达式</a></li><li class="chapter-item "><a href="../../appendix/derive.html"><strong aria-hidden="true">16.4.</strong> 派生特征 trait</a></li><li class="chapter-item "><a href="../../appendix/prelude.html"><strong aria-hidden="true">16.5.</strong> prelude 模块 todo</a></li><li class="chapter-item "><a href="../../appendix/rust-version.html"><strong aria-hidden="true">16.6.</strong> Rust 版本说明</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/intro.html"><strong aria-hidden="true">16.7.</strong> Rust 历次版本更新解读</a><a class="toggle"><div>❱</div></a></li><li><ol class="section"><li class="chapter-item "><a href="../../appendix/rust-versions/1.58.html"><strong aria-hidden="true">16.7.1.</strong> 1.58</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.59.html"><strong aria-hidden="true">16.7.2.</strong> 1.59</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.60.html"><strong aria-hidden="true">16.7.3.</strong> 1.60</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.61.html"><strong aria-hidden="true">16.7.4.</strong> 1.61</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.62.html"><strong aria-hidden="true">16.7.5.</strong> 1.62</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.63.html"><strong aria-hidden="true">16.7.6.</strong> 1.63</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.64.html"><strong aria-hidden="true">16.7.7.</strong> 1.64</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.65.html"><strong aria-hidden="true">16.7.8.</strong> 1.65</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.66.html"><strong aria-hidden="true">16.7.9.</strong> 1.66</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.67.html"><strong aria-hidden="true">16.7.10.</strong> 1.67</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.68.html"><strong aria-hidden="true">16.7.11.</strong> 1.68</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.69.html"><strong aria-hidden="true">16.7.12.</strong> 1.69</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.70.html"><strong aria-hidden="true">16.7.13.</strong> 1.70</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.71.html"><strong aria-hidden="true">16.7.14.</strong> 1.71</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.72.html"><strong aria-hidden="true">16.7.15.</strong> 1.72</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.73.html"><strong aria-hidden="true">16.7.16.</strong> 1.73</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.74.html"><strong aria-hidden="true">16.7.17.</strong> 1.74</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.75.html"><strong aria-hidden="true">16.7.18.</strong> 1.75</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.76.html"><strong aria-hidden="true">16.7.19.</strong> 1.76</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.77.html"><strong aria-hidden="true">16.7.20.</strong> 1.77</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.78.html"><strong aria-hidden="true">16.7.21.</strong> 1.78</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.79.html"><strong aria-hidden="true">16.7.22.</strong> 1.79</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.80.html"><strong aria-hidden="true">16.7.23.</strong> 1.80</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.81.html"><strong aria-hidden="true">16.7.24.</strong> 1.81</a></li><li class="chapter-item "><a href="../../appendix/rust-versions/1.82.html"><strong aria-hidden="true">16.7.25.</strong> 1.82</a></li></ol></li></ol></li></ol>
|
|
|
</div>
|
|
|
<div id="sidebar-resize-handle" class="sidebar-resize-handle">
|
|
|
<div class="sidebar-resize-indicator"></div>
|
|
|
</div>
|
|
|
</nav>
|
|
|
|
|
|
<!-- Track and set sidebar scroll position -->
|
|
|
<script>
|
|
|
var sidebarScrollbox = document.querySelector('#sidebar .sidebar-scrollbox');
|
|
|
sidebarScrollbox.addEventListener('click', function(e) {
|
|
|
if (e.target.tagName === 'A') {
|
|
|
sessionStorage.setItem('sidebar-scroll', sidebarScrollbox.scrollTop);
|
|
|
}
|
|
|
}, { passive: true });
|
|
|
var sidebarScrollTop = sessionStorage.getItem('sidebar-scroll');
|
|
|
sessionStorage.removeItem('sidebar-scroll');
|
|
|
if (sidebarScrollTop) {
|
|
|
// preserve sidebar scroll position when navigating via links within sidebar
|
|
|
sidebarScrollbox.scrollTop = sidebarScrollTop;
|
|
|
} else {
|
|
|
// scroll sidebar to current active section when navigating via "next/previous chapter" buttons
|
|
|
var activeSection = document.querySelector('#sidebar .active');
|
|
|
if (activeSection) {
|
|
|
activeSection.scrollIntoView({ block: 'center' });
|
|
|
}
|
|
|
}
|
|
|
</script>
|
|
|
|
|
|
<div id="page-wrapper" class="page-wrapper">
|
|
|
|
|
|
<div class="page">
|
|
|
<div id="menu-bar-hover-placeholder"></div>
|
|
|
<div id="menu-bar" class="menu-bar sticky">
|
|
|
<div class="left-buttons">
|
|
|
<label id="sidebar-toggle" class="icon-button" for="sidebar-toggle-anchor" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar">
|
|
|
<i class="fa fa-bars"></i>
|
|
|
</label>
|
|
|
<button id="theme-toggle" class="icon-button" type="button" title="Change theme" aria-label="Change theme" aria-haspopup="true" aria-expanded="false" aria-controls="theme-list">
|
|
|
<i class="fa fa-paint-brush"></i>
|
|
|
</button>
|
|
|
<ul id="theme-list" class="theme-popup" aria-label="Themes" role="menu">
|
|
|
<li role="none"><button role="menuitem" class="theme" id="light">Light</button></li>
|
|
|
<li role="none"><button role="menuitem" class="theme" id="rust">Rust</button></li>
|
|
|
<li role="none"><button role="menuitem" class="theme" id="coal">Coal</button></li>
|
|
|
<li role="none"><button role="menuitem" class="theme" id="navy">Navy</button></li>
|
|
|
<li role="none"><button role="menuitem" class="theme" id="ayu">Ayu</button></li>
|
|
|
</ul>
|
|
|
<button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
|
|
|
<i class="fa fa-search"></i>
|
|
|
</button>
|
|
|
</div>
|
|
|
|
|
|
<h1 class="menu-title">Rust语言圣经(Rust Course)</h1>
|
|
|
|
|
|
<div class="right-buttons">
|
|
|
<a href="../../print.html" title="Print this book" aria-label="Print this book">
|
|
|
<i id="print-button" class="fa fa-print"></i>
|
|
|
</a>
|
|
|
<a href="https://github.com/sunface/rust-course" title="Git repository" aria-label="Git repository">
|
|
|
<i id="git-repository-button" class="fa fa-github"></i>
|
|
|
</a>
|
|
|
<a href="https://github.com/sunface/rust-course/edit/main/src/basic/trait/generic.md" title="Suggest an edit" aria-label="Suggest an edit">
|
|
|
<i id="git-edit-button" class="fa fa-edit"></i>
|
|
|
</a>
|
|
|
|
|
|
</div>
|
|
|
</div>
|
|
|
|
|
|
<div id="search-wrapper" class="hidden">
|
|
|
<form id="searchbar-outer" class="searchbar-outer">
|
|
|
<input type="search" id="searchbar" name="searchbar" placeholder="Search this book ..." aria-controls="searchresults-outer" aria-describedby="searchresults-header">
|
|
|
</form>
|
|
|
<div id="searchresults-outer" class="searchresults-outer hidden">
|
|
|
<div id="searchresults-header" class="searchresults-header"></div>
|
|
|
<ul id="searchresults">
|
|
|
</ul>
|
|
|
</div>
|
|
|
</div>
|
|
|
|
|
|
<!-- Apply ARIA attributes after the sidebar and the sidebar toggle button are added to the DOM -->
|
|
|
<script>
|
|
|
document.getElementById('sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible');
|
|
|
document.getElementById('sidebar').setAttribute('aria-hidden', sidebar !== 'visible');
|
|
|
Array.from(document.querySelectorAll('#sidebar a')).forEach(function(link) {
|
|
|
link.setAttribute('tabIndex', sidebar === 'visible' ? 0 : -1);
|
|
|
});
|
|
|
</script>
|
|
|
|
|
|
<div id="content" class="content">
|
|
|
<!-- Page table of contents -->
|
|
|
<div class="sidetoc"><nav class="pagetoc"></nav></div>
|
|
|
<main>
|
|
|
<h1 id="泛型-generics"><a class="header" href="#泛型-generics">泛型 Generics</a></h1>
|
|
|
<p>Go 语言在 2022 年，就要正式引入泛型，被视为在 1.0 版本后，语言特性发展迈出的一大步，为什么泛型这么重要？到底什么是泛型？Rust 的泛型有几种？
|
|
|
本章将一一为你讲解。</p>
|
|
|
<p>我们在编程中，经常有这样的需求：用同一功能的函数处理不同类型的数据，例如两个数的加法，无论是整数还是浮点数，甚至是自定义类型，都能进行支持。在不支持泛型的编程语言中，通常需要为每一种类型编写一个函数：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021">fn add_i8(a:i8, b:i8) -> i8 {
|
|
|
a + b
|
|
|
}
|
|
|
fn add_i32(a:i32, b:i32) -> i32 {
|
|
|
a + b
|
|
|
}
|
|
|
fn add_f64(a:f64, b:f64) -> f64 {
|
|
|
a + b
|
|
|
}
|
|
|
|
|
|
fn main() {
|
|
|
println!("add i8: {}", add_i8(2i8, 3i8));
|
|
|
println!("add i32: {}", add_i32(20, 30));
|
|
|
println!("add f64: {}", add_f64(1.23, 1.23));
|
|
|
}</code></pre></pre>
|
|
|
<p>上述代码可以正常运行，但是很啰嗦，如果你要支持更多的类型，那么会更繁琐。程序员或多或少都有强迫症，一个好程序员的公认特征就是 —— 懒，这么勤快的写一大堆代码，显然不是咱们的优良传统，是不？</p>
|
|
|
<p>在开始讲解 Rust 的泛型之前，先来看看什么是多态。</p>
|
|
|
<p>在编程的时候，我们经常利用多态。通俗的讲，多态就是好比坦克的炮管，既可以发射普通弹药，也可以发射制导炮弹（导弹），也可以发射贫铀穿甲弹，甚至发射子母弹，没有必要为每一种炮弹都在坦克上分别安装一个专用炮管，即使生产商愿意，炮手也不愿意，累死人啊。所以在编程开发中，我们也需要这样“通用的炮管”，这个“通用的炮管”就是多态。</p>
|
|
|
<p>实际上，泛型就是一种多态。泛型主要目的是为程序员提供编程的便利，减少代码的臃肿，同时可以极大地丰富语言本身的表达能力，为程序员提供了一个合适的炮管。想想，一个函数，可以代替几十个，甚至数百个函数，是一件多么让人兴奋的事情：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021">fn add<T>(a:T, b:T) -> T {
|
|
|
a + b
|
|
|
}
|
|
|
|
|
|
fn main() {
|
|
|
println!("add i8: {}", add(2i8, 3i8));
|
|
|
println!("add i32: {}", add(20, 30));
|
|
|
println!("add f64: {}", add(1.23, 1.23));
|
|
|
}</code></pre></pre>
|
|
|
<p>将之前的代码改成上面这样，就是 Rust 泛型的初印象，这段代码虽然很简洁，但是并不能编译通过，我们会在后面进行详细讲解，现在只要对泛型有个大概的印象即可。</p>
|
|
|
<h2 id="泛型详解"><a class="header" href="#泛型详解">泛型详解</a></h2>
|
|
|
<p>上面代码的 <code>T</code> 就是<strong>泛型参数</strong>，实际上在 Rust 中，泛型参数的名称你可以任意起，但是出于惯例，我们都用 <code>T</code> （<code>T</code> 是 <code>type</code> 的首字母）来作为首选，这个名称越短越好，除非需要表达含义，否则一个字母是最完美的。</p>
|
|
|
<p>使用泛型参数，有一个先决条件，必需在使用前对其进行声明：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>fn largest<T>(list: &[T]) -> T {
|
|
|
<span class="boring">}</span></code></pre></pre>
|
|
|
<p>该泛型函数的作用是从列表中找出最大的值，其中列表中的元素类型为 T。首先 <code>largest<T></code> 对泛型参数 <code>T</code> 进行了声明，然后才在函数参数中进行使用该泛型参数 <code>list: &[T]</code> （还记得 <code>&[T]</code> 类型吧？这是<a href="https://course.rs/basic/compound-type/array.html#%E6%95%B0%E7%BB%84%E5%88%87%E7%89%87">数组切片</a>）。</p>
|
|
|
<p>总之，我们可以这样理解这个函数定义：函数 <code>largest</code> 有泛型类型 <code>T</code>，它有个参数 <code>list</code>，其类型是元素为 <code>T</code> 的数组切片，最后，该函数返回值的类型也是 <code>T</code>。</p>
|
|
|
<p>下面是一个错误的泛型函数的实现：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021">fn largest<T>(list: &[T]) -> T {
|
|
|
let mut largest = list[0];
|
|
|
|
|
|
for &item in list.iter() {
|
|
|
if item > largest {
|
|
|
largest = item;
|
|
|
}
|
|
|
}
|
|
|
|
|
|
largest
|
|
|
}
|
|
|
|
|
|
fn main() {
|
|
|
let number_list = vec![34, 50, 25, 100, 65];
|
|
|
|
|
|
let result = largest(&number_list);
|
|
|
println!("The largest number is {}", result);
|
|
|
|
|
|
let char_list = vec!['y', 'm', 'a', 'q'];
|
|
|
|
|
|
let result = largest(&char_list);
|
|
|
println!("The largest char is {}", result);
|
|
|
}</code></pre></pre>
|
|
|
<p>运行后报错：</p>
|
|
|
<pre><code class="language-console">error[E0369]: binary operation `>` cannot be applied to type `T` // `>`操作符不能用于类型`T`
|
|
|
--> src/main.rs:5:17
|
|
|
|
|
|
|
5 | if item > largest {
|
|
|
| ---- ^ ------- T
|
|
|
| |
|
|
|
| T
|
|
|
|
|
|
|
help: consider restricting type parameter `T` // 考虑对T进行类型上的限制 :
|
|
|
|
|
|
|
1 | fn largest<T: std::cmp::PartialOrd>(list: &[T]) -> T {
|
|
|
| ++++++++++++++++++++++
|
|
|
</code></pre>
|
|
|
<p>因为 <code>T</code> 可以是任何类型，但不是所有的类型都能进行比较，因此上面的错误中，编译器建议我们给 <code>T</code> 添加一个类型限制：使用 <code>std::cmp::PartialOrd</code> 特征（Trait）对 <code>T</code> 进行限制，特征在下一节会详细介绍，现在你只要理解，该特征的目的就是让<strong>类型实现可比较的功能</strong>。</p>
|
|
|
<p>还记得我们一开始的 <code>add</code> 泛型函数吗？如果你运行它，会得到以下的报错：</p>
|
|
|
<pre><code class="language-console">error[E0369]: cannot add `T` to `T` // 无法将 `T` 类型跟 `T` 类型进行相加
|
|
|
--> src/main.rs:2:7
|
|
|
|
|
|
|
2 | a + b
|
|
|
| - ^ - T
|
|
|
| |
|
|
|
| T
|
|
|
|
|
|
|
help: consider restricting type parameter `T`
|
|
|
|
|
|
|
1 | fn add<T: std::ops::Add<Output = T>>(a:T, b:T) -> T {
|
|
|
| +++++++++++++++++++++++++++
|
|
|
</code></pre>
|
|
|
<p>同样的，不是所有 <code>T</code> 类型都能进行相加操作，因此我们需要用 <code>std::ops::Add<Output = T></code> 对 <code>T</code> 进行限制：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>fn add<T: std::ops::Add<Output = T>>(a:T, b:T) -> T {
|
|
|
a + b
|
|
|
}
|
|
|
<span class="boring">}</span></code></pre></pre>
|
|
|
<p>进行如上修改后，就可以正常运行。</p>
|
|
|
<h3 id="显式地指定泛型的类型参数"><a class="header" href="#显式地指定泛型的类型参数">显式地指定泛型的类型参数</a></h3>
|
|
|
<p>有时候，编译器无法推断你想要的泛型参数：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021">use std::fmt::Display;
|
|
|
|
|
|
fn create_and_print<T>() where T: From<i32> + Display {
|
|
|
let a: T = 100.into(); // 创建了类型为 T 的变量 a，它的初始值由 100 转换而来
|
|
|
println!("a is: {}", a);
|
|
|
}
|
|
|
|
|
|
fn main() {
|
|
|
create_and_print();
|
|
|
}</code></pre></pre>
|
|
|
<p>如果运行以上代码，会得到报错：</p>
|
|
|
<pre><code class="language-console">error[E0283]: type annotations needed // 需要标明类型
|
|
|
--> src/main.rs:9:5
|
|
|
|
|
|
|
9 | create_and_print();
|
|
|
| ^^^^^^^^^^^^^^^^ cannot infer type of the type parameter `T` declared on the function `create_and_print` // 无法推断函数 `create_and_print` 的类型参数 `T` 的类型
|
|
|
|
|
|
|
= note: multiple `impl`s satisfying `_: From<i32>` found in the `core` crate:
|
|
|
- impl From<i32> for AtomicI32;
|
|
|
- impl From<i32> for f64;
|
|
|
- impl From<i32> for i128;
|
|
|
- impl From<i32> for i64;
|
|
|
note: required by a bound in `create_and_print`
|
|
|
--> src/main.rs:3:35
|
|
|
|
|
|
|
3 | fn create_and_print<T>() where T: From<i32> + Display {
|
|
|
| ^^^^^^^^^ required by this bound in `create_and_print`
|
|
|
help: consider specifying the generic argument // 尝试指定泛型参数
|
|
|
|
|
|
|
9 | create_and_print::<T>();
|
|
|
| +++++
|
|
|
</code></pre>
|
|
|
<p>报错里说得很清楚，编译器不知道 <code>T</code> 到底应该是什么类型。不过好心的编译器已经帮我们列出了满足条件的类型，然后告诉我们解决方法：显式指定类型：<code>create_and_print::<T>()</code>。</p>
|
|
|
<p>于是，我们修改代码：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021">use std::fmt::Display;
|
|
|
|
|
|
fn create_and_print<T>() where T: From<i32> + Display {
|
|
|
let a: T = 100.into(); // 创建了类型为 T 的变量 a，它的初始值由 100 转换而来
|
|
|
println!("a is: {}", a);
|
|
|
}
|
|
|
|
|
|
fn main() {
|
|
|
create_and_print::<i64>();
|
|
|
}</code></pre></pre>
|
|
|
<p>即可成功运行。</p>
|
|
|
<h2 id="结构体中使用泛型"><a class="header" href="#结构体中使用泛型">结构体中使用泛型</a></h2>
|
|
|
<p>结构体中的字段类型也可以用泛型来定义，下面代码定义了一个坐标点 <code>Point</code>，它可以存放任何类型的坐标值：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021">struct Point<T> {
|
|
|
x: T,
|
|
|
y: T,
|
|
|
}
|
|
|
|
|
|
fn main() {
|
|
|
let integer = Point { x: 5, y: 10 };
|
|
|
let float = Point { x: 1.0, y: 4.0 };
|
|
|
}</code></pre></pre>
|
|
|
<p>这里有两点需要特别的注意：</p>
|
|
|
<ul>
|
|
|
<li><strong>提前声明</strong>，跟泛型函数定义类似，首先我们在使用泛型参数之前必需要进行声明 <code>Point<T></code>，接着就可以在结构体的字段类型中使用 <code>T</code> 来替代具体的类型</li>
|
|
|
<li><strong>x 和 y 是相同的类型</strong></li>
|
|
|
</ul>
|
|
|
<p>第二点非常重要，如果使用不同的类型，那么它会导致下面代码的报错：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021">struct Point<T> {
|
|
|
x: T,
|
|
|
y: T,
|
|
|
}
|
|
|
|
|
|
fn main() {
|
|
|
let p = Point{x: 1, y :1.1};
|
|
|
}</code></pre></pre>
|
|
|
<p>错误如下：</p>
|
|
|
<pre><code class="language-console">error[E0308]: mismatched types //类型不匹配
|
|
|
--> src/main.rs:7:28
|
|
|
|
|
|
|
7 | let p = Point{x: 1, y :1.1};
|
|
|
| ^^^ expected integer, found floating-point number //期望y是整数，但是却是浮点数
|
|
|
|
|
|
</code></pre>
|
|
|
<p>当把 <code>1</code> 赋值给 <code>x</code> 时，变量 <code>p</code> 的 <code>T</code> 类型就被确定为整数类型，因此 <code>y</code> 也必须是整数类型，但是我们却给它赋予了浮点数，因此导致报错。</p>
|
|
|
<p>如果想让 <code>x</code> 和 <code>y</code> 既能类型相同，又能类型不同，就需要使用不同的泛型参数：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021">struct Point<T,U> {
|
|
|
x: T,
|
|
|
y: U,
|
|
|
}
|
|
|
fn main() {
|
|
|
let p = Point{x: 1, y :1.1};
|
|
|
}</code></pre></pre>
|
|
|
<p>切记，所有的泛型参数都要提前声明：<code>Point<T,U></code> ! 但是如果你的结构体变成这鬼样：<code>struct Woo<T,U,V,W,X></code>，那么你需要考虑拆分这个结构体，减少泛型参数的个数和代码复杂度。</p>
|
|
|
<h2 id="枚举中使用泛型"><a class="header" href="#枚举中使用泛型">枚举中使用泛型</a></h2>
|
|
|
<p>提到枚举类型，<code>Option</code> 永远是第一个应该被想起来的，在之前的章节中，它也多次出现：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>enum Option<T> {
|
|
|
Some(T),
|
|
|
None,
|
|
|
}
|
|
|
<span class="boring">}</span></code></pre></pre>
|
|
|
<p><code>Option<T></code> 是一个拥有泛型 <code>T</code> 的枚举类型，它第一个成员是 <code>Some(T)</code>，存放了一个类型为 <code>T</code> 的值。得益于泛型的引入，我们可以在任何一个需要返回值的函数中，去使用 <code>Option<T></code> 枚举类型来做为返回值，用于返回一个任意类型的值 <code>Some(T)</code>，或者没有值 <code>None</code>。</p>
|
|
|
<p>对于枚举而言，卧龙凤雏永远是绕不过去的存在：如果是 <code>Option</code> 是卧龙，那么 <code>Result</code> 就一定是凤雏，得两者可得天下：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>enum Result<T, E> {
|
|
|
Ok(T),
|
|
|
Err(E),
|
|
|
}
|
|
|
<span class="boring">}</span></code></pre></pre>
|
|
|
<p>这个枚举和 <code>Option</code> 一样，主要用于函数返回值，与 <code>Option</code> 用于值的存在与否不同，<code>Result </code>关注的主要是值的正确性。</p>
|
|
|
<p>如果函数正常运行，则最后返回一个 <code>Ok(T)</code>，<code>T</code> 是函数具体的返回值类型，如果函数异常运行，则返回一个 <code>Err(E)</code>，<code>E</code> 是错误类型。例如打开一个文件：如果成功打开文件，则返回 <code>Ok(std::fs::File)</code>，因此 <code>T</code> 对应的是 <code>std::fs::File</code> 类型；而当打开文件时出现问题时，返回 <code>Err(std::io::Error)</code>，<code>E</code> 对应的就是 <code>std::io::Error</code> 类型。</p>
|
|
|
<h2 id="方法中使用泛型"><a class="header" href="#方法中使用泛型">方法中使用泛型</a></h2>
|
|
|
<p>上一章中，我们讲到什么是方法以及如何在结构体和枚举上定义方法。方法上也可以使用泛型：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021">struct Point<T> {
|
|
|
x: T,
|
|
|
y: T,
|
|
|
}
|
|
|
|
|
|
impl<T> Point<T> {
|
|
|
fn x(&self) -> &T {
|
|
|
&self.x
|
|
|
}
|
|
|
}
|
|
|
|
|
|
fn main() {
|
|
|
let p = Point { x: 5, y: 10 };
|
|
|
|
|
|
println!("p.x = {}", p.x());
|
|
|
}</code></pre></pre>
|
|
|
<p>使用泛型参数前，依然需要提前声明：<code>impl<T></code>，只有提前声明了，我们才能在<code>Point<T></code>中使用它，这样 Rust 就知道 <code>Point</code> 的尖括号中的类型是泛型而不是具体类型。需要注意的是，这里的 <code>Point<T></code> 不再是泛型声明，而是一个完整的结构体类型，因为我们定义的结构体就是 <code>Point<T></code> 而不再是 <code>Point</code>。</p>
|
|
|
<p>除了结构体中的泛型参数，我们还能在该结构体的方法中定义额外的泛型参数，就跟泛型函数一样：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021">struct Point<T, U> {
|
|
|
x: T,
|
|
|
y: U,
|
|
|
}
|
|
|
|
|
|
impl<T, U> Point<T, U> {
|
|
|
fn mixup<V, W>(self, other: Point<V, W>) -> Point<T, W> {
|
|
|
Point {
|
|
|
x: self.x,
|
|
|
y: other.y,
|
|
|
}
|
|
|
}
|
|
|
}
|
|
|
|
|
|
fn main() {
|
|
|
let p1 = Point { x: 5, y: 10.4 };
|
|
|
let p2 = Point { x: "Hello", y: 'c'};
|
|
|
|
|
|
let p3 = p1.mixup(p2);
|
|
|
|
|
|
println!("p3.x = {}, p3.y = {}", p3.x, p3.y);
|
|
|
}</code></pre></pre>
|
|
|
<p>这个例子中，<code>T,U</code> 是定义在结构体 <code>Point</code> 上的泛型参数，<code>V,W</code> 是单独定义在方法 <code>mixup</code> 上的泛型参数，它们并不冲突，说白了，你可以理解为，一个是结构体泛型，一个是函数泛型。</p>
|
|
|
<h4 id="为具体的泛型类型实现方法"><a class="header" href="#为具体的泛型类型实现方法">为具体的泛型类型实现方法</a></h4>
|
|
|
<p>对于 <code>Point<T></code> 类型，你不仅能定义基于 <code>T</code> 的方法，还能针对特定的具体类型，进行方法定义：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>impl Point<f32> {
|
|
|
fn distance_from_origin(&self) -> f32 {
|
|
|
(self.x.powi(2) + self.y.powi(2)).sqrt()
|
|
|
}
|
|
|
}
|
|
|
<span class="boring">}</span></code></pre></pre>
|
|
|
<p>这段代码意味着 <code>Point<f32></code> 类型会有一个方法 <code>distance_from_origin</code>，而其他 <code>T</code> 不是 <code>f32</code> 类型的 <code>Point<T> </code>实例则没有定义此方法。这个方法计算点实例与坐标<code>(0.0, 0.0)</code> 之间的距离，并使用了只能用于浮点型的数学运算符。</p>
|
|
|
<p>这样我们就能针对特定的泛型类型实现某个特定的方法，对于其它泛型类型则没有定义该方法。</p>
|
|
|
<h2 id="const-泛型rust-151-版本引入的重要特性"><a class="header" href="#const-泛型rust-151-版本引入的重要特性">const 泛型（Rust 1.51 版本引入的重要特性）</a></h2>
|
|
|
<p>在之前的泛型中，可以抽象为一句话：针对类型实现的泛型，所有的泛型都是为了抽象不同的类型，那有没有针对值的泛型？可能很多同学感觉很难理解，值怎么使用泛型？不急，我们先从数组讲起。</p>
|
|
|
<p>在<a href="https://course.rs/basic/compound-type/array.html">数组</a>那节，有提到过很重要的一点：<code>[i32; 2]</code> 和 <code>[i32; 3]</code> 是不同的数组类型，比如下面的代码：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021">fn display_array(arr: [i32; 3]) {
|
|
|
println!("{:?}", arr);
|
|
|
}
|
|
|
fn main() {
|
|
|
let arr: [i32; 3] = [1, 2, 3];
|
|
|
display_array(arr);
|
|
|
|
|
|
let arr: [i32; 2] = [1, 2];
|
|
|
display_array(arr);
|
|
|
}</code></pre></pre>
|
|
|
<p>运行后报错：</p>
|
|
|
<pre><code class="language-console">error[E0308]: mismatched types // 类型不匹配
|
|
|
--> src/main.rs:10:19
|
|
|
|
|
|
|
10 | display_array(arr);
|
|
|
| ^^^ expected an array with a fixed size of 3 elements, found one with 2 elements
|
|
|
// 期望一个长度为3的数组，却发现一个长度为2的
|
|
|
</code></pre>
|
|
|
<p>结合代码和报错，可以很清楚的看出，<code>[i32; 3]</code> 和 <code>[i32; 2]</code> 确实是两个完全不同的类型，因此无法用同一个函数调用。</p>
|
|
|
<p>首先，让我们修改代码，让 <code>display_array</code> 能打印任意长度的 <code>i32</code> 数组：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021">fn display_array(arr: &[i32]) {
|
|
|
println!("{:?}", arr);
|
|
|
}
|
|
|
fn main() {
|
|
|
let arr: [i32; 3] = [1, 2, 3];
|
|
|
display_array(&arr);
|
|
|
|
|
|
let arr: [i32; 2] = [1, 2];
|
|
|
display_array(&arr);
|
|
|
}</code></pre></pre>
|
|
|
<p>很简单，只要使用数组切片，然后传入 <code>arr</code> 的不可变引用即可。</p>
|
|
|
<p>接着，将 <code>i32</code> 改成所有类型的数组：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021">fn display_array<T: std::fmt::Debug>(arr: &[T]) {
|
|
|
println!("{:?}", arr);
|
|
|
}
|
|
|
fn main() {
|
|
|
let arr: [i32; 3] = [1, 2, 3];
|
|
|
display_array(&arr);
|
|
|
|
|
|
let arr: [i32; 2] = [1, 2];
|
|
|
display_array(&arr);
|
|
|
}</code></pre></pre>
|
|
|
<p>也不难，唯一要注意的是需要对 <code>T</code> 加一个限制 <code>std::fmt::Debug</code>，该限制表明 <code>T</code> 可以用在 <code>println!("{:?}", arr)</code> 中，因为 <code>{:?}</code> 形式的格式化输出需要 <code>arr</code> 实现该特征。</p>
|
|
|
<p>通过引用，我们可以很轻松的解决处理任何类型数组的问题，但是如果在某些场景下引用不适宜用或者干脆不能用呢？你们知道为什么以前 Rust 的一些数组库，在使用的时候都限定长度不超过 32 吗？因为它们会为每个长度都单独实现一个函数，简直。。。毫无人性。难道没有什么办法可以解决这个问题吗？</p>
|
|
|
<p>好在，现在咱们有了 const 泛型，也就是针对值的泛型，正好可以用于处理数组长度的问题：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021">fn display_array<T: std::fmt::Debug, const N: usize>(arr: [T; N]) {
|
|
|
println!("{:?}", arr);
|
|
|
}
|
|
|
fn main() {
|
|
|
let arr: [i32; 3] = [1, 2, 3];
|
|
|
display_array(arr);
|
|
|
|
|
|
let arr: [i32; 2] = [1, 2];
|
|
|
display_array(arr);
|
|
|
}</code></pre></pre>
|
|
|
<p>如上所示，我们定义了一个类型为 <code>[T; N]</code> 的数组，其中 <code>T</code> 是一个基于类型的泛型参数，这个和之前讲的泛型没有区别，而重点在于 <code>N</code> 这个泛型参数，它是一个基于值的泛型参数！因为它用来替代的是数组的长度。</p>
|
|
|
<p><code>N</code> 就是 const 泛型，定义的语法是 <code>const N: usize</code>，表示 const 泛型 <code>N</code> ，它基于的值类型是 <code>usize</code>。</p>
|
|
|
<p>在泛型参数之前，Rust 完全不适合复杂矩阵的运算，自从有了 const 泛型，一切即将改变。</p>
|
|
|
<h4 id="const-泛型表达式"><a class="header" href="#const-泛型表达式">const 泛型表达式</a></h4>
|
|
|
<p>假设我们某段代码需要在内存很小的平台上工作，因此需要限制函数参数占用的内存大小，此时就可以使用 const 泛型表达式来实现：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021">// 目前只能在nightly版本下使用
|
|
|
#![allow(incomplete_features)]
|
|
|
#![feature(generic_const_exprs)]
|
|
|
|
|
|
fn something<T>(val: T)
|
|
|
where
|
|
|
Assert<{ core::mem::size_of::<T>() < 768 }>: IsTrue,
|
|
|
// ^-----------------------------^ 这里是一个 const 表达式，换成其它的 const 表达式也可以
|
|
|
{
|
|
|
//
|
|
|
}
|
|
|
|
|
|
fn main() {
|
|
|
something([0u8; 0]); // ok
|
|
|
something([0u8; 512]); // ok
|
|
|
something([0u8; 1024]); // 编译错误，数组长度是1024字节，超过了768字节的参数长度限制
|
|
|
}
|
|
|
|
|
|
// ---
|
|
|
|
|
|
pub enum Assert<const CHECK: bool> {
|
|
|
//
|
|
|
}
|
|
|
|
|
|
pub trait IsTrue {
|
|
|
//
|
|
|
}
|
|
|
|
|
|
impl IsTrue for Assert<true> {
|
|
|
//
|
|
|
}</code></pre></pre>
|
|
|
<h4 id="const-fn"><a class="header" href="#const-fn">const fn</a></h4>
|
|
|
<p>在讨论完 <code>const</code> 泛型后，不得不提及另一个与之密切相关且强大的特性：<code>const fn</code>，即常量函数。<code>const fn</code> 允许我们在编译期对函数进行求值，从而实现更高效、更灵活的代码设计。</p>
|
|
|
<h5 id="为什么需要-const-fn"><a class="header" href="#为什么需要-const-fn">为什么需要 const fn</a></h5>
|
|
|
<p>通常情况下，函数是在运行时被调用和执行的。然而，在某些场景下，我们希望在编译期就计算出一些值，以提高运行时的性能或满足某些编译期的约束条件。例如，定义数组的长度、计算常量值等。</p>
|
|
|
<p>有了 <code>const fn</code>，我们可以在编译期执行这些函数，从而将计算结果直接嵌入到生成的代码中。这不仅以高了运行时的性能，还使代码更加简洁和安全。</p>
|
|
|
<h5 id="const-fn-的基本用法"><a class="header" href="#const-fn-的基本用法">const fn 的基本用法</a></h5>
|
|
|
<p>要定义一个常量函数，只需要在函数声明前加上 <code>const</code> 关键字。例如：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021">const fn add(a: usize, b: usize) -> usize {
|
|
|
a + b
|
|
|
}
|
|
|
|
|
|
const RESULT: usize = add(5, 10);
|
|
|
|
|
|
fn main() {
|
|
|
println!("The result is: {}", RESULT);
|
|
|
}</code></pre></pre>
|
|
|
<h5 id="const-fn-的限制"><a class="header" href="#const-fn-的限制">const fn 的限制</a></h5>
|
|
|
<p>虽然 <code>const fn</code> 提供了很多便利，但是由于其在编译期执行，以确保函数能在编译期被安全地求值，因此有一些限制，例如，不可将随机数生成器写成 <code>const fn</code>。</p>
|
|
|
<p>无论在编译时还是运行时调用 <code>const fn</code>，它们的结果总是相同，即使多次调用也是如此。唯一的例外是，如果你在极端情况下进行复杂的浮点操作，你可能会得到（非常轻微的）不同结果。因此，不建议使 <code>数组长度 (arr.len())</code> 和 <code>Enum判别式</code> 依赖于浮点计算。</p>
|
|
|
<h5 id="结合-const-fn-与-const-泛型"><a class="header" href="#结合-const-fn-与-const-泛型">结合 const fn 与 const 泛型</a></h5>
|
|
|
<p>将 <code>const fn</code> 与 <code>const 泛型</code> 结合，可以实现更加灵活和高效的代码设计。例如，创建一个固定大小的缓冲区结构，其中缓冲区大小由编译期计算确定：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021">struct Buffer<const N: usize> {
|
|
|
data: [u8; N],
|
|
|
}
|
|
|
|
|
|
const fn compute_buffer_size(factor: usize) -> usize {
|
|
|
factor * 1024
|
|
|
}
|
|
|
|
|
|
fn main() {
|
|
|
const SIZE: usize = compute_buffer_size(4);
|
|
|
let buffer = Buffer::<SIZE> {
|
|
|
data: [0; SIZE],
|
|
|
};
|
|
|
println!("Buffer size: {} bytes", buffer.data.len());
|
|
|
}</code></pre></pre>
|
|
|
<p>在这个例子中，<code>compute_buffer_size</code> 是一个常量函数，它根据传入的 <code>factor</code> 计算缓冲区的大小。在 <code>main</code> 函数中，我们使用 <code>compute_buffer_size(4)</code> 来计算缓冲区大小为 4096 字节，并将其作为泛型参数传递给 <code>Buffer</code> 结构体。这样，缓冲区的大小在编译期就被确定下来，避免了运行时的计算开销。</p>
|
|
|
<h2 id="泛型的性能"><a class="header" href="#泛型的性能">泛型的性能</a></h2>
|
|
|
<p>在 Rust 中泛型是零成本的抽象，意味着你在使用泛型时，完全不用担心性能上的问题。</p>
|
|
|
<p>但是任何选择都是权衡得失的，既然我们获得了性能上的巨大优势，那么又失去了什么呢？Rust 是在编译期为泛型对应的多个类型，生成各自的代码，因此损失了编译速度和增大了最终生成文件的大小。</p>
|
|
|
<p>具体来说：</p>
|
|
|
<p>Rust 通过在编译时进行泛型代码的 <strong>单态化</strong>(<em>monomorphization</em>)来保证效率。单态化是一个通过填充编译时使用的具体类型，将通用代码转换为特定代码的过程。</p>
|
|
|
<p>编译器所做的工作正好与我们创建泛型函数的步骤相反，编译器寻找所有泛型代码被调用的位置并针对具体类型生成代码。</p>
|
|
|
<p>让我们看看一个使用标准库中 <code>Option</code> 枚举的例子：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>let integer = Some(5);
|
|
|
let float = Some(5.0);
|
|
|
<span class="boring">}</span></code></pre></pre>
|
|
|
<p>当 Rust 编译这些代码的时候，它会进行单态化。编译器会读取传递给 <code>Option<T></code> 的值并发现有两种 <code>Option<T></code>：一种对应 <code>i32</code> 另一种对应 <code>f64</code>。为此，它会将泛型定义 <code>Option<T></code> 展开为 <code>Option_i32</code> 和 <code>Option_f64</code>，接着将泛型定义替换为这两个具体的定义。</p>
|
|
|
<p>编译器生成的单态化版本的代码看起来像这样：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021">enum Option_i32 {
|
|
|
Some(i32),
|
|
|
None,
|
|
|
}
|
|
|
|
|
|
enum Option_f64 {
|
|
|
Some(f64),
|
|
|
None,
|
|
|
}
|
|
|
|
|
|
fn main() {
|
|
|
let integer = Option_i32::Some(5);
|
|
|
let float = Option_f64::Some(5.0);
|
|
|
}</code></pre></pre>
|
|
|
<p>我们可以使用泛型来编写不重复的代码，而 Rust 将会为每一个实例编译其特定类型的代码。这意味着在使用泛型时没有运行时开销；当代码运行，它的执行效率就跟好像手写每个具体定义的重复代码一样。这个单态化过程正是 Rust 泛型在运行时极其高效的原因。</p>
|
|
|
<h2 id="课后练习"><a class="header" href="#课后练习">课后练习</a></h2>
|
|
|
<blockquote>
|
|
|
<p>Rust By Practice，支持代码在线编辑和运行，并提供详细的习题解答。</p>
|
|
|
<ul>
|
|
|
<li><a href="https://practice-zh.course.rs/generics-traits/generics.html">泛型</a>
|
|
|
<ul>
|
|
|
<li><a href="https://github.com/sunface/rust-by-practice/blob/master/solutions/generics-traits/generics.md">习题解答</a></li>
|
|
|
</ul>
|
|
|
</li>
|
|
|
<li><a href="https://practice-zh.course.rs/generics-traits/const-generics.html">const 泛型</a>
|
|
|
<ul>
|
|
|
<li><a href="https://github.com/sunface/rust-by-practice/blob/master/solutions/generics-traits/const-generics.md">习题解答</a></li>
|
|
|
</ul>
|
|
|
</li>
|
|
|
</ul>
|
|
|
</blockquote>
|
|
|
|
|
|
<div id="giscus-container"></div>
|
|
|
</main>
|
|
|
|
|
|
<nav class="nav-wrapper" aria-label="Page navigation">
|
|
|
<!-- Mobile navigation buttons -->
|
|
|
<a rel="prev" href="../../basic/trait/intro.html" class="mobile-nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
|
|
|
<i class="fa fa-angle-left"></i>
|
|
|
</a>
|
|
|
|
|
|
<a rel="next prefetch" href="../../basic/trait/trait.html" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
|
|
|
<i class="fa fa-angle-right"></i>
|
|
|
</a>
|
|
|
|
|
|
<div style="clear: both"></div>
|
|
|
</nav>
|
|
|
</div>
|
|
|
</div>
|
|
|
|
|
|
<nav class="nav-wide-wrapper" aria-label="Page navigation">
|
|
|
<a rel="prev" href="../../basic/trait/intro.html" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
|
|
|
<i class="fa fa-angle-left"></i>
|
|
|
</a>
|
|
|
|
|
|
<a rel="next prefetch" href="../../basic/trait/trait.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
|
|
|
<i class="fa fa-angle-right"></i>
|
|
|
</a>
|
|
|
</nav>
|
|
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<script>
|
|
|
window.playground_copyable = true;
|
|
|
</script>
|
|
|
|
|
|
<script src="../../ace.js"></script>
|
|
|
<script src="../../editor.js"></script>
|
|
|
<script src="../../mode-rust.js"></script>
|
|
|
<script src="../../theme-dawn.js"></script>
|
|
|
<script src="../../theme-tomorrow_night.js"></script>
|
|
|
|
|
|
<script src="../../elasticlunr.min.js"></script>
|
|
|
<script src="../../mark.min.js"></script>
|
|
|
<script src="../../searcher.js"></script>
|
|
|
|
|
|
<script src="../../clipboard.min.js"></script>
|
|
|
<script src="../../highlight.js"></script>
|
|
|
<script src="../../book.js"></script>
|
|
|
|
|
|
<script type="text/javascript" charset="utf-8">
|
|
|
var pagePath = "basic/trait/generic.md"
|
|
|
</script>
|
|
|
|
|
|
|
|
|
<!-- Custom JS scripts -->
|
|
|
<script src="../../assets/custom.js"></script>
|
|
|
<script src="../../assets/bigPicture.js"></script>
|
|
|
|
|
|
|
|
|
</div>
|
|
|
</body>
|
|
|
</html> |
