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<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 "><a href="../../basic/trait/generic.html"><strong aria-hidden="true">2.8.1.</strong> 泛型 Generics</a></li><li class="chapter-item expanded "><a href="../../basic/trait/trait.html" class="active"><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>
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<main>
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<h1 id="特征-trait"><a class="header" href="#特征-trait">特征 Trait</a></h1>
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<p>如果我们想定义一个文件系统，那么把该系统跟底层存储解耦是很重要的。文件操作主要包含四个：<code>open</code> 、<code>write</code>、<code>read</code>、<code>close</code>，这些操作可以发生在硬盘，可以发生在内存，还可以发生在网络 IO 甚至（...我实在编不下去了，大家来帮帮我）。总之如果你要为每一种情况都单独实现一套代码，那这种实现将过于繁杂，而且也没那个必要。</p>
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<p>要解决上述问题，需要把这些行为抽象出来，就要使用 Rust 中的特征 <code>trait</code> 概念。可能你是第一次听说这个名词，但是不要怕，如果学过其他语言，那么大概率你听说过接口，没错，特征跟接口很类似。</p>
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<p>在之前的代码中，我们也多次见过特征的使用，例如 <code>#[derive(Debug)]</code>，它在我们定义的类型(<code>struct</code>)上自动派生 <code>Debug</code> 特征，接着可以使用 <code>println!("{:?}", x)</code> 打印这个类型；再例如：</p>
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<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
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</span><span class="boring">fn main() {
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</span>fn add<T: std::ops::Add<Output = T>>(a:T, b:T) -> T {
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a + b
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}
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<span class="boring">}</span></code></pre></pre>
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<p>通过 <code>std::ops::Add</code> 特征来限制 <code>T</code>，只有 <code>T</code> 实现了 <code>std::ops::Add</code> 才能进行合法的加法操作，毕竟不是所有的类型都能进行相加。</p>
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<p>这些都说明一个道理，特征定义了<strong>一组可以被共享的行为，只要实现了特征，你就能使用这组行为</strong>。</p>
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<h2 id="定义特征"><a class="header" href="#定义特征">定义特征</a></h2>
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<p>如果不同的类型具有相同的行为，那么我们就可以定义一个特征，然后为这些类型实现该特征。<strong>定义特征</strong>是把一些方法组合在一起，目的是定义一个实现某些目标所必需的行为的集合。</p>
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<p>例如，我们现在有文章 <code>Post</code> 和微博 <code>Weibo</code> 两种内容载体，而我们想对相应的内容进行总结，也就是无论是文章内容，还是微博内容，都可以在某个时间点进行总结，那么总结这个行为就是共享的，因此可以用特征来定义：</p>
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<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
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</span><span class="boring">fn main() {
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</span>pub trait Summary {
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fn summarize(&self) -> String;
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}
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<span class="boring">}</span></code></pre></pre>
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<p>这里使用 <code>trait</code> 关键字来声明一个特征，<code>Summary</code> 是特征名。在大括号中定义了该特征的所有方法，在这个例子中是： <code>fn summarize(&self) -> String</code>。</p>
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<p>特征只定义行为看起来是什么样的，而不定义行为具体是怎么样的。因此，我们只定义特征方法的签名，而不进行实现，此时方法签名结尾是 <code>;</code>，而不是一个 <code>{}</code>。</p>
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<p>接下来，每一个实现这个特征的类型都需要具体实现该特征的相应方法，编译器也会确保任何实现 <code>Summary</code> 特征的类型都拥有与这个签名的定义完全一致的 <code>summarize</code> 方法。</p>
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<h2 id="为类型实现特征"><a class="header" href="#为类型实现特征">为类型实现特征</a></h2>
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<p>因为特征只定义行为看起来是什么样的，因此我们需要为类型实现具体的特征，定义行为具体是怎么样的。</p>
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<p>首先来为 <code>Post</code> 和 <code>Weibo</code> 实现 <code>Summary</code> 特征：</p>
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<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
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</span><span class="boring">fn main() {
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</span>pub trait Summary {
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fn summarize(&self) -> String;
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}
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pub struct Post {
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pub title: String, // 标题
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pub author: String, // 作者
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pub content: String, // 内容
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}
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|
|
|
|
|
impl Summary for Post {
|
|
|
fn summarize(&self) -> String {
|
|
|
format!("文章{}, 作者是{}", self.title, self.author)
|
|
|
}
|
|
|
}
|
|
|
|
|
|
pub struct Weibo {
|
|
|
pub username: String,
|
|
|
pub content: String
|
|
|
}
|
|
|
|
|
|
impl Summary for Weibo {
|
|
|
fn summarize(&self) -> String {
|
|
|
format!("{}发表了微博{}", self.username, self.content)
|
|
|
}
|
|
|
}
|
|
|
<span class="boring">}</span></code></pre></pre>
|
|
|
<p>实现特征的语法与为结构体、枚举实现方法很像：<code>impl Summary for Post</code>，读作“为 <code>Post</code> 类型实现 <code>Summary</code> 特征”，然后在 <code>impl</code> 的花括号中实现该特征的具体方法。</p>
|
|
|
<p>接下来就可以在这个类型上调用特征的方法：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021">fn main() {
|
|
|
let post = Post{title: "Rust语言简介".to_string(),author: "Sunface".to_string(), content: "Rust棒极了!".to_string()};
|
|
|
let weibo = Weibo{username: "sunface".to_string(),content: "好像微博没Tweet好用".to_string()};
|
|
|
|
|
|
println!("{}",post.summarize());
|
|
|
println!("{}",weibo.summarize());
|
|
|
}</code></pre></pre>
|
|
|
<p>运行输出：</p>
|
|
|
<pre><code class="language-console">文章 Rust 语言简介, 作者是Sunface
|
|
|
sunface发表了微博好像微博没Tweet好用
|
|
|
</code></pre>
|
|
|
<p>说实话，如果特征仅仅如此，你可能会觉得花里胡哨没啥用，接下来就让你见识下 <code>trait</code> 真正的威力。</p>
|
|
|
<h4 id="特征定义与实现的位置孤儿规则"><a class="header" href="#特征定义与实现的位置孤儿规则">特征定义与实现的位置(孤儿规则)</a></h4>
|
|
|
<p>上面我们将 <code>Summary</code> 定义成了 <code>pub</code> 公开的。这样，如果他人想要使用我们的 <code>Summary</code> 特征，则可以引入到他们的包中，然后再进行实现。</p>
|
|
|
<p>关于特征实现与定义的位置，有一条非常重要的原则：<strong>如果你想要为类型</strong> <code>A</code> <strong>实现特征</strong> <code>T</code><strong>，那么</strong> <code>A</code> <strong>或者</strong> <code>T</code> <strong>至少有一个是在当前作用域中定义的！</strong> 例如我们可以为上面的 <code>Post</code> 类型实现标准库中的 <code>Display</code> 特征，这是因为 <code>Post</code> 类型定义在当前的作用域中。同时，我们也可以在当前包中为 <code>String</code> 类型实现 <code>Summary</code> 特征，因为 <code>Summary</code> 定义在当前作用域中。</p>
|
|
|
<p>但是你无法在当前作用域中，为 <code>String</code> 类型实现 <code>Display</code> 特征，因为它们俩都定义在标准库中，其定义所在的位置都不在当前作用域，跟你半毛钱关系都没有，看看就行了。</p>
|
|
|
<p>该规则被称为<strong>孤儿规则</strong>，可以确保其它人编写的代码不会破坏你的代码，也确保了你不会莫名其妙就破坏了风马牛不相及的代码。</p>
|
|
|
<h4 id="默认实现"><a class="header" href="#默认实现">默认实现</a></h4>
|
|
|
<p>你可以在特征中定义具有<strong>默认实现</strong>的方法，这样其它类型无需再实现该方法，或者也可以选择重载该方法：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>pub trait Summary {
|
|
|
fn summarize(&self) -> String {
|
|
|
String::from("(Read more...)")
|
|
|
}
|
|
|
}
|
|
|
<span class="boring">}</span></code></pre></pre>
|
|
|
<p>上面为 <code>Summary</code> 定义了一个默认实现，下面我们编写段代码来测试下：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>impl Summary for Post {}
|
|
|
|
|
|
impl Summary for Weibo {
|
|
|
fn summarize(&self) -> String {
|
|
|
format!("{}发表了微博{}", self.username, self.content)
|
|
|
}
|
|
|
}
|
|
|
<span class="boring">}</span></code></pre></pre>
|
|
|
<p>可以看到，<code>Post</code> 选择了默认实现，而 <code>Weibo</code> 重载了该方法，调用和输出如下：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span> println!("{}",post.summarize());
|
|
|
println!("{}",weibo.summarize());
|
|
|
<span class="boring">}</span></code></pre></pre>
|
|
|
<pre><code class="language-console">(Read more...)
|
|
|
sunface发表了微博好像微博没Tweet好用
|
|
|
</code></pre>
|
|
|
<p>默认实现允许调用相同特征中的其他方法，哪怕这些方法没有默认实现。如此，特征可以提供很多有用的功能而只需要实现指定的一小部分内容。例如，我们可以定义 <code>Summary</code> 特征，使其具有一个需要实现的 <code>summarize_author</code> 方法，然后定义一个 <code>summarize</code> 方法，此方法的默认实现调用 <code>summarize_author</code> 方法：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>pub trait Summary {
|
|
|
fn summarize_author(&self) -> String;
|
|
|
|
|
|
fn summarize(&self) -> String {
|
|
|
format!("(Read more from {}...)", self.summarize_author())
|
|
|
}
|
|
|
}
|
|
|
<span class="boring">}</span></code></pre></pre>
|
|
|
<p>为了使用 <code>Summary</code>，只需要实现 <code>summarize_author</code> 方法即可：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>impl Summary for Weibo {
|
|
|
fn summarize_author(&self) -> String {
|
|
|
format!("@{}", self.username)
|
|
|
}
|
|
|
}
|
|
|
println!("1 new weibo: {}", weibo.summarize());
|
|
|
|
|
|
<span class="boring">}</span></code></pre></pre>
|
|
|
<p><code>weibo.summarize()</code> 会先调用 <code>Summary</code> 特征默认实现的 <code>summarize</code> 方法，通过该方法进而调用 <code>Weibo</code> 为 <code>Summary</code> 实现的 <code>summarize_author</code> 方法，最终输出：<code>1 new weibo: (Read more from @horse_ebooks...)</code>。</p>
|
|
|
<h2 id="使用特征作为函数参数"><a class="header" href="#使用特征作为函数参数">使用特征作为函数参数</a></h2>
|
|
|
<p>之前提到过，特征如果仅仅是用来实现方法，那真的有些大材小用，现在我们来讲下，真正可以让特征大放光彩的地方。</p>
|
|
|
<p>现在，先定义一个函数，使用特征作为函数参数：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>pub fn notify(item: &impl Summary) {
|
|
|
println!("Breaking news! {}", item.summarize());
|
|
|
}
|
|
|
<span class="boring">}</span></code></pre></pre>
|
|
|
<p><code>impl Summary</code>，只能说想出这个类型的人真的是起名鬼才，简直太贴切了，顾名思义，它的意思是 <strong>实现了<code>Summary</code>特征</strong> 的 <code>item</code> 参数。</p>
|
|
|
<p>你可以使用任何实现了 <code>Summary</code> 特征的类型作为该函数的参数，同时在函数体内，还可以调用该特征的方法，例如 <code>summarize</code> 方法。具体的说，可以传递 <code>Post</code> 或 <code>Weibo</code> 的实例来作为参数，而其它类如 <code>String</code> 或者 <code>i32</code> 的类型则不能用做该函数的参数，因为它们没有实现 <code>Summary</code> 特征。</p>
|
|
|
<h2 id="特征约束trait-bound"><a class="header" href="#特征约束trait-bound">特征约束(trait bound)</a></h2>
|
|
|
<p>虽然 <code>impl Trait</code> 这种语法非常好理解，但是实际上它只是一个语法糖：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>pub fn notify<T: Summary>(item: &T) {
|
|
|
println!("Breaking news! {}", item.summarize());
|
|
|
}
|
|
|
<span class="boring">}</span></code></pre></pre>
|
|
|
<p>真正的完整书写形式如上所述，形如 <code>T: Summary</code> 被称为<strong>特征约束</strong>。</p>
|
|
|
<p>在简单的场景下 <code>impl Trait</code> 这种语法糖就足够使用，但是对于复杂的场景，特征约束可以让我们拥有更大的灵活性和语法表现能力，例如一个函数接受两个 <code>impl Summary</code> 的参数：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>pub fn notify(item1: &impl Summary, item2: &impl Summary) {}
|
|
|
<span class="boring">}</span></code></pre></pre>
|
|
|
<p>如果函数两个参数是不同的类型，那么上面的方法很好，只要这两个类型都实现了 <code>Summary</code> 特征即可。但是如果我们想要强制函数的两个参数是同一类型呢？上面的语法就无法做到这种限制，此时我们只能使特征约束来实现：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>pub fn notify<T: Summary>(item1: &T, item2: &T) {}
|
|
|
<span class="boring">}</span></code></pre></pre>
|
|
|
<p>泛型类型 <code>T</code> 说明了 <code>item1</code> 和 <code>item2</code> 必须拥有同样的类型，同时 <code>T: Summary</code> 说明了 <code>T</code> 必须实现 <code>Summary</code> 特征。</p>
|
|
|
<h4 id="多重约束"><a class="header" href="#多重约束">多重约束</a></h4>
|
|
|
<p>除了单个约束条件，我们还可以指定多个约束条件，例如除了让参数实现 <code>Summary</code> 特征外，还可以让参数实现 <code>Display</code> 特征以控制它的格式化输出：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>pub fn notify(item: &(impl Summary + Display)) {}
|
|
|
<span class="boring">}</span></code></pre></pre>
|
|
|
<p>除了上述的语法糖形式，还能使用特征约束的形式：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>pub fn notify<T: Summary + Display>(item: &T) {}
|
|
|
<span class="boring">}</span></code></pre></pre>
|
|
|
<p>通过这两个特征，就可以使用 <code>item.summarize</code> 方法，以及通过 <code>println!("{}", item)</code> 来格式化输出 <code>item</code>。</p>
|
|
|
<h4 id="where-约束"><a class="header" href="#where-约束">Where 约束</a></h4>
|
|
|
<p>当特征约束变得很多时，函数的签名将变得很复杂：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>fn some_function<T: Display + Clone, U: Clone + Debug>(t: &T, u: &U) -> i32 {}
|
|
|
<span class="boring">}</span></code></pre></pre>
|
|
|
<p>严格来说，上面的例子还是不够复杂，但是我们还是能对其做一些形式上的改进，通过 <code>where</code>：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>fn some_function<T, U>(t: &T, u: &U) -> i32
|
|
|
where T: Display + Clone,
|
|
|
U: Clone + Debug
|
|
|
{}
|
|
|
<span class="boring">}</span></code></pre></pre>
|
|
|
<h4 id="使用特征约束有条件地实现方法或特征"><a class="header" href="#使用特征约束有条件地实现方法或特征">使用特征约束有条件地实现方法或特征</a></h4>
|
|
|
<p>特征约束，可以让我们在指定类型 + 指定特征的条件下去实现方法，例如：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>use std::fmt::Display;
|
|
|
|
|
|
struct Pair<T> {
|
|
|
x: T,
|
|
|
y: T,
|
|
|
}
|
|
|
|
|
|
impl<T> Pair<T> {
|
|
|
fn new(x: T, y: T) -> Self {
|
|
|
Self {
|
|
|
x,
|
|
|
y,
|
|
|
}
|
|
|
}
|
|
|
}
|
|
|
|
|
|
impl<T: Display + PartialOrd> Pair<T> {
|
|
|
fn cmp_display(&self) {
|
|
|
if self.x >= self.y {
|
|
|
println!("The largest member is x = {}", self.x);
|
|
|
} else {
|
|
|
println!("The largest member is y = {}", self.y);
|
|
|
}
|
|
|
}
|
|
|
}
|
|
|
<span class="boring">}</span></code></pre></pre>
|
|
|
<p><code>cmp_display</code> 方法，并不是所有的 <code>Pair<T></code> 结构体对象都可以拥有，只有 <code>T</code> 同时实现了 <code>Display + PartialOrd</code> 的 <code>Pair<T></code> 才可以拥有此方法。
|
|
|
该函数可读性会更好，因为泛型参数、参数、返回值都在一起，可以快速的阅读，同时每个泛型参数的特征也在新的代码行中通过<strong>特征约束</strong>进行了约束。</p>
|
|
|
<p><strong>也可以有条件地实现特征</strong>，例如，标准库为任何实现了 <code>Display</code> 特征的类型实现了 <code>ToString</code> 特征：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>impl<T: Display> ToString for T {
|
|
|
// --snip--
|
|
|
}
|
|
|
<span class="boring">}</span></code></pre></pre>
|
|
|
<p>我们可以对任何实现了 <code>Display</code> 特征的类型调用由 <code>ToString</code> 定义的 <code>to_string</code> 方法。例如，可以将整型转换为对应的 <code>String</code> 值，因为整型实现了 <code>Display</code>：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>let s = 3.to_string();
|
|
|
<span class="boring">}</span></code></pre></pre>
|
|
|
<h2 id="函数返回中的-impl-trait"><a class="header" href="#函数返回中的-impl-trait">函数返回中的 <code>impl Trait</code></a></h2>
|
|
|
<p>可以通过 <code>impl Trait</code> 来说明一个函数返回了一个类型，该类型实现了某个特征：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>fn returns_summarizable() -> impl Summary {
|
|
|
Weibo {
|
|
|
username: String::from("sunface"),
|
|
|
content: String::from(
|
|
|
"m1 max太厉害了，电脑再也不会卡",
|
|
|
)
|
|
|
}
|
|
|
}
|
|
|
<span class="boring">}</span></code></pre></pre>
|
|
|
<p>因为 <code>Weibo</code> 实现了 <code>Summary</code>，因此这里可以用它来作为返回值。要注意的是，虽然我们知道这里是一个 <code>Weibo</code> 类型，但是对于 <code>returns_summarizable</code> 的调用者而言，他只知道返回了一个实现了 <code>Summary</code> 特征的对象，但是并不知道返回了一个 <code>Weibo</code> 类型。</p>
|
|
|
<p>这种 <code>impl Trait</code> 形式的返回值，在一种场景下非常非常有用，那就是返回的真实类型非常复杂，你不知道该怎么声明时（毕竟 Rust 要求你必须标出所有的类型），此时就可以用 <code>impl Trait</code> 的方式简单返回。例如，闭包和迭代器就是很复杂，只有编译器才知道那玩意的真实类型，如果让你写出来它们的具体类型，估计内心有一万只草泥马奔腾，好在你可以用 <code>impl Iterator</code> 来告诉调用者，返回了一个迭代器，因为所有迭代器都会实现 <code>Iterator</code> 特征。</p>
|
|
|
<p>但是这种返回值方式有一个很大的限制：只能有一个具体的类型，例如：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>fn returns_summarizable(switch: bool) -> impl Summary {
|
|
|
if switch {
|
|
|
Post {
|
|
|
title: String::from(
|
|
|
"Penguins win the Stanley Cup Championship!",
|
|
|
),
|
|
|
author: String::from("Iceburgh"),
|
|
|
content: String::from(
|
|
|
"The Pittsburgh Penguins once again are the best \
|
|
|
hockey team in the NHL.",
|
|
|
),
|
|
|
}
|
|
|
} else {
|
|
|
Weibo {
|
|
|
username: String::from("horse_ebooks"),
|
|
|
content: String::from(
|
|
|
"of course, as you probably already know, people",
|
|
|
),
|
|
|
}
|
|
|
}
|
|
|
}
|
|
|
<span class="boring">}</span></code></pre></pre>
|
|
|
<p>以上的代码就无法通过编译，因为它返回了两个不同的类型 <code>Post</code> 和 <code>Weibo</code>。</p>
|
|
|
<pre><code class="language-console">`if` and `else` have incompatible types
|
|
|
expected struct `Post`, found struct `Weibo`
|
|
|
</code></pre>
|
|
|
<p>报错提示我们 <code>if</code> 和 <code>else</code> 返回了不同的类型。如果想要实现返回不同的类型，需要使用下一章节中的<a href="https://course.rs/basic/trait/trait-object.html">特征对象</a>。</p>
|
|
|
<h2 id="修复上一节中的-largest-函数"><a class="header" href="#修复上一节中的-largest-函数">修复上一节中的 <code>largest</code> 函数</a></h2>
|
|
|
<p>还记得上一节中的<a href="https://course.rs/basic/trait/generic.html#%E6%B3%9B%E5%9E%8B%E8%AF%A6%E8%A7%A3">例子</a>吧，当时留下一个疑问，该如何解决编译报错：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>error[E0369]: binary operation `>` cannot be applied to type `T` // 无法在 `T` 类型上应用`>`运算符
|
|
|
--> src/main.rs:5:17
|
|
|
|
|
|
|
5 | if item > largest {
|
|
|
| ---- ^ ------- T
|
|
|
| |
|
|
|
| T
|
|
|
|
|
|
|
help: consider restricting type parameter `T` // 考虑使用以下的特征来约束 `T`
|
|
|
|
|
|
|
1 | fn largest<T: std::cmp::PartialOrd>(list: &[T]) -> T {
|
|
|
| ^^^^^^^^^^^^^^^^^^^^^^
|
|
|
<span class="boring">}</span></code></pre></pre>
|
|
|
<p>在 <code>largest</code> 函数体中我们想要使用大于运算符（<code>></code>）比较两个 <code>T</code> 类型的值。这个运算符是标准库中特征 <code>std::cmp::PartialOrd</code> 的一个默认方法。所以需要在 <code>T</code> 的特征约束中指定 <code>PartialOrd</code>，这样 <code>largest</code> 函数可以用于内部元素类型可比较大小的数组切片。</p>
|
|
|
<p>由于 <code>PartialOrd</code> 位于 <code>prelude</code> 中所以并不需要通过 <code>std::cmp</code> 手动将其引入作用域。所以可以将 <code>largest</code> 的签名修改为如下：</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: PartialOrd>(list: &[T]) -> T {}
|
|
|
<span class="boring">}</span></code></pre></pre>
|
|
|
<p>但是此时编译，又会出现新的错误：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021"><span class="boring">#![allow(unused)]
|
|
|
</span><span class="boring">fn main() {
|
|
|
</span>error[E0508]: cannot move out of type `[T]`, a non-copy slice
|
|
|
--> src/main.rs:2:23
|
|
|
|
|
|
|
2 | let mut largest = list[0];
|
|
|
| ^^^^^^^
|
|
|
| |
|
|
|
| cannot move out of here
|
|
|
| help: consider using a reference instead: `&list[0]`
|
|
|
|
|
|
error[E0507]: cannot move out of borrowed content
|
|
|
--> src/main.rs:4:9
|
|
|
|
|
|
|
4 | for &item in list.iter() {
|
|
|
| ^----
|
|
|
| ||
|
|
|
| |hint: to prevent move, use `ref item` or `ref mut item`
|
|
|
| cannot move out of borrowed content
|
|
|
<span class="boring">}</span></code></pre></pre>
|
|
|
<p>错误的核心是 <code>cannot move out of type [T], a non-copy slice</code>，原因是 <code>T</code> 没有<a href="https://course.rs/basic/ownership/ownership.html#%E6%8B%B7%E8%B4%9D%E6%B5%85%E6%8B%B7%E8%B4%9D">实现 <code>Copy</code> 特性</a>，因此我们只能把所有权进行转移，毕竟只有 <code>i32</code> 等基础类型才实现了 <code>Copy</code> 特性，可以存储在栈上，而 <code>T</code> 可以指代任何类型（严格来说是实现了 <code>PartialOrd</code> 特征的所有类型）。</p>
|
|
|
<p>因此，为了让 <code>T</code> 拥有 <code>Copy</code> 特性，我们可以增加特征约束：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021">fn largest<T: PartialOrd + Copy>(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>如果并不希望限制 <code>largest</code> 函数只能用于实现了 <code>Copy</code> 特征的类型，我们可以在 <code>T</code> 的特征约束中指定 <a href="https://course.rs/basic/ownership/ownership.html#%E5%85%8B%E9%9A%86%E6%B7%B1%E6%8B%B7%E8%B4%9D"><code>Clone</code> 特征</a> 而不是 <code>Copy</code> 特征。并克隆 <code>list</code> 中的每一个值使得 <code>largest</code> 函数拥有其所有权。使用 <code>clone</code> 函数意味着对于类似 <code>String</code> 这样拥有堆上数据的类型，会潜在地分配更多堆上空间，而堆分配在涉及大量数据时可能会相当缓慢。</p>
|
|
|
<p>另一种 <code>largest</code> 的实现方式是返回在 <code>list</code> 中 <code>T</code> 值的引用。如果我们将函数返回值从 <code>T</code> 改为 <code>&T</code> 并改变函数体使其能够返回一个引用，我们将不需要任何 <code>Clone</code> 或 <code>Copy</code> 的特征约束而且也不会有任何的堆分配。尝试自己实现这种替代解决方式吧！</p>
|
|
|
<h2 id="通过-derive-派生特征"><a class="header" href="#通过-derive-派生特征">通过 <code>derive</code> 派生特征</a></h2>
|
|
|
<p>在本书中，形如 <code>#[derive(Debug)]</code> 的代码已经出现了很多次，这种是一种特征派生语法，被 <code>derive</code> 标记的对象会自动实现对应的默认特征代码，继承相应的功能。</p>
|
|
|
<p>例如 <code>Debug</code> 特征，它有一套自动实现的默认代码，当你给一个结构体标记后，就可以使用 <code>println!("{:?}", s)</code> 的形式打印该结构体的对象。</p>
|
|
|
<p>再如 <code>Copy</code> 特征，它也有一套自动实现的默认代码，当标记到一个类型上时，可以让这个类型自动实现 <code>Copy</code> 特征，进而可以调用 <code>copy</code> 方法，进行自我复制。</p>
|
|
|
<p>总之，<code>derive</code> 派生出来的是 Rust 默认给我们提供的特征，在开发过程中极大的简化了自己手动实现相应特征的需求，当然，如果你有特殊的需求，还可以自己手动重载该实现。</p>
|
|
|
<p>详细的 <code>derive</code> 列表参见<a href="https://course.rs/appendix/derive.html">附录-派生特征</a>。</p>
|
|
|
<h2 id="调用方法需要引入特征"><a class="header" href="#调用方法需要引入特征">调用方法需要引入特征</a></h2>
|
|
|
<p>在一些场景中，使用 <code>as</code> 关键字做类型转换会有比较大的限制，因为你想要在类型转换上拥有完全的控制，例如处理转换错误，那么你将需要 <code>TryInto</code>：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021">use std::convert::TryInto;
|
|
|
|
|
|
fn main() {
|
|
|
let a: i32 = 10;
|
|
|
let b: u16 = 100;
|
|
|
|
|
|
let b_ = b.try_into()
|
|
|
.unwrap();
|
|
|
|
|
|
if a < b_ {
|
|
|
println!("Ten is less than one hundred.");
|
|
|
}
|
|
|
}</code></pre></pre>
|
|
|
<p>上面代码中引入了 <code>std::convert::TryInto</code> 特征，但是却没有使用它，可能有些同学会为此困惑，主要原因在于<strong>如果你要使用一个特征的方法，那么你需要将该特征引入当前的作用域中</strong>，我们在上面用到了 <code>try_into</code> 方法，因此需要引入对应的特征。</p>
|
|
|
<p>但是 Rust 又提供了一个非常便利的办法，即把最常用的标准库中的特征通过 <a href="https://course.rs/appendix/prelude.html"><code>std::prelude</code></a> 模块提前引入到当前作用域中，其中包括了 <code>std::convert::TryInto</code>，你可以尝试删除第一行的代码 <code>use ...</code>，看看是否会报错。</p>
|
|
|
<h2 id="几个综合例子"><a class="header" href="#几个综合例子">几个综合例子</a></h2>
|
|
|
<h4 id="为自定义类型实现--操作"><a class="header" href="#为自定义类型实现--操作">为自定义类型实现 <code>+</code> 操作</a></h4>
|
|
|
<p>在 Rust 中除了数值类型的加法，<code>String</code> 也可以做<a href="https://course.rs/basic/compound-type/string-slice.html#%E6%93%8D%E4%BD%9C%E5%AD%97%E7%AC%A6%E4%B8%B2">加法</a>，因为 Rust 为该类型实现了 <code>std::ops::Add</code> 特征，同理，如果我们为自定义类型实现了该特征，那就可以自己实现 <code>Point1 + Point2</code> 的操作:</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021">use std::ops::Add;
|
|
|
|
|
|
// 为Point结构体派生Debug特征，用于格式化输出
|
|
|
#[derive(Debug)]
|
|
|
struct Point<T: Add<T, Output = T>> { //限制类型T必须实现了Add特征，否则无法进行+操作。
|
|
|
x: T,
|
|
|
y: T,
|
|
|
}
|
|
|
|
|
|
impl<T: Add<T, Output = T>> Add for Point<T> {
|
|
|
type Output = Point<T>;
|
|
|
|
|
|
fn add(self, p: Point<T>) -> Point<T> {
|
|
|
Point{
|
|
|
x: self.x + p.x,
|
|
|
y: self.y + p.y,
|
|
|
}
|
|
|
}
|
|
|
}
|
|
|
|
|
|
fn add<T: Add<T, Output=T>>(a:T, b:T) -> T {
|
|
|
a + b
|
|
|
}
|
|
|
|
|
|
fn main() {
|
|
|
let p1 = Point{x: 1.1f32, y: 1.1f32};
|
|
|
let p2 = Point{x: 2.1f32, y: 2.1f32};
|
|
|
println!("{:?}", add(p1, p2));
|
|
|
|
|
|
let p3 = Point{x: 1i32, y: 1i32};
|
|
|
let p4 = Point{x: 2i32, y: 2i32};
|
|
|
println!("{:?}", add(p3, p4));
|
|
|
}</code></pre></pre>
|
|
|
<h4 id="自定义类型的打印输出"><a class="header" href="#自定义类型的打印输出">自定义类型的打印输出</a></h4>
|
|
|
<p>在开发过程中，往往只要使用 <code>#[derive(Debug)]</code> 对我们的自定义类型进行标注，即可实现打印输出的功能：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021">#[derive(Debug)]
|
|
|
struct Point{
|
|
|
x: i32,
|
|
|
y: i32
|
|
|
}
|
|
|
fn main() {
|
|
|
let p = Point{x:3,y:3};
|
|
|
println!("{:?}",p);
|
|
|
}</code></pre></pre>
|
|
|
<p>但是在实际项目中，往往需要对我们的自定义类型进行自定义的格式化输出，以让用户更好的阅读理解我们的类型，此时就要为自定义类型实现 <code>std::fmt::Display</code> 特征：</p>
|
|
|
<pre><pre class="playground"><code class="language-rust edition2021">#![allow(dead_code)]
|
|
|
|
|
|
use std::fmt;
|
|
|
use std::fmt::{Display};
|
|
|
|
|
|
#[derive(Debug,PartialEq)]
|
|
|
enum FileState {
|
|
|
Open,
|
|
|
Closed,
|
|
|
}
|
|
|
|
|
|
#[derive(Debug)]
|
|
|
struct File {
|
|
|
name: String,
|
|
|
data: Vec<u8>,
|
|
|
state: FileState,
|
|
|
}
|
|
|
|
|
|
impl Display for FileState {
|
|
|
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
|
|
|
match *self {
|
|
|
FileState::Open => write!(f, "OPEN"),
|
|
|
FileState::Closed => write!(f, "CLOSED"),
|
|
|
}
|
|
|
}
|
|
|
}
|
|
|
|
|
|
impl Display for File {
|
|
|
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
|
|
|
write!(f, "<{} ({})>",
|
|
|
self.name, self.state)
|
|
|
}
|
|
|
}
|
|
|
|
|
|
impl File {
|
|
|
fn new(name: &str) -> File {
|
|
|
File {
|
|
|
name: String::from(name),
|
|
|
data: Vec::new(),
|
|
|
state: FileState::Closed,
|
|
|
}
|
|
|
}
|
|
|
}
|
|
|
|
|
|
fn main() {
|
|
|
let f6 = File::new("f6.txt");
|
|
|
//...
|
|
|
println!("{:?}", f6);
|
|
|
println!("{}", f6);
|
|
|
}</code></pre></pre>
|
|
|
<p>以上两个例子较为复杂，目的是为读者展示下真实的使用场景长什么样，因此需要读者细细阅读，最终消化这些知识对于你的 Rust 之路会有莫大的帮助。</p>
|
|
|
<p>最后，特征和特征约束，是 Rust 中极其重要的概念，如果你还是没搞懂，强烈建议回头再看一遍，或者寻找相关的资料进行补充学习。如果已经觉得掌握了，那么就可以进入下一节的学习。</p>
|
|
|
<h2 id="课后练习"><a class="header" href="#课后练习">课后练习</a></h2>
|
|
|
<blockquote>
|
|
|
<p><a href="https://practice-zh.course.rs/generics-traits/traits.html">Rust By Practice</a>，支持代码在线编辑和运行，并提供详细的<a href="https://github.com/sunface/rust-by-practice/blob/master/solutions/generics-traits/traits.md">习题解答</a>。</p>
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