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<ul class="chapter"><li><a href="ch01-00-introduction.html"><strong>1.</strong> 介绍</a></li><li><ul class="section"><li><a href="ch01-01-installation.html"><strong>1.1.</strong> 安装</a></li><li><a href="ch01-02-hello-world.html"><strong>1.2.</strong> Hello, World!</a></li></ul></li><li><a href="ch02-00-guessing-game-tutorial.html"><strong>2.</strong> 猜猜看教程</a></li><li><a href="ch03-00-common-programming-concepts.html"><strong>3.</strong> 通用编程概念</a></li><li><ul class="section"><li><a href="ch03-01-variables-and-mutability.html"><strong>3.1.</strong> 变量和可变性</a></li><li><a href="ch03-02-data-types.html"><strong>3.2.</strong> 数据类型</a></li><li><a href="ch03-03-how-functions-work.html"><strong>3.3.</strong> 函数如何工作</a></li><li><a href="ch03-04-comments.html"><strong>3.4.</strong> 注释</a></li><li><a href="ch03-05-control-flow.html"><strong>3.5.</strong> 控制流</a></li></ul></li><li><a href="ch04-00-understanding-ownership.html"><strong>4.</strong> 认识所有权</a></li><li><ul class="section"><li><a href="ch04-01-what-is-ownership.html"><strong>4.1.</strong> 什么是所有权</a></li><li><a href="ch04-02-references-and-borrowing.html"><strong>4.2.</strong> 引用 & 借用</a></li><li><a href="ch04-03-slices.html"><strong>4.3.</strong> Slices</a></li></ul></li><li><a href="ch05-00-structs.html"><strong>5.</strong> 结构体</a></li><li><ul class="section"><li><a href="ch05-01-method-syntax.html"><strong>5.1.</strong> 方法语法</a></li></ul></li><li><a href="ch06-00-enums.html"><strong>6.</strong> 枚举和模式匹配</a></li><li><ul class="section"><li><a href="ch06-01-defining-an-enum.html"><strong>6.1.</strong> 定义枚举</a></li><li><a href="ch06-02-match.html"><strong>6.2.</strong> <code>match</code>控制流运算符</a></li><li><a href="ch06-03-if-let.html"><strong>6.3.</strong> <code>if let</code>简单控制流</a></li></ul></li><li><a href="ch07-00-modules.html"><strong>7.</strong> 模块</a></li><li><ul class="section"><li><a href="ch07-01-mod-and-the-filesystem.html"><strong>7.1.</strong> <code>mod</code>和文件系统</a></li><li><a href="ch07-02-controlling-visibility-with-pub.html"><strong>7.2.</strong> 使用<code>pub</code>控制可见性</a></li><li><a href="ch07-03-importing-names-with-use.html"><strong>7.3.</strong> 使用<code>use</code>导入命名</a></li></ul></li><li><a href="ch08-00-common-collections.html"><strong>8.</strong> 通用集合类型</a></li><li><ul class="section"><li><a href="ch08-01-vectors.html"><strong>8.1.</strong> vector</a></li><li><a href="ch08-02-strings.html"><strong>8.2.</strong> 字符串</a></li><li><a href="ch08-03-hash-maps.html"><strong>8.3.</strong> 哈希 map</a></li></ul></li><li><a href="ch09-00-error-handling.html"><strong>9.</strong> 错误处理</a></li><li><ul class="section"><li><a href="ch09-01-unrecoverable-errors-with-panic.html"><strong>9.1.</strong> <code>panic!</code>与不可恢复的错误</a></li><li><a href="ch09-02-recoverable-errors-with-result.html"><strong>9.2.</strong> <code>Result</code>与可恢复的错误</a></li><li><a href="ch09-03-to-panic-or-not-to-panic.html"><strong>9.3.</strong> <code>panic!</code>还是不<code>panic!</code></a></li></ul></li><li><a href="ch10-00-generics.html"><strong>10.</strong> 泛型、trait 和生命周期</a></li><li><ul class="section"><li><a href="ch10-01-syntax.html"><strong>10.1.</strong> 泛型数据类型</a></li><li><a href="ch10-02-traits.html"><strong>10.2.</strong> trait：定义共享的行为</a></li><li><a href="ch10-03-lifetime-syntax.html"><strong>10.3.</strong> 生命周期与引用有效性</a></li></ul></li><li><a href="ch11-00-testing.html"><strong>11.</strong> 测试</a></li><li><ul class="section"><li><a href="ch11-01-writing-tests.html"><strong>11.1.</strong> 编写测试</a></li><li><a href="ch11-02-running-tests.html"><strong>11.2.</strong> 运行测试</a></li><li><a href="ch11-03-test-organization.html"><strong>11.3.</strong> 测试的组织结构</a></li></ul></li><li><a href="ch12-00-an-io-project.html"><strong>12.</strong> 一个 I/O 项目</a></li><li><ul class="section"><li><a href="ch12-01-accepting-command-line-arguments.html"><strong>12.1.</strong> 接受命令行参数</a></li><li><a href="ch12-02-reading-a-file.html"><strong>12.2.</strong> 读取文件</a></li><li><a href="ch12-03-improving-error-handling-and-modularity.html"><strong>12.3.</strong> 增强错误处理和模块化</a></li><li><a href="ch12-04-testing-the-librarys-functionality.html"><strong>12.4.</strong> 测试库的功能</a></li><li><a href="ch12-05-working-with-environment-variables.html"><strong>12.5.</strong> 处理环境变量</a></li><li><a href="ch12-06-writing-to-stderr-instead-of-stdout.html"><strong>12.6.</strong> 输出到<code>stderr</code>而不是<code>stdout</code></a></li></ul></li><li><a href="ch13-00-functional-features.html"><strong>13.</strong> Rust 中的函数式语言功能</a></li><li><ul class="section"><li><a href="ch13-01-closures.html"><strong>13.1.</strong> 闭包</a></li><li><a href="ch13-02-iterators.html"><strong>13.2.</strong> 迭代器</a></li><li><a href="ch13-03-improving-our-io-project.html"><strong>13.3.</strong> 改进 I/O 项目</a></li><li><a href="ch13-04-performance.html"><strong>13.4.</strong> 性能</a></li></ul></li><li><a href="ch14-00-more-about-cargo.html"><strong>14.</strong> 更多关于 Cargo 和 Crates.io</a></li><li><ul class="section"><li><a href="ch14-01-release-profiles.html"><strong>14.1.</strong> 发布配置</a></li><li><a href="ch14-02-publishing-to-crates-io.html"><strong>14.2.</strong> 将 crate 发布到 Crates.io</a></li><li><a href="ch14-03-cargo-workspaces.html" class="active"><strong>14.3.</strong> Cargo 工作空间</a></li><li><a href="ch14-04-installing-binaries.html"><strong>14.4.</strong> 使用<code>cargo install</code>从 Crates.io 安装文件</a></li><li><a href="ch14-05-extending-cargo.html"><strong>14.5.</strong> Cargo 自定义扩展命令</a></li></ul></li><li><a href="ch15-00-smart-pointers.html"><strong>15.</strong> 智能指针</a></li><li><ul class="section"><li><a href="ch15-01-box.html"><strong>15.1.</strong> <code>Box<T></code>用于已知大小的堆上数据</a></li><li><a href="ch15-02-deref.html"><strong>15.2.</strong> <code>Deref</code> Trait 允许通过引用访问数据</a></li><li><a href="ch15-03-drop.html"><strong>15.3.</strong> <code>Drop</code> Trait 运行清理代码</a></li><li><a href="ch15-04-rc.html"><strong>15.4.</strong> <code>Rc<T></code> 引用计数智能指针</a></li><li><a href="ch15-05-interior-mutability.html"><strong>15.5.</strong> <code>RefCell<T></code>和内部可变性模式</a></li><li><a href="ch15-06-reference-cycles.html"><strong>15.6.</strong> 引用循环和内存泄漏是安全的</a></li></ul></li><li><a href="ch16-00-concurrency.html"><strong>16.</strong> 无畏并发</a></li><li><ul class="section"><li><a href="ch16-01-threads.html"><strong>16.1.</strong> 线程</a></li><li><a href="ch16-02-message-passing.html"><strong>16.2.</strong> 消息传递</a></li><li><a href="ch16-03-shared-state.html"><strong>16.3.</strong> 共享状态</a></li><li><a href="ch16-04-extensible-concurrency-sync-and-send.html"><strong>16.4.</strong> 可扩展的并发：<code>Sync</code>和<code>Send</code></a></li></ul></li><li><a href="ch17-00-oop.html"><strong>17.</strong> 面向对象</a></li><li><ul class="section"><li><a href="ch17-01-what-is-oo.html"><strong>17.1.</strong> 什么是面向对象？</a></li><li><a href="ch17-02-trait-objects.html"><strong>17.2.</strong> 为使用不同类型的值而设计的 trait 对象</a></li><li><a href="ch17-03-oo-design-patterns.html"><strong>17.3.</strong> 面向对象设计模式的实现</a></li></ul></li></ul>
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<h1 class="menu-title">Rust 程序设计语言 简体中文版</h1>
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<a class="header" href="#cargo-工作空间" name="cargo-工作空间"><h2>Cargo 工作空间</h2></a>
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<blockquote>
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<p><a href="https://github.com/rust-lang/book/blob/master/second-edition/src/ch14-03-cargo-workspaces.md">ch14-03-cargo-workspaces.md</a>
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<br>
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commit d945f6d4046f4fc3c09326213100492790aebb45</p>
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</blockquote>
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<p>第十二章中，我们构建一个包含二进制 crate 和库 crate 的包。不过如果库 crate 继续变得更大而我们想要进一步将包拆分为多个库 crate 呢？随着包增长，拆分出其主要组件将是非常有帮助的。对于这种情况，Cargo 提供了一个叫<strong>工作空间</strong>（<em>workspaces</em>）的功能，它可以帮助我们管理多个相关的并行开发的包。</p>
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<p><strong>工作空间</strong>是一系列的包都共享同样的 <em>Cargo.lock</em> 和输出目录。让我们使用工作空间创建一个项目，这是我们熟悉的所以就可以关注工作空间的结构了。这里有一个二进制项目它使用了两个库：一个会提供<code>add_one</code>方法而第二个会提供<code>add_two</code>方法。让我们为这个二进制项目创建一个新 crate 作为开始：</p>
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<pre><code>$ cargo new --bin adder
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Created binary (application) `adder` project
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$ cd adder
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</code></pre>
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<p>需要修改二进制包的 <em>Cargo.toml</em> 来告诉 Cargo 包<code>adder</code>是一个工作空间。再文件末尾增加如下：</p>
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<pre><code class="language-toml">[workspace]
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</code></pre>
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<p>类似于很多 Cargo 的功能，工作空间支持配置惯例：只要遵循这些惯例就无需再增加任何配置了。这个惯例是任何作为子目录依赖的 crate 将是工作空间的一部分。让我们像这样在 <em>Cargo.toml</em> 中的<code>[dependencies]</code>增加一个<code>adder</code> crate 的路径依赖：</p>
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<pre><code class="language-toml">[dependencies]
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add-one = { path = "add-one" }
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</code></pre>
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<p>如果增加依赖但没有指定<code>path</code>，这将是一个不位于工作空间的正常的依赖。</p>
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<p>接下来，在<code>adder</code>目录中生成<code>add-one</code> crate：</p>
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<pre><code>$ cargo new add-one
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Created library `add-one` project
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</code></pre>
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<p>现在<code>adder</code>目录应该有如下目录和文件：</p>
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<pre><code>├── Cargo.toml
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├── add-one
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│ ├── Cargo.toml
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│ └── src
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│ └── lib.rs
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└── src
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└── main.rs
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</code></pre>
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<p>在 <em>add-one/src/lib.rs</em> 中增加<code>add_one</code>函数的实现：</p>
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<p><span class="filename">Filename: add-one/src/lib.rs</span></p>
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<pre><code class="language-rust">pub fn add_one(x: i32) -> i32 {
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x + 1
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}
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</code></pre>
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<p>打开<code>adder</code>的 <em>src/main.rs</em> 并增加一行<code>extern crate</code>将新的<code>add-one</code>库引入作用域，并修改<code>main</code>函数来使用<code>add_one</code>函数：</p>
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<pre><code class="language-rust,ignore">extern crate add_one;
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fn main() {
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let num = 10;
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println!("Hello, world! {} plus one is {}!", num, add_one::add_one(num));
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}
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</code></pre>
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<p>让我们构建一下！</p>
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<pre><code>$ cargo build
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Compiling add-one v0.1.0 (file:///projects/adder/add-one)
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Compiling adder v0.1.0 (file:///projects/adder)
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Finished debug [unoptimized + debuginfo] target(s) in 0.68 secs
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</code></pre>
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<p>注意在 <em>adder</em> 目录运行<code>cargo build</code>会构建这个 crate 和 <em>adder/add-one</em> 中的<code>add-one</code> crate，不过只创建一个 <em>Cargo.lock</em> 和一个 <em>target</em> 目录，他们都位于 <em>adder</em> 目录。试试你能否用相同的方式增加<code>add-two</code> crate。</p>
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<p>假如我们想要在<code>add-one</code> crate 中使用<code>rand</code> crate。一如既往在<code>Cargo.toml</code>的<code>[dependencies]</code>部分增加这个 crate：</p>
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<p><span class="filename">Filename: add-one/Cargo.toml</span></p>
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<pre><code class="language-toml">[dependencies]
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rand = "0.3.14"
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</code></pre>
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<p>如果在 <em>add-one/src/lib.rs</em> 中加上<code>extern crate rand;</code>后再运行<code>cargo build</code>，则会编译成功：</p>
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<pre><code>$ cargo build
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Updating registry `https://github.com/rust-lang/crates.io-index`
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Downloading rand v0.3.14
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...snip...
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Compiling rand v0.3.14
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Compiling add-one v0.1.0 (file:///projects/adder/add-one)
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Compiling adder v0.1.0 (file:///projects/adder)
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Finished debug [unoptimized + debuginfo] target(s) in 10.18 secs
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</code></pre>
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<p>现在 <em>Cargo.lock</em> 的顶部反映了<code>add-one</code>依赖<code>rand</code>这一事实。然而即使在工作空间的某处使用了<code>rand</code>，也不能在工作空间的其他 crate 使用它，除非在对应的 <em>Cargo.toml</em> 也增加<code>rand</code>的依赖。例如，如果在顶层的<code>adder</code> crate 的 <em>src/main.rs</em> 中增加<code>extern crate rand;</code>，将会出现一个错误：</p>
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<pre><code>$ cargo build
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Compiling adder v0.1.0 (file:///projects/adder)
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error[E0463]: can't find crate for `rand`
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--> src/main.rs:1:1
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|
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1 | extern crate rand;
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| ^^^^^^^^^^^^^^^^^^^ can't find crate
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</code></pre>
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<p>为了修复这个错误，修改顶层的 <em>Cargo.toml</em> 并表明<code>rand</code>是<code>adder</code> crate 的一个依赖。</p>
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<p>作为另一个提高，为 crate 中的<code>add_one::add_one</code>函数增加一个测试：</p>
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<p><span class="filename">Filename: add-one/src/lib.rs</span></p>
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<pre><code class="language-rust">pub fn add_one(x: i32) -> i32 {
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x + 1
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[test]
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fn it_works() {
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assert_eq!(3, add_one(2));
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}
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}
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</code></pre>
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<p>现在在顶层的 <em>adder</em> 目录运行<code>cargo test</code>：</p>
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<pre><code>$ cargo test
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Compiling adder v0.1.0 (file:///projects/adder)
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Finished debug [unoptimized + debuginfo] target(s) in 0.27 secs
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Running target/debug/adder-f0253159197f7841
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running 0 tests
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test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured
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</code></pre>
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<p>等等，零个测试？我们不是刚增加了一个吗？如果我们观察输出，就不难发现在工作空间中的<code>cargo test</code>只运行顶层 crate 的测试。为了运行其他 crate 的测试，需要使用<code>-p</code>参数来表明我们希望运行指定包的测试：</p>
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<pre><code>$ cargo test -p add-one
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Finished debug [unoptimized + debuginfo] target(s) in 0.0 secs
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Running target/debug/deps/add_one-abcabcabc
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running 1 test
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test tests::it_works ... ok
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test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured
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Doc-tests add-one
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running 0 tests
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test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured
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</code></pre>
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<p>类似的，如果选择将工作空间发布到 crates.io，其中的每一个包都需要单独发布。</p>
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<p>随着项目增长，考虑使用工作空间：每一个更小的组件比一大块代码要容易理解。将 crate 保持在工作空间中易于协调他们的改变，如果他们一起运行并经常需要同时被修改的话。</p>
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