Shikong/trpl-zh-cn
1
0
Fork 0
mirror of https://github.com/KaiserY/trpl-zh-cn synced 2024-11-13 03:21:20 +08:00
Code Issues Packages Projects Releases Wiki Activity
7503403e01
trpl-zh-cn/docs/ch17-01-what-is-oo.html
KaiserY d465e2ff96 wip update ch12-03
2017-04-05 23:13:49 +08:00

166 lines
15 KiB
HTML
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

<!DOCTYPE HTML>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>什么是面向对象 - Rust 程序设计语言 简体中文版</title>
<meta content="text/html; charset=utf-8" http-equiv="Content-Type">
<meta name="description" content="Rust 程序设计语言 简体中文版">
<meta name="viewport" content="width=device-width, initial-scale=1">
<base href="">
<link rel="stylesheet" href="book.css">
<link href='https://fonts.googleapis.com/css?family=Open+Sans:300italic,400italic,600italic,700italic,800italic,400,300,600,700,800' rel='stylesheet' type='text/css'>
<link rel="shortcut icon" href="favicon.png">
<!-- Font Awesome -->
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/font-awesome/4.3.0/css/font-awesome.min.css">
<link rel="stylesheet" href="highlight.css">
<link rel="stylesheet" href="tomorrow-night.css">
<!-- MathJax -->
<script type="text/javascript" src="https://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML"></script>
<!-- Fetch JQuery from CDN but have a local fallback -->
<script src="https://code.jquery.com/jquery-2.1.4.min.js"></script>
<script>
if (typeof jQuery == 'undefined') {
document.write(unescape("%3Cscript src='jquery.js'%3E%3C/script%3E"));
}
</script>
</head>
<body class="light">
<!-- Set the theme before any content is loaded, prevents flash -->
<script type="text/javascript">
var theme = localStorage.getItem('theme');
if (theme == null) { theme = 'light'; }
$('body').removeClass().addClass(theme);
</script>
<!-- Hide / unhide sidebar before it is displayed -->
<script type="text/javascript">
var sidebar = localStorage.getItem('sidebar');
if (sidebar === "hidden") { $("html").addClass("sidebar-hidden") }
else if (sidebar === "visible") { $("html").addClass("sidebar-visible") }
</script>
<div id="sidebar" class="sidebar">
<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 &amp; 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"><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&lt;T&gt;</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&lt;T&gt;</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&lt;T&gt;</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" class="active"><strong>17.1.</strong> 什么是面向对象</a></li></ul></li></ul>
</div>
<div id="page-wrapper" class="page-wrapper">
<div class="page">
<div id="menu-bar" class="menu-bar">
<div class="left-buttons">
<i id="sidebar-toggle" class="fa fa-bars"></i>
<i id="theme-toggle" class="fa fa-paint-brush"></i>
</div>
<h1 class="menu-title">Rust 程序设计语言 简体中文版</h1>
<div class="right-buttons">
<i id="print-button" class="fa fa-print" title="Print this book"></i>
</div>
</div>
<div id="content" class="content">
<a class="header" href="#什么是面向对象" name="什么是面向对象"><h2>什么是面向对象？</h2></a>
<blockquote>
<p><a href="https://github.com/rust-lang/book/blob/master/second-edition/src/ch17-01-what-is-oo.md">ch17-01-what-is-oo.md</a>
<br>
commit 46334522e22d6217b392451cff8b4feca2d69d79</p>
</blockquote>
<p>关于一门语言是否需要是面向对象，在编程社区内并达成一致意见。Rust被很多不同的编程模式影响，我们探索了13章提到的函数式编程的特性。面向对象编程语言的一些特性往往是对象、封装和继承。我们看一下每个的含义和Rust是否支持它们。</p>
<a class="header" href="#对象包含数据和行为" name="对象包含数据和行为"><h2>对象包含数据和行为</h2></a>
<p><code>Design Patterns: Elements of Reusable Object-Oriented Software</code>这本书被俗称为<code>The Gang of Four book</code>，是面向对象编程模式的目录。它这样定义面向对象编程：</p>
<blockquote>
<p>面向对象的程序是由对象组成的。一个对象包数据和操作这些数据的程序。程序通常被称为方法或操作。</p>
</blockquote>
<p>在这个定一下，Rust是面向对象的：结构体和枚举包含数据和impl块提供了在结构体和枚举上的方法。虽然带有方法的结构体和枚举不称为对象，但是他们提供了和对象相同的功能，使用了<code>Gang of Four</code>定义的对象。</p>
<a class="header" href="#隐藏了实现细节的封装" name="隐藏了实现细节的封装"><h2>隐藏了实现细节的封装</h2></a>
<p>通常与面向对象编程相关的另一个方面是封装的思想：对象的实现细节不能被使用对象的代码获取到。唯一与对象交互的方式是通过对象提供的public API，使用对象的代码无法深入到对象内部并直接改变数据或者行为。封装使得改变和重构对象的内部，无需改变使用对象的代码。</p>
<p>就像我们在第7张讨论的那样，我们可以使用pub关键字来决定模块、类型函数和方法是public的（默认情况下一切都是private）。比如，我们可以定义一个结构体<code>AveragedCollection</code>包含一个<code>i32</code>类型的vector。结构体也可以有一个字段，该字段保存了vector中所有值的平均值。这样，希望知道结构体中的vector的平均值的人可以随着获取到，而无需自己计算。<code>AveragedCollection</code> 会为我们缓存平均值结果。 Listing 17-1有<code>AveragedCollection</code> 结构体的定义。</p>
<p>Filename: src/lib.rs</p>
<pre><code>pub struct AveragedCollection {
list: Vec&lt;i32&gt;,
average: f64,
}
</code></pre>
<p><code>AveragedCollection</code>结构体维护了一个Integer列表和集合中所有元素的平均值。</p>
<p>注意，结构体本身被标记为pub，这样其他代码可以使用这个结构体，但是在结构体内部的字段仍然是private。这是非常重要的，因为我们希望保证变量被增加到列表或者被从列表删除时，也会同时更新平均值。我们通过在结构体上实现add、remove和average方法来做到这一点（ Listing 17-2:）：</p>
<p>Filename: src/lib.rs</p>
<pre><code># pub struct AveragedCollection {
# list: Vec&lt;i32&gt;,
# average: f64,
# }
impl AveragedCollection {
pub fn add(&amp;mut self, value: i32) {
self.list.push(value);
self.update_average();
}
pub fn remove(&amp;mut self) -&gt; Option&lt;i32&gt; {
let result = self.list.pop();
match result {
Some(value) =&gt; {
self.update_average();
Some(value)
},
None =&gt; None,
}
}
pub fn average(&amp;self) -&gt; f64 {
self.average
}
fn update_average(&amp;mut self) {
let total: i32 = self.list.iter().sum();
self.average = total as f64 / self.list.len() as f64;
}
}
</code></pre>
<p>Listing 17-2:在<code>AveragedCollection</code>结构体上实现了add、remove和average public方法</p>
</div>
<!-- Mobile navigation buttons -->
<a href="ch17-00-oop.html" class="mobile-nav-chapters previous">
<i class="fa fa-angle-left"></i>
</a>
</div>
<a href="ch17-00-oop.html" class="nav-chapters previous" title="You can navigate through the chapters using the arrow keys">
<i class="fa fa-angle-left"></i>
</a>
</div>
<!-- Local fallback for Font Awesome -->
<script>
if ($(".fa").css("font-family") !== "FontAwesome") {
$('<link rel="stylesheet" type="text/css" href="_FontAwesome/css/font-awesome.css">').prependTo('head');
}
</script>
<!-- Livereload script (if served using the cli tool) -->
<script src="highlight.js"></script>
<script src="book.js"></script>
</body>
</html>
Reference in New Issue View Git Blame Copy Permalink