2022-08-04 06:59:33 +00:00
<!DOCTYPE HTML>
< html lang = "zh" class = "sidebar-visible no-js light" >
< head >
2024-08-13 00:15:53 +00:00
<!-- Book generated using https://github.com/wa - lang/wabook -->
2022-08-04 06:59:33 +00:00
< meta charset = "UTF-8" >
< title > 通过嵌入结构体来扩展类型 - Go语言圣经< / title >
<!-- Custom HTML head -->
< meta content = "text/html; charset=utf-8" http-equiv = "Content-Type" >
2024-08-08 07:47:03 +00:00
< meta name = "description" content = "" >
2022-08-04 06:59:33 +00:00
< meta name = "viewport" content = "width=device-width, initial-scale=1" >
< meta name = "theme-color" content = "#ffffff" / >
2024-08-08 07:47:03 +00:00
< link rel = "icon" href = "../favicon.svg" >
< link rel = "shortcut icon" href = "../favicon.png" >
2024-08-13 00:15:53 +00:00
< link rel = "stylesheet" href = "../static/wabook/css/variables.css" >
< link rel = "stylesheet" href = "../static/wabook/css/general.css" >
< link rel = "stylesheet" href = "../static/wabook/css/chrome.css" >
< link rel = "stylesheet" href = "../static/wabook/css/print.css" media = "print" >
2022-08-04 06:59:33 +00:00
<!-- Fonts -->
2024-08-13 00:15:53 +00:00
< link rel = "stylesheet" href = "../static/wabook/FontAwesome/css/font-awesome.css" >
< link rel = "stylesheet" href = "../static/wabook/fonts/fonts.css" >
2022-08-04 06:59:33 +00:00
<!-- Highlight.js Stylesheets -->
2024-08-13 00:15:53 +00:00
< link rel = "stylesheet" href = "../static/wabook/highlight.css" >
< link rel = "stylesheet" href = "../static/wabook/tomorrow-night.css" >
< link rel = "stylesheet" href = "../static/wabook/ayu-highlight.css" >
2022-08-04 06:59:33 +00:00
<!-- Custom theme stylesheets -->
< / head >
< body >
<!-- Provide site root to javascript -->
< script type = "text/javascript" >
var path_to_root = "../";
var default_theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? "navy" : "light";
< / script >
<!-- Work around some values being stored in localStorage wrapped in quotes -->
< script type = "text/javascript" >
try {
2024-08-13 00:15:53 +00:00
var theme = localStorage.getItem('wabook-theme');
var sidebar = localStorage.getItem('wabook-sidebar');
2022-08-04 06:59:33 +00:00
if (theme.startsWith('"') & & theme.endsWith('"')) {
2024-08-13 00:15:53 +00:00
localStorage.setItem('wabook-theme', theme.slice(1, theme.length - 1));
2022-08-04 06:59:33 +00:00
}
if (sidebar.startsWith('"') & & sidebar.endsWith('"')) {
2024-08-13 00:15:53 +00:00
localStorage.setItem('wabook-sidebar', sidebar.slice(1, sidebar.length - 1));
2022-08-04 06:59:33 +00:00
}
} catch (e) { }
< / script >
<!-- Set the theme before any content is loaded, prevents flash -->
< script type = "text/javascript" >
var theme;
2024-08-13 00:15:53 +00:00
try { theme = localStorage.getItem('wabook-theme'); } catch(e) { }
2022-08-04 06:59:33 +00:00
if (theme === null || theme === undefined) { theme = default_theme; }
var html = document.querySelector('html');
html.classList.remove('no-js')
html.classList.remove('light')
html.classList.add(theme);
html.classList.add('js');
< / script >
<!-- Hide / unhide sidebar before it is displayed -->
< script type = "text/javascript" >
var html = document.querySelector('html');
var sidebar = 'hidden';
if (document.body.clientWidth >= 1080) {
2024-08-13 00:15:53 +00:00
try { sidebar = localStorage.getItem('wabook-sidebar'); } catch(e) { }
2022-08-04 06:59:33 +00:00
sidebar = sidebar || 'visible';
}
html.classList.remove('sidebar-visible');
html.classList.add("sidebar-" + sidebar);
< / script >
< nav id = "sidebar" class = "sidebar" aria-label = "Table of contents" >
< div class = "sidebar-scrollbox" >
2024-08-08 07:47:03 +00:00
< ol class = "chapter" >
< li class = "chapter-item expanded " >
< a href = "../index.html" > Go语言圣经< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../preface-zh.html" > 译者序< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../preface.html" > 前言< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch1/ch1.html" > < strong aria-hidden = "true" > 1.< / strong > 入门< / a >
< / li >
< ol class = "section" >
< li class = "chapter-item expanded " >
< a href = "../ch1/ch1-01.html" > < strong aria-hidden = "true" > 1.1.< / strong > Hello, World< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch1/ch1-02.html" > < strong aria-hidden = "true" > 1.2.< / strong > 命令行参数< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch1/ch1-03.html" > < strong aria-hidden = "true" > 1.3.< / strong > 查找重复的行< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch1/ch1-04.html" > < strong aria-hidden = "true" > 1.4.< / strong > GIF动画< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch1/ch1-05.html" > < strong aria-hidden = "true" > 1.5.< / strong > 获取URL< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch1/ch1-06.html" > < strong aria-hidden = "true" > 1.6.< / strong > 并发获取多个URL< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch1/ch1-07.html" > < strong aria-hidden = "true" > 1.7.< / strong > Web服务< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch1/ch1-08.html" > < strong aria-hidden = "true" > 1.8.< / strong > 本章要点< / a >
< / li >
< / ol >
< li class = "chapter-item expanded " >
< a href = "../ch2/ch2.html" > < strong aria-hidden = "true" > 2.< / strong > 程序结构< / a >
< / li >
< ol class = "section" >
< li class = "chapter-item expanded " >
< a href = "../ch2/ch2-01.html" > < strong aria-hidden = "true" > 2.1.< / strong > 命名< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch2/ch2-02.html" > < strong aria-hidden = "true" > 2.2.< / strong > 声明< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch2/ch2-03.html" > < strong aria-hidden = "true" > 2.3.< / strong > 变量< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch2/ch2-04.html" > < strong aria-hidden = "true" > 2.4.< / strong > 赋值< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch2/ch2-05.html" > < strong aria-hidden = "true" > 2.5.< / strong > 类型< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch2/ch2-06.html" > < strong aria-hidden = "true" > 2.6.< / strong > 包和文件< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch2/ch2-07.html" > < strong aria-hidden = "true" > 2.7.< / strong > 作用域< / a >
< / li >
< / ol >
< li class = "chapter-item expanded " >
< a href = "../ch3/ch3.html" > < strong aria-hidden = "true" > 3.< / strong > 基础数据类型< / a >
< / li >
< ol class = "section" >
< li class = "chapter-item expanded " >
< a href = "../ch3/ch3-01.html" > < strong aria-hidden = "true" > 3.1.< / strong > 整型< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch3/ch3-02.html" > < strong aria-hidden = "true" > 3.2.< / strong > 浮点数< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch3/ch3-03.html" > < strong aria-hidden = "true" > 3.3.< / strong > 复数< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch3/ch3-04.html" > < strong aria-hidden = "true" > 3.4.< / strong > 布尔型< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch3/ch3-05.html" > < strong aria-hidden = "true" > 3.5.< / strong > 字符串< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch3/ch3-06.html" > < strong aria-hidden = "true" > 3.6.< / strong > 常量< / a >
< / li >
< / ol >
< li class = "chapter-item expanded " >
< a href = "../ch4/ch4.html" > < strong aria-hidden = "true" > 4.< / strong > 复合数据类型< / a >
< / li >
< ol class = "section" >
< li class = "chapter-item expanded " >
< a href = "../ch4/ch4-01.html" > < strong aria-hidden = "true" > 4.1.< / strong > 数组< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch4/ch4-02.html" > < strong aria-hidden = "true" > 4.2.< / strong > Slice< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch4/ch4-03.html" > < strong aria-hidden = "true" > 4.3.< / strong > Map< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch4/ch4-04.html" > < strong aria-hidden = "true" > 4.4.< / strong > 结构体< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch4/ch4-05.html" > < strong aria-hidden = "true" > 4.5.< / strong > JSON< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch4/ch4-06.html" > < strong aria-hidden = "true" > 4.6.< / strong > 文本和HTML模板< / a >
< / li >
< / ol >
< li class = "chapter-item expanded " >
< a href = "../ch5/ch5.html" > < strong aria-hidden = "true" > 5.< / strong > 函数< / a >
< / li >
< ol class = "section" >
< li class = "chapter-item expanded " >
< a href = "../ch5/ch5-01.html" > < strong aria-hidden = "true" > 5.1.< / strong > 函数声明< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch5/ch5-02.html" > < strong aria-hidden = "true" > 5.2.< / strong > 递归< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch5/ch5-03.html" > < strong aria-hidden = "true" > 5.3.< / strong > 多返回值< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch5/ch5-04.html" > < strong aria-hidden = "true" > 5.4.< / strong > 错误< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch5/ch5-05.html" > < strong aria-hidden = "true" > 5.5.< / strong > 函数值< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch5/ch5-06.html" > < strong aria-hidden = "true" > 5.6.< / strong > 匿名函数< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch5/ch5-07.html" > < strong aria-hidden = "true" > 5.7.< / strong > 可变参数< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch5/ch5-08.html" > < strong aria-hidden = "true" > 5.8.< / strong > Deferred函数< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch5/ch5-09.html" > < strong aria-hidden = "true" > 5.9.< / strong > Panic异常< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch5/ch5-10.html" > < strong aria-hidden = "true" > 5.10.< / strong > Recover捕获异常< / a >
< / li >
< / ol >
< li class = "chapter-item expanded " >
< a href = "../ch6/ch6.html" > < strong aria-hidden = "true" > 6.< / strong > 方法< / a >
< / li >
< ol class = "section" >
< li class = "chapter-item expanded " >
< a href = "../ch6/ch6-01.html" > < strong aria-hidden = "true" > 6.1.< / strong > 方法声明< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch6/ch6-02.html" > < strong aria-hidden = "true" > 6.2.< / strong > 基于指针对象的方法< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch6/ch6-03.html" class = "active" > < strong aria-hidden = "true" > 6.3.< / strong > 通过嵌入结构体来扩展类型< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch6/ch6-04.html" > < strong aria-hidden = "true" > 6.4.< / strong > 方法值和方法表达式< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch6/ch6-05.html" > < strong aria-hidden = "true" > 6.5.< / strong > 示例: Bit数组< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch6/ch6-06.html" > < strong aria-hidden = "true" > 6.6.< / strong > 封装< / a >
< / li >
< / ol >
< li class = "chapter-item expanded " >
< a href = "../ch7/ch7.html" > < strong aria-hidden = "true" > 7.< / strong > 接口< / a >
< / li >
< ol class = "section" >
< li class = "chapter-item expanded " >
< a href = "../ch7/ch7-01.html" > < strong aria-hidden = "true" > 7.1.< / strong > 接口是合约< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch7/ch7-02.html" > < strong aria-hidden = "true" > 7.2.< / strong > 接口类型< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch7/ch7-03.html" > < strong aria-hidden = "true" > 7.3.< / strong > 实现接口的条件< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch7/ch7-04.html" > < strong aria-hidden = "true" > 7.4.< / strong > flag.Value接口< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch7/ch7-05.html" > < strong aria-hidden = "true" > 7.5.< / strong > 接口值< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch7/ch7-06.html" > < strong aria-hidden = "true" > 7.6.< / strong > sort.Interface接口< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch7/ch7-07.html" > < strong aria-hidden = "true" > 7.7.< / strong > http.Handler接口< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch7/ch7-08.html" > < strong aria-hidden = "true" > 7.8.< / strong > error接口< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch7/ch7-09.html" > < strong aria-hidden = "true" > 7.9.< / strong > 示例: 表达式求值< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch7/ch7-10.html" > < strong aria-hidden = "true" > 7.10.< / strong > 类型断言< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch7/ch7-11.html" > < strong aria-hidden = "true" > 7.11.< / strong > 基于类型断言识别错误类型< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch7/ch7-12.html" > < strong aria-hidden = "true" > 7.12.< / strong > 通过类型断言查询接口< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch7/ch7-13.html" > < strong aria-hidden = "true" > 7.13.< / strong > 类型分支< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch7/ch7-14.html" > < strong aria-hidden = "true" > 7.14.< / strong > 示例: 基于标记的XML解码< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch7/ch7-15.html" > < strong aria-hidden = "true" > 7.15.< / strong > 补充几点< / a >
< / li >
< / ol >
< li class = "chapter-item expanded " >
< a href = "../ch8/ch8.html" > < strong aria-hidden = "true" > 8.< / strong > Goroutines和Channels< / a >
< / li >
< ol class = "section" >
< li class = "chapter-item expanded " >
< a href = "../ch8/ch8-01.html" > < strong aria-hidden = "true" > 8.1.< / strong > Goroutines< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch8/ch8-02.html" > < strong aria-hidden = "true" > 8.2.< / strong > 示例: 并发的Clock服务< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch8/ch8-03.html" > < strong aria-hidden = "true" > 8.3.< / strong > 示例: 并发的Echo服务< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch8/ch8-04.html" > < strong aria-hidden = "true" > 8.4.< / strong > Channels< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch8/ch8-05.html" > < strong aria-hidden = "true" > 8.5.< / strong > 并发的循环< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch8/ch8-06.html" > < strong aria-hidden = "true" > 8.6.< / strong > 示例: 并发的Web爬虫< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch8/ch8-07.html" > < strong aria-hidden = "true" > 8.7.< / strong > 基于select的多路复用< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch8/ch8-08.html" > < strong aria-hidden = "true" > 8.8.< / strong > 示例: 并发的目录遍历< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch8/ch8-09.html" > < strong aria-hidden = "true" > 8.9.< / strong > 并发的退出< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch8/ch8-10.html" > < strong aria-hidden = "true" > 8.10.< / strong > 示例: 聊天服务< / a >
< / li >
< / ol >
< li class = "chapter-item expanded " >
< a href = "../ch9/ch9.html" > < strong aria-hidden = "true" > 9.< / strong > 基于共享变量的并发< / a >
< / li >
< ol class = "section" >
< li class = "chapter-item expanded " >
< a href = "../ch9/ch9-01.html" > < strong aria-hidden = "true" > 9.1.< / strong > 竞争条件< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch9/ch9-02.html" > < strong aria-hidden = "true" > 9.2.< / strong > sync.Mutex互斥锁< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch9/ch9-03.html" > < strong aria-hidden = "true" > 9.3.< / strong > sync.RWMutex读写锁< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch9/ch9-04.html" > < strong aria-hidden = "true" > 9.4.< / strong > 内存同步< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch9/ch9-05.html" > < strong aria-hidden = "true" > 9.5.< / strong > sync.Once惰性初始化< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch9/ch9-06.html" > < strong aria-hidden = "true" > 9.6.< / strong > 竞争条件检测< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch9/ch9-07.html" > < strong aria-hidden = "true" > 9.7.< / strong > 示例: 并发的非阻塞缓存< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch9/ch9-08.html" > < strong aria-hidden = "true" > 9.8.< / strong > Goroutines和线程< / a >
< / li >
< / ol >
< li class = "chapter-item expanded " >
< a href = "../ch10/ch10.html" > < strong aria-hidden = "true" > 10.< / strong > 包和工具< / a >
< / li >
< ol class = "section" >
< li class = "chapter-item expanded " >
< a href = "../ch10/ch10-01.html" > < strong aria-hidden = "true" > 10.1.< / strong > 包简介< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch10/ch10-02.html" > < strong aria-hidden = "true" > 10.2.< / strong > 导入路径< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch10/ch10-03.html" > < strong aria-hidden = "true" > 10.3.< / strong > 包声明< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch10/ch10-04.html" > < strong aria-hidden = "true" > 10.4.< / strong > 导入声明< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch10/ch10-05.html" > < strong aria-hidden = "true" > 10.5.< / strong > 包的匿名导入< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch10/ch10-06.html" > < strong aria-hidden = "true" > 10.6.< / strong > 包和命名< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch10/ch10-07.html" > < strong aria-hidden = "true" > 10.7.< / strong > 工具< / a >
< / li >
< / ol >
< li class = "chapter-item expanded " >
< a href = "../ch11/ch11.html" > < strong aria-hidden = "true" > 11.< / strong > 测试< / a >
< / li >
< ol class = "section" >
< li class = "chapter-item expanded " >
< a href = "../ch11/ch11-01.html" > < strong aria-hidden = "true" > 11.1.< / strong > go test< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch11/ch11-02.html" > < strong aria-hidden = "true" > 11.2.< / strong > 测试函数< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch11/ch11-03.html" > < strong aria-hidden = "true" > 11.3.< / strong > 测试覆盖率< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch11/ch11-04.html" > < strong aria-hidden = "true" > 11.4.< / strong > 基准测试< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch11/ch11-05.html" > < strong aria-hidden = "true" > 11.5.< / strong > 剖析< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch11/ch11-06.html" > < strong aria-hidden = "true" > 11.6.< / strong > 示例函数< / a >
< / li >
< / ol >
< li class = "chapter-item expanded " >
< a href = "../ch12/ch12.html" > < strong aria-hidden = "true" > 12.< / strong > 反射< / a >
< / li >
< ol class = "section" >
< li class = "chapter-item expanded " >
< a href = "../ch12/ch12-01.html" > < strong aria-hidden = "true" > 12.1.< / strong > 为何需要反射?< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch12/ch12-02.html" > < strong aria-hidden = "true" > 12.2.< / strong > reflect.Type和reflect.Value< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch12/ch12-03.html" > < strong aria-hidden = "true" > 12.3.< / strong > Display递归打印< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch12/ch12-04.html" > < strong aria-hidden = "true" > 12.4.< / strong > 示例: 编码S表达式< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch12/ch12-05.html" > < strong aria-hidden = "true" > 12.5.< / strong > 通过reflect.Value修改值< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch12/ch12-06.html" > < strong aria-hidden = "true" > 12.6.< / strong > 示例: 解码S表达式< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch12/ch12-07.html" > < strong aria-hidden = "true" > 12.7.< / strong > 获取结构体字段标签< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch12/ch12-08.html" > < strong aria-hidden = "true" > 12.8.< / strong > 显示一个类型的方法集< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch12/ch12-09.html" > < strong aria-hidden = "true" > 12.9.< / strong > 几点忠告< / a >
< / li >
< / ol >
< li class = "chapter-item expanded " >
< a href = "../ch13/ch13.html" > < strong aria-hidden = "true" > 13.< / strong > 底层编程< / a >
< / li >
< ol class = "section" >
< li class = "chapter-item expanded " >
< a href = "../ch13/ch13-01.html" > < strong aria-hidden = "true" > 13.1.< / strong > unsafe.Sizeof, Alignof 和 Offsetof< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch13/ch13-02.html" > < strong aria-hidden = "true" > 13.2.< / strong > unsafe.Pointer< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch13/ch13-03.html" > < strong aria-hidden = "true" > 13.3.< / strong > 示例: 深度相等判断< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch13/ch13-04.html" > < strong aria-hidden = "true" > 13.4.< / strong > 通过cgo调用C代码< / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../ch13/ch13-05.html" > < strong aria-hidden = "true" > 13.5.< / strong > 几点忠告< / a >
< / li >
< / ol >
< li class = "chapter-item expanded " >
< a href = "../appendix/appendix.html" > < strong aria-hidden = "true" > 14.< / strong > 附录< / a >
< / li >
< ol class = "section" >
< li class = "chapter-item expanded " >
< a href = "../appendix/appendix-a-errata.html" > < strong aria-hidden = "true" > 14.1.< / strong > 附录A： < / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../appendix/appendix-b-author.html" > < strong aria-hidden = "true" > 14.2.< / strong > 附录B： < / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../appendix/appendix-c-cpoyright.html" > < strong aria-hidden = "true" > 14.3.< / strong > 附录C： < / a >
< / li >
< li class = "chapter-item expanded " >
< a href = "../appendix/appendix-d-translations.html" > < strong aria-hidden = "true" > 14.4.< / strong > 附录D： < / a >
< / li >
< / ol >
< / ol >
< / div >
2022-08-04 06:59:33 +00:00
< div id = "sidebar-resize-handle" class = "sidebar-resize-handle" > < / div >
< / nav >
< div id = "page-wrapper" class = "page-wrapper" >
< div class = "page" >
< div id = "menu-bar-hover-placeholder" > < / div >
< div id = "menu-bar" class = "menu-bar sticky bordered" >
< div class = "left-buttons" >
< button id = "sidebar-toggle" class = "icon-button" type = "button" title = "Toggle Table of Contents" aria-label = "Toggle Table of Contents" aria-controls = "sidebar" >
< i class = "fa fa-bars" > < / i >
< / button >
< button id = "theme-toggle" class = "icon-button" type = "button" title = "Change theme" aria-label = "Change theme" aria-haspopup = "true" aria-expanded = "false" aria-controls = "theme-list" >
< i class = "fa fa-paint-brush" > < / i >
< / button >
< ul id = "theme-list" class = "theme-popup" aria-label = "Themes" role = "menu" >
< li role = "none" > < button role = "menuitem" class = "theme" id = "light" > Light (default)< / button > < / li >
< li role = "none" > < button role = "menuitem" class = "theme" id = "coal" > Coal< / button > < / li >
< li role = "none" > < button role = "menuitem" class = "theme" id = "navy" > Navy< / button > < / li >
< li role = "none" > < button role = "menuitem" class = "theme" id = "ayu" > Ayu< / button > < / li >
< / ul >
2024-08-08 07:47:03 +00:00
< / div >
2022-08-04 06:59:33 +00:00
2024-08-08 07:47:03 +00:00
< h1 class = "menu-title" > < a href = "../index.html" > Go语言圣经< / a > < / h1 >
2022-08-04 06:59:33 +00:00
< div class = "right-buttons" >
2024-08-08 07:47:03 +00:00
< a href = "https://github.com/gopl-zh/gopl-zh.github.com" title = "Git repository" aria-label = "Git repository" >
2022-08-04 06:59:33 +00:00
< i id = "git-repository-button" class = "fa fa-github" > < / i >
< / a >
2024-08-08 07:47:03 +00:00
< a href = "https://github.com/gopl-zh/gopl-zh.github.com/edit/master/ch6/ch6-03.md" title = "Suggest an edit" aria-label = "Suggest an edit" >
2022-08-04 06:59:33 +00:00
< i id = "git-edit-button" class = "fa fa-edit" > < / i >
< / a >
< / div >
< / div >
<!-- Apply ARIA attributes after the sidebar and the sidebar toggle button are added to the DOM -->
< script type = "text/javascript" >
document.getElementById('sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible');
document.getElementById('sidebar').setAttribute('aria-hidden', sidebar !== 'visible');
Array.from(document.querySelectorAll('#sidebar a')).forEach(function(link) {
link.setAttribute('tabIndex', sidebar === 'visible' ? 0 : -1);
});
< / script >
< div id = "content" class = "content" >
<!-- Page table of contents -->
< div class = "sidetoc" > < nav class = "pagetoc" > < / nav > < / div >
2024-08-08 07:47:03 +00:00
2022-08-04 06:59:33 +00:00
< main >
2024-08-13 00:15:53 +00:00
< ul dir = "auto" > < li > < em > 凹语言(Go实现, 面向WASM设计): < a href = "https://github.com/wa-lang/wa" > https://github.com/wa-lang/wa< / a > < / em > < / li > < li > < em > WaBook(Go语言实现的MD电子书构建工具): < a href = "https://github.com/wa-lang/wabook" > https://github.com/wa-lang/wabook< / a > < / em > < / li > < / ul > < hr >
2022-08-04 06:59:33 +00:00
2024-08-08 07:47:03 +00:00
< h2 > 6.3. 通过嵌入结构体来扩展类型< / h2 >
2022-08-04 06:59:33 +00:00
< p > 来看看ColoredPoint这个类型： < / p >
2024-08-08 07:47:03 +00:00
< p > <!-- raw HTML omitted --> <!-- raw HTML omitted --> gopl.io/ch6/coloredpoint<!-- raw HTML omitted --> <!-- raw HTML omitted --> < / p >
< pre > < code class = "language-go" > import " image/color"
type Point struct{ X, Y float64 }
type ColoredPoint struct {
Point
Color color.RGBA
}
2022-08-04 06:59:33 +00:00
< / code > < / pre >
< p > 我们完全可以将ColoredPoint定义为一个有三个字段的struct， ， ， ， ， ， ， < / p >
2024-08-08 07:47:03 +00:00
< pre > < code class = "language-go" > var cp ColoredPoint
cp.X = 1
fmt.Println(cp.Point.X) // " 1"
cp.Point.Y = 2
fmt.Println(cp.Y) // " 2"
2022-08-04 06:59:33 +00:00
< / code > < / pre >
< p > 对于Point中的方法我们也有类似的用法， ， ： < / p >
2024-08-08 07:47:03 +00:00
< pre > < code class = "language-go" > red := color.RGBA{255, 0, 0, 255}
blue := color.RGBA{0, 0, 255, 255}
var p = ColoredPoint{Point{1, 1}, red}
var q = ColoredPoint{Point{5, 4}, blue}
fmt.Println(p.Distance(q.Point)) // " 5"
p.ScaleBy(2)
q.ScaleBy(2)
fmt.Println(p.Distance(q.Point)) // " 10"
2022-08-04 06:59:33 +00:00
< / code > < / pre >
< p > Point类的方法也被引入了ColoredPoint。用这种方式， ， ， ， < / p >
< p > 读者如果对基于类来实现面向对象的语言比较熟悉的话， ， ， " is a" Point类型。但这是错误的理解。请注意上面例子中对Distance方法的调用。Distance有一个参数是Point类型， ， ， ： < / p >
2024-08-08 07:47:03 +00:00
< pre > < code class = "language-go" > p.Distance(q) // compile error: cannot use q (ColoredPoint) as Point
2022-08-04 06:59:33 +00:00
< / code > < / pre >
< p > 一个ColoredPoint并不是一个Point， " has a" Point， ， ， ： < / p >
2024-08-08 07:47:03 +00:00
< pre > < code class = "language-go" > func (p ColoredPoint) Distance(q Point) float64 {
return p.Point.Distance(q)
}
func (p *ColoredPoint) ScaleBy(factor float64) {
p.Point.ScaleBy(factor)
}
2022-08-04 06:59:33 +00:00
< / code > < / pre >
< p > 当Point.Distance被第一个包装方法调用时， ， ， ， ， < / p >
< p > 在类型中内嵌的匿名字段也可能是一个命名类型的指针， （ ： ） < / p >
2024-08-08 07:47:03 +00:00
< pre > < code class = "language-go" > type ColoredPoint struct {
*Point
Color color.RGBA
}
p := ColoredPoint{& Point{1, 1}, red}
q := ColoredPoint{& Point{5, 4}, blue}
fmt.Println(p.Distance(*q.Point)) // " 5"
q.Point = p.Point // p and q now share the same Point
p.ScaleBy(2)
fmt.Println(*p.Point, *q.Point) // " {2 2} {2 2}"
2022-08-04 06:59:33 +00:00
< / code > < / pre >
< p > 一个struct类型也可能会有多个匿名字段。我们将ColoredPoint定义为下面这样： < / p >
2024-08-08 07:47:03 +00:00
< pre > < code class = "language-go" > type ColoredPoint struct {
Point
color.RGBA
}
2022-08-04 06:59:33 +00:00
< / code > < / pre >
< p > 然后这种类型的值便会拥有Point和RGBA类型的所有方法， ， ， ， ， ， ， < / p >
< p > 方法只能在命名类型（ ） ， ， < / p >
2022-09-06 12:13:56 +00:00
< p > 下面是一个小trick。这个例子展示了简单的cache， ， （ ） ： < / p >
2024-08-08 07:47:03 +00:00
< pre > < code class = "language-go" > var (
mu sync.Mutex // guards mapping
mapping = make(map[string]string)
)
func Lookup(key string) string {
mu.Lock()
v := mapping[key]
mu.Unlock()
return v
}
2022-08-04 06:59:33 +00:00
< / code > < / pre >
< p > 下面这个版本在功能上是一致的， ： < / p >
2024-08-08 07:47:03 +00:00
< pre > < code class = "language-go" > var cache = struct {
sync.Mutex
mapping map[string]string
}{
mapping: make(map[string]string),
}
func Lookup(key string) string {
cache.Lock()
v := cache.mapping[key]
cache.Unlock()
return v
}
2022-08-04 06:59:33 +00:00
< / code > < / pre >
< p > 我们给新的变量起了一个更具表达性的名字： ， ， < / p >
2024-08-08 07:47:03 +00:00
< hr > < table > < tr > < td > < img width = "222px" src = "https://chai2010.cn/advanced-go-programming-book/css.png" > < / td > < td > < img width = "222px" src = "https://chai2010.cn/advanced-go-programming-book/cch.png" > < / td > < / tr > < / table >
< div id = "giscus-container" > < / div >
2022-08-04 06:59:33 +00:00
2024-08-08 07:47:03 +00:00
< footer class = "page-footer" >
< span > © 2015-2016 | < a href = "https://github.com/gopl-zh" > Go语言圣经中文版< / a > , 仅学习交流使用< / span >
< / footer >
2022-08-04 06:59:33 +00:00
< / main >
< nav class = "nav-wrapper" aria-label = "Page navigation" >
<!-- Mobile navigation buttons -->
2024-08-08 07:47:03 +00:00
< a rel = "prev" href = "../ch6/ch6-02.html" class = "mobile-nav-chapters previous" title = "Previous chapter" aria-label = "Previous chapter" aria-keyshortcuts = "Left" >
2022-08-04 06:59:33 +00:00
< i class = "fa fa-angle-left" > < / i >
< / a >
2024-08-08 07:47:03 +00:00
<!-- ../ch6/ch6 - 04.html -->
< a rel = "next" href = "../ch6/ch6-04.html" class = "mobile-nav-chapters next" title = "Next chapter" aria-label = "Next chapter" aria-keyshortcuts = "Right" >
2022-08-04 06:59:33 +00:00
< i class = "fa fa-angle-right" > < / i >
< / a >
< div style = "clear: both" > < / div >
< / nav >
< / div >
< / div >
< nav class = "nav-wide-wrapper" aria-label = "Page navigation" >
2024-08-08 07:47:03 +00:00
< a rel = "prev" href = "../ch6/ch6-02.html" class = "nav-chapters previous" title = "Previous chapter" aria-label = "Previous chapter" aria-keyshortcuts = "Left" >
2022-08-04 06:59:33 +00:00
< i class = "fa fa-angle-left" > < / i >
< / a >
2024-08-08 07:47:03 +00:00
< a rel = "next" href = "../ch6/ch6-04.html" class = "nav-chapters next" title = "Next chapter" aria-label = "Next chapter" aria-keyshortcuts = "Right" >
2022-08-04 06:59:33 +00:00
< i class = "fa fa-angle-right" > < / i >
< / a >
2024-08-08 07:47:03 +00:00
< / nav >
2022-08-04 06:59:33 +00:00
< / div >
2024-08-08 07:47:03 +00:00
< script type = "text/javascript" >
2022-08-04 06:59:33 +00:00
window.playground_copyable = true;
< / script >
2024-08-13 00:15:53 +00:00
< script src = "../static/wabook/mark.min.js" type = "text/javascript" charset = "utf-8" > < / script >
< script src = "../static/wabook/clipboard.min.js" type = "text/javascript" charset = "utf-8" > < / script >
< script src = "../static/wabook/highlight.js" type = "text/javascript" charset = "utf-8" > < / script >
< script src = "../static/wabook/book.js" type = "text/javascript" charset = "utf-8" > < / script >
2022-08-04 06:59:33 +00:00
< script type = "text/javascript" charset = "utf-8" >
2024-08-08 07:47:03 +00:00
var pagePath = "ch6/ch6-03.md"
2022-08-04 06:59:33 +00:00
< / script >
<!-- Custom JS scripts -->
2024-08-13 00:15:53 +00:00
< script src = "../static/wabook/giscus.js" type = "text/javascript" charset = "utf-8" > < / script >
2022-08-04 06:59:33 +00:00
2024-08-08 07:47:03 +00:00
2022-08-04 06:59:33 +00:00
< / body >
< / html >
