January 2021
Intermediate to advanced
505 pages
9h 45m
Chinese
Content preview from PHP编程：第4版
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158
｜
第
6
章
对象
论你如何设计你的面向对象系统，总可以用
PHP
来实现。下面介绍一些深入这种编程方
法必须了解的关键术语和概念。
术语
每种面向对象的语言都有其独特的术语，但表达的往往是相同的概念。本节介绍
PHP
所
使用的术语，要注意，在其他不同的语言中，某个字面文字相同的术语可能表达的是另
一个意思。
让我们回到
BBS
的用户这个例子中，对于每个用户，我们要跟踪的信息类型是相同的，
而且在每个用户的数据结构中调用的函数也是相同的。当你设计程序时，可以决定用户
的字段，为调用的函数做准备。用
OOP
的术语来说，你正在设计
user
类
，一个类就是
创建对象的一个模板。
对象
是类的实例，在这个例子中，它是一个带有附加代码的用户数据结构。对象和类的
关系类似数据的值和数据类型的关系
：只存在一个整型数据类型，但可能有各种不同的
整数值。类似地，你的程序只定义了一个
user
类，但可以用来创建多个不同的（或相同的）
用户。
对象所带的数据被称为对象的
属性
（
property
），对象所带有的功能函数被称为对象的
方
法
（
method
）。当定义一个类时，你可以定义类的属性名称，并写出类方法的相应代码。
如果你使用了
封装
的办法，调试和维护程序会变得容易很多。封装的思路是
：一个类提
供特定的类方法（接口），给其他要使用这个类的代码来调用，因此外部的代码不能直接
访问对象的数据结构。这样调试就变得简单了，因为你知道要在哪部分代码中找出
Bug
（只
有位于类内部的代码才能改变对象的数据，所以直接找这部分代码即可）。维护也变得容 ...
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.