php面向对象编程,php面向对象_PHP教程

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Release: 2016-07-12 08:57:30
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php面向对象编程,php面向对象

面向对象编程的基本原则:

  • 单一职责:一个类,只需要做好一件事
  • 开放封闭:一个类,应该是可扩展的,而不是可修改的
  • 依赖倒置:一个类,不应该强依赖另一个类。每个类对应另外一个类都是可替换的
  • 配置化:尽可能地使用配置,而不是硬编码
  • 面向接口编程:只需要关心接口,不需要关心实现

 1、设置类的属性

<span>class</span><span> ShopProduct {
    </span><span>public</span> <span>$title</span> = 'default product'<span>;
    </span><span>public</span> <span>$producterMainName</span> = 'main name'<span>;
    </span><span>public</span> <span>$producterFirstName</span> = 'first name'<span>;
    </span><span>public</span> <span>$price</span> = 0<span>;
}

</span><span>$product1</span> = <span>new</span><span> ShopProduct();

</span><span>//</span><span>设置属性</span>
<span>$product1</span>->title = "My Antonia"<span>;
</span><span>$product1</span>->producterFirstName = "Cather"<span>;
</span><span>$product1</span>->producterMainName = "Willa"<span>;
</span><span>$product1</span>->price = 5.99<span>;

</span><span>//</span><span>访问</span>
<span>echo</span> 'author: '.<span>$product1</span>->producterFirstName.' '.<span>$product1</span>->producterMainName;
Copy after login

用以上方法设置属性值会有很多问题:

第一:PHP允许动态设置属性,如果拼错或忘记属性名时并不会得到警告。例如错误地把

<span>$product1</span>->producterMainName = "Willa";
Copy after login

写作

<span>$product1</span>->producterSecondName = "Willa";
Copy after login

,当我们输出作者名字的时候,会有意想不到的结果。

第二:类太过松散,我们没有强制设置标题、价格或者产品名称,客户端代码可以确定的是这些属性存在,但是面对的可能是默认值也可能不是,理想情况下,我们希望实例化ShopProduct对象时设置有意义的属性值。

第三:不得不重复做一些经常做的事,比如多次需要完整输出作者的名字,就要重复使用

<span>echo</span> 'author: '.<span>$product1</span>->producterFirstName.' '.<span>$product1</span>->producterMainName;
Copy after login

 

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