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Home Backend Development PHP Tutorial 使用了单例模式的类,有一些关于其静态成员的问题

使用了单例模式的类,有一些关于其静态成员的问题

Jun 20, 2016 pm 12:44 PM

如下单例模式的数据库类:

class Database{	static private $db;	private function __construct(){	}	static function getInstance(){		if(self::$db){			return self::$db;		}else{			self::$db = new self();			return self::$db;		}			}}
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有一个说法是:静态方法不能调用非静态成员。
那么这个类的定义里有这么一句:self::$db = new self();这个self()方法不就是非静态的构造函数吗?
还是“静态方法不能调用非静态成员”这个说法是不准确的?请各位前辈指教一下。


回复讨论(解决方案)

好吧,问错了,那个是实例化对象的语句,并不是调用成员的

self 和 $this 都是指类本身
只不过前者用于静态方法中,后者用于动态(实例化后的对象)方法中

new 是实例化类,构造函数不可能是静态的

注意,由于历史的原因,关闭掉 E_STRICT 级别检查,php 的类就没有静态不静态了

error_reporting(E_ALL ^ E_NOTICE ^ E_STRICT );class T {  function a() {    echo 'abc';  }}T::a();
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abc

这就是 php 的本原
是不是去掉那些加锁更欢快淋漓呢

self 和 $this 都是指类本身
只不过前者用于静态方法中,后者用于动态(实例化后的对象)方法中

new 是实例化类,构造函数不可能是静态的

注意,由于历史的原因,关闭掉 E_STRICT 级别检查,php 的类就没有静态不静态了


嗯,明白了,谢谢解答
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