PHP 继承和静态方法和属性

Question

在 PHP 中不能继承静态属性和方法是否安全？几个例子会有所帮助。

Answer 1

没有。这不是真的。 Static Methods and properties会得到 inherited与非静态方法和属性相同，并遵守相同的 visibility rules:

class A {
    static private $a = 1;
    static protected $b = 2;
    static public $c = 3;
    public static function getA()
    {
        return self::$a;
    }
}

class B extends A {
    public static function getB()
    {
        return self::$b;
    }
}

echo B::getA(); // 1 - called inherited method getA from class A
echo B::getB(); // 2 - accessed inherited property $b from class A
echo A::$c++;   // 3 - incremented public property C in class A
echo B::$c++;   // 4 - because it was incremented previously in A
echo A::$c;     // 5 - because it was incremented previously in B

最后两个是显着的区别。在基类中增加继承的静态属性也会在所有子类中增加它，反之亦然。