通過非靜態方法+繼承訪問靜態變量

Question

我有以下結構

class Foo
{
    public static $a = "parent";

    public static function Load()
    {
        return static::$a;
    }

    public function Update()
    {
        return self::$a; 
    }

}

class Bar extends Foo
{
    private static $a = "child";
}

我希望Update函數也能夠返回$ a，但是我無法使其正常工作。

Bar::Load();  //returns child, Correct.
$bar = new Bar();
$bar->Update(); //returns parent, Wrong.

我嘗試了self ::，static ::和get_class（）都沒有成功。

Answer 1

在update()更改self::$a

class Foo
{
    protected static $a = "parent"; // Notice this is now "protected"

    public function child()
    {
        return static::$a; 
    }

    public function parent()
    {
        return self::$a; 
    }
}

class Bar extends Foo
{
    protected static $a = "child"; // Notice this is now "protected"
}

$bar = new Bar();
print $bar->child() . "\n";
print $bar->parent() . "\n";

Answer 2

看我的代碼

class Foo
{
    protected static $a = "parent";

    public static function Load()
    {
        return static::$a;
    }

    public function Update()
    {
        return static::$a; 
    }

}

class Bar extends Foo
{
    protected static $a = "child";
}
Bar::Load();  //returns child, Correct.
$bar = new Bar();
$bar->Update(); //returns child, Correct.