php - 在非静态方法+继承中访问静态变量

Question

我有以下结构

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";
}

我希望更新函数也能够返回 $a，但我无法让它工作。

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

我试过 self::， static::和 get_class() 没有成功。

Answer 1

更改self::$a在 update()

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";