區別PHP中new self() 和 new static()

class Father
{
    public function getNewFather()
    {
        return new self();
    }
  
    public function getNewCaller()
    {
        return new static();
    }
}
  
$f = new Father();
  
var_dump(get_class($f->getNewFather())); // Father
var_dump(get_class($f->getNewCaller())); // Father

class Sun1 extends Father{
  
}
  
$sun1 = new Sun1();
  
var_dump($sun1->getNewFather()); // object(Father)#4 (0) { }
var_dump($sun1->getNewCaller()); // object(Sun1)#4 (0) { }