php static的三种使用方法

class Product {              

    public static function getNew( ): static {    

        $new = new static;  

        return $new;

    }

}

class SubProduct extends Product{

}

$p1 = Product::getNew( );

$p2 = SubProduct::getNew();

var_dump($p1);    //object(Product)#24

var_dump($p2);    //object(SubProduct)#27