class Father{
    public static function getStatic(){
        return new static();
    }
    public static function getSelf(){
        return new self();
    }
}
trait GrandFather{
    public static function getStatic(){
        return new static();
    }
    public static function getSelf(){
        return new self();
    }
}
class Son1{
 use GrandFather;
}
class Son2 extends Father {

}
$o1 = Son1::getStatic();
$o2 = Son2::getStatic();