__clone方法为什么还是浅拷贝？
class E
{
public $age = 0;
public $username = "";
public $obj = null;
public function __clone()
{
// TODO: Implement __clone() method.
$this->obj = clone $this->obj;
}
}
class F {
public $sex = 0;
}
$e = new E();
$e->obj = new F();
$f = clone $e;
$f->obj->sex = 8;
var_dump($f->obj->sex);//int(8)，为什么还是8，应该为0啊
