如何使用指针来访问类的内部变量

class talker {
    private $data = 'Hi';
    public function &get() {
        return $this->data;
    }
    public function out() {
        var_dump($this->data);
    }
}

$aa = new talker();
$d = &$aa->get();

$d = array('You');
$aa->out();

---------- PHP ----------
array(1) {
  [0]=>
  string(3) "You"
}
输出完成 (耗时 0 秒) - 正常终止