类中构造回调函数,注意，回调处要有return才可以;`

class A{    private function getpreuid($uid){        $work = M('work');        $preuid = $uid - 1;        if ($preuid > 0){            $map = array(                'status' => 1,                'uid' => $preuid,                'award_id' => array('gt','1')            );            $w_flag = $work->where($map)->find();            if (!$w_flag){                return $this->getpreuid($preuid);//这里有return 才会有值返回;            }else{                return $preuid;            }        }else{            return 0;        }    }}