Message: Only variables should be passed by reference 이 오류가 무엇인지 알려주세요..

Severity: Runtime Notice

Message: Only variables should be passed by reference

Filename: libraries/Widget.php

Line Number: 21

<?php (defined('BASEPATH')) OR exit('No direct script access allowed');

define('WIDGET', TRUE);

class Widget {    function __construct() {        $this->_assign_libraries();    }

    function run($controller) {        if (strpos($controller, '.') !== FALSE) {            list($controller, $method) = explode('.', $controller);        }

        require_once APPPATH.'controllers/'.$controller.EXT;

        // default method       

if (!isset($method)) $method = 'index';

        // class name       

$class = end(explode('/', $controller));  // 이부분 21번째 에러 

        if ($class =& new $class()) {            if (method_exists($class, $method)) {                           $args = func_get_args();                //return call_user_func_array(array(&$widget, 'index'), array_slice($args, 1));                            return call_user_func_array(array($class, $method), array_slice($args, 1));            }        }    }

    function _assign_libraries() {        $CI =& get_instance();        foreach (get_object_vars($CI) as $key => $object) {            $this->$key =& $CI->$key;        }    }}