PHP 包含/需要不传递变量

I am using Joomla, and I am getting the error documented here ("Illegal Variables ..."). The php script is an AJAX script that sends data back to the browser, so this script takes a lot of POST variables, does a database query, then echos the result. I am trying to tighten up security, so I put an include in this script to authenticate the user with the built it Joomla modules. I got the idea from here for the user authentication script.
The authentication script works for some pages, but with others I get the error mentioned above. So I want to include the authentication script without passing any variables to it. Is this possible?

这里有更多细节.

在 ajax 脚本中我有这个:

<?php
    include '/var/www/joomla-auth.php';
...

<?php

define( '_JEXEC', 1 );
define('JPATH_BASE', dirname(__FILE__));
define( 'DS', DIRECTORY_SEPARATOR );
require_once ( JPATH_BASE .DS.'includes'.DS.'defines.php' );
require_once ( JPATH_BASE .DS.'includes'.DS.'framework.php' );

/* Create the Application */
$mainframe =& JFactory::getApplication('site');

/* Make sure we are logged in at all. */
if (JFactory::getUser()->id == 0)
    die("Access denied: login required.");

$user =& JFactory::getUser();

function get_creds(){
    include '/var/www/joomla-auth.php';
    return Array($username,$password);
}

$creds = get_creds();
$username = $creds[0];
$password = $creds[1];
....