array references call_user_func

[Kudose]

In regards to: http://us2.php.net/manual/en/language.references.pass.php#45310

Can someone please explain to me why this is the case?

<?php

    $arr = array('something' => 'else', 'goes' => 'here');

    function changeIt(&$vals){
            $vals = array_map('strtoupper', $vals);
    }

    print_r($arr); // lower

    changeIt($arr);

    print_r($arr); // upper

    class test {
            static public function changeIt(&$arr){
                    $vals = array_map('strtolower', $arr);
            }
    }

    print_r(test::changeIt($arr)); // lower -- doesn't work

    call_user_func('changeIt', $arr);

    print_r($arr); // upper -- might work, data is already upper

    call_user_func(array('test', 'changeIt'), &$arr);

    print_r($arr); // lower -- doesn't work!!!

    call_user_func(array('test', 'changeIt'), $arr);

    print_r($arr); // lower -- doesn't work!!!

    call_user_func_array(array('test', 'changeIt'), array(&$arr));

    print_r($arr); // lower -- doesn't work

Anyone know of a way around having to explicitly call the function?