Add get_called_class support for php < 5.3. It will be slower though as it uses debug_backtrace.

get_called_class.php

<?php

if (!function_exists('get_called_class') && version_compare(PHP_VERSION, '5.3', '<')) {
    function get_called_class() {
        $bt = debug_backtrace();
        $l = 0;
        do {
            $l++;
            $lines = file($bt[$l]['file']);
            $callerLine = $lines[$bt[$l]['line']-1];
            preg_match('/([a-zA-Z0-9\_]+)::'.$bt[$l]['function'].'/', $callerLine, $matches);
        } while ($matches[1] === 'parent' && $matches[1]);	
        return $matches[1];
    }
}