getTraceAsString implementation

public function getTraceAsString(Exception $ex) {
    $str = '';
    foreach($ex->getTrace() as $index => $trace) {
        $str .= "#$index {$trace['file']}({$trace['line']}): {$trace['class']}->{$trace['function']}(";
        $args = array();
        foreach($trace['args'] as $arg) {
            if (is_object($arg))
                $args[] = 'Object(' . get_class($arg) . ')';
            elseif (is_array($arg))
                $args[] = 'Array';
            else
                $args[] = var_export($arg, true);
        }
        $str .= join(', ', $args);
        $str .= ")\n";
    }
    $index++;
    $str .= "#$index {main}";

    return $str;
}