protected function _parseBlockCallback($m) {
        if (!class_exists('block' . $m[1])) {
            $blockFunction = '<?php class block' . $m[1] . ' extends \Gcs\Framework\Core\Gcs\Framework\Core\Template\Template { public static function ' . $m[1] . '(){ ?> ';
            $blockFunction .= $m[2];
            $blockFunction .= ' <?php } } ?>';

            return $blockFunction;
        }
        else {
            $this->addError('the class "block' . $m[1] . '" already exists', __FILE__, __LINE__, ERROR_FATAL);

            return '';
        }
    }