public static function getExporter($type) {
        // normalize type
        $className = 'Garp_Content_Export_' . ucfirst($type);
        $obj = new $className();
        if (!$obj instanceof Garp_Content_Export_Abstract) {
            throw new Garp_Content_Export_Exception(
                "Class $className does not implement Garp_Content_Export_Abstract."
            );
        }
        return $obj;
    }