public static function getModel($model, $params = array()) { require_once ST_MODEL_PATH . DIRECTORY_SEPARATOR . 'model.php'; require_once ST_MODEL_PATH . DIRECTORY_SEPARATOR . $model . DIRECTORY_SEPARATOR . $model . '.php'; if (!self::$_model) { $class = ST_MODEL_PREFIX . $model; self::$_model = new $class($params); } return self::$_model; }