public function getPathByClass($class, $with_app_namespace = true)
    {
        $class_path = str_replace('\\', DS, $class);
        $class_path = str_replace('_', DS, $class_path) . '.php';

        foreach ($this->app->config('directory.apps') as $app) {
            $file = ($with_app_namespace ? $app['root'] : $app['dir']) . DS . $class_path;
            $file = new FileSystem\File($file);
            if ($file->isExists()) return $file;
        }
        return null;
    }