public function addApp(string $path, $ext, string $module)
    {
        $ext_key = empty($ext) ? '_' : $ext;
        if (!isset($this->apps[$ext_key]))
        {
            $this->apps[$ext_key] = array(
                'path' => $path,
                'module' => $module, 
                'route' => $this->route, 
                'ext' => $ext,
                'depth' => $this->depth
            );
        }
        return $this;
    }