protected function newDoctrineCacheImpl($namespace)
    {
        $config  = $this->get('config');
        $factory = $config->get('psx_cache_factory');

        if ($factory instanceof \Closure) {
            return $factory($config, $namespace);
        } else {
            return new DoctrineCache\FilesystemCache($this->get('config')->get('psx_path_cache') . '/' . $namespace);
        }
    }