public function logException($exception)
    {
        $category = get_class($exception);
        if ($exception instanceof HttpException) {
            $category = 'Zilf\\web\\HttpException:' . $exception->statusCode;
        } elseif ($exception instanceof \ErrorException) {
            $category .= ':' . $exception->getSeverity();
        }
        Zilf::error($exception, $category);
    }