public function init( $config = [ ] )
    {
        foreach ( $config as $key => $value )
        {
            switch ( $key )
            {
                case 'level':
                    $this->_level = ( int ) $value;
                    break;

                case 'mailer':
                    $this->_mailer = $value;
                    break;

                case 'formatter':
                    $this->_formatter = new $value();
                    break;

                default:
                    // do nothing
                    break;
            }
        }
    }