public function getSortableDirection($direction = null)
    {
        if ( ! is_null($direction))
        {
            return $this->validateSortableDirection($direction);
        }

        return $this->getDefaultSortableDirection();
    }
public function getSortableDirection($direction = null)
    {
        if ( ! is_null($direction))
        {
            return $this->validateSortableDirection($direction);
        }

        return $this->getDefaultSortableDirection();
    }
public function getSortableDirection ( $ direction = null ) { if ( ! is_null ( $ direction ) ) { return $ this -> validateSortableDirection ( $ direction ) ; } return $ this -> getDefaultSortableDirection ( ) ; }
Returns default direction if isset or validates direction

@param string|null $direction
@return string
Returns default direction if isset or validates direction