public function setPublishing($publishing = null)
    {
        if ($publishing === null) {
            $this->_publishing = null;
        } else {
            $this->_publishing = $this->validatePublishing($publishing);
        }

        return $this;
    }
public function setPublishing($publishing = null)
    {
        if ($publishing === null) {
            $this->_publishing = null;
        } else {
            $this->_publishing = $this->validatePublishing($publishing);
        }

        return $this;
    }
public function setPublishing ( $ publishing = null ) { if ( $ publishing === null ) { $ this -> _publishing = null ; } else { $ this -> _publishing = $ this -> validatePublishing ( $ publishing ) ; } return $ this ; }
Sets the publishing date.

@param  \DateTime|null       $publishing

@return Page
Sets the publishing date .