function _setRefreshTime() 
    {
        if (is_null($this->_lifeTime)) {
            $this->_refreshTime = null;
        } else {
            $this->_refreshTime = time() - $this->_lifeTime;
        }
    }
function _setRefreshTime() 
    {
        if (is_null($this->_lifeTime)) {
            $this->_refreshTime = null;
        } else {
            $this->_refreshTime = time() - $this->_lifeTime;
        }
    }
function _setRefreshTime ( ) { if ( is_null ( $ this -> _lifeTime ) ) { $ this -> _refreshTime = null ; } else { $ this -> _refreshTime = time ( ) - $ this -> _lifeTime ; } }
Compute & set the refresh time

@access private
Compute & set the refresh time