function &_get_datasource()
 {
     if (!isset($this->parameters['datasource_path'])) {
         $this->parameters['datasource_path'] = '/fetch_sub_branch_datasource';
     }
     $ds =& parent::_get_datasource();
     return $ds;
 }
 function &_get_datasource()
 {
     if (!isset($this->parameters['datasource_path'])) {
         $this->parameters['datasource_path'] = '/fetch_sub_branch_datasource';
     }
     $ds =& parent::_get_datasource();
     if (!is_a($ds, 'fetch_sub_branch_datasource')) {
         error('not allowed type of datasource, should be inherited from fetch_sub_branch_datasource class', __FILE__ . ' : ' . __LINE__ . ' : ' . __FUNCTION__, array('datasource' => get_class($ds)));
     }
     return $ds;
 }