function create($class_name)
  {
    DataMapperFactory :: _includeClassFile($class_name);

    $mapper =& new $class_name();
    if(!is_a($mapper, 'AbstractDataMapper'))
      die($class_name . ' does not implement AbstractDataMapper interface');

    return $mapper;
  }
 public function createDataMapper($mapper_path)
 {
   include_once(LIMB_DIR . '/class/core/data_mappers/DataMapperFactory.class.php');
   return DataMapperFactory :: create($mapper_path);
 }