interface DataMapperInterface
    {
            public function find($params);
            public function save($object);
            public function delete($object);
    }

    class DataMapper_User implements DataMapperInterface
    {
            public function find($params)
            {
                    //Execute code to retrieve data from data source
                    return someDataRetrievalMethod($params);
            }

            public function save($object)
            {
                    throw new Exception('Method not yet implemented.');
            }

            public function delete($object)
            {
                    throw new Exception('Method not yet implemented.');
            }
    }

interface DataMapperInterface
    {
            public function find($params);
            public function save($object);
            public function delete($object);
    }

    abstract class DataMapper_User implements DataMapperInterface
    {
            public function find($params)
            {
                    //Execute code to retrieve data from data source
                    return someDataRetrievalMethod($params);
            }

    }