from sqlalchemy.orm import sessionmaker

class WithSession(object):

    '''a with statement for a database session connection'''

    def __init__(self, engine, autocommit=False):

        self.engine = engine

        self.autocommit=autocommit

    def __enter__(self):

        return self.session

    def __exit__(self,exc_type, exc_value, traceback):

        if exc_type is None:

            if self.autocommit:

                self.session.commit()

        else:

            self.session.rollback()

        self.session.close()