python类features()的实例源码

def connections_support_transactions():
    """
    Returns True if all connections support transactions.
    """
    return all(conn.features.supports_transactions
               for conn in connections.all())

def skipIfDBFeature(*features):
    """
    Skip a test if a database has at least one of the named features.
    """
    return _deferredSkip(
        lambda: any(getattr(connection.features, feature, False) for feature in features),
        "Database has feature(s) %s" % ", ".join(features)
    )

def skipUnlessDBFeature(*features):
    """
    Skip a test unless a database has all the named features.
    """
    return _deferredSkip(
        lambda: not all(getattr(connection.features, feature, False) for feature in features),
        "Database doesn't support feature(s): %s" % ", ".join(features)
    )