@classmethod
def get_log_string(cls, error_type, rp, exc):
    """Return log string to put in error log"""
    assert error_type == 'ListError' or error_type == 'UpdateError' or error_type == 'SpecialFileError', 'Unknown type ' + error_type
    return "%s: '%s' %s" % (error_type, cls.get_indexpath(rp), exc)
