__init__.py 文件源码

def get_client_class(api_name, version, version_map):
    """Returns the client class for the requested API version

    :param api_name: the name of the API, e.g. 'compute', 'image', etc
    :param version: the requested API version
    :param version_map: a dict of client classes keyed by version
    :rtype: a client class for the requested API version
    """
    try:
        client_path = version_map[str(version)]
    except (KeyError, ValueError):
        sorted_versions = sorted(version_map.keys(),
                                 key=lambda s: list(map(int, s.split('.'))))
        msg = _(
            "Invalid %(api_name)s client version '%(version)s'. "
            "must be one of: %(version_map)s"
        )
        raise exceptions.UnsupportedVersion(msg % {
            'api_name': api_name,
            'version': version,
            'version_map': ', '.join(sorted_versions),
        })

    return importutils.import_class(client_path)