chinadns.py 文件源码

def check_handler(value):
    h = None
    HANDLER_PREFIX = "handler_"
    name = HANDLER_PREFIX + "base"
    base_mod = load_mod(PKG_NAME, name)
    if not base_mod:
        print("load module %s failed" % (name), file=sys.stderr)
        sys.exit(1)
    try:
        base_cls = getattr(base_mod, "HandlerBase")
    except AttributeError as e:
        print("err=%s, can't find HandlerBase class" % (e), file=sys.stderr)
        sys.exit(1)

    name = HANDLER_PREFIX + value
    mod = load_mod(PKG_NAME, name)
    if not mod:
        print("load module %s failed" % (name), file=sys.stderr)
        sys.exit(1)
    for v in dir(mod):
        cls = getattr(mod, v)
        if inspect.isclass(cls) and issubclass(cls, base_cls):
            return cls()
    if h is None:
        raise argparse.ArgumentTypeError("%s is an invalid handler" % value)