使装饰器同时支持带参数和不带参数

magic_decorator.py

def ban_attr(ban):
    if callable(ban):
        def _wrapper():
            raise AttributeError("Cannot write from Greywood to Dale")
        return _wrapper
    else:
        assert isinstance(ban, bool), TypeError("ban_attr: want bool, got %s" % type(ban))
        def _wrapper(f):
            @wraps(f)
            def __wrapper(*args, **kwargs):
                if ban:
                    raise AttributeError("Cannot write from Greywood to Dale")
                else:
                    return f(*args, **kwargs)
            return __wrapper
        return _wrapper