Yeah, that is the 1 case, and ActiveSupport has had a BasicObject for a while now. This is another case where proponents would say it is great that you can undefine a method, but I would say that is a hack for lack of any namespace management. Now that there is a BasicObject I am not sure that there is any practical use for undefining a method- probably only for dealing with namespace collisions, which again seems to point out a language flaw, not a feature of dynamism.