From: Ryan Davis <ryand-ruby@...>
Date: 2012-11-04T08:25:33+09:00
Subject: Re: why does UnboundMethod need to remember the class it was retrieved from (not merely owner)?


On Nov 3, 2012, at 16:30 , Mean L. <lists@ruby-forum.com> wrote:

> Igor Pirnovar wrote in post #1082666:
>> Mean L. wrote in post #1082655:
>> 
>>> This does not answer the question.
>> 
>> How comes?
> 
> Because "it's the rule" is a not a meaningful answer to why?
> 
> If you don't know why, that's ok, neither do I, that just means you need 
> to wait for an answer instead of repeating, "it's the rule".
> 
> AFAICT it should be sufficient to test that the object you are binding 
> to is_a?(owner) (Base.new.is_a?(sub_foo.owner))
> 
> This would also make base_foo and sub_foo equal as they refer to the 
> same foo in base.

Unfortunately, the answer really is because "it's the rule".

The slightly longer answer is "because Matz is worried we'll try to bind a C method (eg Array#join) to a different class and cause a crash". I've proposed the change that gets rid of "the rule" and it got shot down with this explanation. Why we can't just say that the rule is only in effect for C methods is beyond me.

I think it'd be a fantastic change to allow for agent / prototype-based / genetic programming.