From: Robert Klemme <bob.news@...>
Date: 2004-10-23T19:04:11+09:00
Subject: Re: #extend_object only for #extend and not #include


"Gavin Kistner" <gavin@refinery.com> schrieb im Newsbeitrag 
news:DB3F483A-2483-11D9-845E-000A959CF5AC@refinery.com...
> On Oct 22, 2004, at 8:09 AM, Robert Klemme wrote:
>> "Gavin Kistner" <gavin@refinery.com> schrieb im Newsbeitrag
>> news:8529C86C-2430-11D9-A186-000A959CF5AC@refinery.com...
>>> Just thought I'd point out my surprise that the Module#extend_object
>>> callback only fires when #extend is explicitly called, and not when the
>>> module extends the class via #include:
>> Well, that's quite logical, isn't it?  I mean, include and extend are two
>> different cups of tea.
>
> Are they? Other than different receivers (and thus the ability for #extend 
> to operate on instances) are they functionally different and I'm a moron 
> for not realizing it?

Well, maybe I'm the moron.  Lemmesee...  I think, we're both right: include 
and extend are different because they have different receivers: include's 
receiver must be a Module (or sub class) while extend's receiver must be an 
instance.  Behind the scenes of course, extend should do something like 
this - at least conceptually:

def extend(x)
  class << self
    include x
  end
end

I guess the reason why we see differences here is the fact that singleton 
classes are handled specially and thus maybe don't invoke Module#included.

>>   def self.included( o )
>>     p "#{o} just included #{self}"
>>   end
>
> Apparently I didn't know about this. That'll do...thanks! :)

So now you have two options: either recognize include and extend differently 
or treat them alike.  I find this pretty complete: you got the choice. :-)

Btw: *I* didn't know about append_features - so we all have learned 
something. :-)

Kind regards

    robert