From: ara.t.howard@...
Date: 2006-06-13T02:29:46+09:00
Subject: Re: Why the lack of mixing-in support for Class methods?

On Tue, 13 Jun 2006 transfire@gmail.com wrote:

>
> Daniel Schierbeck wrote:
>> Logan Capaldo wrote:
>>> Then you have multiple inheritance.
>>
>> Yes.
>
> Not really. Mulitple Inheritance provides orthogonal heirarchies.
> Ruby's is strictly linear. If what you say were true then Ruby would
> already be MI since modules can be used to add behavior to both class
> and instance levels, and readily associated together as well, as Ara's
> example clearly demonstrates. To think this consititutes MI and thus
> making specialized restrictions of code separation to repress it, only
> serves to complixify the situation, not the other way around. It's like
> trying to prevent someone from getting to their destinatin by not
> allowing them to turn right --they'll still get there, they'll just
> turn left three times.
>
> T.

in my mind it's this that makes it __not__ mi

     harp:~ > cat a.rb
     module A
       def foo() 'foo' end
     end
     module B
       def bar() 'bar' end
     end
     module C
       def bar() foo() end
     end

     class D
       include A
       include B
       include C
     end

     p D.new.foo


     harp:~ > ruby a.rb
     "foo"

now, if ruby was truely mi then i could write something (imagined) like

   class D < (A, B, C)
   end

   p D.new.foo

and ruby would be free to print either 'foo' or 'bar'.  clearly it would be
one or the other and a ruleset would exist to make it un-ambiguous, but the
difference between ruby deciding and having built-in rules vs me deciding and
have explicit call hierachies aranged manually is a rather large one.

so, to me, this is the crucial thing which prevents me from considering ruby
to be a true mi lang.  the cool thing, of course, is that it's only a few
lines of code to make is behave as if it was.

cheers.


-a
-- 
suffering increases your inner strength.  also, the wishing for suffering
makes the suffering disappear.
- h.h. the 14th dali lama