From: Robert Dober <robert.dober@...>
Date: 2008-04-08T08:47:41+09:00
Subject: Re: How to override a method defined in Ruby module

On Mon, Apr 7, 2008 at 1:45 PM, Rick DeNatale <rick.denatale@gmail.com> wrote:
> On Mon, Apr 7, 2008 at 7:33 AM, Sonar Volta <buistov@softline.kiev.ua> wrote:
>
>  >  Is there module inheritance in Ruby?
>
>  No, and yes.
>
>  You can't do
>
>  module A
>  end
>
>  module B < A
>  end
>
>  but you can do:
>
>  module B
>    include A
>  end
>
>  Which acts like a sort of inheritance.
It does indeed look like that if you ask ruby itself, very much to my
dispair :( (but that's why I have implemented traits)

irb(main):001:0> a=Module::new
=> #<Module:0xb7cf35e8>
irb(main):002:0> b=Module::new
=> #<Module:0xb7cebf78>
irb(main):003:0> b.send :include, a
=> #<Module:0xb7cebf78>
irb(main):005:0> b < a
=> true
irb(main):006:0> c=Class::new
=> #<Class:0xb7cd8edc>
irb(main):007:0> c.send :include, b
=> #<Class:0xb7cd8edc>
irb(main):008:0> c.new.is_a? a
=> true

I believe that this is misleading I might agree to
c.new.behaves_like? a
but if we go all the way to ducktyping even that is unacceptable.
And yes you guessed correctly I am an inheritance skeptic but that is
not because it is a bad feature (single inheritance) but it is not the
right feature for code reuse, it is the right feature for modeling.

Smalltalk which had no mixins suffered a lot from having to use SI for
refactoring and code reuse, Squeak implemented traits for that very
reason if I understood correctly.

Cheers
Robert
>  --
>  Rick DeNatale
>
>  My blog on Ruby
>  http://talklikeaduck.denhaven2.com/
>
>



-- 
http://ruby-smalltalk.blogspot.com/

---
Whereof one cannot speak, thereof one must be silent.
Ludwig Wittgenstein