From: Trans <transfire@...>
Date: 2007-10-16T05:33:35+09:00
Subject: Re: RubyTraits 0.1



On Oct 15, 9:49 am, Daniel Berger <djber...@gmail.com> wrote:
> On Oct 15, 9:38 am, Yukihiro Matsumoto <m...@ruby-lang.org> wrote:
>
>
>
> > Hi,
>
> > In message "Re: RubyTraits 0.1"
> >     on Tue, 16 Oct 2007 00:23:43 +0900, Trans <transf...@gmail.com> writes:
>
> > |I see. So you don't really like the fact that modules fit into the
> > |inheritance chain? That's interesting.
>
> > Actually they both have their own good.  I like them both.  I dislike
> > to have them both in a language.  Traits injection is clear and less
> > error prone (there's no possibility of conflicts), but sometimes
> > method overriding is _very_ useful, where aliasing is very poor way to
> > create method combination.
>
> > If someone come to the idea to allow modules to have merits from both
> > mixins and traits at once (without demerit), I'd love to hear.
>
> I solved this "problem" over two years ago with fine grained mixins.
> Please seehttp://rubyforge.org/docman/view.php/735/309/README.html
> and look at the synopsis. Ideas (and code) in that library also came
> from Ara Howard and Mauricio Fernandez.
>
> I don't want up front object composition. To me that's like static
> typing, except for object composition. At worst, a warning should be
> issued if a double inclusion occurs. This is what the 'use' library
> does in verbose mode.

Kind of like #integrate.

  # Using integrate is just like using include except the
  # module included is a reconstruction of the one given
  # altered by the commands given in the block.
  #
  # Convenient commands available are: #rename, #redef,
  # #remove, #nodef and #wrap. But any module method
  # can be used.
  #
  #   module W
  #     def q ; "q" ; end
  #     def y ; "y" ; end
  #   end
  #
  #   class X
  #     integrate W do
  #       nodef :y
  #     end
  #   end
  #
  #   x = X.new
  #   x.q  #=> "q"
  #   x.y  #=> NoMethodError
  #
  # This is like #revisal, but #revisal only
  # returns the reconstructred module. It does not
  # include it.

The significant difference between this and your #use method is that
#use can more easily add a small select group of methods from a module
--I think that's that gist of your lib. However, if you find yourself
"cherry picking" methods from a module like that, it's time to rethink
the design. Plus, implementation of that is terribly inefficient
(having to remove all other methods).

At any rate, Traits are much prettier:

    class X
      include W - :y
    end

T.