From: Robert Dober <robert.dober@...>
Date: 2006-08-29T17:10:10+09:00
Subject: Re: Partial append_features?

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On 8/29/06, Eero Saynatkari <eero.saynatkari@kolumbus.fi> wrote:
>
> Robert Dober wrote:
> > On 8/28/06, Logan Capaldo <logancapaldo@gmail.com> wrote:
> <original code snipped>




unfortunately that approach undefines eralier defined methods in the
> > appendee, especially inherited ones :(
> > I guess that could be fixed but the code will become rather clumsy.
>
> Heh, take another look:


That is needless, I do not understand the code ;)

Ruby does however:
508/31 > cat append.rb && ./append.rb
#!/usr/local/bin/ruby -w

class Module
  def append_from( mod, *methods_to_keep )
    methods_to_keep.map! { |m| m.to_s }
    methods_to_remove =3D mod.instance_methods(false) - methods_to_keep
    new_mod =3D Module.new
    new_mod.module_eval do
      include mod
      methods_to_remove.each { |meth| undef_method meth }
    end
    include new_mod
  end
end

class Base
        def c
                puts "inherited c"
        end
end

module M
  def a
    puts "a"
  end
  def c
    puts "c"
  end
end

class A < Base
  append_from M, :a
end

a =3D A.new
a.a
a.c
a
./append.rb:38: undefined method `c' for #<A:0xb7d4a174> (NoMethodError)


     new_mod =3D Module.new     # Only this anonymous is affected
>      new_mod.module_eval do
>        include mod  # The appender (not appendee, sorry I wrote this at
> 1:00)


is the receiver

       methods_to_remove.each { |meth| undef_method meth }


and thus undef_method also undefines the method in the receiver
that should be clear from the design of the solution.
I cannot fix it but  I guess Logan could

     end
>
> A rather nice solution.


Well I like Logan's posts a lot and this too,  it is interesting code, but
sorry if I fail to agree
it is not a solution.

>
>
Cheers
Robert

--=20
Deux choses sont infinies : l'univers et la b=EAtise humaine ; en ce qui
concerne l'univers, je n'en ai pas acquis la certitude absolue.

- Albert Einstein

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