From: "Ara.T.Howard" <Ara.T.Howard@...>
Date: 2005-08-02T08:21:04+09:00
Subject: Re: Selective mixins; who can improve on this?

On Tue, 2 Aug 2005, Trans wrote:


<snip>
>> There has to be a more elegant way to do this.  What is it?
>>
>
<snip>
> Am interested in other people's solutions too.

   harp:~ > cat a.rb
   class Module
     def import desc
       desc.each do |a_module, a_list|
         m = Module::new
         m.module_eval do
           include a_module
           a = a_module.instance_methods
           b = [ a_list ].flatten.map{|b| b.to_s}
           (a - b).each{|um| undef_method um}
         end
         module_eval{ include m }
       end
     end
   end

   module Foo
     def foo
       p self
       p 42
     end
     def foobar
       p self
       p @foobar
     end
   end

   module Bar
     def bar
       p self
       p 42.0
     end
     def barfoo
       p self
       p @barfoo
     end
     def not_imported
     end
   end

   class C
     import Foo => %w( foo foobar ),
            Bar => %w( bar barfoo )

     def initialize
       @foobar = 'foobar'
       @barfoo = 'barfoo'
     end
   end

   c = C::new

   c.foo
   c.bar
   c.foobar
   c.barfoo
   c.not_imported


   harp:~ > ruby a.rb
#<C:0xb75d060c @barfoo="barfoo", @foobar="foobar">
   42
#<C:0xb75d060c @barfoo="barfoo", @foobar="foobar">
   42.0
#<C:0xb75d060c @barfoo="barfoo", @foobar="foobar">
   "foobar"
#<C:0xb75d060c @barfoo="barfoo", @foobar="foobar">
   "barfoo"
   a.rb:56: undefined method `not_imported' for #<C:0xb75d060c @barfoo="barfoo", @foobar="foobar"> (NoMethodError)


seems to work.  i'm probably missing something though...

cheers.

-a
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