From: transfire@...
Date: 2006-05-28T11:33:48+09:00
Subject: Re: modularizing class methods [LONG]

Interesting approach. It's a little bit of a misnomer mind you, becasue
you have taken over the include processes such that you are not
actually including module definitions, but rather are defining code in
the base class itself. In other words, while your class will report
ancestors of NameFields and AddressFields, there are actually no
methods defined in those modules.

I have seen another common way of doing this:

  module NameFields
    def included( base )
      base.class_eval %{
        field :first, :last, :middle
      }
    end
  end

This works too, of course, though I think your technique is more clever
and worth additional study. Nonetheless there is still the fact in
either case of being real module inclusion. Maybe it would be better
not to use the include mechinism. Ie. just create a different module
method to do the work. You could still go about it the same way, but
just use a different method other than #include.

Here is an example of what I came up with some time ago.


 class Module

  def package( name, &block )
    @__package__ ||= {}
    return @__package__ unless block_given?
    @__package__[name.to_sym] = block
  end

  def provide_features( base, *selection )
    selection.each do |s|
      base.class_eval( &@__package__[s.to_sym] )
    end
  end

  def use( package, *selection )
    if String === package or Symbol === package
      package = constant(package)
    end
    package.provide_features( self, *selection )
  end

 end


 #  _____         _
 # |_   _|__  ___| |_
 #   | |/ _ \/ __| __|
 #   | |  __/\__ \ |_
 #   |_|\___||___/\__|
 #

  require 'test/unit'

  class TCModule < Test::Unit::TestCase

    module MyPackages
      package :foo do
        def foo
          "yes"
        end
      end
    end

    class Y
      use MyPackages, :foo
    end

    def  test_package
      y = Y.new
      assert_equal( "yes", y.foo )
    end

  end


Though it may need some tweaking to work for your usecase, I suspect
something like this woud do the job nicely.

In any case I'm gogin to give your code some more thought. Please let
us know if you improve upon it.

T.