Meta module madness

gistfile1.rb

module Foo

  def self.included(base)
    class << base
      attr_accessor :bar
    end
    base.instance_eval do
      @bar ||= proc{self.snakes}.call
    end
  end
end


class Baz
  def self.snakes
    [:cobra]
  end
  include Foo
end

class Boom < Baz
  @bar = [:copperhead]
end

class Bam < Baz
  def self.snakes
    [:mamba]
  end
end


Baz.bar  # [:cobra], cool, so far so good                                                                                                                                                                 
Boom.bar # [:copperhead], also cool, setting @bar like we want                                                                                                                                            
Bam.bar  # nil !!!  I want this to be [:mamba]                                                                                                                                                            


# I understand that the proc is called at the time of include, and thus Bam (and its snakes method) haven't been defined yet.                                                                             
# What I want to know is, can I delay the evaluation of the proc somehow so that it won't be triggered until I try and get the value of @bar?