brittle example (irc)

brittle.rb

module Change
  def Change.included klass
    klass.class_eval do
      def klass.change
        def changed?; true end
      end
    end
  end
end

class Without
  include Change
  def changed?; false end
end

class With
  include Change
  def changed?; false end
end

With.change
With.new.changed?
#=> true

Without.new.changed?
#=> false