iterator.rb

require 'concord'

class Iterator < Module
  include Concord.new(:collection)

  private

  def included(host)
    enumerable = collection
    host.class_eval do
      include Enumerable
      define_method :each do |&block|
        return to_enum unless block
        send(enumerable).each(&block)
        self
      end
    end
  end
end # Iterator