Enum_Generator.rb

#require "Fiber"

class Enum_Generator
  def initialize re , method 
    @f = Fiber.new do
      re.__send__(method) do | n |
        Fiber.yield n
      end
    end
  end
  def next
    @f.resume
  end
end

f = Enum_Generator.new [1,2,3], :cycle

6.times do p f.next end

toggle = Enum_Generator.new [true,false], :cycle

4.times do p toggle.next end

a  = [true,false].cycle

4.times do p a.next end