gem 'wisper-bubbleable'

class CoffeeStatePublisher
  include Wisper::Publisher
  include Wisper::Bubbleable

  def change(state)
    if state == true
      broadcast(:power_on, 'Power On')
    elsif state == false
      broadcast(:power_off, 'Power Off')
    else
      broadcast(:invalid_state, state)
    end
  end
end

class CoffeeMakerPublisher
  include Wisper::Publisher
  include Wisper::Bubbleable

  def power(on_or_off)
    state = CoffeeStatePublisher.new
    # ** bubble events here **
    state.bubble(:power_on, :power_off).to(self)
    state.on(:power_on) { broadcast(:warming) }
    state.on(:invalid_state) { |x| broadcast(:error, x) }
    state.change(on_or_off)
  end
end

class Listener
  def output(msg); puts msg; end
  alias power_on output
  alias power_off output
  def warming; puts 'Warming up...'; end
end

maker = CoffeeMakerPublisher.new and nil
maker.subscribe(Listener.new) and nil
maker.power(true) and nil
# => Power On
# => Warming up...
maker.power(false) and nil
# => Power Off
maker.power('boy') and nil
# => <No thing happen>