How to use the State pattern with MicroMachine, the simplest FSM lib out there :)

state_pattern_with_micromachine.rb

# This aims to reproduce the State pattern using MicroMachine.
# We're just implementing the example from http://github.com/dcadenas/state_pattern

require "micromachine"

module Stop
  def self.color
    "red"
  end

  def self.duration
    3
  end
end

module Go
  def self.color
    "green"
  end

  def self.duration
    2
  end
end

module Caution
  def self.color
    "yellow"
  end

  def self.duration
    1
  end
end

street_light = MicroMachine.new(Stop).tap do |fsm|
  fsm.transitions_for[:next] = { Stop    => Go,
                                 Go      => Caution,
                                 Caution => Stop }

  fsm.on(:next) { sleep fsm.state.duration }
end

loop do
  puts street_light.state.color
  street_light.trigger(:next)
end

__END__

Or, if you want delegation…

  require "forwardable"

  street_light.extend Forwardable
  street_light.def_instance_delegators :state, :color, :duration