parallel event for state_machine

require 'state_machine'
class StateMachine::Machine
  def par_event events, test_field, trans
    i = 1
    # binary 11....1
    full = (1 << events.size) - 1
    events.each do |e|
      j = i
      event e do
        transition(hash.merge(:if => (lambda{ |obj|
          # if all events are fired
          # then test_field == full
          # then transition will be done
          new_tf = ((obj.send(test_field) || 0) | j) # new test field
          obj.send "#{test_field}=", new_tf
          full == new_tf
        })))
      end
      i = i << 1
    end
  end
end