SOLIDify Transition

[charlierudolph]

I'd like to do a number of things around Transition.

I was about to create a PR with the following

• Move transition configuration into its own class
  • Blocks during configuration are handed a TransitionConfiguration instance instead of a Transition instance (which just sets things on the Transition instance)
• Remove state from transition (just have the state machine always pass it in), this allows the need to only yield a single transition instead of multiple when multiple are created

In doing so I came up with another change I would like to implement

• Store TransitionConfiguration instead of Transition and when we need to transition, create a new Transition object passing it the the state machine, old state, the new state, the transition configuration, the mode and just execute call

def transition(state, params = {}, mode = self.class.mode)
  @failure_messages = []
  @success_messages = []
  previous_state = self.state ? self.state.to_sym : self.state
  state = state.to_sym
  mode = __sm_actual_mode(mode)
  transition_configuration = __sm_transition_configuration_for(previous_state, state)
  Transition.new(self, previous_state, state, transition_configuration, mode).call  
end

I think this will help move a lot of transition logic out of the state machine and into its own class. Didn't create a PR for the current work as if you agree, TransitionConfiguration becomes quite different.

[alexpeachey]

Thanks @charlierudolph, yes please move forward with this. It's been on our list for a while to make StateMachine know a lot less about Transitions. Pretty much all of the relevant logic in the gem in encapsulated in the StateMachine class.

I like the idea of a TransitionConfiguration class that has the relevant info about the guards, concluders, etc. And then a Transition class that would take over a lot of the logic wrapped up inside StateMachine.

Ideally you can do this as a pure refactor and not have any changes to the API. If you do find you need to change the API, please call it out clearly.