*Update see this post for the latest version*

Here is an implementation of a simple State Machine for pureMVC that I whipped up for a project. This is really useful for anyone creating applications, honest, its saved my life a few times :) It suddenly occurred to me that because its so simple I’ve been taking its power for granted, and I should share it for the greater geek good. I’ve been using it in combination with trilec’s command chaining utility as a way of controling my command structures.

Have put the code in the svn on my google code page and will prepare a download when I’ve documented it.

Initiate the StateMachine

// instanitate
var stateMachine:StateMachine = new StateMachine();
// register with the facade before registering any commands
facade.registerMediator(stateMachine);
// create a state
var state:State = new State(ApplicationStates.STATE_ONE)
// register the commands to be triggered when
// entering and exiting that state
stateMachine.registerStateChangeCommands(EnterStateOne,
                                         ExitStateOne,
				         state);
// repeat for each state (this can be done any time)
state = new State(ApplicationStates.STATE_TWO)
stateMachine.registerStateChangeCommands(EnterStateTwo,
                                         ExitStateTwo,
				         state);

Changing State
This is very simple, just send a notification from anywhere within the pureMVC framework with a new state as its body:

// create a state
var state:State = new State(ApplicationStates.STATE_TWO)
sendNotification(StateNoteNames.CHANGE_APPLICATION_STATE,
                 state))