Events during transition states

[Nethken]

I'd like to have my transition states also be able to handle events, but trying

    transitions: {
        MyState: {
            origin: 'state0', target: 'state1',
            action: function () { /* async stuff here */ },
            events: {
                request: function() { /* add listeners for ongoing async stuff */ } 
           }
       }
    }

doesn't seem to have worked, the code never gets hit in the node debugger, and the request function does return a promise but in the testing code the returned value is undefined.

[nickfargo]

Including an action in a transition expression allows the Transitions generated from it to be asynchronous, wherein the Transition remains current until its end method is called, after which it will then proceed to its target state.

Therefore it is the expected responsibility of action either to call this.end() itself (synchronously), or to arrange for end() to be called later elsewhere (asynchronously).

So your example could work something like this:

var state = require('state');

var object = {};

state( object, {
  state0: state('initial'),
  state1: state,

  transitions: {
    MyTransitionState: {
      origin: 'state0', target: 'state1',
      action: function () {
        var transition = this;
        transition.emit('request');
        setTimeout( function () {
          transition.emit('request');
          transition.end();
        }, 100);
      },
      events: {
        request: function () {
          console.log("Emitted event 'request'");
        }
      }
    }
  }
});

object.state('-> state1');
// log <<< "Emitted event 'request'"
// >>> Transition

// ... 100 ms ...

// log <<< "Emitted event 'request'"