`change:a.x` fired, while no `change:a` firing?

[claydodo]

I'm using ampersand-state 4.9.1 and have a State defined like this:

var MyState = State.extend({
    props: {
        a: 'state'
    },
    
    setA: function(x, y) {
        this.a.set({x: x, y: y});
    }
})

where a is always an instance of A:

var A = State.extend({
    props: {
        x: 'number',
        y: 'number'
    }
})

When using MyState's instance someObj.setA(3, 5), etc, I find that the following events are fired:

• change:a.x
• change:a.y
• change (someObj's own change event)

But there's no change.a fired, which is desired. Because in my app I want to observe MyState's change:a to handle the changes of x and y at the same time, instead of observing change:a.x and change:a.y (which suites other scenarios, though) as independent events.

Is this an issue worth consideration? Or am I using sub-states in a wrong way?

[dhritzkiv]

I think it's definitely worth considering the behaviour a little more closely, especially since someObj fires a change event for itself.

When looking at it like this, I think there's a strong case for emitting "change:a"

|||- x (change event fired)
|||- y (change event fired)
||- a (change event NOT fired)
|- someObj (change event fired)

Presently, I believe change:a is only fired when the actual reference to the state instance is changed:

someObj.a = new A(); //this should emit a `change:a` event

---

Out of curiosity, what happens when you set someObj.a.parent = someObj? Does that have any effect?

[claydodo]

I tried the parent stuff, but there's no effect.

I'm using some other approach to overcome this issue for now, and waiting for the upgrade of the library.