Tween chain never completes

[IBwWG]

• Flixel version: 4.0.0
• OpenFL version: 3.6.1
• Lime version: 2.9.1
• Affected targets: windows/debug

---

Code snippet reproducing the issue:

package;
import flixel.FlxState;
import flixel.tweens.FlxTween;

class PlayState extends FlxState
{
    override public function create():Void 
    {
        var fakeThing = { a: 0, b: 0 };

        FlxTween.tween(fakeThing, { a: 1 }).then(FlxTween.num(0,1).then(FlxTween.num(0,1))).onComplete = function (dummy:FlxTween)
        {
            trace("done A");
        };
        FlxTween.tween(fakeThing, { b: 1 }).then(FlxTween.num(0,1).then(FlxTween.num(0,1,1, {onComplete: function (dummy:FlxTween)
        {
            trace("done B");
        }})));
    }
}

---

Observed behavior: done B not traced
Expected behavior: done B should be traced

I realize the two things are not semantically equivalent, but they should both call their completion functions, shouldn't they? The first one should tween, trace, num, num (tracing after 1 second); the second should tween, num, num, trace (tracing after 3 seconds). But the second one never traces. (And of course, this is the one you'd expect from a general concept of chaining.)

Take out a num tween, or take away the tween tween, and they both trace as expected.

[IBwWG]

One workaround:

        FlxTween.tween(fakeThing, { c: 1 }, 1, { onComplete:function (dummy:FlxTween) {
            FlxTween.num(0, 1).then(FlxTween.num(0, 1, 1, { onComplete: function (dummy:FlxTween) {
                trace("done C");
            }}));
        }});

This traces properly, and after 3 seconds.

[Gama11]

Chaining simply didn't account for nested chains... I hope it works as expected now.

Writing the unit tests for this one was fun. :D

[IBwWG]

Huh...I'll have to try it out, but that's interesting, because in the above example, it does work with nested chains, just not 3 levels, for some reason...2 worked fine.

But I also wonder, do I have the chaining syntax incorrect? Is it supposed to be .then(tween).then() instead of .then(tween.then()) in normal usage? For some reason I thought I had either tried that or traced it and thought it needed to be nested to work. I thought because .then() returned the original tween, so originalTween.then(tweenA).then(tweenB) would start A and B simultaneously after original finished.

[Gama11]

The .then(tween).then() seems more common to me.

originalTween.then(tweenA).then(tweenB) shouldn't start A and B at the same time, it should run originalTween, A and then B.

[IBwWG]

You're right! I could've sworn I tried that. Maybe I got confused because I was trying to finish with .onComplete = ... at the same time, which isn't possible with chained tweens because it applies to the first tween rather than the last. Thanks for the sanity check!