Confusing behavior on setindex! of a vector Observable

[vilim]

I find the following behavior a bit confusing (from Makie examples):

points = Observable(Point2f0[(0, 0), (0.5, 0.5), (1.0, 0.0)]) # AbstractPlotting renames Observables to Nodes it seems

later, in a function

          points[][idx[]] = pos
          points[] = points[]

The example does not work if the last line is excluded, even though it seems to be doing nothing. Is the issue that points[][idx[]] = pos somehow does not send a change signal?

[mschauer]

My take: points[] = ... calls setindex! on an observable, triggering a signal.
points[][1] = ... calls getindex on an observable (and setindex!es the result), not triggering a signal.

[vilim]

Ah, that makes sense, thanks! Maybe there could be a more intuitive method of triggering the signal, somehting like trigger(points), that executes the rest of the setindex[] method, without the first line? Or just as an alias for that line? Performance-wise, I guess o.val = val is anyway compiled to a no-op.

[goretkin]

Probably more semantically obvious than points[] = points[] is to do Observables.notify!(points).

[twavv]

I'm going to close this as intended behavior.

It might make sense to warn more about using mutable values inside of observables in the documentation.