Question

I need a GUI control to update whenever a persistent data structure (PDS) is updated.

I need to have the PDS updated when the user takes certain actions.

So, for example, an SWT Tree and a simple tree data structure.

There are lots of manual, ugly ways to do this, but it seems to me this is a very common situation and there would likely be a very clean approach out there.

I’ve been reading about FRP, Lenses, Actors, etc… seems like there could be a very simple, clean, effective approach to handling this type of situation.

Answer 1

What I can think about is having a component with a mutable reference to the PDS. This component could raise an event with the new version of the PDS every time it changes the value of the var. Your GUI control could be listening to that event and react to it by redrawing itself with the new info. Other option is that the component that listens to the event be the parent of your GUI control, reacting by creating a new instance of it, so the control can receive the PDS in the constructor and draw itself only once.