VMDButton.setAction() execution overhead

[antoinelamy]

Because setAction perform a subscribe on a publisher, setting an action on a large number of items becomes an expensive operation. If possible, refactor this so there is no unnecessary subscription for buttons that are not tapped.

fun setAction(action: () -> Unit) {
    actionPublisher
        .observeOn(VMDDispatchQueues.uiQueue)
        .subscribe(
            cancellableManager,
            onNext = {
                action()
            }
        )
}

[marcantoinefortier]

I would even go for removing entirely the publisher around viewModel's action. We should only expose a single action block to be called from the UI, and in that block we can do asynchronous work if needed.

❌

interface ViewModel {
    val action: Publisher<ViewModelAction>
}

val myViewModel = object : ViewModel {
    override val action = myPublisher.map {
        ViewModelAction {
            // do work
        }
    }
}

✅

interface ViewModel {
    val action: ViewModelActionBlock
}

val myViewModel = object : ViewModel {
    override val action = {
        myPublisher.first().subscribe(...) {
            // do work
        }
    }
}

[antoinelamy]

@marcantoinefortier yeah that's exactly the solution I was aiming to. 👍🏻