mashtonian
commented
1 year ago Hi,
I'm interested in this as I am trying to implement an "Undo" function that allows the machine to go "backwards" through previous states.
As I exit each state, I store it in an undoList, then when processing the Undo event, I pass that state as an argument and attempt to set targetState to it, in the onTriggered listener of the Undo event:
when (shot) {
is UNDO -> {
val undoState: State? = undoList.removeLastOrNull()
if (undoState != null) {
stateMachine.processEvent(shot, argument = undoState)
}
}
else -> stateMachine.processEvent(shot)
}
...
private val stateMachine = createStateMachine {
onTransition {
if (it.transition.sourceState.name != null) {
println("Exiting state ${it.transition.sourceState.name}")
println("Entering state ${it.direction.targetState?.name}")
if (it.event !is UNDO)
undoList.add(it.transition.sourceState as State)
}
}
transition<UNDO> {
onTriggered {
targetState = it.argument as State
removeLastShot()
}
}
...
Unfortunately this doesn't work.
I also can't set the targetState in it.direction, as that is immutable.
Can you advise if this is possible?
nsk90
planning to add shallow history state and deep history state