Im trying to switch between flows depending on another flow 🙂

val result = state.transformLatest {
            when (it) {
                "a" -> emitAll(emitter("A"))
                "c" -> emitAll(emitter("C"))
            }
        }

        result.collect {
            println(it)
        }

this will print a flow of A+<counter> or “C” +<counter> depending on the last value from “state”. I would like to ignore “unknown” states, but since transformLatest cancels the previous flow even if i don’t emit anything new, setting the state to “B” will just cancel the output, not continue on the previous selected output. Is there a nice way to achieve what I want?

you could filter the unknown states before

transformLatest

?

Yes, its possible, but then I’ll have 2 places to update and keep in sync when new values should be “known”

I don’t think there’s an API for that, other than being able to implement your own operator (which in case of

transform

isn’t that straightforward I think). I’d probably just go for some pattern like

Map<String, ???>

so that I have single source of truth for

filter { handlers.contains(it) }

and for the transform

great minds and all that 🙂 I ended up fixing it with a

mapOf<State, Flow<String>>

and filter

How about:

myFlow
   .filter { it.isNotUnknown() }
   .distinctUntilChanged()
   .flatMapLatest {
      // Choose output flow
   }

you can just map letter to flow before transform latest:

state.mapNotNull { 
    when (it) {
       "a" -> emitter("a")
       "b" -> emitter("b")
       else -> null
     }
}.flatMapLatest { it }