Hi everyone! Huge respect to JB! I have some question about StateFlow. What if I have 2 stateFlows and non-suspend transformer function, and I’d like to create a new StateFlow like a combination of theese two, transformed by the transformer function? It seems like current api does not allow to create such a StateFlow<>.combine operator? (sorry for bad English)

You can combine state flows but the result would a Flow and not a StateFlow. I think it’s because let’s say you combined two `MutableStateFlow`s, and got a

StateFlow

back. It would mean that every time you set value in one of the combined (source) flows, the resulting one would need to run the transform function to provide proper

value

. But since the source flows can’t push value downstream, it’s the downstream that needs to be collecting. Just calling

combine

can’t start collecting because collection needs to happen in a scope

but I want to be able to call like this: combinedFlow.getValue() and, theoretically, I could have the value (because both state flows has their own value, and the transform function is non-suspend)

In that case you can create

val myValue get() = combineFun(flow1.value, flow2.value)

so the question is: are you planning to create some function like StateFlow<>.combine(…): StateFlow<> ?

I solved this with a helper function (can be generalised to multiple stateflows). Note that it requires a

CoroutineScope

as receiver for scheduling the transformation function itself.

fun <T1, T2, R> CoroutineScope.combineState(
    flow1: StateFlow<T1>,
    flow2: StateFlow<T2>,
    sharingStarted: SharingStarted = SharingStarted.Eagerly,
    transform: (T1, T2) -> R
): StateFlow<R> = combine(flow1, flow2) { o1, o2 ->
    transform.invoke(o1, o2)
}.stateIn(this, sharingStarted, transform.invoke(flow1.value, flow2.value))