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06/11/2021, 8:47 AM
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j

Joost Klitsie

06/11/2021, 11:54 AM
If you give it a default value then you can use 
stateIn
without having to use a suspend function. Of course, then you will have to duplicate (or extra a helper method) to get the same result as from the combine method
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val firstField: StateFlow<String> = MutableStateFlow("a")
val secondField: StateFlow<Int> = MutableStateFlow(11)
    
val scope = CoroutineScope(Dispatchers.Default)
val canDoSomethingScary: StateFlow<Boolean> = scope.combineStates(firstField, secondField) { first, second ->
    first.isNotBlank() && second > 0 && second < 10
}

fun <T, U, R> CoroutineScope.combineStates(
    stateFlow1: StateFlow<T>, 
    stateFlow2: StateFlow<U>, 
    started: SharingStarted = SharingStarted.Eagerly,
	suspendTransform: suspend (T,U) -> R = { arg1, arg2 -> transform(arg1, arg2) },
    transform: (T, U) -> R) = 
    combine(stateFlow1, stateFlow2, suspendTransform).stateIn(this, started, transform(stateFlow1.value, stateFlow2.value))
k

Kirill Vasilenko

06/11/2021, 1:23 PM
The main idea is to avoid being suspended and couroutine scopes where it is possible. Making view models should be as simple as possible.
I will remove the post everywhere except #coroutines channel. So please ask your questions there or, that would be better, on GitHub.
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