Is there a way to chain `onEach` with `MutableStat...

# coroutines

[kevin.cianfarini]

Is there a way to chain onEach with MutableStateFlow and return a MutableStateFlow?

My use case -- calling SavedStateHandle.getLiveData(key: String) will automatically save new emissions to that live data into the saved state. I would like something like this to be possible with StateFlow

fun <T> SavedStateHandle.getStateFlow(key: String, defaultValue: T): MutableStateFlow<T> {
    return MutableStateFlow(this[key] ?: defaultValue).onEach {
        this[key] = it
    }
}

However, onEach returns a regular instance of Flow. Is this something that's been discussed? If not, I'm more than willing to open an issue.

[Zach Klippenstein (he/him) [MOD]]

I asked about this sort of thing a few months ago, the response was “it’s harder than it looks” for transforming operators, but I don’t think that argument applies to side effect operators like onEach.

If you file this, you might want to contrast it with the issue I filed: https://github.com/Kotlin/kotlinx.coroutines/issues/2081

[kevin.cianfarini]

Thanks! I think I will file this issue.

[Zach Klippenstein (he/him) [MOD]]

Cool, please link here when you do so people can follow up!

[kevin.cianfarini]

Fresh off the presses! https://github.com/Kotlin/kotlinx.coroutines/issues/2343

[kevin.cianfarini]

Aaaaaaaand it was closed.