what is the best way to expose state from `ViewModel`? am using compose’s `MutableState` but I see a...

# compose

[Marko Novakovic]

what is the best way to expose state from ViewModel? am using compose’s MutableState but I see a lot of examples with Flow but I don’t see any need for using Flow to expose state in pure compose app. is Flow used in app in transition from View to Compose to bridge the gap and use some of the existing code or Flow is for some reason more favourable than MutableState?

[Colton Idle]

I've been using snapshot state (mutableState*Of) and from what I've read from Adam Powell, it makes sense because even if you use Flow or LiveData, you still need to call collectAsState somewhere which turns it into snapshot state anyway.

To me, it seems like you should only use a flow/livedata if it's out of your control/somewhere upstream is using those observable patterns.

[Marko Novakovic]

exactly

[Colton Idle]

My comment above comes with the caveat that I actually understood Adam correctly. 🙃

[Adam Powell]

Close enough 🙂 Flows are useful if you have cold data sources but if you're using MutableStateFlow anywhere you're probably better off with mutableStateOf instead

[Colton Idle]

Still need to read up on hot vs cold flows 😅

[Manuel Vivo]

The only benefit you get using LiveData or Flow.flowWithLifecycle is that you’re going to avoid recompositions when the app is in the background.

If you don’t care about that and you don’t need the power of Flow operators (that shouldn’t be needed for uiState), then mutableStateOf is perfect!

[Marko Novakovic]

what is flowWithLifecycle actually doing in compose world?

[Adam Powell]

Recompositions in the background aren't generally worth worrying about. Compose currently halts all recomposition in the background anyway (though future versions will probably just throttle it instead). What you have to worry about is the ongoing work performed by the producers of cold data sources

[Adam Powell]

If you subscribe to a flow that listens to realtime GPS location updates, for example, that has a non-trivial power cost on a mobile device, not to mention user privacy expectations

[Marko Novakovic]

I see. thanks all