I have a flow that I'm getting state from with `co...

# compose

[eygraber]

I have a flow that I'm getting state from with collectAsState. When that state updates, it means that something else (that isn't directly observable or a state) updated as well, and I want to use that in a composable. What's the better approach (aside from refactoring to get away from this issue):

val current by foo.updates.collectAsState()
val bar by remember(current) { foo.bar }

or

val current by foo.updates.collectAsState()
val bar by remember {
  derivedStateOf {
    current // just to get the update
    foo.bar
  }
}

[eygraber]

I'm using remember(current) in the first one because it doesn't seem like the whole scope recomposes when current updates; only the scopes where current is actually read.

[Ian Lake]

Have you considered using produceState? https://developer.android.com/jetpack/compose/side-effects#producestate

val bar by produceState(initialValue = foo.bar, foo) {
  foo.updates.collect {
    value = foo.bar
  }
}

[Ian Lake]

If you look at the source code for collectAsState(), you can see it is just using produceState under the hood

[eygraber]

Would that still be a good choice if I also use the value of current further down the composable?

[Ian Lake]

No, I'd just use the first one then