As I understand when some composable "X" uses `value` on some `State<T>` "S", then the Compose...

# compose

[Julius Marozas]

As I understand when some composable "X" uses value on some State<T> "S", then the Compose runtime automatically recomposes X when S changes. Potentially bypassing recomposing any composables that just forward S to X without calling value.

In my app, I have a "container composables" that are responsible for observing streams from a view model and passing the observed values to children composables. In one of the containers I have StateFlow<List<T>>.collectAsState() and I pass State<List<T>> to children of the container. What should I do, if I want to pass a boolean indicating whether List<T> is empty? Can I somehow create a new State<Boolean>?

And in general, should I always prefer to pass State<T> to composables instead of just T?

[Julius Marozas]

I guess something like this would work:

val items = viewModel.items.collectAsState()

val isEmpty = items.value.isEmpty()
val isEmptyState: State<Boolean> = remember(isEmpty) {
    mutableStateOf(isEmpty)
}

Child1(items)
Child2(isEmptyState)

But it seems quite weird.

[jim]

Don't over think it, just pass the boolean to Child2.

[jim]

val items = viewModel.items.collectAsState()
Child1(items)
Child2(items.value.isEmpty())

[jim]

Reading from a mutableStateOf has it's own costs to manage subscriptions that are likely to far exceed the costs of just passing the boolean, which will be memoized when the value is unchanged.