would it be a bad idea, to have a CompositionLocalProvider for a callback, to communicate with root ...

# compose

[Peter Mandeljc]

would it be a bad idea, to have a CompositionLocalProvider for a callback, to communicate with root composable, like post msg on a msg bus?

[Peter Mandeljc]

typealias Callback = (String) -> Unit

// Fixme: composition policy
val LocalActiveCallback = compositionLocalOf<Callback> { error("No active callback") }

@Composable
@Preview
fun Parent() {
    val callback: Callback = { msg ->
        Timber.e(msg)
    }

    CompositionLocalProvider(LocalActiveCallback provides callback) {
        Child()
    }
}

@Composable
private fun Child() {
    val callback = LocalActiveCallback.current

    Button(onClick = {
        callback("hello")
    }) {
        Text("call me")
    }
}

[Csaba Kozák]

I also used this technique to communicate from a tab screen to the root screen, as i needed to animate the bottom nav according to some state in a very deep composable function. I would try to avoid this as possible, still it is working in my case.

[K Merle]

It looks super handy indeed. My main concern is testing, after that, hiding implementations. It could get very hard to debug I would imagine if app gets big.