Has anyone came up with an issue of having to sync compose state to some external state each time it...

# compose

[Big Chungus]

Has anyone came up with an issue of having to sync compose state to some external state each time it changes on compose side? How did you tackle it?

[than_]

just launch an effect for every state change and do whatever needs to be done there 🙂

[Big Chungus]

As in LaunchedEffect?

[Alexander Maryanovsky]

https://developer.android.com/jetpack/compose/side-effects#sideeffect-publish

[Big Chungus]

But side effect executes on every recomposition, regardless which piece of state changes. Therefore you cannot pinpoint a particular piece of state and map only its changes to external state.

[than_]

so you need to actually diff the change?

[Big Chungus]

Well no. Assume i have states a, b and c. Only c needs to be pushed to external state. Having an effect executing as part of a or b changes will waste the execution time on the effect even though c hasn't changed.

[KamilH]

Isn’t snapshotFlow what you are looking for? It lets you create a flow from state, subscribe to it and collect whenever state changes

[than_]

well that depends. how do you know only C should be pushed? I agree with KamilH that that the solution is probably gonna be a snapshot flow. Some debounce probably won't hurt either.

[Big Chungus]

I'm only interested in c as it's the only one I'm using to invoke external state setter with

[Alexander Maryanovsky]

Pass the state that you want to depend on into another @Composable function, and call the side effect there.

[Big Chungus]

Good idea. I can just write my own effect based on side effect that supports keys that way

[Adam Powell]

What created and owns the thing you're trying to update/manipulate with effects?

[Big Chungus]

Here's a minified example of my use-case with comments.

Note that mdcComponent is only attached to native DOM element because I couldn't think of a better way to make it accessible to the composition scope later on.

example.kt