as we know the `SideEffect` gets triggered on ever...

# compose

[Mjahangiry75]

as we know the SideEffect gets triggered on every recomposition
so it works fine in the code below(triggered only once when MainScreen starts composition), but if I uncomment the LaunchedEffect the SideEffect block will get triggered whenever the count state changes, while if I comment the LaunchedEffect block it will not. why?

[Alexander Maryanovsky]

Because of the count access when calling LaunchedEffect

[Mjahangiry75]

yes LaunchedEffect has access but SideEffect doesn't, how does LaunchedEffect affect SideEffect?

[Adam Powell]

It doesn't. If you split out your parameters into temporary variables and expand the property delegation you can see what's happening:

val count = remember { mutableStateOf(0) }

SideEffect { ... }

val currentCount = count.value // accessing count's value invalidates MainScreen

LaunchedEffect(currentCount) { ... }

MainScreen is reading count and listening for invalidations of it in order to obtain the value to pass as the LaunchedEffect key

[Adam Powell]

But if you comment out the line of code that contains the count read, then MainScreen no longer invalidates when count changes. It has no reason to.

[Zoltan Demant]

If you place LaunchedEffect inside the Scaffold, the SideEffect wouldnt run again would it?

[Adam Powell]

It shouldn't, but inline composables share an invalidation scope with their caller, so you'll see no difference with things like Box. You can't just count the {} nesting 🙂

[Adam Powell]

If you have to think about this sort of thing this hard to make your code behave correctly, you're probably relying too much on side effects in general. This can be useful to know when analyzing performance, but it should never affect correctness

[Colton Idle]

@Adam Powell I'm being a bit pedantic here because I'm also really trying to learn sideEffects but the OP says "as we know the SideEffect gets triggered on every recomposition" is that true or is it better/more accurate to say "gets triggered at the end of every successful recomposition"?

[Stylianos Gakis]

Definitely being pedantic yeah 😅 This detail can be omitted in the context of what is being discussed here imo

[Adam Powell]

if you want to dial pedantry to 11...

"The SideEffect function executes on every recomposition of the recompose scope it appears in, scheduling the provided function parameter to execute after the changes from the composition are successfully applied and RememberObservers have run"