is there any variation of LaunchedEffect(boolean) ...

# compose

[myanmarking]

is there any variation of LaunchedEffect(boolean) that will only run when it is true?. Using a boolean works, but then the scope is restarted in true -> false. I have nothing to do on false so it seems quite a waste

[Adam Powell]

if (condition) {
  LaunchedEffect...

[myanmarking]

Doing like that, the effect is disposed when it is false ?

[Adam Powell]

Yes, the effect leaves the composition when the condition branch is not taken in a recomposition

[myanmarking]

oh, that makes things simpler. Thanks!

[Adam Powell]

Just like when you do

if (condition) {
  Text("condition is true!")
}

[myanmarking]

yeah, it makes sense

[myanmarking]

Doing something like this, is it safe:

LaunchedEffect(key1 = Unit) {
    while (true) {
        delay(autoScrollInterval)
        state.animateToNextPage()
    }
}

[myanmarking]

i’m concerned about while(true), maybe i should replace with isActive instead 😛 ?

[myanmarking]

delay is cancellable, but it should be the best practice in this case i think

[myanmarking]

code is something like this:

if (autoScroll.value) {
    LaunchedEffect(key1 = Unit) {
        while (isActive) {
            delay(autoScrollInterval)
            state.animateToNextPage()
        }
    }
}

[Zach Klippenstein (he/him) [MOD]]

It probably doesn't matter. But what you should also do is pass dependencies to your effect as keys - in this case state. This is more correct because if the value of state changes between compositions, it doesn't make sense for the effect to continue executing on the old state.

For autoScrollInterval, if the interval changes while scrolling, you probably don't want to cancel the current scroll, but rather just use the new interval for the next iteration, so it's better to use rememberUpdatedState and not pass it as a key.

[myanmarking]

oh nice. thank you