Hi, I need an advice. I would like to call suspend function on

TextButton.onClick

. as

onClick

is not Composable. I can’t use

launchInComposition

so, I tried the below. but I’m not sure if this is proper approach or not. I searched on this channel but. it was difficult to find the discussion.

scope = remember { CoroutineScope(SupervisorJob() + Dispatchers.Main.immediate) }
onDispose { scope.cancel() }

TextButton(onClick={ scope.launch { doSuspendFunction() }})

what is the best approach on this case?

good question. We might want to provide an API like this but we don’t yet. Haven’t tested anything or tried this out. but something close to this might be a good interim solution. Ideally we provide something that allows you to use the corountinescope that

launchInComposition

uses which will work a little bit better but for the most part I think this would work okay:

class ComposableCoroutineScopeImpl(
    val context: CoroutineContext
) : CoroutineScope, CompositionLifecycleObserver {
    val job = Job()
    override val coroutineContext: CoroutineContext
        get() = Dispatchers.Default + job
    override fun onEnter() {}
    override fun onLeave() { job.cancel() }
}

@Composable
fun composableCoroutineScope(
    context: CoroutineContext = EmptyCoroutineContext
): CoroutineScope = remember {
    ComposableCoroutineScopeImpl(context)
}

@Leland Richardson [G] I’m really appreciated for the answer.🙏🙏🙏 I’ll do below with your code.

scope = composableCoroutineScope()

TextButton(onClick={ scope.launch { doSuspendFunction() }})

Are the contracts for

onDispose

and

CompositionLifecycleListener.onLeave

different? I thought the former would not get called if the composition failed before committing, and if that's true for the latter as well that means this code could leak the job/coroutine. https://kotlinlang.slack.com/archives/CJLTWPH7S/p1591660760450000?thread_ts=1591653158.447300&cid=CJLTWPH7S

hmm. tbh i didn’t think too carefully when i wrote this code. It’s possible if the composition got cancelled that it would have the wrong semantics, but if it got canceled then the onClick handler would never have a chance to get fired so i’m not sure this is an issue?