Hello everyone :wave: Simple question: Is it ok to have a `LaunchedEffect` inside of Modifier extens...

# compose

[henrikhorbovyi]

Hello everyone 👋
Simple question: Is it ok to have a LaunchedEffect inside of Modifier extension?

private fun Modifier.myModifier(): Modifier = composed {
    val shape = // ...
    LaunchedEffect(condition) {
        // ...
    }

    this then background(shape = shape)
}

Context: Detekt is complaining about the use of `composed` or @Composable on Modifier extensions. So we need to add a Suppress, and our goal is to remove the composed or @Composable notation.

[ephemient]

The recommendation of composed over @Composable has been rescinded, https://developer.android.com/develop/ui/compose/custom-modifiers#create_a_custom_modifier_using_a_composable_modifier_factory

[ephemient]

but depending on what you're doing, a custom Modifier.Node may be better. you'll have a coroutine scope to use too

[henrikhorbovyi]

I tried using a Modifier.Node , but I couldn't use LaunchedEffect inside of it

[ephemient]

it has coroutineScope onAttach and onDetach

[henrikhorbovyi]

hm, but where do I place my LaunchedEffect block?

[henrikhorbovyi]

onAttach and onDetach don't have a composable scope

[ephemient]

you launch it into the scope and cancel it

[henrikhorbovyi]

or do I replace LaunchedEffect by onAttach?

[ephemient]

or use a side effect, depending on what you're doing

[henrikhorbovyi]

image.png

[henrikhorbovyi]

I'm not understanding how to use the side effect inside of the Modifier.Node

[Louis Pullen-Freilich [G]]

The logic you previously had inside launched effect can go inside that launch there

[Louis Pullen-Freilich [G]]

LaunchedEffect() { suspendFoo() }

Becomes

scope.launch { suspendFoo() }

Inside onAttach

[ephemient]

I'd probably do

var job: Job? = null
fun onAttach() {
    job?.cancel()
    job = coroutineScope.launch { ... }
}
fun onDetach() {
    job?.cancel()
    job = null
}

for more completeness

[Louis Pullen-Freilich [G]]

The scope will automatically be cancelled on attach and detach anyway, but yeah that’s also fine

[henrikhorbovyi]

hm... Got it

[henrikhorbovyi]

Thank you guys