Hi, quick question! Is there no `Dispatcher.Main` in Compose for Desktop? Or should I just depend on...

# compose-desktop

[serandel]

Hi, quick question! Is there no Dispatcher.Main in Compose for Desktop? Or should I just depend on kotlinx-coroutines-android ?

[serandel]

I’m getting this error when starting

[serandel]

Exception in thread "AWT-EventQueue-0" java.lang.IllegalStateException: Module with the Main dispatcher is missing. Add dependency providing the Main dispatcher, e.g. 'kotlinx-coroutines-android' and ensure it has the same version as 'kotlinx-coroutines-core'

[serandel]

composeVersion=1.1.1
coroutinesVersion=1.6.1
javaVersion=17
kotlinVersion=1.6.10

[ephemient]

you need to provide a main dispatcher as appropriate for your app's runtime. in the case of compose-desktop, https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-swing/ will work

[serandel]

that’s fab, thanks!

[serandel]

a follow-up question: my use case is something like this:

[serandel]

@Composable
fun App(stateFlow: StateFlow<MyState>) {
    val state: MyState by stateFlow.collectAsState(context = Dispatchers.Main)

    RenderUI(state)
}

[serandel]

where RenderUI is also a @Composable

[serandel]

am i just being overly cautious by trying to make sure that the state flow is collected in the Main thread, which I understand as the UI one?

[serandel]

or by being collected inside a composable it’s going to be collected in that thread anyway?

[ephemient]

you do not need to use the main dispatcher, it will use the composable's coroutinescope

[serandel]

which is an appropiate one anyway

[serandel]

thanks!

[ephemient]

in theory composables do not necessarily use the main thread. in practice they currently do, but possibly in the future they'll do multi-threaded composition or something

[serandel]

it makes sense

[Adam Brown]

I do an expect/actual of a global val called "mainDispatcher" which each platform provides their main disaptcher to

[ephemient]

you need a real main dispatcher for delay to work in kotlinx.coroutines 1.6.0, unless you set -Dkotlinx.coroutines.main.delay=false (but it looks like they rolled that back in 1.6.1)

[orangy]

There is MainUIDispatcher in org.jetbrains.skiko package

[ephemient]

ah, https://github.com/JetBrains/compose-jb/issues/1943

[ephemient]

it is still fine for an application to use kotlinx-coroutines-swing, it's being avoided in the libraries to prevent conflicts?