From the android arch docs... trying to understand something ```... LaunchedEffect(userMess...

# compose

[Colton Idle]

From the android arch docs... trying to understand something

...
        LaunchedEffect(userMessage) {
            snackbarHostState.showSnackbar(userMessage.message)
            // Once the message is displayed and dismissed, notify the ViewModel.
            viewModel.userMessageShown(userMessage.id)
        }
...

Is showSnackbar a synchrnous call? i.e. userMessageShown() will be called ONLY after showSnackbar is done/dismissed?

[heckfyxe]

No, showSnackbar is suspend function. It works because LaunchedEffect gets lamdba with coroutine scope, so you can call suspend functions in LaunchedEffect

[heckfyxe]

And yes, userMessageShown will be called only after showSnackbar completes

[Adam Powell]

Or to be a bit more nitpicky, showSnackbar is synchronous but non-blocking. It won't return until the snackbar it shows is dealt with by the user, but it doesn't block the calling thread, it suspends instead.

[Colton Idle]

And yes, userMessageShown will be called only after showSnackbar completes

Thanks. I guess I was seeing it more of an "async" thing like toast which is a fire and forget sort of operation. so in this case I'm 100% "acknowledging" that the message was shown ONLY after it has been dismissed. Cool. That's a really big yet subtle point that the comment is making IMO and I wanted to make sure I understood it.

This means that on rotation, the snackbar will still be shown if it hasn't yet been dismissed (from what I can understand) which is a good thing.

[uli]

Not sure, but as a suspend function I would expect it to be destroyed when the scope is canceled

[Colton Idle]

But it would show the message again because its still in the "queue" so to speak?

[heckfyxe]

Yep, if it won't be dismissed and showSnackbar will be cancelled, it will be called again. If showSnackbar will be completed, then dismiss will be called anyway, because it's blocking and cannot be cancelled

[Colton Idle]

Very cool. Thanks everyone for teaching me!