Does

@Compose

support side effects, like launching a dialog or a

Snackbar

that auto-dismisses itself after a short time?

It is posible to express side effects. A good example of this would be the entrance/exit animation for a snackbar. There's two main APIs you should look at: onCommit and launchInComposition. onCommit – create a new lifecycle for the keys passed, allowing you to trigger an idempotent side effect when the keys change and cleanup from it in it's onDestroy block

onCommit(snackBarShown) {
    // animate it
    onDispose {
       // the keys changed, or the containing composable has been removed
    }
}

launchInComposition – launch a coroutine (this is the preferred way to express fixed intervals like 1_000ms, do other coroutines type things)

launchInComposition(snackbarShown) {
   // launch a new coroutine when snackbarShown changes
}

Making side effects inside of composition (in the main body of a composable function or lambda) is not a supported use case.

Oh for sure. I would just be consuming from a regular

Channel()

to async display a UI component. But do these side effect UIs persist/restore themselves across config changes?

What do you mean?

like if you launch a

DialogFragment

then do a config change, the

DialogFragment

is still visible because the

FragmentManager

handles restoring its state

Ah – so the execution units defined by onCommit and launchInComposition are tied to their calling composable being part of the tree. During rotation currently, the tree will be rebuilt and these execution units will be restarted.

@zak.taccardi did you ever look into the auto-dismiss side effect further?