BackHandler Composable

[swankjesse]

Lets hook up something like Compose UI’s BackHandler.

@Composable
fun BackHandler(enabled: Boolean = true, onBack: () -> Unit) {
}

[JakeWharton]

I'm not sure we can do this at either level of abstraction we provide. Definitely not Redwood but even with Treehouse it seems like a stretch. We know nothing about screens, navigation, or, in the case of Android, the platform back-handling third-party library you need to use.

[swankjesse]

Good call. Probably this goes in the Cash layer on top.

[JakeWharton]

We may be able to pull it off in Treehouse at some point, but yeah the question is whether we want to impose the necessary bits to wire this up. Maybe a sample to show how it's wired?

[swankjesse]

interface FrameContext : ZiplineService {
  var backHandler: BackHandler?
}

interface BackHandler : ZiplineService {
  fun onBack()
}

[JakeWharton]

In Compose:

BackHandler(true /* or state derived */) {
  // must handle
}

[JakeWharton]

I've since come around to this being supported at the Redwood layer because it relies on things like #1116 which previously did not exist as a concept.