Composables

PulseHost

@Composable
fun <Broadcast : PulseBroadcast, Unicast : PulseUnicast> PulseHost(
    container: PulseContainer<Broadcast, Unicast>,
    content: @Composable (
        onRefresh: () -> Unit,
        onBroadcast: (Broadcast) -> Unit,
    ) -> Unit = { _, _ -> },
)

Desktop only. Scopes a PulseContainer to this subtree. It emits no UI of its own and does two things: it publishes the Container key, so the PulseContent composables inside respond to container.refresh(), and it provides onRefresh and onBroadcast to the content block.

An app can contain several of them. In the demo, each destination that owns a Container hosts its own.

Parameters

Parameter	Type	Description
container	PulseContainer<Broadcast, Unicast>	The container to observe
content	@Composable (onRefresh, onBroadcast) -> Unit	Content block receiving the two callbacks

Example

PulseHost(container = appContainer) { onRefresh, onBroadcast ->
    Column {
        Button(onClick = { onBroadcast(AppBroadcast.Sync) }) {
            Text("Sync All")
        }
        Button(onClick = { onRefresh() }) {
            Text("Refresh View")
        }
        MyContent(viewModel = myViewModel)
    }
}

---

PulseContent

@Composable
fun <
    State : PulseState,
    Action : PulseAction,
    Event : PulseEvent,
    Broadcast : PulseBroadcast,
    Unicast : PulseUnicast,
>
PulseContent(
    viewModel: PulseViewModel<State, Action, Event, Broadcast, Unicast>,
    onEvent: (Event) -> Unit = {},
    content: @Composable (State, (Action) -> Unit) -> Unit = { _, _ -> },
)

Observes a PulseViewModel and provides state and an action dispatcher to the content block. In mvi-mobile it takes the three-parameter PulseViewModel<State, Action, Event>, and it never re-creates its content on a refresh, since there is no PulseHost. It runs onSetup() the first time it observes an instance, but never cancels one.

Observe each instance from one PulseContent at a time. event is a single-consumer channel.

Parameters

Parameter	Type	Description
viewModel	PulseViewModel<State, Action, Event, Broadcast, Unicast>	The ViewModel to observe
onEvent	(Event) -> Unit	Called for each one-time side effect emitted by the ViewModel
content	@Composable (State, (Action) -> Unit) -> Unit	Renders the current state; receives a dispatcher to send actions

Lifecycle behavior

• PulseContent never cancels the ViewModel; teardown belongs to whoever owns it
• LaunchedEffect(viewModel) collects event. It always delivers through the latest onEvent passed in
• onSetup() runs once, the first time a PulseContent observes the ViewModel
• The scope is cancelled when the owning ViewModelStoreOwner is cleared
• Leaving and re-entering composition — a navigation destination covering the route, for example — never repeats onSetup()
• Inside PulseHost, the composable is wrapped in key(containerKey). It re-creates on refresh()

Example

PulseContent(
    viewModel = counterViewModel,
    onEvent = { event ->
        when (event) {
            is CounterEvent.ShowMessage ->
                scope.launch { snackbarHostState.showSnackbar(event.message) }
        }
    },
) { state, onAction ->
    Column {
        Text("Count: ${state.count}")
        Button(onClick = { onAction(CounterAction.Increment) }) {
            Text("+")
        }
    }
}