Broadcast

Broadcast delivers a typed message from a PulseContainer to all of its registered PulseViewModel instances at once.

Defining a Broadcast

Implement PulseBroadcast with a sealed class:

sealed class AppBroadcast : PulseBroadcast {
    data object Sync : AppBroadcast()
    data object UserLoggedOut : AppBroadcast()
    data class ThemeChanged(val isDark: Boolean) : AppBroadcast()
}

Sending a Broadcast

Call broadcast() on the Container:

container.broadcast(AppBroadcast.ThemeChanged(isDark = true))

Receiving a Broadcast

Override onReceive() in each ViewModel that needs to react:

override fun onReceive(broadcast: AppBroadcast) {
    when (broadcast) {
        AppBroadcast.Sync -> syncData()
        AppBroadcast.UserLoggedOut -> update { AppState() }
        is AppBroadcast.ThemeChanged -> update { copy(isDark = broadcast.isDark) }
    }
}

Broadcast vs Event

	Broadcast	Event
Direction	Container → all ViewModels	ViewModel → UI
Cardinality	One-to-many	One-to-one
Purpose	Cross-ViewModel coordination	One-time UI side effects
Type parameter	PulseBroadcast	PulseEvent

Example: Syncing Multiple ViewModels

// Two ViewModels sharing the same Broadcast and Unicast types
class HeaderViewModel : PulseViewModel<HeaderState, HeaderAction, HeaderEvent, AppBroadcast, AppUnicast>(...) {
    override fun onReceive(broadcast: AppBroadcast) {
        if (broadcast is AppBroadcast.UserLoggedOut) update { HeaderState() }
    }
}

class SidebarViewModel : PulseViewModel<SidebarState, SidebarAction, SidebarEvent, AppBroadcast, AppUnicast>(...) {
    override fun onReceive(broadcast: AppBroadcast) {
        if (broadcast is AppBroadcast.UserLoggedOut) update { SidebarState() }
    }
}

// One call resets both ViewModels
container.broadcast(AppBroadcast.UserLoggedOut)