Flow

Flow is a class that applies the observer pattern. It exposes subscribe and unsubscribe method.

Kaskade has an extension to subscribe to states using Flow instead of using the onStateChanged function.

fun <A : Action, S : State> Kaskade<A, S>.stateFlow(): Flow<S>

DamFlow

There's a subclass of Flow called DamFlow. The name comes from the concept of dam that is a barrier that prevents water from flowing.

DamFlow saves values emitted by type. In subscribing states, every type that it is emitted is saved in the dam. It saves every latest emission by type except for SingleEvent. SingleEvents are not saved into the Dam.

sealed class SampleState : State {
    data class Screen(
        val items: List<String>,
        val errorMessage: String,
        val isLoading: Boolean
    ) : SampleState()

    data class Error(val message: String) : SampleState(), SingleEvent
}

Error state being a SingleEvent does not get saved to the Dam and is only emitted by the Flow.

Saved values in a DamFlow are emitted when the flow is subscribed again.

LiveData

For more information see LiveData section