Effects only in Actor

Once the complexity grows inside your Actor, you might be tempted to extract some responsibilities to other classes.

This is fine, however, don't do this:

class ActorImpl(
    private val executor1: Executor1,
    private val executor2: Executor2
) : Actor<State, Wish, Effect> {

    override fun invoke(state: State, wish: Wish): Observable<Effect> = when (wish) {
        is Wish1 -> executor1.doSomething()
        is Wish2 -> executor2.doSomething()
    }
}

// In some other files:

class Executor1 {
    fun doSomething(): Observable<Effect> = TODO()
}

class Executor2 {
    fun doSomething(): Observable<Effect> = TODO()
}

This way the reader of your code can have no simple understanding of what Effect is the result of what and where.

Resolution:

1. Keep your Effects internal to your Feature
2. In your extracted classes use only local result types
3. Map those results to Effects in your Actor, ensuring that all business logic is understandable in a high-level overview in one place.

Example:

class ActorImpl(
    private val executor1: Executor1,
    private val executor2: Executor2
) : Actor<State, Wish, Effect> {

    override fun invoke(state: State, wish: Wish): Observable<Effect> = when (wish) {
        is Wish1 -> executor1
            .doSomething()
            .map { when (it) {
                is SomethingHappened1 -> Effect1(it.data)
                is SomethingHappened2 -> Effect2
            }}

        is Wish2 -> executor2
            .doSomething()
            .map { when (it) {
                is SomethingElseHappened1 -> Effect3
                is SomethingElseHappened2 -> Effect4(it.error)
            }}
    }
}

// In some other files:

class Executor1 {
    fun doSomething(): Observable<LocalResult> = TODO()

    sealed class LocalResult {
        data class SomethingHappened1(val data: Any) : LocalResult()
        object SomethingHappened2 : LocalResult()
    }
}

class Executor2 {
    fun doSomething(): Observable<LocalResult> = TODO()

    sealed class LocalResult {
        object SomethingElseHappened1 : LocalResult()
        data class SomethingElseHappened2(val error: Throwable) : LocalResult()
    }
}