What does this userInput() do?

[mgai]

Hi Vadim and all experts,

Thank you very much for your great tutorial. I have a question here is, the userInput() feedback seems just pass through the input without doing anything. If this is the case, why do we still reed it?

Also another question is, for multiple feedbacks, are they processed in parallel or sequential? Or as for declarative principle, we should not care about the order and they should be independent?

Thank you for your answer, and take care in this challenging time.

Cheers,
Ming

[mgai]

OK, after a while, I think I kinda figured them out myself -

userInput

It just pass through the event to the subscribers, for further processing by reducer if needed, to see if it should be picked up for state change.

    private let input = PassthroughSubject<Event, Never>()
//...
                Self.userInput(input: input.eraseToAnyPublisher())

Multiple feedback processing

It's done by the map call one by one (well, it's in fact clearly illustrated in the diagram on the tutorial page...), as defined in the System -

        let events = feedbacks.map { feedback in feedback.run(state.eraseToAnyPublisher()) }