Bloc: Why mapEventToState must return a new state?

[darek607]

According to docs the mapEventToState function must return a new state:

/// Takes the incoming [event] as the argument.
/// [mapEventToState] is called whenever an [event] is [add]ed.
/// [mapEventToState] must convert that [event] into a new [state]
/// and return the new [state] in the form of a Stream<State>.

Is it really obligatory to yield a new state per event? What if the event did not change the state for some reason? (should I return a copy of existing state in such case)?

Thank you for this library!

[narcodico]

Hi @darek607 👋

I see why that might be confusing, there's probably room for improvement with the description.

Is it really obligatory to yield a new state per event?

You're not forced to yield a new state as a result of an event. You can yield a new state, multiple states or no state at all.

What if the event did not change the state for some reason? (should I return a copy of existing state in such case)?

No, you don't have to yield anything in this case.

Hope that helps ✌

[felangel]

Hi @darek607 👋
Thanks for opening an issue!

As @RollyPeres mentioned, it's not necessary and I've updated the documentation as part of #1698 👍

[darek607]

Thank you guys very much🙇