substateStream<Substate> method

Stream<SubstateChange<Substate>> substateStream<Substate>(StateMapper<State, StateBuilder, Substate> mapper)

substateStream returns a stream to the state that is returned by the mapper function. For example: say my state object had a property count, then store.substateStream((state) => state.count), would return a stream that fires whenever count changes.

Implementation

Stream<SubstateChange<Substate>> substateStream<Substate>(
  StateMapper<State, StateBuilder, Substate> mapper,
) =>
    stream
        .map((c) => SubstateChange<Substate>(
              mapper(c.prev),
              mapper(c.next),
            ))
        .where((c) => c.prev != c.next);