Migrating to Popsicle 2.1

Popsicle 2.1 keeps the 2.0 declaration and Scope model, while tightening the state-transition vocabulary and adding opt-in Store capabilities.

State transition rename

Use commit(...) for persistent Store state:

// Before
emit(nextState);

// 2.1
commit(nextState);

effect(...) is unchanged and remains the one-shot output channel.

UI projection rename

Use .ui():

// Before
counter.view(
  (context, state, store) => Text('$state'),
);

// 2.1
counter.ui(
  (context, state, store) => Text('$state'),
);

The corresponding public extension names are now PopsicleStoreUi and ReactiveValueUi.

Undo / redo

Add History<State> only to Stores that need it:

class EditorStore extends Store<EditorState> with History<EditorState> {
  EditorStore() : super(const EditorState());
}

Then use:

store.undo();
store.redo();
store.canUndo;
store.canRedo;

Normal Stores have no history behavior or history storage.

Streams

A Store can now own stream subscriptions through listenTo(...):

class LiveStore extends Store<LiveState> {
  LiveStore(Stream<Event> events) : super(const LiveState()) {
    listenTo(
      events,
      onData: (event) {
        commit(state.apply(event));
      },
    );
  }
}

Subscriptions registered with listenTo are cancelled automatically when the Store is disposed.

What did not change

The recommended declarations remain:

Popsicle.inject(...)
Popsicle.value(...)
Popsicle.create(...)
Popsicle.params(...)

Scope remains:

scope.get(...)
scope.use(...)
scope.store(...)
scope.select(...)

And the core types remain Store, IntentStore, ReactiveValue, and AsyncState.