Implement notifyListeners method on StateNotifier

[jamiewest]

I think it would be helpful to have a notifyListeners method on the StateNotifier class to more closely resemble a ChangeNotifier.

This would go along with using StateNotifier in manner similar to ChangeNotifier.

class Person extends StateNotifier<Person> {
   String _email;
   const Person({this.name});

   final String name;

   String get email => _email;

   set email(String value) {
      _email = value;
      notifyListeners();
      // as opposed to... 
      state = this; // would even this work??
   }
}

[rrousselGit]

This is not how you should use StateNotifier. You should not have state that needs to be listened, that is not part of the state variable.

Instead do:

class Person {
  String email = '';
  String name = '';
}

class PersonController extends StateNotifier<Person> {
  PersonController(): super(Person());

  set email(String value) {
    state = Person()
      ..email = value
      ..name = state.name;
  }
}

[jamiewest]

Was this a design choice to have the State and StateNotifier be to separate components or was due to an engineering requirement in order to make things work with provider?

[rrousselGit]

This is a design choice. StateNotifier is not ChangeNotifier, but ValueNotifier

[jamiewest]

I see, that is probably where I am confusing things. Thank you.

[venkatd]

Not sure if this is against the intended design, but if you're looking for something like ChangeNotifier but decoupled from Flutter, you can accomplish something like it as so:

abstract class StateChangeNotifier extends StateNotifier<void> {
  StateChangeNotifier() : super(null);
  void notifyListeners() => state = null;
}

I wouldn't recommend this is in many cases because StateNotifier forces you to separate the state into its own object which ends up with cleaner code.