Command Pattern in Dart (binder)

base_command.dart

abstract class BaseCommand<T> {
  BuildContext _context;

  BaseCommand(this._context);

  T locate<T>(LogicRef<T> ref) => _context.use(ref);
  T read<T>(StateRef<T> ref) => _context.read(ref);

  Future<T> run();
}

user.service.dart

class UserService with Logic {
  UserService(this.scope);

  Future<bool> login(String user, String pass) => Future.value(true);

  @override
  final Scope scope;
}

final userServiceRef = LogicRef((scope) => UserService(scope));

user_controller.logic.dart

class UserController with Logic {
  const UserController(this.scope);

  @override
  final Scope scope;

  void updateUser(String user) => write(userStateRef, User(user));
}

final userControllerRef = LogicRef((scope) => UserController(scope));

user_login.command.dart

class LoginCommand extends BaseCommand<bool> {
  final String user;
  final String pass;

  LoginCommand(BuildContext context, {this.user, this.pass}) : super(context);

  @override
  run() async {
    UserService userService = locate(userServiceRef);
    UserController userController = locate(userControllerRef);

    // Await some service call
    bool loginSuccess = await userService.login(user, pass);

    // Update appModel with current user. Any views bound to this will rebuild
    userController.updateUser(loginSuccess ? user : null);

    // Return the result to whoever called us, in case they care
    return loginSuccess;
  }
}

user_state.dart

class User {
  final String user;

  User(this.user);
}

final userStateRef = StateRef<User>(null);