Presenter class abstract

A Presenter prepares data for the Controller, listens to UseCase, and handles its creation and distruction. A Presenter should be aggregated inside a Controller. Its dependencies are also provided by the Controller. Once the Controller is disposed, it should also call dispose() of the Presenter in order to dispose of the UseCase. The Presenter utilizes an Observer to listen to the UseCase. However, it is a separate class since Dart does not yet support inner or anonymous classes.


    class LoginPresenter() {

      Function loginOnComplete; // alternatively `void loginOnComplete();`
      Function loginOnError;
      Function loginOnNext; // not needed in the case of a login presenter

      final LoginUseCase loginUseCase;
      // dependency injection from controller
      LoginPresenter(authenticationRepo): loginUseCase = LoginUseCase(authenticationRepo);

      /// login function called by the controller
      void login(String email, String password) {
        loginUseCase.execute(_LoginUseCaseObserver(this), LoginUseCaseParams(email, password));
      }

       /// Disposes of the [LoginUseCase] and unsubscribes
       @override
       void dispose() {
         _loginUseCase.dispose();
       }
    }

    /// The [Observer] used to observe the `Observable` of the [LoginUseCase]
    class _LoginUseCaseObserver implements Observer<void> {

      // The above presenter
      // This is not optimal, but it is a workaround due to dart limitations. Dart does
      // not support inner classes or anonymous classes.
      final LoginPresenter loginPresenter;

      _LoginUseCaseObserver(this.loginPresenter);

      /// implement if the `Observable` emits a value
      // in this case, unnecessary
      void onNext(_) {}

      /// Login is successfull, trigger event in [LoginController]
      void onComplete() {
        // any cleaning or preparation goes here
        assert(loginPresenter.loginOnComplete != null);
        loginPresenter.loginOnComplete();

      }

      /// Login was unsuccessful, trigger event in [LoginController]
      void onError(e) {
        // any cleaning or preparation goes here
        assert(loginPresenter.loginOnError != null);
        loginPresenter.loginOnError(e);
      }
    }

Constructors

Presenter()

Properties

hashCode → int
The hash code for this object.
no setterinherited
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited

Methods

dispose() → void
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
toString() → String
A string representation of this object.
inherited

Operators

operator ==(Object other) → bool
The equality operator.
inherited