Factory injection in Angular-Dart DI library

问题:

In my Dart application I'm using the MVP pattern and the angular-dart Dependency Injection library(angular-di).

In the example above, I cannot inject MyView or MyPresenter, as this is a circular dependency.

class MyView {
    MyPresenter presenter;
    MyView(this.presenter);
}
class MyPresenter {
    MyView view;
    MyPresenter(this.view);
}

The way I usually did this in Java with Guice was injecting a Factory, like:

class MyView {
    MyPresenter presenter;
    MyView(this.presenter);
}
class MyPresenter {
    Factory<MyView> factoryView;
    MyView view;
    MyPresenter(this.factoryView) {
        view = factoryView(this);
    }
}

How do I accomplish this using angular-di? Is there possible to inject the factory without having to write the factory itself?

回答1:

Angular 2 Dart

typedef MyView MyViewFactoryFn(MyPresenter p);
provide(MyView, useValue: (MyPresenter p) => new MyView(p));

MyPresenter(MyViewFactoryFn vf) {
  view = vf(this);
}

or

typedef MyView MyViewFactoryFn(MyPresenter p);

MyView viewFactory(MyPresenter p) => new MyView(p)

const Provider(MyView, useFactory: viewFactory);

MyPresenter(MyViewFactoryFn vf) {
  view = vf(this);
}

See also

• https://webdev.dartlang.org/angular/api/angular2.core/Provider-class
• https://webdev.dartlang.org/angular/api/angular2.core/provide

Angular 1 Dart

You can bind a closure

typedef MyView MyViewFactoryFn(MyPresenter p);
bind(MyView, toValue: (MyPresenter p) => new MyView(p));

the constructor should then look like

MyPresenter(MyViewFactoryFn vf) {
  view = vf(this);
}

There is also a toFactory: but I guess DI will call the factory itself but I guess toValue: with a closure could work (not tried though).