Treat an object as a singleton in one scope, the Yo-Dawg way

gistfile1.java

@Module(injects = MyActivityModule.class)
class MotherModule {
  // ...snip
}

@Module(
  addsTo = MotherModule.class,
  injects = {MyActivity.class, MyFragment.class}
)
class MyActivityModule {
  private MyPresenter presenter;
  
  @Inject public SubModule(MyPresenter presenter) {
    this.presenter = presenter;
  }
  
  @Provides @Singleton MyPresenter providePresenter() {
    return presenter;
  }
}

class MyPresenter {
  @Inject public MyPresenter(Database database, View view) {
    // ...snip
  }
}

class MyActivity extends Activity {
  private ObjectGraph activityObjectGraph;
  
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    ObjectGraph motherGraph = ((MyApp) getApplication()).getObjectGraph();
    activityObjectGraph = motherGraph.plus(motherGraph.get(MyActivityModule.class);
  }
  
  public void inject(Object object) {
    activityObjectGraph.inject(object);
  }
}

class MyFragment extends Fragment {
  public void onActivityCreated() {
    ((MyActivity) getActivity()).inject(this);
  }
}