abstract-providers-sketch.ts

// belongs to SpecialModule which is a generic lib, every App needs to provide their implementation of UserService.
// The lib uses this special implementation as UserService internally
abstract class UserService {
}

@Injectable()
class SpecialService {

  constructer(private userService: UserService) {}
}


@NgModule({
  imports: [SpecialModule],
  providers: [
    SpecialService
  ]
})
SpecialModule ()


@NgModule({
  imports: [SpecialModule],
  providers: [
    {
      provide UserService,
      useClass: ConcreteUserService,
    }
  ]
})
AppModule()