How to make my app easily being added new features using GetIt?

[iandis]

Hi, thanks for your great library! However I need a way to make my app easily being added new features using GetIt.

For instance, I have an abstract base class BaseMoviesRepository

abstract class BaseMoviesRepository {
  Future<List<Movie>> getMovieListById(List<BaseMovie> movieIds);
  Future<MovieDetail> getMovieDetail(int id);
  Future<List<Movie>> getNowPlaying({int page = 1});
  Future<List<Movie>> getUpcoming({int page = 1});
  Future<List<Movie>> searchMovie(String keyword, {int page = 1});
}

with its implementation

class MoviesRepository implements BaseMoviesRepository {
  final BaseNetworkService _networkService;

  MoviesRepository({
    BaseNetworkService? networkService,
  }) : _networkService = networkService ?? GetIt.I<BaseNetworkService>();
  
  ...

then next time if I need to add a new feature, I don't want to add anything to BaseMoviesRepository, so I create

abstract class BaseMovies2Repository extends BaseMoviesRepository{
  Future<List<Movie>> getPopular({int page = 1});
}

with its implementation

class Movies2Repository extends MoviesRepository implements BaseMovies2Repository {
  @override
  Future<List<Movie>> getPopular({int page = 1}) {
    ...
  }
} 

now suggest that I already have an app that most of its current features depend on BaseMoviesRepository but I need to register BaseMovies2Repository because I need the new feature getPopular.

the problem here is GetIt does not recognize BaseMoviesRepository as a parent class of BaseMovies2Repository, so if I try

GetIt.I.registerSingleton<BaseNetworkService>(NetworkService());
GetIt.I.registerSingleton<BaseMovies2Repository>(Movies2Repository());
final moviesRepo = GetIt.I<BaseMoviesRepository>();

or

GetIt.I.registerSingleton<BaseNetworkService>(NetworkService());
GetIt.I.registerSingleton<BaseMoviesRepository>(Movies2Repository());
final moviesRepo = GetIt.I<BaseMovies2Repository>();

will throw

Failed assertion: line 372 pos 7: 'instanceFactory != null': Object/factory with  type BaseMoviesRepository is not registered inside GetIt. 
(Did you accidentally do GetIt sl=GetIt.instance(); instead of GetIt sl=GetIt.instance;
Did you forget to register it?)

am I missing something here? or do I need to register a new instance instead?

[iandis]

solved it by creating an extension that casts the parent class to the child one

extension GetItFromAs on GetIt {
  AS fromAs<FROM extends Object, AS extends FROM>() {
    return call<FROM>() as AS;
  }
}

void main() {
  GetIt.I.registerSingleton<BaseNetworkService>(NetworkService());
  GetIt.I.registerSingleton<BaseMoviesRepository>(Movies2Repository());
  final moviesRepo = GetIt.I.fromAs<BaseMoviesRepository, BaseMovies2Repository>();
  ...
}