可注入的性能，get_it Flutter

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I have a question. In my project, I have some class with singleton.

• DioMethod (some api configs),
• Repository (Connect ApiProvider and BLoc class),
• ApiProvider (call api => get data => pass to Repository ),
• Some BloC classes such as MoviesBloc , MovieDetailBloc ,.. i created a BLoC class for each Screen .

and init all at $initGetIt the same.

_i1.GetIt $initGetIt(_i1.GetIt get,
    {String? environment, _i2.EnvironmentFilter? environmentFilter}) {
  final gh = _i2.GetItHelper(get, environment, environmentFilter);
  gh.singleton<_i3.DioConfig>(_i3.DioConfig());
  gh.singleton<_i4.DioMethod>(_i4.DioMethod(get<_i3.DioConfig>()));
  gh.singleton<_i5.MovieApiProvider>(
      _i5.MovieApiProvider(get<_i4.DioMethod>()));
  gh.singleton<_i6.Repository>(_i6.Repository());
  gh.lazySingleton<_i7.MovieDetailBloc>(
      () => _i7.MovieDetailBloc(get<_i6.Repository>()),
      dispose: (i) => i.dispose());
  gh.lazySingleton<_i8.MoviesBloc>(() => _i8.MoviesBloc(get<_i6.Repository>()),
      dispose: (i) => i.dispose());
  return get;
}

I think If I scale my project, I can get some problem.

1. This function will be too large and we have too much singleton still live in app.
2. We need to init a lot of Object when opening the app => Can delay app?
3. How to create a singleton only alive when access to the screen and destroyed after pop this screen.

Thank you for your anwser!

Answer 1

This function will be too large and we have too much singleton still live in app.

I have hundreds of GetIt singletons and I do not see any problems.

We need to init a lot of Object when opening the app => Can delay app?

If you are worried about number of Object s - do not need to worry. When Flutter builds a frame (you know, it builds 60 frames per second), it creates a huge widget tree contains thousands of widgets and each widget contains dozens of objects. So hundreds of objects are really a very small number . Dart's Garbage Collector is designed for the many-object case.

How to create a singleton only alive when access to the screen and destroyed after pop this screen.

class MyPageOne extends StatefulWidget {
  const MyPageOne({Key? key}) : super(key: key);

  @override
  _MyPageOneState createState() => _MyPageOneState();
}

class _MyPageOneState extends State<MyPageOne> {
  @override
  void initState() {
    super.initState();
    GetIt.I.registerSingleton<MyClass>(MyClass());
  }
  
  @override
  void dispose() {
    GetIt.I.unregister<MyClass>();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return ...your page...;
  }
}

This is just an example and you can, for example, encapsulate it into a widget.