dependencies

dependencies is a library for managing dependencies in Flutter applications. It provides a convenient way to initialize and access services or repositories via an InheritedWidget.

Why it Rocks 🚀

  • Initialize dependencies before launching the app
  • Access dependencies from anywhere in the widget tree
  • Log initialization times for each dependency
  • Clean and extensible way to manage dependencies
  • Easy to use and integrate with existing codebases

Installation

Add the package to your pubspec.yaml:

dependencies:
  depend: ^0.0.1

Then run:

$ flutter pub get

Example Usage

Example 1: Define Dependencies

Step 1: Create a List of Dependencies

Start by creating a list of dependencies that will be initialized when your app starts. Each dependency can rely on another through DependenciesProgress:

List<DependenciesProgress> progress = [
  (progress) async => ApiService(), // Example of an independent dependency
  (progress) async {
    return AuthRepository(
      dataSource: AuthDataSource(
        apiService: progress.dependencies.get<ApiService>(),
      ),
    );
  },
];

Step 2: Initialize Dependencies

Use DependenciesInit to initialize your dependencies before launching the app:

void main() async {
  final dependencies = await DependenciesInit().init(progress: progress);

  runApp(
    MyApp(
      dependencies: dependencies,
    ),
  );
}

Step 3: Access Dependencies with InheritedWidget

Once initialized, dependencies can be accessed from anywhere in the widget tree using Dependencies.of(context).get<T>():

class MyApp extends StatelessWidget {
  final DependenciesLibrary dependencies;

  const MyApp({super.key, required this.dependencies});

  @override
  Widget build(BuildContext context) {
    return Dependencies(
      dependencies: dependencies,
      child: MaterialApp(
        title: 'Flutter Demo',
        home: BlocProvider(
          create: (context) => DefaultBloc(
            Dependencies.of(context).get<AuthRepository>(),
          ),
          child: MyHomePage(),
        ),
      ),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key});

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  void _login() {
    context.read<DefaultBloc>().add(DefaultEvent());
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SafeArea(
        child: SingleChildScrollView(
          child: Column(
            children: [
              BlocBuilder<DefaultBloc, DefaultState>(
                builder: (context, state) {
                  return Text('Login: ${state.authorized}');
                },
              ),
              Builder(
                builder: (context) {
                  return ElevatedButton(
                    onPressed: _login,
                    child: const Text('Login'),
                  );
                },
              )
            ],
          ),
        ),
      ),
    );
  }
}

Example 2: Example Usage with Bloc

You can also use dependencies with Bloc for state management. Here’s an example where the AuthRepository is injected into an AuthBloc:

/// Authentication BLoC

class DefaultBloc extends Bloc<DefaultEvent, DefaultState> {
  final AuthRepository _authRepository;

  DefaultBloc(this._authRepository) : super(DefaultState()) {
    on<DefaultEvent>((event, emit) {
      _authRepository.login();
      emit(DefaultState(authorized: true));
    });
  }
}


BlocProvider(
    create: (context) => DefaultBloc(
      Dependencies.of(context).get<AuthRepository>(),
    ),
    child: MyWidget(),
),

In this example:

  • We create an AuthBloc that depends on AuthRepository (which is initialized through the dependencies library).
  • The AuthBloc is provided using BlocProvider, and we inject the AuthRepository from the dependencies into the BLoC.
  • The UI responds to authentication events and displays different states like AuthSuccess or AuthFailure.

Logging and Debugging

During initialization, each dependency logs the time it took to initialize:

💡 ApiService: initialized successfully for 10 ms
💡 AuthRepository: initialized successfully for 0 ms

This is useful for tracking performance and initialization times.

Conclusion

The dependencies library provides a clean and extensible way to manage dependencies in your Flutter app, including integration with Bloc for state management.

Libraries

depend