depend

depend 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

---

• dependencies
  • Why it Rocks 🚀
  • Installation
  • Example Usage
    • Example 1: Define Dependencies
      • Step 2: Initialize Dependencies
      • Step 3: Access Dependencies with InheritedWidget
    • Example 2: Use Parent Dependencies
      • Step 1: Define Parent Dependencies
  • Logging and Debugging

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: Extends DependenciesLibrary

Create a DependenciesLibrary that extends DependenciesLibrary and initializes your dependencies:

class RootLibrary extends DependenciesLibrary {
  late final ApiService apiService;

  @override
  Future<void> init() async {
    await log(() async => apiService = await ApiService().init());
  }
}

Step 2: Initialize Dependencies

Use DependenciesInit to initialize your dependencies before launching the app:

void main() {
  runApp(
    Dependencies<RootLibrary>(
      library: RootLibrary(),
      placeholder: const ColoredBox(
        color: Colors.white,
        child: Center(child: CircularProgressIndicator()),
      ),
      child: const MyApp(),
    ),
  );
}

Step 3: Access Dependencies with InheritedWidget

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

/// The repository for the example
final class AuthRepository {
  final AuthDataSource dataSource;

  AuthRepository({required this.dataSource});

  Future<String> login() => dataSource.login();
  
  void dispose() {
    // stream.close();
  }
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      home: Dependencies<ModuleLibrary>(
        library: ModuleLibrary(
          parent: Dependencies.of<RootLibrary>(context),
        ),
        child: BlocProvider(
          create: (context) => DefaultBloc(
            Dependencies.of<ModuleLibrary>(context).authRepository,
          ),
          child: const 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: Use Parent Dependencies

Step 1: Define Parent Dependencies

class RootLibrary extends DependenciesLibrary {
  late final ApiService apiService;

  @override
  Future<void> init() async {
    apiService = await ApiService().init();
  }
}

class ModuleLibrary extends DependenciesLibrary<RootLibrary> {
  late final AuthRepository authRepository;

  ModuleLibrary({required super.parent});

  @override
  Future<void> init() async {
    // initialize dependencies
    authRepository = AuthRepository(
      dataSource: AuthDataSource(
        apiService: parent.apiService, // parent - RootLibrary
      ),
    );
  }

  @override
  void dispose() {
    authRepository.dispose();
  }
}

Logging and Debugging

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

class ModuleLibrary extends DependenciesLibrary<RootLibrary> {
  late final AuthRepository authRepository;

  ModuleLibrary({required super.parent});

  @override
  Future<void> init() async {
    await log(() async => authRepository = AuthRepository(
          dataSource: AuthDataSource(
            apiService: parent.apiService,
          ),
        ),
    );
  }
}

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

This is useful for tracking performance and initialization times.

Codecov