Dependency Injection

Setiap project wajib menggunakan Dependency Injection (DI) untuk memudahkan testing dan decoupling.

Rekomendasi per Platform

Platform	DI Framework	Tipe
Android	Hilt (recommended) / Koin	Compile-time / Runtime
iOS	Factory / swift-dependencies	Runtime
Flutter	GetIt + Injectable	Runtime
React Native	Manual DI / tsyringe	Manual / Runtime

Prinsip

1. Constructor Injection — Selalu inject dependency melalui constructor.
2. Program to Interface — Inject interface, bukan implementasi langsung.
3. Single Responsibility — Setiap module DI bertanggung jawab atas satu scope.

Android (Hilt)

@Module
@InstallIn(SingletonComponent::class)
abstract class RepositoryModule {
    @Binds
    @Singleton
    abstract fun bindUserRepository(
        impl: UserRepositoryImpl
    ): UserRepository
}

@Module
@InstallIn(ViewModelComponent::class)
object UseCaseModule {
    @Provides
    fun provideGetUserUseCase(
        repository: UserRepository
    ): GetUserUseCase = GetUserUseCase(repository)
}

Flutter (GetIt)

final getIt = GetIt.instance;

void setupDI() {
  // Data sources
  getIt.registerLazySingleton<UserRemoteDataSource>(
    () => UserRemoteDataSourceImpl(getIt()),
  );
  
  // Repositories
  getIt.registerLazySingleton<UserRepository>(
    () => UserRepositoryImpl(getIt(), getIt()),
  );
  
  // Use cases
  getIt.registerFactory(() => GetUserUseCase(getIt()));
  
  // Cubits
  getIt.registerFactory(() => UserCubit(getIt()));
}

React Native

// Simple manual DI container
class DIContainer {
  private static instance: DIContainer;
  
  private constructor() {}
  
  static getInstance(): DIContainer {
    if (!DIContainer.instance) {
      DIContainer.instance = new DIContainer();
    }
    return DIContainer.instance;
  }

  get userRepository(): UserRepository {
    return new UserRepositoryImpl(
      new UserApiService(this.apiClient),
      new UserLocalStorage(),
    );
  }

  get getUserUseCase(): GetUserUseCase {
    return new GetUserUseCase(this.userRepository);
  }
}