Agent Skills: Dependency Injection

Dependency Injection

Priority: P1 (HIGH)

Automated class dependency management using get_it and injectable.

Structure

core/injection/
├── injection.dart  # Initialization & setup
└── modules/        # Third-party dependency modules (Dio, Storage)

Implementation Workflow

1. Annotate classes — Use @injectable annotations; avoid manual registry calls.
2. Choose scope — Default to @LazySingleton for repositories, services, and data sources (init on demand).
3. Register BLoCs as factories — Use @injectable (Factory) for BLoCs to ensure state resets per instance. Never use @Singleton() for BLoCs.
4. Inject abstractions — Always register implementations as abstract interfaces (as: IService).
5. Register third-party deps — Use @module for external instances (Dio, Hive, SharedPreferences).
6. Prefer constructor injection — Use mandatory constructor parameters; injectable resolves them automatically.

Registration & Test Mock Examples

See implementation examples for module registration and test mock swap patterns.

Reference & Examples

For module configuration and initialization templates: See references/REFERENCE.md.

Anti-Patterns

• ❌ getIt<OrderRepository>() inside widget build() — inject via constructor, not GetIt calls in UI
• ❌ @Singleton() on a BLoC — BLoCs must use @injectable (Factory) so state resets per instance
• ❌ Injecting the concrete class: OrderRepositoryImpl repo — always inject the abstract interface
• ❌ getIt.registerLazySingleton<X>(() => X()) in production code — use @injectable annotations; manual registration is only for tests

Related Topics

layer-based-clean-architecture | testing