AgentSkillsCN

Dependency Injection

DI 最佳实践、inject() 的使用方式与 Provider 的规范。

SKILL.md
--- frontmatter
name: Dependency Injection
description: Best practices for DI, inject() usage, and providers.
metadata:
  labels: [angular, di, injection, providers]
  triggers:
    files: ['**/*.service.ts', '**/*.ts']
    keywords: [angular inject, providedIn, injection token]

Dependency Injection

Priority: P0 (CRITICAL)

Principles

  • •inject() over Constructor: Use the inject() function for cleaner injection updates and type inference.
  • •Tree Shaking: Always use providedIn: 'root' for services unless specific scoping is required.
  • •Tokens: Use InjectionToken<T> for configuration, primitives, or interface abstraction.

Guidelines

  • •Providers: Prefer provide* functions (e.g., provideHttpClient()) in app.config.ts over importing modules.
  • •Factories: Use useFactory strictly when dependencies need runtime configuration.

Anti-Patterns

  • •Global State: Avoid providedIn: 'platform' unless absolutely necessary (share between Micro Frontends).
  • •Circular Deps: Use forwardRef only as a last resort; refactor architecture instead.

References