# Implementing Code

> Write clean, efficient, maintainable code. Use when implementing features, writing functions, or creating new modules. Covers SOLID principles, error handling, and code organization.

- Skill: `majiayu000/implementing-code` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add majiayu000/implementing-code`
- Raw SKILL.md: https://api.skillmd.com/api/skills/majiayu000/implementing-code/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: majiayu000 (https://skillmd.com/u/majiayu000)
- Updated: 2026-09-09
- Page: https://skillmd.com/skills/majiayu000/implementing-code

---


# Implementing Code

## Workflows

- [ ] **Security Check**: Injection flaws, auth issues, sensitive data exposure
- [ ] **Performance Check**: N+1 queries, memory leaks, inefficient algorithms
- [ ] **Readability Check**: SOLID principles, naming conventions, comments
- [ ] **Testing Check**: Edge cases, error paths, happy paths

## Feedback Loops

1. Implement feature or fix
2. Run local tests (unit/integration)
3. Run linter/formatter
4. If failure, fix and repeat

## Reference Implementation

### SOLID Compliant Class (TypeScript)

```typescript
// Abstraction (Interface Segregation)
interface ILogger {
  log(message: string): void;
}

interface IUserRepository {
  save(user: User): Promise<void>;
}

// Domain Entity
class User {
  constructor(public readonly id: string, public readonly email: string) {}
}

// Implementation (Single Responsibility)
class UserService {
  constructor(
    private readonly userRepository: IUserRepository,
    private readonly logger: ILogger
  ) {}

  public async registerUser(email: string): Promise<User> {
    if (!email.includes('@')) {
      throw new Error("Invalid email format");
    }

    const user = new User(crypto.randomUUID(), email);
    await this.userRepository.save(user);
    this.logger.log(`User registered: ${user.id}`);

    return user;
  }
}
```

## Code Review Checklist

- [ ] No hardcoded secrets or credentials
- [ ] Input validation on all external data
- [ ] Proper error handling with meaningful messages
- [ ] No N+1 query patterns
- [ ] Functions follow single responsibility principle
- [ ] Dependencies injected, not instantiated inline
- [ ] Tests cover happy path and edge cases