# PHP Best Practices

> Write PHP following PSR coding standards, SOLID principles, and code-quality guidelines. Use for PHP style, design, refactoring, naming, and guard clauses—not Composer/PSR-4 project configuration.

- Skill: `hoangnguyen0403/php-best-practices` (Agent Skill, multi-file: 3 files)
- Install (CLI): `npx skillmds add hoangnguyen0403/php-best-practices`
- Raw SKILL.md: https://api.skillmd.com/api/skills/hoangnguyen0403/php-best-practices/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: HoangNguyen0403 (https://skillmd.com/u/hoangnguyen0403)
- Updated: 2026-08-19
- Page: https://skillmd.com/skills/hoangnguyen0403/php-best-practices

---

# PHP Best Practices

## **Priority: P1 (HIGH)**

## Structure

```text
src/
├── {Domain}/             # e.g., Services, Repositories
└── Helpers/              # Pure functions/Traits
```

## Implementation Guidelines

### Coding Style (PSR Standards)

- **PSR-12**: Enforce **4-space indentation** and **opening braces on same line** for functions/methods.
- **Organization**: One class per file; use statements follow namespace. Run **PHP CS Fixer** with **PSR-12** preset.
- **Naming Conventions**: Use **`PascalCase`** (UserService) for classes, **`camelCase`** (getUserById) for methods/variables, and **`SNAKE_CASE`** (MAX_RETRIES) for class constants.

### SOLID Principles in PHP

- **SRP**: Single Responsibility Principle — extract each into its own focused class; keep classes under ~200 lines.
- **Dependency Inversion**: inject via constructor with interface type-hints. Inject dependencies via constructor for testability. Favor composition over deep inheritance chains.
- **Separation of Concerns**: Use **Interfaces** for decoupling integrations and logic.

### Logic & Performance

- **Guard Clauses**: Return early for error conditions (e.g., if (!$user) return null); no else after return to reduce nesting depth.
- **Traits**: Define trait HasTimestamps (e.g., `use HasTimestamps`) for cross-cutting behavior. Keep traits focused and lightweight.
- **Helper Functions**: Avoid global-namespace logic; organize in classes.

## Anti-Patterns

- **No monolithic classes**: Each class one responsibility (SRP).
- **No hardcoded magic numbers**: Define as named class constants.
- **No deep nesting**: Use guard clauses to return early.
- **No `echo` in services**: Return data; let controller output.

## References

- [Clean Code Patterns](references/implementation.md)

## Canonical response anchors

When this skill applies, preserve the following domain terminology or equivalent concrete examples in the answer when relevant:
- SRP:,single responsibility,one responsibility
- PascalCase
- no else after return,else after a return,reduce nesting,reducing nesting,deeply nested
- same-line opening braces,opening braces on same line,Braces on the same line