Clean Code Reference
A comprehensive reference for writing clean, maintainable code based on Robert Martin's "Clean Code" and related works. This skill provides language-agnostic principles with examples that apply to any programming language.
When This Skill Activates
This skill automatically activates when you:
- Review code for quality or maintainability
- Need guidance on naming conventions
- Discuss refactoring or code smells
- Apply SOLID principles
- Improve code readability or structure
- Write or review unit tests
Quick Reference
SOLID Principles
| Principle | Summary | Violation Sign |
|---|---|---|
| Single Responsibility (SRP) | One reason to change | Class does too many things |
| Open/Closed (OCP) | Open for extension, closed for modification | Modifying existing code for new features |
| Liskov Substitution (LSP) | Subtypes must be substitutable | Subclass breaks parent behavior |
| Interface Segregation (ISP) | No forced dependencies on unused methods | Fat interfaces |
| Dependency Inversion (DIP) | Depend on abstractions, not concretions | High-level modules import low-level |
Clean Code Practices
| Practice | Key Points |
|---|---|
| Meaningful Names | Intention-revealing, pronounceable, searchable |
| Functions | Small, do one thing, one level of abstraction |
| Comments | Code should be self-documenting; comments explain why, not what |
| Formatting | Consistent style, vertical density, horizontal alignment |
| Error Handling | Exceptions over error codes, fail fast, don't return null |
| Unit Testing | F.I.R.S.T. principles, one assert per test, test behavior |
| Code Smells | Recognition and refactoring of common problems |
| Boy Scout Rule | Leave code cleaner than you found it |
The Boy Scout Rule
"Leave the campground cleaner than you found it."
Every time you touch code, make it a little better. Small, incremental improvements compound over time.
Code Quality Checklist
Before committing code, verify:
- Names - Are all names intention-revealing?
- Functions - Is each function doing exactly one thing?
- Comments - Are comments explaining why, not what?
- DRY - Is there any duplicated logic?
- SOLID - Are principles being followed?
- Tests - Is the code tested and testable?
- Error Handling - Are errors handled gracefully?
Language Translation Notes
Examples use generic pseudocode. Adapt to your language:
- PHP:
class,function,->, type hints - JavaScript/TypeScript:
class, arrow functions,. - Python:
class,def,., type hints - Java/C#: Direct mapping with access modifiers
*Based on concepts from "Clean Code: A Handbook of Agile Software Craftsmanship" by Robert C. Martin, 2008.*