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.