solid-principles-skill

What I do

I help you apply SOLID principles to write maintainable, flexible, and testable code:

1. Analyze Code Structure: Evaluate classes, modules, and functions for SOLID compliance
2. Detect Violations: Identify which SOLID principle is being violated with specific examples
3. Provide Refactoring Guidance: Suggest concrete fixes with before/after code examples
4. Apply at Multiple Levels: From class-level to architecture-level SOLID application
5. Create Detection Questions: Provide questions to ask when reviewing code
6. Generate Quick Reference: Create lookup tables for rapid SOLID assessment

When to use me

Use this skill when:

• Writing new code and want to ensure SOLID compliance from the start
• Refactoring existing code that feels "wrong" or hard to change
• Reviewing code (peer review, PR review) for quality issues
• Teaching or learning SOLID principles with practical examples
• Diagnosing why a particular class or module is difficult to maintain
• Planning architecture and want SOLID at the system level
• Setting up coding standards for a team or project

Prerequisites

• Understanding of basic object-oriented programming concepts
• Code to analyze (existing or being written)
• Willingness to refactor and improve code quality
• Basic knowledge of dependency injection and interfaces

SOLID Principles Overview

SOLID helps structure software to be flexible, maintainable, and testable. These principles reduce coupling and increase cohesion.

S - Single Responsibility Principle (SRP)

"A class should have one, and only one, reason to change."

Problem It Solves

God objects that do everything - hard to test, hard to change, hard to understand.

How to Apply

Each class handles ONE responsibility. If you find yourself saying "and" when describing what a class does, split it.

Language-Agnostic Example:

# BAD: Multiple responsibilities
class Order:
    def calculate_total(self): ...
    def save_to_database(self): ...    # Persistence
    def generate_invoice(self): ...    # Presentation