ruby-oop-patterns_skill

Overview

This skill is a comprehensive guide to Object-Oriented Programming in Ruby and Rails, covering classes, modules, design patterns, SOLID principles, and modern Ruby 3.x features. It distills practical examples, idiomatic patterns, and Rails-specific best practices for building maintainable enterprise applications. Use it to learn, audit, or refactor Ruby code with clear, production-ready patterns.

How this skill works

The skill inspects OOP constructs and patterns: class definitions, attribute accessors, visibility rules, modules (include/prepend/extend), lookup chains, and metaprogramming techniques like define_method, method_missing, class_eval, and eigenclasses. It also explains Rails-specific structures: concerns (ActiveSupport::Concern), service objects, form and query objects, policy classes, presenters/decorators, and value objects with examples and recommended practices.

When to use it

• When designing or reviewing class and module structure for clarity and testability
• When extracting business logic into service, form, query, or policy objects
• When introducing or reducing metaprogramming to improve maintainability
• When applying SOLID principles to Rails models and controllers
• When implementing decorators, presenters, or value objects to separate concerns

Best practices

• Favor composition and small single-responsibility classes over large models
• Use ActiveSupport::Concern for shared behavior with clear class_methods and included blocks
• Limit method_missing and heavy metaprogramming; provide respond_to_missing? implementations
• Use service and form objects to keep controllers and models thin and testable
• Prefer prepend for behavior overrides and extend for class-level mixins when intent matters

Example use cases

• Refactor a fat User model into readable service objects and query objects
• Implement feature flags or behavior swaps using prepend and modular mixins
• Create form objects for complex multi-model user registration flows
• Build secure, testable authorization using Pundit policy objects and scopes
• Define dynamic attribute accessors or DSLs with define_method while preserving respond_to?