Critical Patterns

Ruby Idioms (REQUIRED)

✅ ALWAYS: Use Ruby idioms

users.map(&:name) # Symbol to proc user&.address&.city # Safe navigation name ||= "Default" # Memoization

Class Structure (REQUIRED)

✅ ALWAYS: Clear class structure

class User attr_reader :name, :email

def initialize(name:, email:) @name = name @email = email end

def admin? role == 'admin' end end

Error Handling (REQUIRED)

✅ Use custom exceptions

class UserNotFoundError < StandardError; end

def find_user!(id) user = User.find_by(id: id) raise UserNotFoundError, "User #{id} not found" unless user user end

Decision Tree

Need attribute access? → Use attr_reader/writer Need boolean check? → Use predicate method (?) Need dangerous operation? → Use bang method (!) Need configuration? → Use block with yield

Commands

ruby script.rb # Run script irb # Interactive Ruby bundle install # Install dependencies rspec # Run tests rubocop # Lint code

Resources

• Clean Code: clean-code.md

• TDD with RSpec: tdd-rspec.md