ruby

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)

```ruby
# ✅ 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

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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

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Commands

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

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Resources

• Clean Code: clean-code.md
• TDD with RSpec: tdd-rspec.md