ruby-development

Ruby Development

Production patterns and idioms for Ruby programming, covering project structure, gems, blocks, testing, metaprogramming, and error handling.

When to Use This Skill

• Starting or structuring a Ruby project
• Working with Bundler and gem dependencies
• Writing idiomatic Ruby with blocks, procs, and lambdas
• Testing with RSpec or Minitest
• Applying Ruby style conventions
• Writing Rake tasks for automation
• Understanding metaprogramming basics

Core Concepts

1. Project Layout

myapp/
├── lib/
│   ├── myapp.rb              # Main entry, requires sub-modules
│   └── myapp/
│       ├── client.rb
│       ├── parser.rb
│       └── errors.rb
├── spec/                     # RSpec tests
│   ├── spec_helper.rb
│   ├── myapp/
│   │   ├── client_spec.rb
│   │   └── parser_spec.rb
│   └── support/
│       └── shared_contexts.rb
├── bin/
│   └── myapp                 # CLI executable
├── Gemfile
├── Gemfile.lock
├── Rakefile
├── myapp.gemspec             # If building a gem
└── README.md

2. Key Principles

Principle	Ruby Idiom
Duck typing	Respond to methods, not check class
Convention	snake_case methods, PascalCase classes
Blocks everywhere	Yield to blocks for callbacks and iteration
Open classes	Extend existing classes carefully
POLA	Principle of Least Astonishment

Quick Start

# Create a new gem skeleton
bundle gem myapp

# Install dependencies
bundle install

# Run tests
bundle exec rspec
bundle exec rake test   # Minitest

# Run linter
bundle exec rubocop

# Interactive console
bundle exec irb -r ./lib/myapp

Patterns

Pattern 1: Error Handling

module MyApp
  # Define a hierarchy of custom errors
  class Error < StandardError; end
  class NotFoundError < Error; end
  class ValidationError < Error
    attr_reader :field

    def initialize(field, message)
      @field = field
      super("Validation failed on #{field}: #{message}")
    end
  end
  class AuthenticationError < Error; end
end

# Raise and rescue with specificity
class UserService
  def find!(id)
    user = repository.find(id)
    raise MyApp::NotFoundError, "User #{id} not found" unless user
    user
  end

  def create(params)
    validate!(params)
    repository.save(User.new(params))
  rescue MyApp::ValidationError => e
    logger.warn("Validation failed: #{e.message}")
    raise
  rescue StandardError => e
    logger.error("Unexpected error: #{e.message}")
    raise MyApp::Error, "Failed to create user: #{e.message}"
  end

  private

  def validate!(params)
    raise MyApp::ValidationError.new(:email, "is required") if params[:email].nil?
    raise MyApp::ValidationError.new(:email, "is invalid") unless params[:email].match?(URI::MailTo::EMAIL_REGEXP)
  end
end

# Ensure cleanup with ensure
def with_temp_file
  file = Tempfile.new("myapp")
  yield file
ensure
  file&.close
  file&.unlink
end