ruby

Ruby

Overview

Ruby programming patterns including blocks, metaprogramming, and idiomatic Ruby code.

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Core Ruby Patterns

Classes and Modules

# Class definition
class User
  attr_accessor :name, :email
  attr_reader :id
  attr_writer :password

  # Class variable
  @@count = 0

  # Class method
  def self.count
    @@count
  end

  # Initialize
  def initialize(name, email)
    @id = SecureRandom.uuid
    @name = name
    @email = email
    @@count += 1
  end

  # Instance method
  def display_name
    "#{name} <#{email}>"
  end

  # Private methods
  private

  def validate_email
    email.include?('@')
  end
end

# Inheritance
class Admin < User
  attr_accessor :permissions

  def initialize(name, email, permissions = [])
    super(name, email)
    @permissions = permissions
  end

  def has_permission?(perm)
    permissions.include?(perm)
  end
end

# Modules for mixins
module Timestampable
  def self.included(base)
    base.extend(ClassMethods)
  end

  module ClassMethods
    def timestamped_attrs
      [:created_at, :updated_at]
    end
  end

  def touch
    @updated_at = Time.now
  end

  def created_at
    @created_at ||= Time.now
  end
end

# Including module
class Document
  include Timestampable
  include Comparable

  attr_accessor :title, :content

  def <=>(other)
    title <=> other.title
  end
end

# Module for namespacing
module MyApp
  module Services
    class UserService
      def create(params)
        # ...
      end
    end
  end
end

Blocks, Procs, and Lambdas

# Block usage
[1, 2, 3].each { |n| puts n }

[1, 2, 3].map do |n|
  n * 2
end

# Yield to block
def with_timing
  start = Time.now
  result = yield
  elapsed = Time.now - start
  puts "Elapsed: #{elapsed}s"
  result
end

with_timing { sleep(0.1) }

# Block with arguments
def transform_items(items)
  items.map { |item| yield(item) }
end

transform_items([1, 2, 3]) { |n| n * 2 }

# Check if block given
def optional_block
  if block_given?
    yield
  else
    "No block provided"
  end
end

# Convert block to proc
def with_block(&block)
  block.call(42)
end

# Proc
my_proc = Proc.new { |x| x * 2 }
my_proc.call(21) # => 42

# Lambda
my_lambda = ->(x) { x * 2 }
my_lambda.call(21) # => 42

# Proc vs Lambda differences
proc_example = Proc.new { |x, y| x }
proc_example.call(1) # Works, y is nil

lambda_example = ->(x, y) { x }
# lambda_example.call(1) # ArgumentError

# Symbol to proc
['a', 'b', 'c'].map(&:upcase)
# Equivalent to: ['a', 'b', 'c'].map { |s| s.upcase }