xpepper

class Movie
  REGULAR = 0
  NEW_RELEASE = 1
  CHILDRENS = 2

  attr_reader :title
  attr_reader :price_code

  def initialize(title, price_code)
    @title, @price_code = title, price_code

xpepper

class MyStruct
  #=> self is MyStruct
  
  def self.new(*attributes)
    #=> self is MyStruct
    Class.new do
      #=> self is the class instance
      attr_accessor(*attributes)
    end
  end

xpepper

class Struct
  @children = []

  def self.inherited(child)
    @children << child
  end
  class << self
    attr_accessor :children
  end
end

xpepper

Reimplementing Module#include method (my_include method):

1. my_include takes one or many modules
2. it goes on a reverse traversal and for each module it adds its features to self
3. calls an home-made hook method

class Module
  def my_include(*modules)
 modules.reverse_each do |each_module|

xpepper

Ruby #4.

class_eval vs. instance_eval

Module#class_eval:

1. set self to the receiver for the duration of the block
2. set the current class to class/module which is the receiver
3. can be called only on classes and modules

• => it's like re-opening the class/module
• => the scope of the block is that class

xpepper

class ShippingOption
  @options = []
  
  def self.inherited(child)
    @options << child
  end
  
  def self.for(weight, international)
    @options.select { |o| o.can_ship?(weight, international)}
  end

xpepper

crontab -l > CT; sed -i -e "1,11d" CT; crontab CT; rm -f CT; crontab -l

xpepper

class Module
  m = instance_method(:const_missing)
  
  define_method :const_missing do |name|
    if name.to_s =~ /^U([0-9a-fA-F]{4})$/
      [$1.to_i(16)].pack("U*")
    else
      m.bind(self).call(name)
    end
  end

xpepper

class Color
  def self.const_missing(name)
    const_set(name, new(name.to_s.downcase))
  end
  
  def initialize(color_name)
    @color_name = color_name
  end
  def to_s
    @color_name

xpepper

class Enum
  def self.new
    Class.new do
      def self.const_missing(name)
        const_set(name, new)
      end
    end
  end
end