Demonstrating Ruby class/module method inheritance hierarcy

inheritance_hierarchy.rb

module Extendable # :nodoc:
  def self.extended(base)
    base.include InstanceMethods
  end

  module InstanceMethods # :nodoc:
    def hello
      puts 'hello from Extendable'
      super
    end
  end

  def hello
    puts 'classy hello from Extendable'
    super
  end
end

module Includable # :nodoc:
  def self.included(base)
    base.singleton_class.include ClassMethods
  end

  module ClassMethods # :nodoc:
    def hello
      puts 'classy hello from Includable'
      super
    end
  end

  def hello
    puts 'hello from Includable'
    super
  end
end

module Prependable # :nodoc:
  def self.prepended(base)
    base.singleton_class.prepend ClassMethods
  end

  # :nodoc:
  module ClassMethods
    def hello
      puts 'classy hello from Prependable'
      super
    end
  end

  def hello
    puts 'hello from Prependable'
    super
  end
end

class Parent # :nodoc:
  def self.hello
    puts 'classy hello from Parent'
    # super
  end

  def hello
    puts 'hello from Parent'
    # super
  end
end

class Class1 < Parent # :nodoc:
  # Note that changing the order of +extend+ and +include+ changes the order of method calls
  extend Extendable
  include Includable
  prepend Prependable

  def self.hello
    puts 'classy hello from Class1'
    super
  end

  def hello
    puts 'hello from Class1'
    super
  end
end

puts "Ancestors: #{Class1.ancestors}"
puts '---'
Class1.hello
puts '---'
Class1.new.hello