Mixin example for #ruby IRC

document.rb

module Document
  def self.included(base)
    base.class_eval do
      def self.name = "#{super}ument"
    end
  end

  module_function

  def print = :printed
end

class Book
  include Document

  def publish = true && print
end

Book.new.publish
#=> :printed

Book.new.print
#!> private method 'print' called for an instance of Bookument (NoMethodError)

Compare with

module ClassMethods
  def name = "#{super}ument"
end

def self.included(base) = base.extend(ClassMethods)