include-extend-idiom

include-extend-idiom.rb

module Goodness
  def great?
    @language == 'Ruby'
  end

  def self.included(base)
    base.extend ClassMethods

    def interesting
      'there are thousands of spoken languages around the world'
    end
  end

  module ClassMethods
    def cool_languages
      %w{Ruby Perl Python Java JavaScript Erlang}
    end
  end
end

class TestLanguage
  include Goodness
  def initialize(language)
    @language = language
  end
end

p TestLanguage.new('Ruby').interesting
p TestLanguage.cool_languages