Use of self.included

self_included_example.rb

module Foo
# Should not really need the check for const_dedined?, but...
  FOO = [] unless const_defined?(:FOO)
  def self.included(host_class)
    FOO << host_class
  end
end

  class Baa
    include Foo
    def baa
      puts "Baa1"
    end
  end

  class Baa2
    include Foo
    def baa
      puts "Baa2"
    end
  end


Foo::FOO.each {|clazz| clazz.new.baa}