gistfile1.txt

require 'rubygems'
require 'activerecord'

module Foo
  def foo
    puts "foo"
  end
end

ActiveRecord::Validations::ClassMethods.send(:include, Foo)
ActiveRecord::Validations.extend( ActiveRecord::Validations::ClassMethods)

class TestClass < ActiveRecord::Base
end

ActiveRecord::Base.send(:include,ActiveRecord::Validations)

TestClass.foo