1  class Object
   2    # Returns the object's singleton class.
   3    def singleton_class
   4      class << self
   5        self
   6      end
   7    end unless respond_to?(:singleton_class)
   8 
   9    # class_eval on an object acts like singleton_class_eval.
  10    def class_eval(*args, &block)
  11      singleton_class.class_eval(*args, &block)
  12    end
  13  end