class Class

  def attr_accessor_with_history(attr_name)
    attr_name = attr_name.to_s
    attr_hist_name = attr_name+'_history'

    #getter
    self.class_eval("def #{attr_name};@#{attr_name};end")

    #setter
    self.class_eval %Q{
      def #{attr_name}=(val)
        # add to history
        @#{attr_hist_name} = [nil] if @#{attr_hist_name}.nil?
        @#{attr_hist_name} << val

        # set the value itself
        @#{attr_name}=val
      end

      def #{attr_hist_name};@#{attr_hist_name};end

                    }

  end

end
class Foo
attr_accessor_with_history :bar

end

f = Foo.new
f.bar = 3
f.bar = :wowzo
f.bar = 'boo!'
puts f.bar_history