attr_accessor_with_history

saas_class_meta.rb

class Class
  def attr_accessor_with_history(attr_name)
    attr_name = attr_name.to_s
    history_method_name = attr_name + "_history"
    attr_reader attr_name
    attr_reader history_method_name
    class_eval(%Q(
      def #{attr_name}=(#{attr_name})
        @#{attr_name} = #{attr_name}
        if @#{history_method_name}
          @#{history_method_name}.push(#{attr_name})
        else
          @#{history_method_name}=[]
          @#{history_method_name}.push(nil)
          @#{history_method_name}.push(#{attr_name})
        end
      end
    ))
  end
end