重构前提条件和后置条件

Question

给出像这样的Ruby方法：

def create_object_and_do_if_necessary params
   if necessary?
      do_precondition_stuff
   end
   object = create_object params
   if necessary?
      do_postcondition_stuff object
   end
end

这段代码可能闻到了。有没有更好的写作方式？

Answer 1

不是真的。如果你想节省空间，你可以使用一个班轮：

def create_object_and_do_if_necessary params
   do_precondition_stuff if necessary?
   object = create_object params
   do_postcondition_stuff object if necessary?
end

Answer 2

这是一个从创建对象中提取条件的示例。

def create_object_and_do_if_necessary(params)
  with_around_conditions { create_object(params) }
end

def with_around_conditions
  do_precondition_stuff if precondition_stuff_necessary?
  object = yield
  do_postcondition_stuff object if postcondition_stuff_necessary?
  object
end

Answer 3

鉴于你在Linuxios的答案评论中写的necessary?是一种沉重的方法，你能做的最好的事情就是保留条件结果的标志。

def create_object_and_do_if_necessary params
  flag = necessary? # which is long or heavy
  do_precondition_stuff if flag
  create_object params
  do_postcondition_stuff object if flag
end