ruby - 重构前置条件和后置条件

Question

给定这样的 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

这段代码可能有异味。有没有更好的方法来写这个？

Answer 1

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 2

并不真地。如果你想节省空间，你可以使用一个衬垫：

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 3

鉴于这necessary?是您在对 Linuxios 答案的评论中所写的一种繁重的方法，您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