捕获，处理，然后Rethrow例外？(Catch, Handle, then Rethrow Exception?)

 我今天遇到了一个有趣的困境。 我有一个处理信息和检查重复值的函数，然后返回下一个不重复的数字。 所以，我有这样的事情： 
 
Public Function GetNextNonDuplicateNumber(NumberToCheck as Long) as Long

      //the non-duplicate the function will return
      Dim NonDuplicate as Long

      If CheckForDuplicate(NumberToCheck) = True Then
          Throw New DuplicateException()
      Else
          NonDuplicate = NumberToCheck
      End If

End Function
 
 然后在函数的底部我有一个catch块，通过递增处理副本，直到我没有重复，如下所示： 
 
Catch ex as DuplicateException
   NonDuplicate = IncrementToNonDuplicateValue(NumberToCheck)
   Throw ex
   Return NonDuplicate
End Function
 
 正如你所看到的，我想特别处理异常，但我也想在完成之后抛出它，因为我想提醒函数之外的其他代码。 
 
 问题是简单地抛出它会使用null值退出函数。 我是在考虑try/catch错误的方式，还是有办法解决这个问题？ 

I ran into an interesting dilemma today. I have a function that handles information and checks for duplicate values, then returns the next number that is not a duplicate. So, I have something like this:
 
Public Function GetNextNonDuplicateNumber(NumberToCheck as Long) as Long

      //the non-duplicate the function will return
      Dim NonDuplicate as Long

      If CheckForDuplicate(NumberToCheck) = True Then
          Throw New DuplicateException()
      Else
          NonDuplicate = NumberToCheck
      End If

End Function
 
Then at the bottom of the function I have a catch block that handles the duplicate by incrementing until I don't have a duplicate any more, like this:
 
Catch ex as DuplicateException
   NonDuplicate = IncrementToNonDuplicateValue(NumberToCheck)
   Throw ex
   Return NonDuplicate
End Function
 
As you can see, I want to handle the exception specifically, but I also want to throw it when I'm done because I want to alert other code outside the function. 
 
The problem is that simply throwing it exits out of the function with a null value. Am I thinking about a try/catch the wrong way, or is there a way around this?

原文：https://stackoverflow.com/questions/1050860