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The goto-less goto!

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4.33/5 (3 votes)
28 Feb 2011CPOL 7.2K   2   2
My favorite is a variant of alternative 2.{ ... DoInit(); status=DoAllActions(); DoCleanup(status); ...}int DoAllActions(){ if (condition1_fails) return status1; ... if (condition2_fails) return status2; ... if(conditionN_fails) ...
My favorite is a variant of alternative 2.

{
  ...
  DoInit();
  status=DoAllActions();
  DoCleanup(status);
  ...
}

int DoAllActions()
{
   if (condition1_fails)
      return status1;
   ...
   if (condition2_fails)
      return status2;
   ...
   if(conditionN_fails)
      return statusN;
   PerformActionOnAllSuccess();
   return statusSUCCESS;
}

DoCleanup(status)
{
 if(status==statusSUCCESS)
   DoNormalCleanup();
 else
   DoFailedCleanup();
}


Avoiding retuns or additional functions, I would write the following code:

{
   if(condition1_fails)
      status=status1;
   else if(condition2_fails)
      status=status2;
   ...
   else if(conditionN_fails)
      status=statusN;
   else
   {
      PerformActionOnAllSuccess();
      status=statusSUCCESS;
   }
   if(status==statusSUCCESS)
     DoNormalCleanup();
   else
     DoFailedCleanup();
}


This form of "else if" is like a case-statement, but much more flexible because you can replace ConditionN by a function-call instead of testing only one value. This untypical arranging of if and else makes clear what the programmer wanted. But often, you have to do a lot of work between the tests which cannot be put into a single function so the first variant is the best and most flexible, I think.

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Comments and Discussions

 
GeneralReason for my vote of 3 This is good, too, but has the disad... Pin
EFEaglehouse5-Apr-11 4:03
EFEaglehouse5-Apr-11 4:03 
GeneralReason for my vote of 5 This is the cleanest separation of '... Pin
Stefan_Lang8-Mar-11 0:41
Stefan_Lang8-Mar-11 0:41 
Reason for my vote of 5
This is the cleanest separation of 'goto conditions' I've seen, and - in my opinion - the best to maintain.

I prefer the second alternative, but I suppose the first is viable as well, depending on the circumstances.

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