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The goto-less goto!

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25 Jan 2011CPOL 41.7K   4   33
Alternative 2 can be enhanced by returning a booleen value if we want to code something similar to the original example. A (early) return value of false would indicate a failure which could then be handle by checking the function result.if (!DoAllActions()){ ...
Alternative 2 can be enhanced by returning a booleen value if we want to code something similar to the original example. A (early) return value of false would indicate a failure which could then be handle by checking the function result.

if (!DoAllActions())
{
   DoFailedCleanup();
}

bool DoAllActions()
{
   if (condition1_fails)
      return false;
   if (condition2_fails)
      return false;
   ...
   if(!conditionN_fails)
      retrun false;
   PerformActionOnAllSuccess();
   DoNormalCleanup();
   return true;
}


Alternatively, if each action are independant, a variation like this might be more appropriate:
if (DoAction1() && 
    DoAction2() && 
    ... && 
    DoActionN())
{
   PerformActionOnAllSuccess();
   DoNormalCleanup();
}
else 
{
   DoFailedCleanup();
}

bool DoAction1()
{
   bool condition1_fails = ...;
   return !condition1_fails;
}
...

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


Written By
Software Developer (Senior)
Canada Canada
Programmer at Maid LABS from 2003 (www.maidlabs.com)

Programmer-Analyst at Viasat Geo Technoligies from 1995 to 2002 (www.viasat-geo.com).

I have studied at École Polytechnique de Montréal in computer engineering.

Comments and Discussions

 
GeneralMy vote of 5 Pin
pasztorpisti26-Aug-13 9:34
pasztorpisti26-Aug-13 9:34 
GeneralRe: Surely anyone can program whatever he wants for himself and ... Pin
Wolfgang_Baron7-Apr-11 6:07
professionalWolfgang_Baron7-Apr-11 6:07 
GeneralRe: Clearly we have difference experiences - and debuggers. One ... Pin
EFEaglehouse7-Apr-11 4:05
EFEaglehouse7-Apr-11 4:05 
GeneralRe: The first person wanting to add a debug statement at the end... Pin
Wolfgang_Baron7-Apr-11 1:45
professionalWolfgang_Baron7-Apr-11 1:45 
GeneralSorry, but in C++ at least, not being able to add a debug st... Pin
jefito12-Apr-11 3:02
jefito12-Apr-11 3:02 
GeneralMultiple returns look clear only to those, who have written ... Pin
Wolfgang_Baron9-Feb-11 5:32
professionalWolfgang_Baron9-Feb-11 5:32 
GeneralRe: Never say never. Sometimes the clearest code is the shortest... Pin
EFEaglehouse5-Apr-11 4:32
EFEaglehouse5-Apr-11 4:32 
GeneralIn fact, with this pattern where the complex function is spl... Pin
Philippe Mori9-Feb-11 5:00
Philippe Mori9-Feb-11 5:00 
GeneralReason for my vote of 1 People who put more than one return ... Pin
Wolfgang_Baron9-Feb-11 4:35
professionalWolfgang_Baron9-Feb-11 4:35 
GeneralRe: Reason for my vote of 1People who put more than one return ... Pin
pasztorpisti26-Aug-13 9:27
pasztorpisti26-Aug-13 9:27 
GeneralRe: Reason for my vote of 1People who put more than one return ... Pin
Wolfgang_Baron7-Oct-13 3:08
professionalWolfgang_Baron7-Oct-13 3:08 
GeneralRe: Reason for my vote of 1People who put more than one return ... Pin
pasztorpisti7-Oct-13 3:24
pasztorpisti7-Oct-13 3:24 
GeneralRe: Reason for my vote of 1People who put more than one return ... Pin
Wolfgang_Baron7-Oct-13 5:10
professionalWolfgang_Baron7-Oct-13 5:10 
GeneralRe: Reason for my vote of 1People who put more than one return ... Pin
pasztorpisti7-Oct-13 5:39
pasztorpisti7-Oct-13 5:39 
GeneralRe: Reason for my vote of 1People who put more than one return ... Pin
Wolfgang_Baron7-Oct-13 13:08
professionalWolfgang_Baron7-Oct-13 13:08 
GeneralRe: Reason for my vote of 1People who put more than one return ... Pin
pasztorpisti7-Oct-13 22:37
pasztorpisti7-Oct-13 22:37 
GeneralRe: Reason for my vote of 1People who put more than one return ... Pin
Wolfgang_Baron9-Oct-13 14:59
professionalWolfgang_Baron9-Oct-13 14:59 
GeneralRe: Reason for my vote of 1People who put more than one return ... Pin
Philippe Mori9-Oct-13 17:35
Philippe Mori9-Oct-13 17:35 
GeneralRe: Reason for my vote of 1People who put more than one return ... Pin
pasztorpisti9-Oct-13 22:07
pasztorpisti9-Oct-13 22:07 
GeneralRe: Reason for my vote of 1People who put more than one return ... Pin
Philippe Mori10-Oct-13 2:24
Philippe Mori10-Oct-13 2:24 
GeneralRe: Reason for my vote of 1People who put more than one return ... Pin
pasztorpisti10-Oct-13 2:46
pasztorpisti10-Oct-13 2:46 
GeneralRe: Reason for my vote of 1People who put more than one return ... Pin
Wolfgang_Baron9-Oct-13 22:29
professionalWolfgang_Baron9-Oct-13 22:29 
Quote:
In simple cases, your sample codes are overkill

We are not doing this to find a good solution for a simple case. We are looking for good patterns to write readable code, which allows the reader to quickly understand, what a function does (and thus support good code quality even after changing the function a few times) while not putting too much stress on the developer.
Quote:
The main problem with this solution is that it does not scale well

Your first solution is exactly, what I would do in simple cases, but what pasztorpisti seems to dislike. Therefore, he asked for alternatives. Making a habit out of using a scalable alternative even for simple cases may be ok, if the alternative is not too complicated.
Quote:
return res1 >= 0 && res2 >= 0 && res3 >= 0 ? res1 + res2 + res3 : 0;

Although I like the ?: operator more than most of the other developers I work with, making return statements complicated is not such a great idea. Always think about the poor guy, who tries to add a debug trace here. Using an extra result variable will not make your code slower, because the compiler will optimize it away and a few extra words often make the code even easier to read and a lot easier to change.
Quote:
Finally, if you make the effort to to go up to the point of using lambda (or function objects), the why not make an array of those functions and call them in a loop.

That is again what I would do, if the functions all have the same interface and the values are combined in a homogeneous way. As we were doing this to find a general pattern, your code in between the calls may not allow that. You'd have to create lots of extra little functors or lambdas and that can be more difficult to read than a sequence of pieces of code. So, I'd say, the best solution just depends on what your program has to do.
GeneralRe: Reason for my vote of 1People who put more than one return ... Pin
Philippe Mori10-Oct-13 2:36
Philippe Mori10-Oct-13 2:36 
GeneralRe: Reason for my vote of 1People who put more than one return ... Pin
pasztorpisti9-Oct-13 22:18
pasztorpisti9-Oct-13 22:18 
GeneralRe: Reason for my vote of 1People who put more than one return ... Pin
Wolfgang_Baron9-Oct-13 22:59
professionalWolfgang_Baron9-Oct-13 22:59 

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