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Posted 25 Jan 2011

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The goto-less goto!

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4.95/5 (12 votes)
25 Jan 2011CPOL
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 
In simple cases, your sample codes are overkill. I think you are going too far by systematically avoiding multiple returns. There are cases, as my alternative demonstrates, where multiple returns is definitively the best solution.

On the other hand for samples like this one, if you don't have more than 3 functions, and prefer single result, then something like that would be more appropriate:
C++
float Func()
{
    float result = 0;

    float res1 = Func1();
    if (res1 >= 0)
    {
        float res2 = Func2();
        if (res2 >= 0)
        {
            float res3 = Func3();
            if (res3 >= 0)
            {
                result = res1 + res2 + res3;
            }
        }
    }

    return result;
}

The main problem with this solution is that it does not scale well. With more than 3 condition, it start to indent a lot and it is much harder to reoder parts than with the multiple returns solution a few replies above.

By the way, if functions are not expensive to call and the main function is not called a lot, then the following code would be adequate:
C++
float Func()
{
    float res1 = Func1();
    float res2 = Func2();
    float res3 = Func3();

    return res1 >= 0 && res2 >= 0 && res3 >= 0 ? res1 + res2 + res3 : 0;
}


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.
Philippe Mori

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 
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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