[petsc-dev] SETERRQ in fortran

[Smith, Barry F.]

> On Jan 5, 2018, at 5:00 PM, Jed Brown <jed at jedbrown.org> wrote:
> 
> "Smith, Barry F." <bsmith at mcs.anl.gov> writes:
> 
>>> On Jan 5, 2018, at 4:18 PM, Jed Brown <jed at jedbrown.org> wrote:
>>> 
>>> "Smith, Barry F." <bsmith at mcs.anl.gov> writes:
>>> 
>>>>> On Jan 5, 2018, at 12:45 PM, Jed Brown <jed at jedbrown.org> wrote:
>>>>> 
>>>>> "Smith, Barry F." <bsmith at mcs.anl.gov> writes:
>>>>> 
>>>>>>> On Jan 4, 2018, at 5:10 PM, Blaise A Bourdin <bourdin at lsu.edu> wrote:
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>>> On Jan 4, 2018, at 3:16 PM, Smith, Barry F. <bsmith at mcs.anl.gov> wrote:
>>>>>>>> 
>>>>>>>> 
>>>>>>>> It's changed a bit.  It is better but you need to understand how the new one works, so take a few minutes to see how it works before converting.
>>>>>>> Got it.
>>>>>>> An example or a link to the fortran macro definition from the man page would be nice 
>>>>>>> I am confused about the rationale for putting the endif in the macro, though.
>>>>>> 
>>>>>> It matches the C paradigm
>>>>> 
>>>>> Hardly.
>>>> 
>>>>  It matches the paradigm as close as can be reasonable done.
>>>> 
>>>>  I debated putting the then into the macros also.
>>>> 
>>>>> #define SETERRQ(c,ierr,s)  then ;call PetscError(c,ierr,0,s);return;endif
>>>> 
>>>>  So usage would be 
>>>> 
>>>>     if (bad) SETERRQ(); 
>>>> 
>>>> would that be better.
>>> 
>>> No, Fortran isn't C.
>>> 
>>> if (bad) then
>>>     SETERRQ(...)
>>> endif
>>> 
>>> It doesn't get used so much from Fortran that we need to conceal the
>>> language constructs.
>> 
>>   It will, eventually I want all Fortran examples/tests to have checks on every call (like with have in C).
> 
> CHKERRQ does the if internally, so it also has the endif.

  What is the relevance of this statement.
> 
> SETERRA/SETERRQ is used a total of 34 times in 17 Fortran files.
> SETERRQ is used a median of zero times and an average of less than 1 in
> the C examples.

   I am not sure why you are saying this. My resistance to change has nothing to do with how often it is used. 

   I am leaning to changing it but don't want to until all the test harness branches etc get into master. So it will be a few days.

> 
>>> 
>>>> 
>>>> 
>>>>> This Fortran:
>>>>> 
>>>>> #define SETERRQ(c,ierr,s)  ;call PetscError(c,ierr,0,s);return;endif
>>>>> 
>>>>> This would be like writing this C
>>>>> 
>>>>> #define SETERRQ(c,ierr,s) return PetscError(...); }
>>>>> 
>>>>> to be used like
>>>>> 
>>>>> if (BAD) { SETERRQ(comm, ierr, "why")
>>>>> 
>>>>> which is just bananas and still not as gross as the Fortran.  You might
>>>>> not have noticed this because SETERRQ is not called from any of PETSc's
>>>>> Fortran examples.
>>>> 
>>>>   But SETERRA() is and has the same pattern.
>>> 
>>> It isn't syntactically correct when !defined(PETSC_USE_ERRORCHECKING).
>>> The endif isn't going to kill anyone and pulling it out of the macro
>>> will make it easier to understand and avoid the circus antics when used
>>> in any context other than a positive conditional with no else clause.
>> 
>>   I'll take this under advisement. Of course in our examples the endif will ALWAYS be on the same line as the rest. Using three lines for a SETERRQ() is ugly.
>> 
>> 
>>> 
>>>>> 
>>>>>>> Beside not having unmatched if / end if in my code, in a select case construct, I have to write something as ugly as
>>>>>>> 
>>>>>>> select case (i)
>>>>>>> 	case(1) 
>>>>>>> 		!do something
>>>>>>> 	case(2)
>>>>>>> 		!do something else
>>>>>>> 	case default
>>>>>>> 		if (0 == 0) then
>>>>>>> 			SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_ARG_OUTOFRANG,”invalid value”)
>>>>>>> end select
>>>>>>> 
>>>>>> What is ugly about this ? except that you put the SETERRQ on a new line which you did not need to do.
>>>>> 
>>>>> Reread the above code.  Requiring the dummy opening if statement is nuts.
>>>> 
>>>>  Agreed. He should not use SETERRQ() in this case, should call the error functions directly)
>>>> 
>>>>> 
>>>>>> How do you want to write it so it is prettier?
>>>>> 
>>>>> SETERRQ should not include that endif.  CHKERRQ has the opening if and
>>>>> thus needs the closing too (so it's as intended).  Also note that your
>>>>> first reply to Blaise was talking about CHKERRQ when he was asking about
>>>>> SETERRQ.
>>>> 
>>>>   Hmm, I'm not sure about. Oh well, it doesn't matter. You have convinced me of anything.