[petsc-dev] changed ISCreateGeneral/NC/WithArray()

[Barry Smith]

On Oct 3, 2010, at 6:00 PM, Lisandro Dalcin wrote:

> On 3 October 2010 19:51, Barry Smith <bsmith at mcs.anl.gov> wrote:
>> 
>>   Well it is always "with array" since you always need to provide an array of indices, so why both with the redundant "withArray" (With VecCreateSeqWithArray() there is also a VecCreateSeq() that does not take an array, hence WithArray in that case is not redundant)?
>> 
> 
> I'm just thinking on user convenience...
> 
>> 
>>   Regarding having two routines: I found having three almost identical routines unneededly complicated.
>> 
> 
> I definitely agree.
> 
>> 
>> You still want to have two routines, one is just a subset of the functionality of the second. That is redundant and hence unneeded.
>> 
> 
> If we were using C++, don't you think we could overload
> ISCreateGeneral?

   How?  the arguments are identical, up to and including even the const on the idx.

   Barry

> But we are in C, and I see that
> ISCreateGeneralWithArray() as a developer-level call, while
> ISCreateGeneral() looks more like an user-level-call.
> 
> I'm proposing making ISCreateGeneral() a wrapper for
> ISCreateGeneralWithArray(). I do not think that the redundancy is too
> much of a trouble in such cases.
> 
>>   I do appreciate your suggestions, please keep on having them even if they don't always convince me.
>> 
> 
> Well, I'm still trying to convince you :-)
> 
>> 
>>   Barry
>> 
>> On Oct 3, 2010, at 5:45 PM, Lisandro Dalcin wrote:
>> 
>>> On 3 October 2010 14:57, Barry Smith <bsmith at mcs.anl.gov> wrote:
>>>> 
>>>>   I find the three routines ISCreateGeneral(), ISCreateGeneralNC() and ISCreateGeneralWithArray() to be confusing and code redundant.
>>>> 
>>>>   Therefore in PETSc-dev I have introduced
>>>> 
>>>> /*E
>>>>    PetscCopyMode  - Determines how an array passed to certain functions is copied or retained
>>>> 
>>>>   Level: beginner
>>>> 
>>>> $   PETSC_COPY_VALUES - the array values are copied into new space, the user is free to reuse or delete the passed in array
>>>> $   PETSC_OWN_POINTER - the array values are NOT copied, the object takes ownership of the array and will free it later, the user cannot change or
>>>> $                       delete the array. The array MUST have been obtained with PetscMalloc(). Hence this mode cannot be used in Fortran.
>>>> $   PETSC_USE_POINTER - the array values are NOT copied, the object uses the array but does NOT take ownership of the array. The user cannot use
>>>>                        the array but the user must delete the array after the object is destroyed.
>>>> 
>>>> E*/
>>>> typedef enum { PETSC_COPY_VALUES, PETSC_OWN_POINTER, PETSC_USE_POINTER} PetscCopyMode;
>>>> extern const char *PetscCopyModes[];
>>>> 
>>>> and merged  ISCreateGeneral/NC/WithArray() into a single routine with an additional PetscCopyMode argument.
>>>> 
>>>> I have also merged ISLocalToGlobalMappingCreate() and ISLocalToGlobalMappingCreateNC() into a single routine.
>>>> 
>>>> There may be other places we can use this paradigm in the future, keep your eyes open,
>>>> 
>>>>  Happy computing,
>>>> 
>>>>    Barry
>>>> 
>>> 
>>> I would prefer to have:
>>> 
>>> ISCreateGeneralWithArray(comm,n,ptr,copy_mode,&is);
>>> 
>>> and then implement
>>> 
>>> ISCreateGeneral(comm,n,ptr,&is) {
>>> return ISCreateGeneralWithArray(comm,n,ptr,PETSC_COPY_VALUES,&is);
>>> }
>>> 
>>> What do you think?
>>> 
>>> --
>>> Lisandro Dalcin
>>> ---------------
>>> CIMEC (INTEC/CONICET-UNL)
>>> Predio CONICET-Santa Fe
>>> Colectora RN 168 Km 472, Paraje El Pozo
>>> Tel: +54-342-4511594 (ext 1011)
>>> Tel/Fax: +54-342-4511169
>> 
>> 
> 
> 
> 
> -- 
> Lisandro Dalcin
> ---------------
> CIMEC (INTEC/CONICET-UNL)
> Predio CONICET-Santa Fe
> Colectora RN 168 Km 472, Paraje El Pozo
> Tel: +54-342-4511594 (ext 1011)
> Tel/Fax: +54-342-4511169