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

[Lisandro Dalcin]

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? 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