[MPI3 Fortran] What if Fortran is the primary interface?

[Jeff Squyres]

FWIW, I don't think the 2-level indirection is necessary.  I think  
that Craig was trying to unify everything, but I would agree with  
Hubert: it would be better if MPI_COMM directly referred to whatever  
the Right stuff is in C.

In Open MPI's case, for example, the private member would be a pointer  
to an ompi_communicator_t struct instance.


On Mar 17, 2008, at 2:54 PM, Hubert Ritzdorf wrote:

> Hi Alexander,
>
> Jeff and Torsten are right. We have special implementations
> for frequently used Fortran functions. But this Fortran MPI
> functions are implemented in C.
>
> I think, that it will be difficult to convince real Fortran  
> programmers
> by this C interface. They have to re-write main parts of the code.
> change it from Fortran Style into C Style and what is the benefit ?
>
> I have an additional question. Is this really guaranteed by the
> Fortran 2003 standard that
>
> type, bind(C) :: MPI_HANDLE
> private  ! Components not visible
> type(C_PTR) :: HANDLE
> end type MPI_HANDLE
>
> type, bind(C) :: MPI_COMM
> private
> type(MPI_HANDLE) :: handle
> end type MPI_COMM
>
> type(MPI_COMM), bind(C), protected :: MPI_COMM_WORLD
>
> err = MPI_Recv (..., ..., MPI_COMM_WORLD, ...)
> in the same C Pointer such as the MPI_Comm MPI_COMM_WORLD ?
> My feeling is that it points to a structure containing the C pointer
> MPI_COMM_WORLD.
>
> Hubert
>
> Supalov, Alexander wrote:
>> Hi everybody,
>>
>> It appears to me that the current proposal basically intends to pass
>> data thru to the presumably existing C implementation layer. How will
>> this work for an implementation where the Fortran binding is a  
>> primary
>> one?
>>
>> I believe that at least NEC has followed this route. I'm adding  
>> Hubert
>> Ritzdorf, in case he's accidentally not involved into this discussion
>> yet, to verify NEC's position.
>>
>> Best regards.
>>
>> Alexander
>> --
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-- 
Jeff Squyres
Cisco Systems