[Mpi-forum] Reserved MPI_ prefix & namespace in C and Fortran

[William Gropp]

The intent of the Forum has always been that all names that begin with MPI_ or PMPI_, and the MPI namespace, are reserved for MPI.  The mistake (a common one) was to attempt to enumerate all of the items to which this applies.  Rather than attempt to cover everything, I would prefer changing the text to match the indent; it can mention specific categories as examples but should not attempt to list them, as this is always error prone.

Bill

William Gropp
Director, Parallel Computing Institute
Deputy Director for Research
Institute for Advanced Computing Applications and Technologies
Paul and Cynthia Saylor Professor of Computer Science
University of Illinois Urbana-Champaign



On Aug 24, 2012, at 10:31 AM, Rolf Rabenseifner wrote:

> Dear all,
> 
> Jeremiah detected a very old inconsistency in the MPI standard:
> 
>> On page 19 line 14, the restriction on use of MPI_* names should also
>> apply to preprocessor macros, namespaces in C++, types, and other
>> things.
> 
> In MPI-2.2, it was page 18, lines 15-16:
> 
>   "Programs must not declare variables or functions 
>    with names beginning with the prefix MPI_."
> 
> Together with MPI-2.2 p4:26
> 
>   "Any correct MPI-2.1 program is a correct MPI-2.2 program."
> 
> and the new constant declaration on p258:17: MPI_DIST_GRAPH,
> the implication is that the MPI standard is inconsistent.
> 
> The solution is very simple, an MPI-2 errata ticket changing
> MPI-2.2, lines 15-16 into (addition marked with {...}):
> 
>   "Programs must not declare variables, functions, 
>    { constants, macros, types, or namespaces }
>    with names beginning with the prefix MPI_."
> 
> And for Fortran on p17:41-42 (addition marked with {...}):
> 
>   "Programs must not declare variables, parameters, functions, 
>    { derived types, or abstract interfaces }
>    with names beginning with the prefix MPI_.  
> 
> It should be a single reading+vote errata ticket, because it does
> not change the standard, it only makes it obvious.
> The reservation was in MPI-2.1 in fact already there through the
> sentence
> 
>   "Any correct MPI-2.1 program is a correct MPI-2.2 program."
> 
> because nobody could foresee, which new things we will 
> have added to MPI-2.2.
> 
> Details are in ticket
> https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/343
> 
> And see markups ticket0.343 on page 11 in
> https://svn.mpi-forum.org/trac/mpi-forum-web/attachment/ticket/343/ticket0.343-terms-2.pdf
> 
> I hope that there is a broad consensus 
> to solve this inconsistency.
> 
> Best regards
> Rolf
> 
> 
> ----- Original Message -----
>> From: "Jeremiah Willcock" <jewillco at osl.iu.edu>
>> To: mpi-comments at mpi-forum.org
>> Sent: Sunday, August 19, 2012 2:13:41 AM
>> Subject: [Mpi-comments] Comments on MPI 3.0 draft 2
>> These are in reference to the draft at
>> <URL:http://meetings.mpi-forum.org/mpi3.0_draft_2.pdf>. Thank you for
>> considering them.
>> 
>> -- Jeremiah Willcock
> ... 
>> On page 19 line 14, the restriction on use of MPI_* names should also
>> apply to preprocessor macros, namespaces in C++, types, and other
>> things.
> 
> -- 
> Dr. Rolf Rabenseifner . . . . . . . . . .. email rabenseifner at hlrs.de
> High Performance Computing Center (HLRS) . phone ++49(0)711/685-65530
> University of Stuttgart . . . . . . . . .. fax ++49(0)711 / 685-65832
> Head of Dpmt Parallel Computing . . . www.hlrs.de/people/rabenseifner
> Nobelstr. 19, D-70550 Stuttgart, Germany . (Office: Allmandring 30)
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