[Mpi-22] Ticket #46: Add const Keyword to the C bindings-implementation

Supalov, Alexander alexander.supalov at [hidden]
Mon Mar 16 05:42:57 CDT 2009



Hi,

I most respectively disagree with the "Const simply captures the previously required semantics of the interface in the syntax" statement. The standard did not prohibit a reversible in-place modification of the send buffer until the very recent change related to #45. Adding const on top will automatically make MPI not the greatest common denominator - some internal networking interfaces that were mentioned in this trail will suddenly become "obsolete". That is, most of the existing networking interfaces will.

Best regards.

Alexander

-----Original Message-----
From: mpi-22-bounces_at_[hidden] [mailto:mpi-22-bounces_at_[hidden]] On Behalf Of William Gropp
Sent: Sunday, March 15, 2009 9:59 PM
To: MPI 2.2
Subject: Re: [Mpi-22] Ticket #46: Add const Keyword to the C bindings-implementation

Actually, MPI has taken the lead in a number of areas, including cross- 
language compatibility, to say nothing of the existence of MPI itself.

And MPI has taken great pains to be the *greatest* common  
denominator.  Const simply captures the previously required semantics  
of the interface in the syntax, and is consistent with the MPI spirit.

Bill
On Mar 13, 2009, at 2:17 PM, Jeff Squyres wrote:

> On Mar 13, 2009, at 9:40 AM, William Gropp wrote:
>
>> First, this is a chicken-and-egg problem; the low level
>> interfaces are unlikely to change to add const unless there is some
>> application that will take advantage of that (and internally, if  
>> their
>> semantics allows it and their compiler can support it, they'll just
>> cast to add the const).  So MPI should take the lead, particularly
>> since using const also provides information to the user.
>>
>
> This is a very scary statement to me.  MPI has not traditionally
> "taken the lead" on forcing issues with other interfaces (look where
> it has gotten us with Fortran...).  Indeed, MPI has taken great pains
> to be the lowest common denominator across a variety of language,
> platforms, and operating systems.
>
> -- 
> Jeff Squyres
> Cisco Systems
>
> _______________________________________________
> mpi-22 mailing list
> mpi-22_at_[hidden]
> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi-22

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

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