From: Jeff Squyres <jsquyres@XXXXXXXXX>
Date: December 7, 2007 7:34:38 AM CST
To: mpi-21@XXXXXXXXXXXXX
Subject: Re: [mpi-21] Missing MPI::CONVERSION_FN_NULL
Reply-To: mpi-21@XXXXXXXXXXXXX

On Dec 6, 2007, at 6:00 PM, Jeff Squyres wrote:

> Here's another item for MPI-2.1: I see MPI_CONVERSION_FN_NULL  
> defined in MPI-2 (see MPI-2:9.5.3).
>
> It would be convenient for implementations (and consistent for all  
> other constants) if MPI::CONVERSION_FN_NULL was also defined, and  
> was the only constant you could use in the C++ bindings (i.e., you  
> couldn't use MPI_CONVERSION_FN_NULL).


The same should also be true for all the pre-defined callback  
function pointer values for attributes: MPI_*_NULL_DELETE_FN (add  
MPI::*_NULL_DELETE_FN, or perhaps even MPI::*::DELETE_FN?),  
MPI_*_NULL_COPY_FN, and MPI_*_DUP_FN (and the deprecated MPI-1  
equivalents).

It would ease implementations by not forcing extra overloaded  
functions and translating back and forth between the C and C++  
function pointers (e.g., it doesn't make sense to create a keyval  
with the C++ binding with a C callback because the callback function  
signatures are different).

It would be simpler/cleaner to say that the C constants should be  
used for C, and the C++ constants should be used for C++.

-- 
Jeff Squyres
Cisco Systems