Possibly you'll have to cast. There are few interfaces that take const for send buffer (like sockets). In other cases you copy the buffer (like with IB) which keeps the const property. Thanks, .Erez -----Original Message----- From: mpi-22-bounces_at_[hidden] [mailto:mpi-22-bounces_at_[hidden]] On Behalf Of Underwood, Keith D Sent: Thursday, March 12, 2009 12:05 PM To: MPI 2.2 Subject: Re: [Mpi-22] Ticket #46: Add const Keyword to the C bindings- implementation It would seem like const would eventually have to be cast away for most lower level interfaces. Portals, Elan, IB Verbs, and as best I can tell MX don't have const on their send buffers... Keith

-----Original Message----- From: mpi-22-bounces_at_[hidden] [mailto:mpi-22-bounces_at_lists.mpi- forum.org] On Behalf Of Erez Haba Sent: Thursday, March 12, 2009 12:44 PM To: MPI 2.2 Subject: Re: [Mpi-22] Ticket #46: Add const Keyword to the C bindings- implementation

No, it's not being cast away (although it is a quick way for you to implement it). In MPICH2 implementation it trickles down to the lower functions. There are very few places where the const is being cast away because ticket #46 does not to break backward compatibility. For example, when the user function is called (const was not added to the MPI_User_function) the implementation must cast away const from the send buffer before calling the user function.

Thanks, .Erez

-----Original Message----- From: mpi-22-bounces_at_[hidden] [mailto:mpi-22-bounces_at_lists.mpi- forum.org] On Behalf Of Jeff Squyres Sent: Thursday, March 12, 2009 11:34 AM To: MPI 2.2 Subject: Re: [Mpi-22] Ticket #46: Add const Keyword to the C bindings- implementation

More importantly, how is const handled? Is it just cast away inside the MPI library?

On Mar 12, 2009, at 2:34 PM, Underwood, Keith D wrote:

...

Since the main purpose of an implementation for something like adding const is to see how invasive the change is, would it be possible to get a diff against the trees that these were created from?

Thanks, Keith

From: mpi-22-bounces_at_[hidden] [mailto:mpi-22- bounces_at_[hidden] ] On Behalf Of Erez Haba Sent: Thursday, March 12, 2009 12:24 PM To: MPI 2.2 Subject: [Mpi-22] Ticket #46: Add const Keyword to the C bindings - implementation

Implementation for ticket #46 is now available from ANL (thanks Pavan)

tarballs

http://www.mcs.anl.gov/research/projects/mpich2/downloads/tarballs/nightly/ const

...

thanks, .Erez

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