Yes, but if there's a public interface for accessing the cache
on the datatype, what prevents the user from messing with your
cached data (accidentally, of course...)? I guess you could
put a magic cookie in your data to make sure it's yours, and
check that there was nothing already cached on the type before
you got it.
> I need MPI_Type_dup for a different reason: The etype and filetype are
> specified only at open time and used thereafter. For safety, I need to
> maintain a copy of them, because the user could free them while the
> file is still open.
I agreee with this.
John
ps. I've redirected this message to mpi-external, since that seems
like a more appropriate list for this discussion.