Re: low level datatype accessing

Steve Huss-Lederman (lederman@cs.wisc.edu)
Tue, 22 Oct 1996 13:18:28 -0500

The choice to remove MPI_UB and MPI_LB was mine. At the meeting it
was raised that there was no statement about what would be returned
for these. Some proposed adding them. I removed them since they
seemed repetative. Also, you will potentially get back lots of UBs
and LBs with the highest and lowest taking effect. I have no strong
opinion about this. You can always ignore the UB and LB and do what
the advice says. Knowing all the intermediate UB and LB may be of
some use to someone. What do others think? I am willing to change
this.

As long as we are discussing this issue, I will raise two other points
that are discussion items this section. First, when you get back a
basic datatype can you tell what type it is? I don't think we say
that the handle you get back from this function is the same. For
example, if the type is MPI_INT will the handle you get back be the
same as the predefined one so you can do a comparison. You will need
to know what the datatype is to encode it with a different scheme then
the ones provided. Second, what are the array_types returned? Is it
just a pointer to the handle or a new handle? That is, does the user
have to free it?

Steve