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[netCDF #MSV-188900]: C++ API for NETCDF version 4.0

Lynton,

> Thanks for the reply.  I had been looking at the cxx directory, not the
> cxx4 directory.
> I see the cxx4 directory appears to have some of the features missing in
> cxx. Do you advise to work from this?

Yes, at least if that seems practical.  When you run the configure
script to build, check, and install netCDF, including the configure
option --enable-cxx-4 will cause the cxx4 directory to be used after
the cxx directory for building.  I just tried it and noticed a
portability problem in cxx4/ncatt.cpp that prevents me from testing
it, but it looks like it would be easy to fix (it assumes
"__FUNCTION__" is a predefined macro that identifies the current
function, used in error messages constructed when an exception is
thrown, e.g. see cxx4/ncatt.cpp line 44 or line 53).

Ed Hartnett was overseeing the summer project to implement this C++
netCDF-4 interface, so he knows more about what didn't get completed
and where work is most needed.  It may already implement enough of the
netCDF-4 interface that you won't need to do much, depending on your
requirements.  I'll CC: Ed on this message in case he wants to add
comments on this issue.

We would really appreciate any contributions you could make to
improving this C++ netCDF-4 implementation, even if it's only an
objective evaluation of what's there and a recommendation for how
practical it will be to complete or how much effort it will take.  Bug
fixes will also be gratefully accepted.

> I presume  (please tell me otherwise!) that I will NOT need to transfer
> stuff from cxx into cxx4.

I think that's right, but Ed may have made some additions to the cxx
sources since the cxx4 sources were written, so I'll let him provide
the definitive answer to that question.

> Are you happy not to make calls to nc__open? I see that the cxx4 uses
> nc_open but has retained in its API a chunk size pointer.

The calls to nc__open were only made to set some infrequently used tuning
parameters for the netCDF-3 files (because the netCDF-4 library is fully
compatible with netCDF-3 and can create netCDF-3 classic files as well as
netCDF-4/HDF5 files).  I have renamed the "chunksize" pointer to a
"bufrsize" pointer in our next release, to avoid confusion with the
variable chunking and chunk sizes supported in netCDF-4, which are
unrelated to this bufrsize parameter used for performance tuning.

> I think my work will be  mainly to tidy up the cxx4 API and make sure it
> is working for me. I can add documentation also.

That would be great!  I hope you find it usable, but if not, please let
us know where it needs work.  Thanks!

> Any advice will of course be useful.

We'll be happy to tell you what we know ...

--Russ

Russ Rew                                         UCAR Unidata Program
address@hidden                     http://www.unidata.ucar.edu



Ticket Details
===================
Ticket ID: MSV-188900
Department: Support netCDF
Priority: Normal
Status: Closed