Re: wrap HDF5 property lists for netCDF-4?

• To: netcdf-hdf@xxxxxxxxxxxxxxxx
• Subject: Re: wrap HDF5 property lists for netCDF-4?
• From: Quincey Koziol <koziol@xxxxxxxxxxxxx>
• Date: Mon, 19 Jul 2004 00:08:00 -0500 (CDT)

Hi Ed,
    Assuming you want to wrap the property lists, you may want to use their
class/object-like properties.  You can extend the HDF5 property list classes,
or create new property list classes for netCDF-4 to use.  See the
test_genprop_class_addprop() code in test/tgenprop.c for how to extend an
existing HDF5 property list class to add netCDF-4 specific properties.  Some
of the other code in that file may be useful for manipulating the property
lists in HDF5 in other ways.

    Quincey

> Quincey raises an interesting question: are we going to somehow wrap
> HDF5 property lists? Or shall we expose them to the netCDF-4 user?
> 
> For example, the HDF5 file creation process involves two property
> lists, one for creation properties and one for access properties.
> 
> Now we currently make various assumptions about what is desired when
> handling a nc_create call. That is, we just go with default property
> lists.
> 
> But we probably also want to add a function to netcdf which directly
> exposes those property lists, allowing the user to construct and
> manipulate them with HDF5 functions, and then taking the property
> lists and handing them down to the HDF5 file creation function that
> gets called.
> 
> This is a bit of a weird mix of HDF5 and netCDF-4, but it will allow
> the user to take advantage of new features in HDF5 without updating
> any netCDF-4 code. 
> 
> Or perhaps this is a bridge too far for Russ and Mike in terms of
> mixing the interface.
> 
> I note that we face a similar decision about compound types. We could
> wrap HDF5 functions in netCDF functions that conform with our current
> interface, but why not just use the perfectly good HDF5 interface for
> creating compound types, and then taking the hid_t into an netCDF
> function?
> 
> (Of course then we have to ask: what if they use a HDF5 type not
> supported in netCDF, if there are any such types?)
> 
> Ed
>