Re: questions about attributes and compound types...

• To: netcdf-hdf@xxxxxxxxxxxxxxxx
• Subject: Re: questions about attributes and compound types...
• From: Quincey Koziol <koziol@xxxxxxxxxxxxx>
• Date: Mon, 19 Jul 2004 14:58:46 -0500 (CDT)

Hi John,

> >>>>>>We've got a question: is there a way to attach an attribute to a
> >>>>>>member of a compound type dataset. That is, if I have a dataset of
> >>>>>>something that is a compound type, can I attach at attribute not to
> >>>>>>the whole dataset, but just to one member of the compound type?
> >>>>>>       
> >>>>>>
> >>>>>>            
> >>>>>>
> >>>>>   Hmm, we've had a couple of requests for similar features, but you 
> >>>>> can't
> >>>>>do this currently.  What's the motivation for this?
> >>>>>
> >>>>>     
> >>>>>
> >>>>>          
> >>>>>
> >>>>I think I will let John answer this part...
> >>>>   
> >>>>
> >>>>        
> >>>>
> >>the motivation comes from creating a unifying model with the opendap 
> >>data model.
> >>
> >>opendap structures contain "first class" variables that can have attributes.
> >>    
> >>
> >    Hmm, interesting...
> >
> >  
> >
> >>however, if thats not feasible, i can do a workaround where opendap 
> >>structures become groups instead.
> >>    
> >>
> >    Well, it definitely isn't currently supported.  Should I open an issue 
> > for
> >this in our tracker so we consider in the future?  I'm just a bit concerned
> >about supporting the full generality of it, like attributes on parts of array
> >datatypes or nested compound datatypes, etc.
> >
> >    Quincey
> >  
> >
> yes, i think its worth considering in the future. this would make 
> structure members first class citizens. the attributes would apply to 
> the structure member as a whole, not individual array elements, just as 
> for an array dataset.
    Ok, I've entered an issue in our bugzilla.

> as i said, the motivation comes from opendap structures. ironically, i 
> suspect that it was at least in part motivated there by mapping hdf 
> (4/5?) into opendap, where they decided to map "groups" into 
> "structures". so we can just undo that and map opendap structures to 
> groups when needed.
    That would probably work OK.

    Quincey

• References:
  • Re: questions about attributes and compound types...
    • From: John Caron