[NeXus-committee] NXgroup: undocumented or inofficial?

[Osborn, Raymond]

I don’t know if this will just add to the confusion, but the Python API uses classes of NXgroup and NXfield as base classes for all other NeXus objects, i.e., all the other NeXus group classes, such as NXentry, NXsample, etc, are inherited from the NXgroup class. NXgroup was chosen partly because it wasn’t in the list of base class definitions (I confess I'm not sure I knew that it was once part of the standard) and because it’s an obvious name for a base class (in the object-oriented sense).

So I would request that NXgroup not be used for another purpose. If we ever resurrect the idea of making the NeXus definitions object-oriented (I assume those discussions are dead, but I am probably out of the loop), then NXgroup would make a good base class name.

Ray
P.S. This might not be so different from what Herbert wanted to use NXgroup for, but I’m not sure I fully understood his proposal.

On Jul 8, 2014, at 6:21 PM, Herbert J. Bernstein <yayahjb at gmail.com> wrote:

> Let's start from scratch on what is needed now.  I am putting together
> very large complex NeXus files for synchrotron diffraction images and
> FEL images.  These files involve large numbers of filed names.  They
> would be much easier to organize and easier for users to read through
> if there were a transparent NXgroup base class that allowed validation
> as if the contents were
> one level up, but which, simply by being a new tree node, avoided any
> potential name conflicts
> -- essentially filling the role in NeXus that parentheses serve in
> C-expressions.
> 
> On Tue, Jul 8, 2014 at 5:52 PM, Pete Jemian <jemian at anl.gov> wrote:
>> Joachim:
>> 
>> 
>> On 7/8/2014 4:29 PM, j.wuttke wrote:
>>> 
>>> Perhaps the name change and it's non-implementation at SNS are a fortunate
>>> coincidence we could use to codify their current use of "NXgroup"?
>> 
>> 
>> NXcollection was finalized at a plenary meeting of the NIAC in 2010.
>> (http://wiki.nexusformat.org/images/2/24/Minutes_of_NeXus_Committee_2010.pdf)
>> The proposal for "NXmeasurement" resulted in "NXcollection".  I cannot find
>> the mention of "NXgroup" in the minutes available online.  A Google search
>> for "NeXus NXgroup base class" is unproductive for this topic. (It does
>> identify that the NeXpy tree API uses a Python class with the NXgroup name.)
>> 
>> Minutes for the various meetings of the NIAC, where such decisions have been
>> made are available online:
>> http://wiki.nexusformat.org/NIAC#Meetings
>> 
>> Pete
>> 
>> 
>> --
>> ----------------------------------------------------------
>> Pete R. Jemian, Ph.D.                <jemian at anl.gov>
>> Beam line Controls and Data Acquisition, Group Leader
>> Advanced Photon Source,   Argonne National Laboratory
>> Argonne, IL  60439                   630 - 252 - 3189
>> -----------------------------------------------------------
>>   Education is the one thing for which people
>>      are willing to pay yet not receive.
>> -----------------------------------------------------------
>> 
>> 
>> 
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-- 
Ray Osborn, Senior Scientist
Materials Science Division
Argonne National Laboratory
Argonne, IL 60439, USA
Phone: +1 (630) 252-9011
Email: ROsborn at anl.gov