[Nexus] question about NeXus classes

[Peterson, Peter F.]

Darren,

Thank you for the question.

The current philosophy of classes is that they are to be thought of as
dictionaries. If you are familiar with xml schema (xsd) the "any" tag is
appropriate. This means that there is one NXdetector which covers all
the various types of detectors in existence. If a particular detector
needs another field that isn't in the current NXdetector, then it should
be added. Subclassing is not an idea that can be applied to the base
classes.

However, the NIAC has noted the similarities in several of classes and
applying the object oriented design techniques such as subclassing. The
committee agreed that this is the direction for the future, but are
waiting until the current definitions (v2.0) can be finalized.

Peter Peterson

-----Original Message-----
From: nexus-bounces at nexusformat.org
[mailto:nexus-bounces at nexusformat.org] On Behalf Of Darren Dale
Sent: Friday, July 25, 2008 12:53 PM
To: nexus at nexusformat.org
Subject: [Nexus] question about NeXus classes

Hello,

I have a question regarding specialization of the generic class
definitions 
listed at  http://www.nexusformat.org/Design#NeXus_Classes . Is it
acceptable 
to create a subclass of NXdetector that is specific to a single- or 
multi-element energy-dispersive detector, called NX_Vortex90EX for
example, 
and save that class name to NX_class? If that is not advisable, I guess
I 
could use an additional attribute like NX_subclass. I'm just trying to
get a 
sense of the intended use of the NX_class attribute and its limitations.

Thanks,
Darren 

-- 
Darren S. Dale, Ph.D.
Staff Scientist
Cornell High Energy Synchrotron Source
Cornell University
275 Wilson Lab
Rt. 366 & Pine Tree Road
Ithaca, NY 14853

darren.dale at cornell.edu
office: (607) 255-3819
fax: (607) 255-9001
http://www.chess.cornell.edu
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