[AstroPy] A quick survey of PyFITS users

Erik Bray embray at stsci.edu
Wed May 25 19:11:57 EDT 2011

Dear AstroPy community,

     Obviously, if you're not a PyFITS user you can skip this :)  As 
some of you know I've been working on the next version of PyFITS, which 
will hopefully be released within the next couple months.  I've called 
it version 3.0 for two primary reasons:  It's the first version to 
support Python 3, and it contains a pretty large overhaul to the source 

     Despite the large changes, I've tried, at least for this release, 
to maintain as much backwards-compatibility as possible with the last 
release (2.4.0).  So most users hopefully shouldn't even notice much of 
a difference.  I've already had a handful of unofficial beta-testers. 
They've been very helpful in helping me squash some bugs, but haven't 
otherwise pointed out any serious API incompatibilities.

     However, there are some large changes to the 'private' API 
(anything prefixed with an underscore), as well as to a few nominally 
'public' methods, but that aren't of much use to most users.  In 
addition, there are a few interfaces that are still supported, but that 
I would like to deprecate.

     So I just wanted to try to get a sense of what interfaces users are 
actually using, and if anybody is likely to experience significant 
difficulties with this new version.  Here are my questions:

1) Are you using any 'private' variables, classes, functions, etc. from 
PyFITS?  That is, is your code using anything imported from pyfits that 
begins with an underscore?

2) Do you use the classExtensions feature at all?

3) Do you have any custom subclasses of any classes in pyfits?

4) Do you use the _ValidHDU.req_cards() method or the Card.fromstring() 
method at all?

5) Are there any other odd PyFITS interfaces you directly access that 
are not documented in the PyFITS Users' Manual?

I hope to deal with as many problems as I can now, so as to not get 
inundated with "bug" reports once users switch to this new version.  Of 
course, not everybody who uses PyFITS is on this mailing list, and that 
will probably happen anyways.  But any information I can gather to 
mitigate that will be greatly helpful.



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