xpa module conflicts with pyds9

[olebole]

Original bug (Ubuntu): https://bugs.launchpad.net/bugs/1733352

Imexam does not play together with pyds9. While both have overlapping use cases, it may be good that a user has the opportunity to install and use them in parallel. One way could be to make the package a subpackage of imexam, another to agree on a common xpa package.

See also ericmandel/pyds9#58 for the pyds9 issue.

[sosey]

@olebole can you comment further on how the xpa module conflicts with imexam?

The xpa C code is a submodule of imexam, imexam uses a cython wrapper to access it's functions and interface with DS9. pyds9 (last time I looked) used ctypes for it's interface.

While the two packages do have overlap, imexam provides a library of methods that help examine and plot images, not just provide access into the xpa ds9 functions. I haven't seen an issue with installing both packages on the same machine, could you give me an example of where or how this is failing for you?

thanks!
megan

[sosey]

I did take a quick look at the bug report you listed, but I don't see anything there that would lead me to believe that having imexam installed in the environment would conflict with importing pyds9. Maybe there's a script install somewhere that's clobbering between the two packages ... I haven't investigated it on my machine yet, but I'll give it a go this afternoon.

[olebole]

I can confirm the bug; when I installed imexam and pyds9, then I get the following when running:

In [1]: import pyds9
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-1-cc12a0b41e5c> in <module>()
----> 1 import pyds9

/usr/lib/python2.7/dist-packages/pyds9.py in <module>()
    798 # case where xpa is not installed, and ds9 is started before python
    799 if "PYDS9_NOXPANS" not in os.environ.keys():
--> 800     ds9_xpans()
    801 
    802 

/usr/lib/python2.7/dist-packages/pyds9.py in ds9_xpans()
    249     of ds9 is displayed.
    250     """
--> 251     if xpa.xpaaccess(b"xpans", None, 1) is None:
    252         _fname = ds9Globals["progs"][0]
    253         if _fname:

AttributeError: 'module' object has no attribute 'xpaaccess'

I think this is because wrappers/xpa.pyx goes to the top namespace?

[sosey]

yah, lemme check that out..

[montefra]

In pyds9 version <= 1.8.1, pyds9.py and xpa.py got installed at the site-packages level. I think that this is what is causing the issue. The next version of pyds9 should have both into a pyds9 directory and might solve the problem. But I don;'t know yet when the new version will be ready.

[jehturner]

We also ran into this, but it appears to be fixed with pyds9 1.9.0.dev.

[jehturner]

PS. Putting a module named xpa directly into site-packages nevertheless seems inadvisable 😉.

[sosey]

true.