Arch Linux

Description:

Right now openbabel python bindings have a bug that do not allow to add
arbitrary attributes to objects. That renders it quite useless.

The problem one might argue arise due to a bug in swig, see below. But
clearly it is mainly a packaging problem easy to correct.

As a general rule - packagers should use the same settings and options
as upstream unless there is a good reason to do otherwise. In the case
of Open Babel you can check what options are used when running swig in
scripts/CMakeLists.txt, so the command should include these options:

swig -python -c++ -small -O -templatereduce -naturalvar

I don't know if Arch devs had any reason to use different ones (if they
had, it should be documented in the build script), but this looks like a
packaging bug. The package currently uses:

swig -I../include/ -python -py3 -c++ openbabel-python.i

only by adding the -O the problem will be solve:

swig -O -I../include/ -python -py3 -c++ openbabel-python.i

Another issue is in SWIG itself. I would not expect the behavior of the
bindings to change because of not using optimization (-O). This command
describes the flag:
~$ swig -python -help
...
-O - Enable the following optimization options:
-modern -fastdispatch -nosafecstrings -fvirtual -noproxydel
-fastproxy -fastinit -fastunpack -fastquery -modernargs -nobuildnone

Arguably in both cases SWIG should generate code allowing to add
arbitrary attributes to objects, but right now it doesn't. Probably
_swig_getattr() and _swig_setattr() should be adjusted for it to first
look for attribute in the Python class itself and only then try to look
it up in c++ code. The reason is, because those functions are set as
__getattr__ and __setattr__ methods in OBAtom class if flag -O is not
used and that breaks setattr() in general case (breaks at least in case
of properies).

So until upstream, either openbabel or swig, solve the issue, please update
the package so that the swiw call contain -O. This solve the issue. I have
attached the corrected PKGBUILD.

Additional info:
* package version(s)

community/python-openbabel 2.3.2-1

* config and/or log files etc.


Steps to reproduce: