Extension Build Question/Recommendation

[Troy Curtis Jr]

I'd like to know what everyone's take on the best way to build python
extensions for both python2 and python3 when the upstream build system can
only build for one at time.

The path I took for the gpsd update I submitted was to use two independent
source trees, then build one for python2 and another for python3.  But of
course if the software is much more than just the python extensions, it is
rebuilding a lot of the same code, with the same result.  This could be
considered a bit wasteful of CPU and disk space, and certainly increases
build time.

The only other option I could come up with would be to build for python2,
install that, and then within the install section, reconfigure with python3
and rebuild (which should hopefully only rebuild the python related parts),
and finally install again with the python3 configured setup.  One pitfall I
see with this method is the potential need to manually clean out certain
python2 based generated files if the reconfigure isn't enough.  Plus this
results in building in the install section, which seems a little bit off.

IMHO the first option is better.  Sure, it wastes some CPU cycles and disk
space, as well as increases package build time.  However, it seems less
prone to needing manual tweaks, provides a much cleaner distinction between
the two build configs, and would make it easier to enable/disable the two
variants as desired.

But that is just my opinion, I'm curious what the Python SIG consensus is.

Troy