Hey, Just forwarding it here so Python folks don't miss it on the main devel list.
Thanks, Mark. -------- Forwarded Message -------- > From: Mark McLoughlin <mar...@redhat.com> > Reply-to: Mark McLoughlin <mar...@redhat.com> > To: Development discussions related to Fedora > <devel@lists.fedoraproject.org> > Subject: Python libraries and backwards compat [was Re: What would it > take to make Software Collections work in Fedora?] > Date: Mon, 04 Mar 2013 22:51:31 +0000 > > On Thu, 2012-12-06 at 07:06 -0800, Adam Williamson wrote: > > On Thu, 2012-12-06 at 15:30 +0100, Nicolas Mailhot wrote: > > > IMHO use of software collections is a symptom of a badly run organisation > > > not devoting enough cycles to maintain the software it uses, and hoping > > > (as in wishful thinking) no problem will go critical before the product > > > they built on top of those collections is end-of-lifed > > > > > > I completely fail to see how entities with that problem will manage to > > > maintain the package number explosion creating software collections will > > > induce. > > > > On the one hand, I agree completely - I think the 'share all > > dependencies dynamically' model that Linux distros have traditionally > > embraced is the right one, and that we're a strong vector for spreading > > the gospel when it comes to that model, and it'd be a shame to > > compromise that. > > > > On the other hand, we've been proselytizing the Java heretics for over a > > decade now, and the Ruby ones for a while, and neither shows any signs > > of conversion or just plain going away, so we may have to call it an > > ecumenical matter and deal with their models somehow. Sucky as it may > > be. I don't know, I'm a bit conflicted. > > It's interesting that you call out Java and Ruby folks as being > heretics. I guess that means all is kosher with Python? > > OpenStack is getting burned by API instability in some Python packages, > so I've started a thread on Python's distutils-sig to try and guage the > level of heresy amongst Python folks :) > > It started here: > > http://mail.python.org/pipermail/distutils-sig/2013-February/020030.html > > and now we're talking about Software Collections here: > > http://mail.python.org/pipermail/distutils-sig/2013-March/020074.html > > Two things I'm picking up from the thread: > > - A trend towards "semantic versioning" and, implicit in that, an > acceptance of API breakages so long as the major number of a library > version is incremented > > - Supporting the parallel installation of incompatible versions of > libraries isn't seen as an issue because you can "just use virtual > environments" ... which amounts to Python Software Collections. > > The combination of those two things suggests to me that the Python world > will start looking a lot less sane to packagers - i.e. library > maintainers breaking API compatibility more often and assuming we can > just use SC or similar to have multiple incompatible versions installed. > > I can see OpenStack upstream reacting to this by "capping" its required > version range for each library it depends so that if the library does > release an incompatible version, OpenStack sticks with the latest > compatible version. > > If that happens, I think OpenStack packagers will need to look seriously > at using Software Collections. Basically, we'd look to package and > maintain our own stack of all the Python libraries we need above the > core Python libraries. > > So, you'd have openstack-nova, openstack-glance, etc. all installed as > normal in /usr, /var, etc. but they'd require python libraries from the > openstack-grizzly SC like openstack-grizzly-python-eventlet which would > be installed in /opt/fedora/openstack-grizzly/root/usr/lib/python. > > I'd appreciate it if someone else with a Fedora Python packaging > background could look into this and, hopefully, explain how the > discussion on distutils-sig isn't so terrifying after all. > > Cheers, > Mark. _______________________________________________ python-devel mailing list python-de...@lists.fedoraproject.org https://admin.fedoraproject.org/mailman/listinfo/python-devel
