On Tue, Mar 24, 2020 at 8:40 AM Miro Hrončok <mhroncok@xxxxxxxxxx> wrote: > > Hello Pythonistas. > > (I've CC'ed the devel list for further exposure. But let's discuss this on > python-devel list please to avoid noise.) > > > We would like ro rename the "python3" component (SRPM) to "python39" to make > maintaining various Python versions in various Fedora versions easier. > The names of binary RPMs would be unchanged; you still do `dnf install python3`. > > The change should only affect packagers of Python itself; not users or packagers > of software written in Python. > The only user-visible or general-packager-visible change is a different > component (SRPM) name. > > Details follow. > > > > Currently, we build the Python interpreters this way: > > - the "main" Python 3 interpreter component is called python3 > - it builds a couple of subpackages, like python3-libs or python3-devel > - the "alternate" Python 3 versions components are called python3X (python37, > python39...) > > For example, Fedora 31 has: > > - python36 > - python3 (the "main" Python, which is 3.7.x) > - python38 > - python39 > > (python37 is retired in f31, but present in Fedora versions where python3 != 3.7) > > This makes updating the "main" Python fairly complicated. To upgrade from 3.7 to > 3.8 in f32, we had to: > > 1) retire python38 > 2) upgrade python3 from 3.7 to 3.8 (this makes python3 obsolete python38) > 3) re-introduce (unretire) python37 > > Such an update comes every few years: > - https://fedoraproject.org/wiki/Changes/Python3.7 (f29) > - https://fedoraproject.org/wiki/Changes/Python3.8 (f32) > - https://fedoraproject.org/wiki/Changes/Python3.9 (f33) > > What's even more complicated is backporting patches across Fedora releases. > Assume there is an important upgrade/fix for Python 3.7 we wish to apply for all > Fedoras including stable. That currently means we need to apply the fix in: > > - master branch of python37 > - f32 branch of python37 > - f31 branch of python3 (!) > - f30 branch of python3 > > While cherry-picking or merging patches between branches of one git repo is > quite straight-forward (the only major obstacle is the release and %chaneglog), > doing this across multiple git repos (and spec filenames) is very tedious and > error-prone (albeit possible). > > With the 3.9 update approaching in Fedora 33, we would end up with the following > scheme when updating Python 3.8: > > - master branch of python38 > - f32 branch of python3 (!) > - f31 branch of python38 (!) > - f30 branch of python38 > > Apart from technological obstacles, this causes nontrivial cognitive overhead. > So far, I've been carrying that overhead myself, but others (who don't work on > the Fedora Python packages daily) always need my assistance with this, because > it's overly complicated and hard to understand without drawing pictures. > > > > For this to be easier for us, while keeping the change minimal for others, we > have decided to retire the python3 component and only continue maintaining the > interpreters in "python3X" components. The names of "binary" packages remain > unchanged. > > Before: > > SRPM: python3 > builds: > - python3 > - python-unversioned-command > - python3-{libs,devel,tkinter,idle,test,debug} > - python3-debug{info,source} > > After: > > SRPM: python39 > builds: > - python3 (unchanged) > - python-unversioned-command (unchanged) > - python3-{libs,devel,tkinter,idle,test,debug} (unchanged) > - python39-debug{info,source} (usually not installed by name) > > To avoid further confusion, the "python3-libs" etc. packages will provide > "python39-libs" as well. > > We plan to do this together with the Python 3.9 upgrade. I'll update the change > page after some feedback happens here. > > The initial implementation is in: > https://src.fedoraproject.org/rpms/python39/pull-request/32 > > > Here are other approaches we have considered: > > > Why not rename the packages to python39-libs etc. (and only provide python3-libs)? > > This would be inconsistent with the way other Python 3 packages are called > (e.g. python39-setuptools). We consider that confusing. > > The goal here is to make our work easier while introducing minimal changes to > our users and contributors. > > > Why not rename all the Python packages to python39-setuptools etc.? > > This would create a mess upon distro boundary Python upgrades. > All python39-foo packages would need to obsolete all python38-foo packages. > Even if we add the obsoletes metadata to all the packages, it would prevent > users from having the two parallel stacks of Python installed on the same OS. > (We don't have such stacks in Fedora, but we intend to continue to make this > possible in third party repos, downstreams of Fedora or other systems built on > top or Fedora). > > See also the "minimal changes" point above. > > > Why not package the alternate stacks as modular streams and keep everything > called just python3- (or even python-)? > > 1) The Python stacks are naturally parallel-installable. This would not be > possible if they were different streams of one module. > 2) Vital system tools (dnf, anaconda, packaging tools) use Python, so the > "main" Python can't be in a module. (We could solve this by a separate > "platform Python" just for these system tools, but that makes everything more > complex and harder to work with -- the opposite of what this change is about.) > > See also the "minimal changes" point above. > > Why are you breaking the world once again? > > Sorry if this breaks anything for you. Could you be as specific as possible? > We anticipate no changes in Fedora packages (other than python3/python39). > As long as there's a flag for doing fully versioned not-flat packages, I think I'd be good with this. That is: python3Y-* packages. -- 真実はいつも一つ！/ Always, there's only one truth! _______________________________________________ devel mailing list -- devel@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to devel-leave@xxxxxxxxxxxxxxxxxxxxxxx Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/devel@xxxxxxxxxxxxxxxxxxxxxxx
