Thanks for bringing attention to this, Victor, and to Ken Jin (GH: Fidget-Spinner) for the PR. I've just completed reviewing and merging the PR, so hopefully anyone affected will now have a more clear idea of how to migrate their asyncio code to 3.10. Having the porting method explicitly documented certainly helps to smooth the version transition process and reduce headaches. :-)
Going forward, I'll try to make more of an active effort to ensure any potentially incompatible changes I'm involved with include a clear method of porting documented in their respective whatsnew. It can be easy to forget at times that a seemingly minor fix which is intuitively clear to the authors of a change may not be as clear to those not involved with it, regardless of how difficult the fix actually is. On Tue, Jan 19, 2021 at 12:03 PM Victor Stinner <vstin...@python.org> wrote: > A PR was proposed to document the removal of the loop parameter: > https://github.com/python/cpython/pull/24256 > > Victor > > On Tue, Jan 19, 2021 at 1:34 PM Victor Stinner <vstin...@python.org> > wrote: > > > > Hi, > > > > We are working on upgrading Python from 3.9 to 3.10 in Fedora and we > > are facing many Python 3.10 incompatible changes. Most changes were > > planned with a deprecation period, but, as usual, projects are not > > tested with DeprecationWarning treated as errors, and so tons of > > packages now fail to build. > > > > I'm not here to talk about DeprecationWarning, but how we communicate > > on incompatible changes made on purpose. For example, What's New in > > Python 3.8 announces: "In asyncio, the explicit passing of a loop > > argument has been deprecated and will be removed in version 3.10". As > > expected, the parameter was removed in Python 3.10 (bpo-42392), but I > > cannot see anything in What's New in Python 3.10. The problem is that > > I don't know how to fix projects broken by this change. I'm not > > complaining about this specific change, but more generally. > > > > I strongly suggest to well document incompatible changes. The bare > > minimum is to mention them in "Porting to Python 3.10" section: > > https://docs.python.org/dev/whatsnew/3.10.html#porting-to-python-3-10 > > > > A link to the bpo sometimes helps to understand how to port code. But > > I would really appreciate if authors of incompatible changes would > > explain how to add Python 3.10 support to existing projects, without > > losing support for older Python versions. Not just "this function is > > now removed, good luck!" :-) > > > > I didn't touch asyncio for at least 1 year, so I don't know what > > happens if I remove a loop argument. Does an application remain > > compatible with Python 3.6 without passing loop? > > > > I know that I made multiple incompatible changes myself and I'm sure > > that the documentation should probably be enhanced, but I also expect > > others to help on that! ;-) > > > > Please think about people who have to port 4000 Python projects to > Python 3.10! > > > > --- > > > > The best would be to ship a tool which adds Python 3.10 support to > > existing projects without losing support with Python 3.6. Maybe > > something like https://github.com/asottile/pyupgrade could be used for > > that? pyupgrade looks more specific to the Python syntax, than the > > usage of the stdlib. > > > > I wrote such tool to add Python 3.10 support to C extensions without > > losing support with Python 2.7. It relies on a header file > > (pythoncapi_compat.h) which provides new C API functions on old Python > > versions. > > https://github.com/pythoncapi/pythoncapi_compat > > > > For example, it replaces "obj->ob_refcnt = refcnt;" with > > "Py_SET_REFCNT(obj, refcnt);" and provides Py_SET_REFCNT() to Python > > 3.8 and older (function added to Python 3.9) > > > > Victor > > -- > > Night gathers, and now my watch begins. It shall not end until my death. > > > > -- > Night gathers, and now my watch begins. It shall not end until my death. > _______________________________________________ > Python-Dev mailing list -- python-dev@python.org > To unsubscribe send an email to python-dev-le...@python.org > https://mail.python.org/mailman3/lists/python-dev.python.org/ > Message archived at > https://mail.python.org/archives/list/python-dev@python.org/message/CVLDV7VIVENV6HMQ4PRAN3VRFU26CMJI/ > Code of Conduct: http://python.org/psf/codeofconduct/ >
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