[RELEASE] Python 3.9.0b1 is now available for testing
On behalf of the entire Python development community, and the currently serving Python release team in particular, I’m pleased to announce the release of Python 3.9.0b1. Get it here: https://www.python.org/downloads/release/python-390b1/ https://www.python.org/downloads/release/python-390b1/ This is a beta preview of Python 3.9 Python 3.9 is still in development. This release, 3.9.0b1, is the first of four planned beta release previews. Beta release previews are intended to give the wider community the opportunity to test new features and bug fixes and to prepare their projects to support the new feature release. Call to action We strongly encourage maintainers of third-party Python projects to test with 3.9 during the beta phase and report issues found to the Python bug tracker https://bugs.python.org/ as soon as possible. While the release is planned to be feature complete entering the beta phase, it is possible that features may be modified or, in rare cases, deleted up until the start of the release candidate phase (2020-08-10). Our goal is have no ABI changes after beta 4 and as few code changes as possible after 3.9.0rc1, the first release candidate. To achieve that, it will be extremely important to get as much exposure for 3.9 as possible during the beta phase. Please keep in mind that this is a preview release and its use is not recommended for production environments. Major new features of the 3.9 series, compared to 3.8 Some of the new major new features and changes in Python 3.9 are: PEP 584 https://www.python.org/dev/peps/pep-0584/, Union Operators in dict PEP 585 https://www.python.org/dev/peps/pep-0585/, Type Hinting Generics In Standard Collections PEP 593 https://www.python.org/dev/peps/pep-0593/, Flexible function and variable annotations PEP 602 https://www.python.org/dev/peps/pep-0602/, Python adopts a stable annual release cadence PEP 616 https://www.python.org/dev/peps/pep-0616/, String methods to remove prefixes and suffixes PEP 617 https://www.python.org/dev/peps/pep-0617/, New PEG parser for CPython BPO 38379 https://bugs.python.org/issue38379, garbage collection does not block on resurrected objects; BPO 38692 https://bugs.python.org/issue38692, os.pidfd_open added that allows process management without races and signals; BPO 39926 https://bugs.python.org/issue39926, Unicode support updated to version 13.0.0; BPO 1635741 https://bugs.python.org/issue1635741, when Python is initialized multiple times in the same process, it does not leak memory anymore; A number of Python builtins (range, tuple, set, frozenset, list, dict) are now sped up using PEP 590 https://www.python.org/dev/peps/pep-0590 vectorcall; A number of Python modules (_abc, audioop, _bz2, _codecs, _contextvars, _crypt, _functools, _json, _locale, operator, resource, time, _weakref) now use multiphase initialization as defined by PEP 489 https://www.python.org/dev/peps/pep-0489/; A number of standard library modules (audioop, ast, grp, _hashlib, pwd, _posixsubprocess, random, select, struct, termios, zlib) are now using the stable ABI defined by PEP 384 https://www.python.org/dev/peps/pep-0384/. (Hey, fellow core developer, if a feature you find important is missing from this list, let Łukasz know mailto:lukasz@python.org.) The next pre-release, the second beta release of Python 3.9, will be 3.9.0b2. It is currently scheduled for 2020-06-08. More resources Online Documentation https://docs.python.org/3.9/ PEP 596 https://www.python.org/dev/peps/pep-0596/, 3.9 Release Schedule Report bugs at https://bugs.python.org https://bugs.python.org/. Help fund Python and its community https://discuss.python.org/psf/donations/. Your friendly release team, Ned Deily @nad https://discuss.python.org/u/nad Steve Dower @steve.dower https://discuss.python.org/u/steve.dower Łukasz Langa @ambv https://discuss.python.org/u/ambv
I know this is late in the cycle to think of this. But I just realized the PEP 584 does not say anything about order guarantees. I think it is safe to assume that existing keys in dictA will not have order modified by `dictA |= dictB`. However, the PEP does not state what order we are given when new keys are added. I reckon it is a kind of insertion, so they must occur after the existing keys. However, stating explicitly that the MUST (or alternately MIGHT NOT) be inserted in the order that dictB has seems worth specifying. Moreover, the new operator explicitly states that it will flexibly deal with mapping types other than dict on the right hand side. So what happens with: dictA |= unorderedmapB I think the "reasonable" belief should be that all new keys will be in some unspecified order amongst themselves, but all occurring after the old keys. I think a sentence or two explicitly indicating what is promised and what is not would be worthwhile.
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PEP 584 https://www.python.org/dev/peps/pep-0584/, Union Operators in dict
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Yes, the assumption (and the implementation) is that newly added keys are
inserted at the end, in the order in which the second object produces them
when iterated over. Please do send us a PR for the peps repo!
On Tue, May 19, 2020 at 12:34 PM David Mertz
I know this is late in the cycle to think of this. But I just realized the PEP 584 does not say anything about order guarantees.
I think it is safe to assume that existing keys in dictA will not have order modified by `dictA |= dictB`. However, the PEP does not state what order we are given when new keys are added. I reckon it is a kind of insertion, so they must occur after the existing keys. However, stating explicitly that the MUST (or alternately MIGHT NOT) be inserted in the order that dictB has seems worth specifying.
Moreover, the new operator explicitly states that it will flexibly deal with mapping types other than dict on the right hand side. So what happens with:
dictA |= unorderedmapB
I think the "reasonable" belief should be that all new keys will be in some unspecified order amongst themselves, but all occurring after the old keys. I think a sentence or two explicitly indicating what is promised and what is not would be worthwhile.
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PEP 584 https://www.python.org/dev/peps/pep-0584/, Union Operators in dict
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The dead increasingly dominate and strangle both the living and the not-yet born. Vampiric capital and undead corporate persons abuse the lives and control the thoughts of homo faber. Ideas, once born, become abortifacients against new conceptions. _______________________________________________ Python-Dev mailing list -- python-dev@python.org To unsubscribe send an email to python-dev-leave@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/4OKQ5DAR... Code of Conduct: http://python.org/psf/codeofconduct/
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Maybe I'm missing something here. The PEP specifically says:
Similarly, the iteration order of the key-value pairs in the dictionary will follow the same semantics as the examples above, with each newly added key (and its value) being appended to the current sequence.
That seems sufficient, no?
I comment on the PR.
On Tue, May 19, 2020 at 4:44 PM Brandt Bucher
Maybe I'm missing something here. The PEP specifically says:
Similarly, the iteration order of the key-value pairs in the dictionary will follow the same semantics as the examples above, with each newly added key (and its value) being appended to the current sequence.
That seems sufficient, no? _______________________________________________ Python-Dev mailing list -- python-dev@python.org To unsubscribe send an email to python-dev-leave@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/NM75M5N7... Code of Conduct: http://python.org/psf/codeofconduct/
-- The dead increasingly dominate and strangle both the living and the not-yet born. Vampiric capital and undead corporate persons abuse the lives and control the thoughts of homo faber. Ideas, once born, become abortifacients against new conceptions.
participants (4)
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Brandt Bucher -
David Mertz -
Guido van Rossum -
Łukasz Langa