Mailman 3 February 2020 - Python-Dev

Three trivial PRs from first-timers in need of merging!
by Brandt Bucher Feb. 21, 2020

Feb. 21, 2020

Hi everybody! I've found a handful of trivial PRs from new contributors that have gone un-core-reviewed since November. CLAs are signed, tests are passing, and I've verified the quality and correctness of each one. If anybody has a few spare minutes to merge these, I know that it would make the authors very happy! :) Clarify numeric padding behaviour in string formatting: - A helpful doc addition (just a few words). - https://github.com/python/cpython/pull/17036 argparse unittest … [View More]

4 4

Python Language Summit at PyCon 2020
by Mariatta Feb. 18, 2020

Feb. 18, 2020

(cross posting to python-committers and python-dev) I'm happy to announce that the signups for Python Language Summit at PyCon 2020 is now open. Full details at: https://us.pycon.org/2020/events/languagesummit/ *TL;DR* When: Wednesday, April 15, 2020, 9am–4pm (Note, we’re starting 1 hour earlier than usual!) Where: David L. Lawrence Convention Center, Pittsburgh, PA, room TBD Sign up to attend: https://forms.gle/Fg7ayhYTaY75J1r7A (closes Feb 29th, 2020 AoE) Sign up to discuss a topic: … [View More]

2 3

[RELEASE] Python 3.8.2rc2 is now available for testing
by Łukasz Langa Feb. 18, 2020

Feb. 18, 2020

Python 3.8.2rc2 is the second release candidate of the second maintenance release of Python 3.8. Go get it here: https://www.python.org/downloads/release/python-382rc2/ <https://www.python.org/downloads/release/python-382rc2/> Why a second release candidate? The major reason for RC2 is that GH-16839 <https://github.com/python/cpython/pull/16839> has been reverted. The original change was supposed to fix for some edge cases in urlparse (numeric paths, recognizing netlocs without /… [View More]

1 0

Azure Pipelines PR: Unresponsive agent
by Kyle Stanley Feb. 17, 2020

Feb. 17, 2020

In a recent PR (https://github.com/python/cpython/pull/18057), I received the following error message in the Azure Pipelines build results: ##[error]We stopped hearing from agent Azure Pipelines 5. Verify the agent machine is running and has a healthy network connection. Anything that terminates an agent process, starves it for CPU, or blocks its network access can cause this error. For more information, see: https://go.microsoft.com/fwlink/?linkid=846610 Build: https://dev.azure.com/Python/… [View More]

4 4

Regarding SSL installation in python
by Naga Chaitanya L Feb. 17, 2020

Feb. 17, 2020

Hi, I want to know how to install ssl certificate in python. please give me referral link. thnk u Regards! chaitanya

2 1

PEP 584: Add Union Operators To dict
by Brandt Bucher Feb. 16, 2020

Feb. 16, 2020

Steven D'Aprano and I have pushed a third draft of PEP 584: https://www.python.org/dev/peps/pep-0584/ The accompanying reference implementation is on GitHub: https://github.com/brandtbucher/cpython/tree/addiction For those who have been following the discussions over the past year on python-ideas, this new draft does not contain much additional content; the most notable difference is that the choice of operator has been changed from + to |. The rest of the revisions are mostly reformatting … [View More]

11 29

pickle.reduce and deconstruct functions
by Andrew Barnert Feb. 16, 2020

Feb. 16, 2020

This was [posted on -ideas][1], but apparently many people didn't see it because of the GMane migration going on at exactly the same time. At any rate, Antoine Pitrou suggested it should be discussed on -dev instead. And this gives me a chance to edit it (apparently it was markdown-is enough to confuse Hyperkitty and turn into a mess). Pickling uses an extensible protocol that lets any class determine how its instances can be deconstructed and reconstructed. Both `pickle` and `copy` use this … [View More]protocol, but it could be useful more generally. Unfortunately, to use it more generally requires relying on undocumented details. I think we should expose a couple of helpers to fix that: # Return the same (shallow) reduction tuple that pickle.py, copy.py, and _pickle.c would use pickle.reduce(obj) -> (callable, args[, state[, litems[, ditem[, statefunc]]]]) # Return a callable and arguments to construct a (shallow) equivalent object # Raise a TypeError when that isn't possible pickle.deconstruct(obj) -> callable, args, kw So, why do you want these? There are many cases where you want to "deconstruct" an object if possible. For example: * Pattern matching depends on being able to deconstruct objects like this * Auto-generating a `__repr__` as suggested in [Chris Angelico's -ideas thread][2]. * Quick&dirty REPL stuff, and deeper reflection stuff using `inspect.signature` and friends. Of course not every type tells `pickle` what to do in an appropriate way that we can use, but a pretty broad range of types do, including (I think; I haven't double-checked all of them) `@dataclass`, `namedtuple`, `(a)attr.s`, many builtin and extension types, almost all reasonable types that use `copyreg`, and any class that pickles via the simplest customization hook `__getnewargs[_ex]__`. That's more than enough to be useful. And, just as important, it won't (except in intentionally pathological cases) give us a false positive, where a type is correctly pickleable and we think we can deconstruct it but the deconstruction is wrong. (For some uses, you are going to want to fall back to heuristics that are often right but sometimes misleadingly wrong, but I don't think the `pickle` module should offer anything like that. Maybe `inspect` should, but I'm not proposing that here.) The way to get the necessary information isn't fully documented, and neither is the way to interpret it. And I don't think it _should_ be documented, because it changes every so often, and for good reasons; we don't want anyone writing third-party code that relies on those details. Plus, a different Python implementation might conceivably do it differently. Public helpers exposed from `pickle` itself won't have those problems. Here's a first take at the code. def reduce(obj, proto=pickle.DEFAULT_PROTOCOL): """reduce(obj) -> (callable, args[, state[, litems[, ditem[, statefunc]]]]) Return the same reduction tuple that the pickle and copy modules use """ cls = type(obj) if reductor := copyreg.dispatch_table.get(cls): return reductor(obj) # Note that this is not a special method call (not looked up on the type) if reductor := getattr(obj, "__reduce_ex__"): return reductor(proto) if reductor := getattr(obj, "__reduce__"): return reductor() raise TypeError(f"{cls.__name__} objects are not reducible") def deconstruct(obj): """deconstruct(obj) -> callable, args, kwargs callable(_args, **kwargs) will construct an equivalent object """ reduction = reduce(obj) # If any of the optional members are included, pickle/copy has to # modify the object after construction, so there is no useful single # call we can deconstruct to. if any(reduction[2:]): raise TypeError(f"{type(obj).__name__} objects are not deconstrutable") func, args,_ _ = reduction # Many types (including @dataclass, namedtuple, and many builtins) # use copyreg.__newobj__ as the constructor func. The args tuple is # the type (or, when appropriate, some other registered # constructor) followed by the actual args. However, any function # with the same name will be treated the same way (because under the # covers, this is optimized to a special opcode). if func.__name__ == "__newobj__": return args[0], args[1:], {} # (Mainly only) used by types that implement __getnewargs_ex__ use # copyreg.__newobj_ex__ as the constructor func. The args tuple # holds the type, *args tuple, and **kwargs dict. Again, this is # special-cased by name. if func.__name__ == "__newobj_ex__": return args # If any other special copyreg functions are added in the future, # this code won't know how to handle them, so bail. if func.__module__ == 'copyreg': raise TypeError(f"{type(obj).__name__} objects are not deconstrutable") # Otherwise, the type implements a custom __reduce__ or __reduce_ex__, # and whatever it specifies as the constructor is the real constructor. return func, args, {} Actually looking at the logic as code, I think it makes a better argument for why we don't want to make all the internal details public. :) Here are some quick (completely untested) examples of other things we could build on it. # in inspect.py def deconstruct(obj): """deconstruct(obj) -> callable, bound_args Calling the callable on the bound_args would construct an equivalent object """ func, args, kw = pickle.deconstruct(obj) sig = inspect.signature(func) return func, sig.bind(_args, **kw) # in reprlib.py, for your __repr__ to delegate to def auto_repr(obj): func, bound_args = inspect.deconstruct(obj) args = itertools.chain( map(repr, bound_args.args), (f"{key!r}={value!r}" for key, value in bound_args.kwargs.items())) return f"{func.__name__}({', '.join(args)})" # or maybe as a class decorator def auto_repr(cls): def __repr__(self): func, bound_args = inspect.deconstruct(self) args = itertools.chain( map(repr, bound_args.args), (f"{key!r}={value!r}" for key, value in bound_args.kwargs.items())) return f"{func.__name__}({', '.join(args)})" cls.__repr__ = __repr__ return cls [1]: https://mail.python.org/archives/list/python-ideas@python.org/thread/RTZGM7… [2]: https://mail.python.org/archives/list/python-ideas@python.org/thread/37UNED… [View Less]

2 2

Summary of Python tracker Issues
by Python tracker Feb. 14, 2020

Feb. 14, 2020

ACTIVITY SUMMARY (2020-02-07 - 2020-02-14) Python tracker at https://bugs.python.org/ To view or respond to any of the issues listed below, click on the issue. Do NOT respond to this message. Issues counts and deltas: open 7277 (-11) closed 44107 (+65) total 51384 (+54) Open issues with patches: 2861 Issues opened (35) ================== #5537: LWPCookieJar cannot handle cookies with expirations of 2038 or https://bugs.python.org/issue5537 reopened by vstinner #38324: [… [View More]

1 0

Re: Maintenance of multiprocessing module: there are a few stalled issues/patches
by mailer＠app.tempr.email Feb. 13, 2020

Feb. 13, 2020

> Did you help move the issues forward by reviewing and testing the patches, or otherwise commenting? If the multiple PRs on an issue are either/or, which seems better? Thanks Terry for the reply. Are regular users supposed to keep reviewing even though the issue already has positive reviews or former change requests have been fixed and are now already "awaiting core review"? Here, the first pull request stalled, but the second one takes over and awaits review: - https://bugs.python.… [View More]

4 3

OpenGrok upgraded and is now self serve
by Sean Wallitsch Feb. 13, 2020

Feb. 13, 2020

OpenGrok <http://opengrok/> has moved to the DreamWorks Cloud! It's on a much beefier VM this time around, which will hopefully alleviate the crashing and downtime that plagued the old instance. In addition, Opengrok now re-indexes every *60 *minutes instead of once a day. It will also auto-pull github changes down during that time. Finally, you can add your own github repositories or folios to be indexed by following "Adding Files to OpenGrok" <http://mydw.dreamworks.net/display/TD/… [View More]

1 1