Mailman 3 April 2021 - Python-Dev

PEP 1, PEP Purpose and Guidelines
by barry＠zope.com 18 May '21

18 May '21

It has been a while since I posted a copy of PEP 1 to the mailing lists and newsgroups. I've recently done some updating of a few sections, so in the interest of gaining wider community participation in the Python development process, I'm posting the latest revision of PEP 1 here. A version of the PEP is always available on-line at http://www.python.org/peps/pep-0001.html Enjoy, -Barry -------------------- snip snip -------------------- PEP: 1 Title: PEP Purpose and Guidelines Version: $Revision: 1.36 $ Last-Modified: $Date: 2002/07/29 18:34:59 $ Author: Barry A. Warsaw, Jeremy Hylton Status: Active Type: Informational Created: 13-Jun-2000 Post-History: 21-Mar-2001, 29-Jul-2002 What is a PEP? PEP stands for Python Enhancement Proposal. A PEP is a design document providing information to the Python community, or describing a new feature for Python. The PEP should provide a concise technical specification of the feature and a rationale for the feature. We intend PEPs to be the primary mechanisms for proposing new features, for collecting community input on an issue, and for documenting the design decisions that have gone into Python. The PEP author is responsible for building consensus within the community and documenting dissenting opinions. Because the PEPs are maintained as plain text files under CVS control, their revision history is the historical record of the feature proposal[1]. Kinds of PEPs There are two kinds of PEPs. A standards track PEP describes a new feature or implementation for Python. An informational PEP describes a Python design issue, or provides general guidelines or information to the Python community, but does not propose a new feature. Informational PEPs do not necessarily represent a Python community consensus or recommendation, so users and implementors are free to ignore informational PEPs or follow their advice. PEP Work Flow The PEP editor, Barry Warsaw <peps(a)python.org>, assigns numbers for each PEP and changes its status. The PEP process begins with a new idea for Python. It is highly recommended that a single PEP contain a single key proposal or new idea. The more focussed the PEP, the more successfully it tends to be. The PEP editor reserves the right to reject PEP proposals if they appear too unfocussed or too broad. If in doubt, split your PEP into several well-focussed ones. Each PEP must have a champion -- someone who writes the PEP using the style and format described below, shepherds the discussions in the appropriate forums, and attempts to build community consensus around the idea. The PEP champion (a.k.a. Author) should first attempt to ascertain whether the idea is PEP-able. Small enhancements or patches often don't need a PEP and can be injected into the Python development work flow with a patch submission to the SourceForge patch manager[2] or feature request tracker[3]. The PEP champion then emails the PEP editor <peps(a)python.org> with a proposed title and a rough, but fleshed out, draft of the PEP. This draft must be written in PEP style as described below. If the PEP editor approves, he will assign the PEP a number, label it as standards track or informational, give it status 'draft', and create and check-in the initial draft of the PEP. The PEP editor will not unreasonably deny a PEP. Reasons for denying PEP status include duplication of effort, being technically unsound, not providing proper motivation or addressing backwards compatibility, or not in keeping with the Python philosophy. The BDFL (Benevolent Dictator for Life, Guido van Rossum) can be consulted during the approval phase, and is the final arbitrator of the draft's PEP-ability. If a pre-PEP is rejected, the author may elect to take the pre-PEP to the comp.lang.python newsgroup (a.k.a. python-list(a)python.org mailing list) to help flesh it out, gain feedback and consensus from the community at large, and improve the PEP for re-submission. The author of the PEP is then responsible for posting the PEP to the community forums, and marshaling community support for it. As updates are necessary, the PEP author can check in new versions if they have CVS commit permissions, or can email new PEP versions to the PEP editor for committing. Standards track PEPs consists of two parts, a design document and a reference implementation. The PEP should be reviewed and accepted before a reference implementation is begun, unless a reference implementation will aid people in studying the PEP. Standards Track PEPs must include an implementation - in the form of code, patch, or URL to same - before it can be considered Final. PEP authors are responsible for collecting community feedback on a PEP before submitting it for review. A PEP that has not been discussed on python-list(a)python.org and/or python-dev(a)python.org will not be accepted. However, wherever possible, long open-ended discussions on public mailing lists should be avoided. Strategies to keep the discussions efficient include, setting up a separate SIG mailing list for the topic, having the PEP author accept private comments in the early design phases, etc. PEP authors should use their discretion here. Once the authors have completed a PEP, they must inform the PEP editor that it is ready for review. PEPs are reviewed by the BDFL and his chosen consultants, who may accept or reject a PEP or send it back to the author(s) for revision. Once a PEP has been accepted, the reference implementation must be completed. When the reference implementation is complete and accepted by the BDFL, the status will be changed to `Final.' A PEP can also be assigned status `Deferred.' The PEP author or editor can assign the PEP this status when no progress is being made on the PEP. Once a PEP is deferred, the PEP editor can re-assign it to draft status. A PEP can also be `Rejected'. Perhaps after all is said and done it was not a good idea. It is still important to have a record of this fact. PEPs can also be replaced by a different PEP, rendering the original obsolete. This is intended for Informational PEPs, where version 2 of an API can replace version 1. PEP work flow is as follows: Draft -> Accepted -> Final -> Replaced ^ +----> Rejected v Deferred Some informational PEPs may also have a status of `Active' if they are never meant to be completed. E.g. PEP 1. What belongs in a successful PEP? Each PEP should have the following parts: 1. Preamble -- RFC822 style headers containing meta-data about the PEP, including the PEP number, a short descriptive title (limited to a maximum of 44 characters), the names, and optionally the contact info for each author, etc. 2. Abstract -- a short (~200 word) description of the technical issue being addressed. 3. Copyright/public domain -- Each PEP must either be explicitly labelled as placed in the public domain (see this PEP as an example) or licensed under the Open Publication License[4]. 4. Specification -- The technical specification should describe the syntax and semantics of any new language feature. The specification should be detailed enough to allow competing, interoperable implementations for any of the current Python platforms (CPython, JPython, Python .NET). 5. Motivation -- The motivation is critical for PEPs that want to change the Python language. It should clearly explain why the existing language specification is inadequate to address the problem that the PEP solves. PEP submissions without sufficient motivation may be rejected outright. 6. Rationale -- The rationale fleshes out the specification by describing what motivated the design and why particular design decisions were made. It should describe alternate designs that were considered and related work, e.g. how the feature is supported in other languages. The rationale should provide evidence of consensus within the community and discuss important objections or concerns raised during discussion. 7. Backwards Compatibility -- All PEPs that introduce backwards incompatibilities must include a section describing these incompatibilities and their severity. The PEP must explain how the author proposes to deal with these incompatibilities. PEP submissions without a sufficient backwards compatibility treatise may be rejected outright. 8. Reference Implementation -- The reference implementation must be completed before any PEP is given status 'Final,' but it need not be completed before the PEP is accepted. It is better to finish the specification and rationale first and reach consensus on it before writing code. The final implementation must include test code and documentation appropriate for either the Python language reference or the standard library reference. PEP Template PEPs are written in plain ASCII text, and should adhere to a rigid style. There is a Python script that parses this style and converts the plain text PEP to HTML for viewing on the web[5]. PEP 9 contains a boilerplate[7] template you can use to get started writing your PEP. Each PEP must begin with an RFC822 style header preamble. The headers must appear in the following order. Headers marked with `*' are optional and are described below. All other headers are required. PEP: <pep number> Title: <pep title> Version: <cvs version string> Last-Modified: <cvs date string> Author: <list of authors' real names and optionally, email addrs> * Discussions-To: <email address> Status: <Draft | Active | Accepted | Deferred | Final | Replaced> Type: <Informational | Standards Track> * Requires: <pep numbers> Created: <date created on, in dd-mmm-yyyy format> * Python-Version: <version number> Post-History: <dates of postings to python-list and python-dev> * Replaces: <pep number> * Replaced-By: <pep number> The Author: header lists the names and optionally, the email addresses of all the authors/owners of the PEP. The format of the author entry should be address(a)dom.ain (Random J. User) if the email address is included, and just Random J. User if the address is not given. If there are multiple authors, each should be on a separate line following RFC 822 continuation line conventions. Note that personal email addresses in PEPs will be obscured as a defense against spam harvesters. Standards track PEPs must have a Python-Version: header which indicates the version of Python that the feature will be released with. Informational PEPs do not need a Python-Version: header. While a PEP is in private discussions (usually during the initial Draft phase), a Discussions-To: header will indicate the mailing list or URL where the PEP is being discussed. No Discussions-To: header is necessary if the PEP is being discussed privately with the author, or on the python-list or python-dev email mailing lists. Note that email addresses in the Discussions-To: header will not be obscured. Created: records the date that the PEP was assigned a number, while Post-History: is used to record the dates of when new versions of the PEP are posted to python-list and/or python-dev. Both headers should be in dd-mmm-yyyy format, e.g. 14-Aug-2001. PEPs may have a Requires: header, indicating the PEP numbers that this PEP depends on. PEPs may also have a Replaced-By: header indicating that a PEP has been rendered obsolete by a later document; the value is the number of the PEP that replaces the current document. The newer PEP must have a Replaces: header containing the number of the PEP that it rendered obsolete. PEP Formatting Requirements PEP headings must begin in column zero and the initial letter of each word must be capitalized as in book titles. Acronyms should be in all capitals. The body of each section must be indented 4 spaces. Code samples inside body sections should be indented a further 4 spaces, and other indentation can be used as required to make the text readable. You must use two blank lines between the last line of a section's body and the next section heading. You must adhere to the Emacs convention of adding two spaces at the end of every sentence. You should fill your paragraphs to column 70, but under no circumstances should your lines extend past column 79. If your code samples spill over column 79, you should rewrite them. Tab characters must never appear in the document at all. A PEP should include the standard Emacs stanza included by example at the bottom of this PEP. A PEP must contain a Copyright section, and it is strongly recommended to put the PEP in the public domain. When referencing an external web page in the body of a PEP, you should include the title of the page in the text, with a footnote reference to the URL. Do not include the URL in the body text of the PEP. E.g. Refer to the Python Language web site [1] for more details. ... [1] http://www.python.org When referring to another PEP, include the PEP number in the body text, such as "PEP 1". The title may optionally appear. Add a footnote reference that includes the PEP's title and author. It may optionally include the explicit URL on a separate line, but only in the References section. Note that the pep2html.py script will calculate URLs automatically, e.g.: ... Refer to PEP 1 [7] for more information about PEP style ... References [7] PEP 1, PEP Purpose and Guidelines, Warsaw, Hylton http://www.python.org/peps/pep-0001.html If you decide to provide an explicit URL for a PEP, please use this as the URL template: http://www.python.org/peps/pep-xxxx.html PEP numbers in URLs must be padded with zeros from the left, so as to be exactly 4 characters wide, however PEP numbers in text are never padded. Reporting PEP Bugs, or Submitting PEP Updates How you report a bug, or submit a PEP update depends on several factors, such as the maturity of the PEP, the preferences of the PEP author, and the nature of your comments. For the early draft stages of the PEP, it's probably best to send your comments and changes directly to the PEP author. For more mature, or finished PEPs you may want to submit corrections to the SourceForge bug manager[6] or better yet, the SourceForge patch manager[2] so that your changes don't get lost. If the PEP author is a SF developer, assign the bug/patch to him, otherwise assign it to the PEP editor. When in doubt about where to send your changes, please check first with the PEP author and/or PEP editor. PEP authors who are also SF committers, can update the PEPs themselves by using "cvs commit" to commit their changes. Remember to also push the formatted PEP text out to the web by doing the following: % python pep2html.py -i NUM where NUM is the number of the PEP you want to push out. See % python pep2html.py --help for details. Transferring PEP Ownership It occasionally becomes necessary to transfer ownership of PEPs to a new champion. In general, we'd like to retain the original author as a co-author of the transferred PEP, but that's really up to the original author. A good reason to transfer ownership is because the original author no longer has the time or interest in updating it or following through with the PEP process, or has fallen off the face of the 'net (i.e. is unreachable or not responding to email). A bad reason to transfer ownership is because you don't agree with the direction of the PEP. We try to build consensus around a PEP, but if that's not possible, you can always submit a competing PEP. If you are interested assuming ownership of a PEP, send a message asking to take over, addressed to both the original author and the PEP editor <peps(a)python.org>. If the original author doesn't respond to email in a timely manner, the PEP editor will make a unilateral decision (it's not like such decisions can be reversed. :). References and Footnotes [1] This historical record is available by the normal CVS commands for retrieving older revisions. For those without direct access to the CVS tree, you can browse the current and past PEP revisions via the SourceForge web site at http://cvs.sourceforge.net/cgi-bin/cvsweb.cgi/python/nondist/peps/?cvsroot=… [2] http://sourceforge.net/tracker/?group_id=5470&atid=305470 [3] http://sourceforge.net/tracker/?atid=355470&group_id=5470&func=browse [4] http://www.opencontent.org/openpub/ [5] The script referred to here is pep2html.py, which lives in the same directory in the CVS tree as the PEPs themselves. Try "pep2html.py --help" for details. The URL for viewing PEPs on the web is http://www.python.org/peps/ [6] http://sourceforge.net/tracker/?group_id=5470&atid=305470 [7] PEP 9, Sample PEP Template http://www.python.org/peps/pep-0009.html Copyright This document has been placed in the public domain. Local Variables: mode: indented-text indent-tabs-mode: nil sentence-end-double-space: t fill-column: 70 End:

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On the migration from master to main
by Python Steering Council 10 May '21

10 May '21

From Thomas Wouters, on behalf of and with full support of the Python Steering Council: This discussion seems to have died down a little, but I still want to make a few things clear: Yes, this is a political decision. Very many decisions are political. The existence of an open-source project is inherently political. The decision to try and make python-dev more welcoming, more open, more helpful is also a political decision -- one that the SC feels is absolutely necessary for the long-term health of the Python language. Not wanting to be bothered by political decisions is a political decision; it’s a decision that you’re happy with politics as they are. I’m afraid you can’t avoid politics. This isn’t just about ‘master’ being rooted in slavery. This is about what the community sees and does. As I mentioned before, we’re not leading the pack in this, we’re merely following along with others (like, say, Django). There are undoubtedly other terms and practices that are genuinely offensive, and the decision on how to handle them will be taken on a case-by-case basis, weighing the cost and the benefit in each case. While you may feel the benefit of this change is small and that it has no real impact, we believe that there is little cost to making this change. We believe this change, while a minor inconvenience to some, helps demonstrate our commitment to acting in the best interests of Python's future. Failure to make a small sacrifice, such as this, signals that the Python core development community would be unlikely to undertake real change for greater benefits. This isn’t happening because GitHub/Microsoft made a political decision. It’s happening because it is incredibly easy to make this move, many projects have already done this, and it reflects badly on any project not making this change. Speaking for the whole SC in this, Thomas.

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PEP 654: Exception Groups and except* [REPOST]
by Irit Katriel 06 May '21

06 May '21

We would like to present for feedback a new version of PEP 654, which incorporates the feedback we received in the discussions so far: https://www.python.org/dev/peps/pep-0654/ The reference implementation has also been updated along with the PEP. The changes we made since the first post are: 1. Instead of ExceptionGroup(BaseException), we will have two new builtin types: BaseExceptionGroup(BaseException) and ExceptionGroup(BaseExceptionGroup, Exception). This is so that "except Exception" catches ExceptionGroups (but not BaseExceptionGroups). BaseExceptionGroup.__new__ inspects the wrapped exceptions, and if they are all Exception subclasses, it creates an ExceptionGroup instead of a BaseExceptionGroup. 2. The exception group classes are not final - they can be subclassed and split()/subgroup() work correctly if the subclass overrides the derive() instance method as described here: https://www.python.org/dev/peps/pep-0654/#subclassing-exception-groups 3. We had some good suggestions on formatting exception groups, which we have implemented as you can see in the output shown for the examples in the PEP. 4. We expanded the section on handling Exception Groups, to show how subgroup can be used (with side effects) to do something for each leaf exception, and how to iterate correctly when the tracebacks of leaf exceptions are needed: https://www.python.org/dev/peps/pep-0654/#handling-exception-groups 5. We expanded the sections on rationale and backwards compatibility to explain our premise and expectations regarding how exception groups will be used and how the transition to using them will be managed. 6. We added several items to the rejected ideas section. We did not receive any comments (or make any changes) to the proposed semantics of except*, hopefully this is because everyone thought they are sensible. Irit, Yury and Guido

14 45

Anyone else gotten bizarre personal replies to mailing list posts?
by Nathaniel Smith 05 May '21

05 May '21

I just got the reply below sent directly to my personal account, and I'm confused about what's going on. If it's just a one off I'll chalk it up to random internet weirdness, but if other folks are getting these too it might be something the list admins should look into? Or... something? ---------- Forwarded message --------- From: Hoi lam Poon <gillcovid19(a)gmail.com> Date: Fri, Apr 23, 2021, 02:01 Subject: Re: [Python-Dev] Re: PEP 654: Exception Groups and except* [REPOST] To: Nathaniel Smith <njs(a)pobox.com> Stop pretending, I can definitely get the key control file, your working group, all past actions and instructions cannot be cleared in front of me at all. You have been playing around for a few days, and I won’t stop you. Your face? I won’t, you know, you can’t drive me away, and that file is all, after I get it, you will be convicted even if you disband, I swear 在 2021年4月23日週五 16:23，Nathaniel Smith <njs(a)pobox.com> 寫道： > On Wed, Apr 21, 2021 at 4:50 PM Guido van Rossum <guido(a)python.org> wrote: > > On Wed, Apr 21, 2021 at 3:26 PM Nathaniel Smith <njs(a)pobox.com> wrote: > >> Sure. This was in my list of reasons why the backwards compatibility > >> tradeoffs are forcing us into awkward compromises. I only elaborated > >> on it b/c in your last email you said you didn't understand why this > >> was a problem :-). And except* is definitely useful. But I think there > >> are options for 'except' that haven't been considered fully. > > > > Do you have any suggestions, or are you just telling us to think harder? > Because we've already thought as hard as we could and within all the > constraints (backwards compatibility and otherwise) we just couldn't think > of a better one. > > The main possibility that I don't think we've examined fully is to > make 'except' blocks fire multiple times when there are multiple > exceptions. We ruled it out early b/c it's incompatible with nested > EGs, but if flat EGs are better anyway, then the balance shifts around > and it might land somewhere different. it's a tricky discussion > though, b/c both the current proposal and the alternative have very > complex implications and downsides. So we probably shouldn't get too > distracted by that until after the flat vs nested discussion has > settled down more. > > I'm not trying to filibuster here -- I really want some form of EGs to > land. I think python has the potential to be the most elegant and > accessible language around for writing concurrent programs, and EGs > are a key part of that. I don't want to fight about anything; I just > want to work together to make sure we have a full picture of our > options, so we can be confident we're making the best choice. > > > The real cost here is that we would need a new "TracebackGroup" concept, > since the internal data structures and APIs keep the traceback chain and > the exception object separated until the exception is caught. In our early > design stages we actually explored this and the complexity of the data > structures was painful. We eventually realized that we didn't need this > concept at all, and the result is much clearer, despite what you seem to > think. > > I'm not talking about TracebackGroups (at least, I think I'm not?). I > think it can be done with exactly our current data structures, nothing > new. > > - When an EG is raised, build the traceback for just that EG while > it's unwinding. This means if any C code peeks at exc_info while it's > in flight, it'll only see the current branch of the traceback tree, > but that seems fine. > - When the exception is caught and we go to write back the traceback > to its __traceback__ attribute, instead "peek through" the EG and > append the built-up traceback entries onto each of the constituent > exceptions. > > You could get cleverer for efficiency, but that basic concept seems > pretty simple and viable to me. What am I missing? > > -n > > -- > Nathaniel J. Smith -- https://vorpus.org > _______________________________________________ > Python-Dev mailing list -- python-dev(a)python.org > To unsubscribe send an email to python-dev-leave(a)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/VOBOWZG… > Code of Conduct: http://python.org/psf/codeofconduct/ >

10 9

Existing asyncio features scheduled for removal in Python 3.9 and 3.10
by Illia Volochii 03 May '21

03 May '21

Hi everyone, There are a couple of uncompleted asyncio feature removals scheduled for 3.9 and 3.10 releases. It will be great if we either complete them or reschedule before the 3.10 feature freeze. There are two stale pull requests related to this. Removal of @asyncio.coroutine in version 3.10 deprecated since version 3.8 Documentation: https://docs.python.org/3.10/library/asyncio-task.html#asyncio.coroutine Issue deprecating the decorator: https://bugs.python.org/issue36921 Issue for the removal: https://bugs.python.org/issue43216 There is no pull request yet, mainly because of an unclarified question regarding types.coroutine in 36921. Prohibiting non-ThreadPoolExecutor in loop.set_default_executor Warning scheduling the prohibiting in version 3.9: https://github.com/python/cpython/blob/425434dadc30d96dc1c0c628f954f9b6f5ed… Issue: https://bugs.python.org/issue43234 Stale pull request: https://github.com/python/cpython/pull/24540 Prohibiting previously deprecated operations on asyncio.trsock.TransportSocket Warning scheduling the prohibiting in version 3.9: https://github.com/python/cpython/blob/425434dadc30d96dc1c0c628f954f9b6f5ed… Issue: https://bugs.python.org/issue43232 Stale pull request: https://github.com/python/cpython/pull/24538 Thanks, Illia

5 6

In what tense should the changelog be written?
by Larry Hastings 01 May '21

01 May '21

When one writes one's "blurb" for the changelog, in what tense should it be? I mostly see entries in present tense: bpo-43660: Fix crash that happens when replacing sys.stderr with a callable that can remove the object while an exception is being printed. Patch by Pablo Galindo. bpo-41561: Add workaround for Ubuntu’s custom OpenSSL security level policy. But occasionally I see entries in past tense: bpo-26053: Fixed bug where the pdb interactive run command echoed the args from the shell command line, even if those have been overridden at the pdb prompt. bpo-40630: Added tracemalloc.reset_peak() to set the peak size of traced memory blocks to the current size, to measure the peak of specific pieces of code. I couldn't find any guidance in the Python Dev Guide after sixty seconds of poking around. Obviously this isn't a big deal. But it might be nice to try and nudge everybody in the same direction. It'd be pleasant if the changelog read in a more unified voice, and using the same tense and sentence structure would help towards that goal. If we arrived at a firm decision, maybe "blurb" et al could add a little text suggesting the proper style. Cheers, //arry/

14 19

Summary of Python tracker Issues
by Python tracker 30 Apr '21

30 Apr '21

ACTIVITY SUMMARY (2021-04-23 - 2021-04-30) 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 7453 (-21) closed 48273 (+86) total 55726 (+65) Open issues with patches: 2968 Issues opened (48) ================== #42737: PEP 563: drop annotations for complex assign targets https://bugs.python.org/issue42737 reopened by BTaskaya #43926: Clean metadata (importlib_metadata 4.0) https://bugs.python.org/issue43926 opened by jaraco #43927: Remove IOError references from the tutorial https://bugs.python.org/issue43927 opened by hugetim #43928: Fix the typo in documentation https://bugs.python.org/issue43928 opened by jeffreytse #43930: Update bundled pip to 21.1 and setuptools to 56.0.0 https://bugs.python.org/issue43930 opened by sbidoul #43931: Add the Python version to the API data. https://bugs.python.org/issue43931 opened by Gabriele Tornetta #43935: Fix typo in Turtle.back docstring https://bugs.python.org/issue43935 opened by tarjeiba #43936: os.path.realpath() normalizes paths before resolving links on https://bugs.python.org/issue43936 opened by barneygale #43937: Turtle uses the default root window https://bugs.python.org/issue43937 opened by serhiy.storchaka #43939: Deadlock in logging https://bugs.python.org/issue43939 opened by DaRoee #43941: Unit test failure in test_gdb only with -O0 https://bugs.python.org/issue43941 opened by larry #43942: RawDescriptionHelpFormatter seems to be ignored for argument d https://bugs.python.org/issue43942 opened by rrt #43943: test_ssl fails in the macos CI https://bugs.python.org/issue43943 opened by pablogsal #43944: Processes in Python 3.9 exiting with code 1 when It's created https://bugs.python.org/issue43944 opened by Genarito #43945: [Enum] standardize format() behavior https://bugs.python.org/issue43945 opened by ethan.furman #43946: unpickling a subclass of list fails when it implements its own https://bugs.python.org/issue43946 opened by gregory.p.smith #43948: sysconfig��s osx_framework_user puts headers in different loc https://bugs.python.org/issue43948 opened by uranusjr #43949: binascii.Error raised in smtplib when initial_response_ok=Fals https://bugs.python.org/issue43949 opened by junpengruan #43950: Include column offsets for bytecode instructions https://bugs.python.org/issue43950 opened by pablogsal #43952: Multiprocessing UNIX socket connection: client freeze if authk https://bugs.python.org/issue43952 opened by anon01 #43953: InitVar should not be available on a @dataclass-decorated clas https://bugs.python.org/issue43953 opened by superbobry #43956: C-API: Incorrect default value for Py_SetProgramName https://bugs.python.org/issue43956 opened by joukewitteveen #43957: [Enum] update __contains__ to return True for valid values https://bugs.python.org/issue43957 opened by ethan.furman #43962: test_interpreters: when TestInterpreterAttrs.test_id_type() is https://bugs.python.org/issue43962 opened by vstinner #43964: ctypes CDLL search path issue on MacOS https://bugs.python.org/issue43964 opened by Victor.Lazzarini #43965: dataclasses.replace breaks when __init__ is overrriden in subc https://bugs.python.org/issue43965 opened by SebastianSpeitel #43967: Valgrind memcheck on Py_Initialize https://bugs.python.org/issue43967 opened by simonaldrich #43968: os.path.realpath() unexpected breaking change: resolves subst' https://bugs.python.org/issue43968 opened by sfmc #43969: "bad magic number" when Python 2's pyc file exists without py https://bugs.python.org/issue43969 opened by mitchhentges #43971: documentation: no spacing around default args in annotated fun https://bugs.python.org/issue43971 opened by moselhy #43972: Simple HTTP Request Handler in http.server does not set a cont https://bugs.python.org/issue43972 opened by sirosen #43974: setup.py should set Py_BUILD_CORE_MODULE as defined macro https://bugs.python.org/issue43974 opened by christian.heimes #43975: Incorrect MIME type returned for .js files Windows 10. https://bugs.python.org/issue43975 opened by smeans #43976: Introduce mechanism to allow Python distributors to add custom https://bugs.python.org/issue43976 opened by FFY00 #43977: Implement the latest semantics for PEP 634 for matching collec https://bugs.python.org/issue43977 opened by Mark.Shannon #43978: Incorrect "versionadded" info in typing.NoReturn documentation https://bugs.python.org/issue43978 opened by Mariatta #43979: Simplify urllib.parse_qsl https://bugs.python.org/issue43979 opened by cito #43980: netrc module looks for .netrc even on Windows where the conven https://bugs.python.org/issue43980 opened by jheiselman #43981: test_idle is leaking references https://bugs.python.org/issue43981 opened by pablogsal #43982: Code coverage on the CI: validate codecov shell script checksu https://bugs.python.org/issue43982 opened by vstinner #43983: Can't install Python v3.9.4 / 0x80070643 / windows 10 64bit https://bugs.python.org/issue43983 opened by Marwan #43984: winreg.SetValueEx should check the returned value https://bugs.python.org/issue43984 opened by r3pwnx #43985: lib2to3 fails on a slash('/') after positional_only paramter i https://bugs.python.org/issue43985 opened by cloud-yu #43986: ipaddress: increment/decrement on IPv*Interface disregards bit https://bugs.python.org/issue43986 opened by katsel #43987: Add "Annotations Best Practices" to HOWTO https://bugs.python.org/issue43987 opened by larry #43988: Add test.support.assert_dissallow_instantiation https://bugs.python.org/issue43988 opened by erlendaasland #43989: Enum deprecation breaks SSL tests https://bugs.python.org/issue43989 opened by christian.heimes #43990: In documentation Section 6.17, Operator precedence, footnotes https://bugs.python.org/issue43990 opened by webbnh Most recent 15 issues with no replies (15) ========================================== #43990: In documentation Section 6.17, Operator precedence, footnotes https://bugs.python.org/issue43990 #43989: Enum deprecation breaks SSL tests https://bugs.python.org/issue43989 #43988: Add test.support.assert_dissallow_instantiation https://bugs.python.org/issue43988 #43987: Add "Annotations Best Practices" to HOWTO https://bugs.python.org/issue43987 #43986: ipaddress: increment/decrement on IPv*Interface disregards bit https://bugs.python.org/issue43986 #43983: Can't install Python v3.9.4 / 0x80070643 / windows 10 64bit https://bugs.python.org/issue43983 #43975: Incorrect MIME type returned for .js files Windows 10. https://bugs.python.org/issue43975 #43972: Simple HTTP Request Handler in http.server does not set a cont https://bugs.python.org/issue43972 #43971: documentation: no spacing around default args in annotated fun https://bugs.python.org/issue43971 #43967: Valgrind memcheck on Py_Initialize https://bugs.python.org/issue43967 #43964: ctypes CDLL search path issue on MacOS https://bugs.python.org/issue43964 #43956: C-API: Incorrect default value for Py_SetProgramName https://bugs.python.org/issue43956 #43952: Multiprocessing UNIX socket connection: client freeze if authk https://bugs.python.org/issue43952 #43949: binascii.Error raised in smtplib when initial_response_ok=Fals https://bugs.python.org/issue43949 #43948: sysconfig��s osx_framework_user puts headers in different loc https://bugs.python.org/issue43948 Most recent 15 issues waiting for review (15) ============================================= #43988: Add test.support.assert_dissallow_instantiation https://bugs.python.org/issue43988 #43987: Add "Annotations Best Practices" to HOWTO https://bugs.python.org/issue43987 #43981: test_idle is leaking references https://bugs.python.org/issue43981 #43980: netrc module looks for .netrc even on Windows where the conven https://bugs.python.org/issue43980 #43979: Simplify urllib.parse_qsl https://bugs.python.org/issue43979 #43977: Implement the latest semantics for PEP 634 for matching collec https://bugs.python.org/issue43977 #43974: setup.py should set Py_BUILD_CORE_MODULE as defined macro https://bugs.python.org/issue43974 #43972: Simple HTTP Request Handler in http.server does not set a cont https://bugs.python.org/issue43972 #43971: documentation: no spacing around default args in annotated fun https://bugs.python.org/issue43971 #43969: "bad magic number" when Python 2's pyc file exists without py https://bugs.python.org/issue43969 #43962: test_interpreters: when TestInterpreterAttrs.test_id_type() is https://bugs.python.org/issue43962 #43957: [Enum] update __contains__ to return True for valid values https://bugs.python.org/issue43957 #43945: [Enum] standardize format() behavior https://bugs.python.org/issue43945 #43937: Turtle uses the default root window https://bugs.python.org/issue43937 #43935: Fix typo in Turtle.back docstring https://bugs.python.org/issue43935 Top 10 most discussed issues (10) ================================= #43908: array.array should remain immutable: add Py_TPFLAGS_IMMUTABLET https://bugs.python.org/issue43908 87 msgs #43916: Mark static types newly converted to heap types as immutable: https://bugs.python.org/issue43916 45 msgs #37387: test_compileall fails randomly on Windows when tests are run i https://bugs.python.org/issue37387 13 msgs #14243: tempfile.NamedTemporaryFile not particularly useful on Windows https://bugs.python.org/issue14243 10 msgs #42725: PEP 563: Should the behavior change for yield/yield from's https://bugs.python.org/issue42725 9 msgs #43981: test_idle is leaking references https://bugs.python.org/issue43981 8 msgs #43651: PEP 597: Fix EncodingWarning warnings in the Python stdlib https://bugs.python.org/issue43651 7 msgs #42998: pathlib.Path: add `username` argument to `home()` https://bugs.python.org/issue42998 6 msgs #43851: Optimise SQLite builds on macOS and Windows https://bugs.python.org/issue43851 6 msgs #41282: Deprecate and remove distutils https://bugs.python.org/issue41282 5 msgs Issues closed (76) ================== #3849: FUD in documentation for urllib.urlopen() https://bugs.python.org/issue3849 closed by iritkatriel #4130: Intel icc 9.1 does not support __int128_t used by ctypes https://bugs.python.org/issue4130 closed by iritkatriel #7405: compiling python 3.1.1 using cygwin 1.7.0 and gcc 4.3.4 https://bugs.python.org/issue7405 closed by iritkatriel #10599: sgmllib.parse_endtag() is not respecting quoted text https://bugs.python.org/issue10599 closed by iritkatriel #11100: test_fdopen: close failed in file object destructor https://bugs.python.org/issue11100 closed by iritkatriel #11975: Fix referencing of built-in types (list, int, ...) https://bugs.python.org/issue11975 closed by rhettinger #12966: cookielib.LWPCookieJar breaks on cookie values with a newline https://bugs.python.org/issue12966 closed by orsenthil #14810: tarfile does not support timestamp older 1970-01-01 https://bugs.python.org/issue14810 closed by iritkatriel #16062: Socket closed prematurely in httplib for https https://bugs.python.org/issue16062 closed by iritkatriel #18125: Out-of-tree build cannot regenerate Makefile.pre https://bugs.python.org/issue18125 closed by iritkatriel #19348: Building _testcapimodule as a builtin results in compile error https://bugs.python.org/issue19348 closed by iritkatriel #20290: inspect module bug for modules with same filename https://bugs.python.org/issue20290 closed by iritkatriel #22972: Timeout making ajax calls to SimpleHTTPServer from internet ex https://bugs.python.org/issue22972 closed by iritkatriel #23336: Thread.LockType is misnamed https://bugs.python.org/issue23336 closed by iritkatriel #24026: Python hangs forever in wait() of threading.py https://bugs.python.org/issue24026 closed by iritkatriel #25817: modsupport: 'countformat' does not handle strings without brac https://bugs.python.org/issue25817 closed by iritkatriel #26215: Make GC_Head a compile-time option https://bugs.python.org/issue26215 closed by vstinner #26629: Need an ability to build standard DLLs with distutils https://bugs.python.org/issue26629 closed by iritkatriel #26810: inconsistent garbage collector behavior across platforms when https://bugs.python.org/issue26810 closed by iritkatriel #27420: Docs for os.link - say what happens if link already exists https://bugs.python.org/issue27420 closed by iritkatriel #28968: xml rpc server fails with connection reset by peer error no 10 https://bugs.python.org/issue28968 closed by iritkatriel #31726: Missing token.COMMENT https://bugs.python.org/issue31726 closed by iritkatriel #31870: add timeout parameter for get_server_certificate in ssl.py https://bugs.python.org/issue31870 closed by christian.heimes #32891: Add 'Integer' as synonym for 'Integral' in numbers module. https://bugs.python.org/issue32891 closed by rhettinger #34463: Discrepancy between traceback.print_exception and sys.__except https://bugs.python.org/issue34463 closed by iritkatriel #36077: Inheritance dataclasses fields and default init statement https://bugs.python.org/issue36077 closed by eric.smith #38490: statistics: add covariance, Pearson's correlation, and simple https://bugs.python.org/issue38490 closed by taleinat #39529: Deprecate get_event_loop() https://bugs.python.org/issue39529 closed by serhiy.storchaka #41139: cgi uses the locale encoding for log files https://bugs.python.org/issue41139 closed by methane #41350: Use of zipfile.Path causes attempt to write after ZipFile is c https://bugs.python.org/issue41350 closed by jaraco #41486: Add _BlocksOutputBuffer for bz2/lzma/zlib module https://bugs.python.org/issue41486 closed by gregory.p.smith #41559: Add support for PEP 612 (Parameter Specification Variables) to https://bugs.python.org/issue41559 closed by kj #41639: Unpickling derived class of list does not call __init__() https://bugs.python.org/issue41639 closed by gregory.p.smith #41735: Thread locks in zlib module may go wrong in rare case https://bugs.python.org/issue41735 closed by lukasz.langa #42589: doc: Wrong "from" keyword link in Exceptions doc https://bugs.python.org/issue42589 closed by Mariatta #42739: Crash when try to disassemble bogus code object https://bugs.python.org/issue42739 closed by Mark.Shannon #42924: bytearray_repeat copies from ob_bytes instead of ob_start https://bugs.python.org/issue42924 closed by lukasz.langa #43193: Installer for All users https://bugs.python.org/issue43193 closed by xmha97 #43312: Interface to select preferred "user" or "home" sysconfig schem https://bugs.python.org/issue43312 closed by ncoghlan #43492: Upgrade to SQLite 3.35.5 in macOS and Windows https://bugs.python.org/issue43492 closed by steve.dower #43534: turtle.textinput window is not transient https://bugs.python.org/issue43534 closed by serhiy.storchaka #43649: time.strftime('%z') doesn't return UTC offset in the form ��HH https://bugs.python.org/issue43649 closed by steve.dower #43652: Upgrade Windows tcl/tk to 8.6.11 https://bugs.python.org/issue43652 closed by steve.dower #43655: Tkinter: make X window & macOS recognize dialogs as such https://bugs.python.org/issue43655 closed by serhiy.storchaka #43664: Compiling long expression leads to segfault (again) https://bugs.python.org/issue43664 closed by serhiy.storchaka #43757: pathlib: move 'resolve()' logic out of path flavour https://bugs.python.org/issue43757 closed by steve.dower #43762: Add audit events for loading of sqlite3 extensions https://bugs.python.org/issue43762 closed by steve.dower #43766: Implement PEP 647 (User-Defined Type Guards) in typing.py https://bugs.python.org/issue43766 closed by kj #43780: Sync importlib_metadata enhancements through 3.10. https://bugs.python.org/issue43780 closed by jaraco #43817: Add inspect.get_annotations() https://bugs.python.org/issue43817 closed by larry #43864: [Windows] test_importlib logs: DeprecationWarning: WindowsRegi https://bugs.python.org/issue43864 closed by brett.cannon #43868: Remove PyOS_ReadlineFunctionPointer from the stable ABI list https://bugs.python.org/issue43868 closed by vstinner #43889: Pickle performance regression in 3.10 https://bugs.python.org/issue43889 closed by kj #43892: Make match patterns explicit in the AST https://bugs.python.org/issue43892 closed by ncoghlan #43901: Lazy-create an empty annotations dict in all unannotated user https://bugs.python.org/issue43901 closed by larry #43907: pickle.py bytearray memoization bug with protocol 5 https://bugs.python.org/issue43907 closed by pitrou #43922: Double dots in quopri transported emails https://bugs.python.org/issue43922 closed by Julien Castiaux #43924: print unexpected values in infinite loop https://bugs.python.org/issue43924 closed by steven.daprano #43929: Raise on threading.Event.__bool__ due to ambiguous nature https://bugs.python.org/issue43929 closed by rhettinger #43932: f-string decimal has leading space https://bugs.python.org/issue43932 closed by mark.dickinson #43933: Regression in python3.10 with traceback frame having lineno of https://bugs.python.org/issue43933 closed by Mark.Shannon #43934: Minimal version of SQLite3 - 3.26 ? https://bugs.python.org/issue43934 closed by matrixise #43938: Document that dataclasses.FrozenInstanceError derives from Att https://bugs.python.org/issue43938 closed by eric.smith #43940: int casting to float results to a different value in memory https://bugs.python.org/issue43940 closed by mark.dickinson #43947: lambdas stored with assignment expressions are unoptimized https://bugs.python.org/issue43947 closed by serhiy.storchaka #43951: Two minor fixes for C module object https://bugs.python.org/issue43951 closed by larry #43954: Possible missing word on unittest doc https://bugs.python.org/issue43954 closed by mdk #43955: Windows: Running the Python test suite sequentially is interru https://bugs.python.org/issue43955 closed by vstinner #43958: Importlib.metadata docs claim PackagePath is a Path subclass https://bugs.python.org/issue43958 closed by jaraco #43959: Improve documentation of PyContextVar C-API https://bugs.python.org/issue43959 closed by scoder #43960: test_pdb fails when only some tests are run https://bugs.python.org/issue43960 closed by vstinner #43961: [Windows] test_logging.test_namer_rotator_inheritance() logs a https://bugs.python.org/issue43961 closed by vstinner #43963: test_interpreters has side effects on test_signal https://bugs.python.org/issue43963 closed by vstinner #43966: F String bugs with numpy.float32 https://bugs.python.org/issue43966 closed by mark.dickinson #43970: Optimize Path.cwd() in pathlib https://bugs.python.org/issue43970 closed by eric.smith #43973: Use Py_TPFLAGS_IMMUTABLETYPE in __class__ assignments check https://bugs.python.org/issue43973 closed by erlendaasland

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SC feedback: PEP 648 -- Extensible customizations of the interpreter at startup
by Barry Warsaw 30 Apr '21

30 Apr '21

Hello Mario, Thank you for your submission of PEP 648 (Extensible customizations of the interpreter at startup). The Python Steering Council has reviewed the PEP and before we can pronounce on it, we have some additional questions and comments we’d like you to address. Once these questions are settled, we are requesting that you post the PEP to python-dev for another round of comments. In general, the SC is in favor of deprecating the executable hack capabilities of pth files, and this PEP is currently the most concrete proposal to get there. We would like to eventually go farther, including deprecation of pth files entirely, but that is outside the scope of this PEP. General PEP feedback The introduction of the section titled “Benefits of __sitecustomize__” seems out of place. It forward references the solution without explanation. It also says “The use of a __sitecustomize__ will allow…”; the question is, a __sitecustomize__ what? Directory? File? Perhaps it should be moved to later in the PEP after the semantics of __sitecustomize__ is defined? Some of the terminology used in the PEP could be clarified. For example, I suggest using the term “directory” instead of “folder” throughout the PEP, and use the term “module” or “file” instead of “script” to describe the things inside __sitecustomize__ directories that Python imports, since “scripts” typically describe standalone files that implement applications. For example, must the files be named with .py extension (or presumably .pyc, .pyo) under the normal Python module import rules? (Later in the PEP you do allude to the requirement that the file name must end in .py, but it would be much better to explain this right up front, in a formal specification.) Another ambiguity is what the PEP means by “executing” said “scripts”. Does that mean importing them? Reading them then exec()’ing them? Something else? This section should be clear that Python will import the modules it found, if that’s indeed what the PEP is proposing. The “Backward compatibility” section has this incomplete sentence: “Ignoring those lines in pth files.” There’s this odd grammar in the “Do nothing” section: “After analysing the impact of this change, we believe it is worth given the enhanced experience it brings.” Perhaps it should read “...it is worth it, given the…”? Definition of “site path” The PEP should precisely define what it means when it says “...a folder named __sitecustomize__ located in any site path”. What exactly is a “site path”? Is this any directory on sys.path? Is it a directory named site-packages? This phrase is also ambiguous: “As the folder will be within sys.path, given that it is located in site paths...”. “sys.path” isn’t a thing that can hold a folder, since it’s just a list of strings, and it also can get extended by any number of means, e.g. by setting the PYTHONPATH environment variable at interpreter startup time. So for example, how does PYTHONPATH affect the algorithm? What is the rationale for adding multiple __sitecustomize__ directories, rather than a single directory (or possibly two, one in Python’s system location and one in the user location)? This would simplify the discovery process, and tools like pip can warn the user if a name collision were to occur. I think the PEP needs to be much more crisp and precise in defining the when and how __sitecustomize__ directories are discovered at start up time. Order of Execution I think this section should outline the entire startup execution order. Exactly when do pth files still get evaluated in relationship to __sitecustomize__ discovery? How do pth file sys.path extensions affect the search for __sitecustomize__ directories? This section also says files in __sitecustomize__ will be executed in “file name sorted order”, but the PEP is unclear whether all such files found in every __sitecustomize__ directory will be sorted together, or only within a single __sitecustomize__ directory. Presumably file system encodings are used to determine file name sort order, but I think the PEP should be explicit about this. I’d like to see the execution order for the entire proposed new Python startup sequence as a recipe, or perhaps even some Python pseudo-code. Impact on startup time We still think that startup performance can be a concern. This section needs more data. For example, while the executable part of pth files is being deprecated, both pth and __sitecustomize__ modules will exist. How does this affect startup time in a world where both have to be discovered and processed? The PEP says: “If the user has custom scripts, we think that the impact on the performance of walking each of the folders is acceptable, as the user wants to use this feature.” Does the user really want to use this feature? Won’t it more likely be the system administrator or Python distribution and packaging ecosystem that chooses to use the __sitecustomize__ feature? Maybe the user won’t even know that it’s being used by the packages being installed? The PEP says: ““Running "./python -c pass" with perf on 50 iterations, repeating 50 times the command on each and getting the geometric mean on a commodity laptop did not reveal any substantial raise on CPU time.” We request more information on the experiments performed, and specific numbers so that the startup impact can be reproduced and confirmed by others. E.g. did you run this experiment on a branch of CPython 3.10 with the PEP 648 reference implementation? Did you convert existing uses of executable pth files to __sitecustomize__ modules? How many such modules did you try it with? How many __sitecustomize__ directories were in your tests? Other questions and issues How does this feature interact with virtual environments? What do packaging tools have to do to support this PEP? The PEP mentions setuptools, but what about other packaging tools in common use? The PEP says “This impact will be reduced in the future as we will remove two other imports: "sitecustomize.py" and "usercustomize.py”.” Why not explicitly deprecate these and executable pth files in PEP 648 and begin the countdown at the same time __sitecustomize__ is added to Python? The PEP says: “To facilitate debugging of the Python startup, a new option will be added to the main of the site module to list all scripts that will be executed as part of the __sitecustomize__ initialization.” The PEP should be explicit about what command line switch is being proposed. We think this should probably be an -X option. Do you have any concerns that this feature will be overused? Does separating the execution feature from the path extension feature make it more or less likely to be used by third party library authors? Will the runtime have any access to the list of __sitecustomize__ modules being executed? I.e. will you collect their paths in a new sys module attribute? Will there be any functions to import or list __sitecustomize__ directories or modules after start has completed? We think io.open_code() should be used so that reading the files can be audited. Conclusion The Python Steering Council again wants to thank you for your PEP contribution! We hope you find this feedback constructive and helpful. We look forward to your responses, and an updated PEP. Cheers, -Barry (on behalf of the Python Steering Council)

5 8

stdlib Flag Enums and the "no value" member
by Ethan Furman 30 Apr '21

30 Apr '21

An excerpt from bpo-31369: re.RegexFlag and `__all__` GvR: ---- > One thing I discovered when developing this example: there doesn't seem to be a flag to > represent 0 (zero), i.e. "no flags". And foo(0) is a type error (even though it works > fine at runtime). Which raises the question: Do we want to have a standard name for stdlib Flags when no flags are set? What should we call it? - NONE - ZERO - EMPTY - ??? -- ~Ethan~

5 8

PEP 652: Python 3.10 will have explicit Limited C API & Stable ABI
by Petr Viktorin 29 Apr '21

29 Apr '21

Hello, I've merged the main part of PEP-652 implementation. The Limited C API (introduced in PEP 384 and used for extension modules that work across Python versions without recompilation) is now explicitly defined and better tested. When changing/extending the limited API: - Stop and think! This API will need to be suppported forever (or until Python 3 reaches end of life, if that comes sooner). A checklist of what to think about is being added to the devguide [0]. - Add/change an entry in `Misc/stable_abi.txt`. - Run `make regen-limited-abi` [sic]. You can run related checks with `make check-limited-abi`. If that or the "Check if generated files are up to date" CI test gives you errors, please let me know! More tests & docs are coming up. [0]: https://cpython-devguide--682.org.readthedocs.build/c-api/

1 0