Mailman 3 January 2020 - Python-Dev

Mixed Python/C debugging
by Skip Montanaro April 26, 2023

April 26, 2023

Having tried comp.lang.python with no response, I turn here... After at least ten years away from Python's run-time interpreter & byte code compiler, I'm getting set to familiarize myself with that again. This will, I think, entail debugging a mixed Python/C environment. I'm an Emacs user and am aware that GDB since 7.0 has support for debugging at the Python code level. Is Emacs+GDB my best bet? Are there any Python IDEs which support C-level breakpoints and debugging? Thanks, Skip

5 6

PEP 448 review
by Guido van Rossum March 29, 2023

March 29, 2023

I'm back, I've re-read the PEP, and I've re-read the long thread with "(no subject)". I think Georg Brandl nailed it: """ *I like the "sequence and dict flattening" part of the PEP, mostly because itis consistent and should be easy to understand, but the comprehension syntaxenhancements seem to be bad for readability and "comprehending" what the codedoes.The call syntax part is a mixed bag on the one hand it is nice to be consistent with the extended possibilities in literals (flattening), but on the other hand there would be small but annoying inconsistencies anyways (e.g. the duplicate kwarg case above).* """ Greg Ewing followed up explaining that the inconsistency between dict flattening and call syntax is inherent in the pre-existing different rules for dicts vs. keyword args: {'a':1, 'a':2} results in {'a':2}, while f(a=1, a=2) is an error. (This form is a SyntaxError; the dynamic case f(a=1, **{'a': 1}) is a TypeError.) For me, allowing f(*a, *b) and f(**d, **e) and all the other combinations for function calls proposed by the PEP is an easy +1 -- it's a straightforward extension of the existing pattern, and anybody who knows what f(x, *a) does will understand f(x, *a, y, *b). Guessing what f(**d, **e) means shouldn't be hard either. Understanding the edge case for duplicate keys with f(**d, **e) is a little harder, but the error messages are pretty clear, and it is not a new edge case. The sequence and dict flattening syntax proposals are also clean and logical -- we already have *-unpacking on the receiving side, so allowing *x in tuple expressions reads pretty naturally (and the similarity with *a in argument lists certainly helps). From here, having [a, *x, b, *y] is also natural, and then the extension to other displays is natural: {a, *x, b, *y} and {a:1, **d, b:2, **e}. This, too, gets a +1 from me. So that leaves comprehensions. IIRC, during the development of the patch we realized that f(*x for x in xs) is sufficiently ambiguous that we decided to disallow it -- note that f(x for x in xs) is already somewhat of a special case because an argument can only be a "bare" generator expression if it is the only argument. The same reasoning doesn't apply (in that form) to list, set and dict comprehensions -- while f(x for x in xs) is identical in meaning to f((x for x in xs)), [x for x in xs] is NOT the same as [(x for x in xs)] (that's a list of one element, and the element is a generator expression). The basic premise of this part of the proposal is that if you have a few iterables, the new proposal (without comprehensions) lets you create a list or generator expression that iterates over all of them, essentially flattening them: >>> xs = [1, 2, 3] >>> ys = ['abc', 'def'] >>> zs = [99] >>> [*xs, *ys, *zs] [1, 2, 3, 'abc', 'def', 99] >>> But now suppose you have a list of iterables: >>> xss = [[1, 2, 3], ['abc', 'def'], [99]] >>> [*xss[0], *xss[1], *xss[2]] [1, 2, 3, 'abc', 'def', 99] >>> Wouldn't it be nice if you could write the latter using a comprehension? >>> xss = [[1, 2, 3], ['abc', 'def'], [99]] >>> [*xs for xs in xss] [1, 2, 3, 'abc', 'def', 99] >>> This is somewhat seductive, and the following is even nicer: the *xs position may be an expression, e.g.: >>> xss = [[1, 2, 3], ['abc', 'def'], [99]] >>> [*xs[:2] for xs in xss] [1, 2, 'abc', 'def', 99] >>> On the other hand, I had to explore the possibilities here by experimenting in the interpreter, and I discovered some odd edge cases (e.g. you can parenthesize the starred expression, but that seems a syntactic accident). All in all I am personally +0 on the comprehension part of the PEP, and I like that it provides a way to "flatten" a sequence of sequences, but I think very few people in the thread have supported this part. Therefore I would like to ask Neil to update the PEP and the patch to take out the comprehension part, so that the two "easy wins" can make it into Python 3.5 (basically, I am accepting two-thirds of the PEP :-). There is some time yet until alpha 2. I would also like code reviewers (Benjamin?) to start reviewing the patch <http://bugs.python.org/issue2292>, taking into account that the comprehension part needs to be removed. -- --Guido van Rossum (python.org/~guido)

7 17

PEP 1, PEP Purpose and Guidelines
by barry＠zope.com May 18, 2021

May 18, 2021

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:

8 14

Boundaries between numbers and identifiers
by Serhiy Storchaka April 15, 2021

April 15, 2021

In Python 2.5 `0or[]` was accepted by the Python parser. It became an error in 2.6 because "0o" became recognizing as an incomplete octal number. `1or[]` still is accepted. On other hand, `1if 2else 3` is accepted despites the fact that "2e" can be recognized as an incomplete floating point number. In this case the tokenizer pushes "e" back and returns "2". Shouldn't it do the same with "0o"? It is possible to make `0or[]` be parseable again. Python implementation is able to tokenize this example: $ echo '0or[]' | ./python -m tokenize 1,0-1,1: NUMBER '0' 1,1-1,3: NAME 'or' 1,3-1,4: OP '[' 1,4-1,5: OP ']' 1,5-1,6: NEWLINE '\n' 2,0-2,0: ENDMARKER '' On other hand, all these examples look weird. There is an assymmetry: `1or 2` is a valid syntax, but `1 or2` is not. It is hard to recognize visually the boundary between a number and the following identifier or keyword, especially if numbers can contain letters ("b", "e", "j", "o", "x") and underscores, and identifiers can contain digits. On both sides of the boundary can be letters, digits, and underscores. I propose to change the Python syntax by adding a requirement that there should be a whitespace or delimiter between a numeric literal and the following keyword.

8 10

The Python 2 death march
by Benjamin Peterson April 16, 2020

April 16, 2020

Hi all, It's finally time to schedule the last releases in Python 2's life. There will be two more releases of Python 2.7: Python 2.7.17 and Python 2.7.18. Python 2.7.17 release candidate 1 will happen on October 5th followed by the final release on October 19th. I'm going to time Python 2.7.18 to coincide with PyCon 2020 in April, so attendees can enjoy some collective catharsis. We'll still say January 1st is the official EOL date. Thanks to Sumana Harihareswara, there's now a FAQ about the Python 2 sunset on the website: https://www.python.org/doc/sunset-python-2/ Regards, Benjamin

24 38

Last call for comments on PEP 573 (Module State Access from C Extension Methods)
by Stefan Behnel March 11, 2020

March 11, 2020

Hi all, I think that PEP 573 is ready to be accepted, to greatly improve the state of extension modules in CPython 3.9. https://www.python.org/dev/peps/pep-0573/ It has come a long way since the original proposal and went through several iterations and discussions by various interested people, effectively reducing its scope quite a bit. So this is the last call for comments on the latest version of the PEP, before I will pronounce on it. Please keep the discussion in this thread. Stefan

3 7

Stalemate on bringing back PEP 523 support into Python 3.8
by Brett Cannon March 10, 2020

March 10, 2020

An unfortunate side-effect of making PyInterpreterState in Python 3.8 opaque is it removed [PEP 523](https://www.python.org/dev/peps/pep-0523/) support. https://www.python.org/dev/peps/pep-0523/ was opened to try and fix this, but there seems to be a stalemate in the issue. A key question is at what API level should setting the frame evaluation function live at? No one is suggesting the stable ABI, but there isn't agreement between CPython or the internal API (there's also seems to be a suggestion to potentially remove PEP 523 support entirely). And regardless of either, there also seems to be a disagreement about providing getters and setters to continue to try and hide PyInterpreterState regardless of which API level support is provided at (if any). If you have an opinion please weight in on the issue.

7 9

Request to postpone some Python 3.9 incompatible changes to Python 3.10
by Victor Stinner March 7, 2020

March 7, 2020

Hi, Python 3.9 introduces many small incompatible changes which broke tons of Python projects, including popular projects, some of them being unmaintained but still widely used (like nose, last release in 2015). Miro and me consider that Python 3.9 is pushing too much pressure on projects maintainers to either abandon Python 2.7 right now (need to update the CI, the documentation, warn users, etc.), or to introduce a *new* compatibility layer to support Python 3.9: layer which would be dropped as soon as Python 2.7 support will be dropped (soon-ish). Python 3.9 is too early to accumulate so many incompatible changes on purpose, some incompatible changes like the removal of collections aliases to ABC should be reverted, and reapplied on Python 3.10. Python 3.9 would be the last release which still contain compatibility layers for Python 2.7. Said differently, we request to maintain the small compatibility layer in Python for one more cycle, instead of requesting every single project maintainer to maintain it on their side. We consider that the general maintenance burden is lower if it's kept in Python for now. == Fedora COPR notify packages broken by Python 3.9 == In Python 3.9, Victor introduced tons of incompatible changes at the beginning of the devcycle. His plan was to push as many as possible, and later decide what to do... This time has come :-) He wrote PEP 606 "Python Compatibility Version" and we wrote PEP 608 "Coordinated Python release", but both have been rejected. At least, it seems like most people agreed that having a CI to get notified of broken projects should help. We are updating the future Fedora 33 to replace Python 3.8 with Python 3.9. We are using a tool called "COPR" which is like a sandbox and can be seen as the CI discussed previously. It rebuilds Fedora using Python 3.9 as /usr/bin/python3 (and /usr/bin/python !). We now have a good overview of broken packages and which incompatible changes broke most packages. https://fedoraproject.org/wiki/Changes/Python3.9 - Describes the Fedora change. https://copr.fedorainfracloud.org/coprs/g/python/python3.9/monitor/ - Has package failures. Some packages fail because of broken dependencies. https://bugzilla.redhat.com/showdependencytree.cgi?id=PYTHON39 - Has open Python 3.9 bug reports for Fedora packages. Some problems have been fixed upstream already before reaching Fedora, most are only fixed when the Fedora maintainers report the problems back to upstream maintainers. Right now, there are 150+ packages broken by Python 3.9 incompatible changes. == Maintenance burden == Many Python projects have not yet removed Python 2 support and Python 2 CI. It's not that they would be in the "we will not drop Python 2 support ever" camp, it's just that they have not done it yet. Removing Python 2 compatibility code from the codebase and removing it from the documentation and metadata and CI is a boring task, doesn't bring anything to users, and it might take a new major release of the library. At this point, we are very early in 2020 to expect most projects to have already done this. At the same time, we would like them to support Python 3.9 as soon in the release cycle as possible. By removing Python 2 compatibility layers from the 3.9 standard library, we are forcing the projects maintainers to re-invent their own compatibility layers and copy-paste stuff like this around. Example: try: from collections.abc import Sequence except ImprotError: # Python 2.7 doesn't have collections.abc from collections import Sequence While if we remove collections.Sequence in 3.10, they will face this decision early in 2021 and they will simply fix their code by adding ".abc" at the proper places, not needing any more compatibility layers. Of course, there will be projects that will still have declared Python 2 support in 2021, but it will arguably not be that many. While it's certainly tempting to have "more pure" code in the standard library, maintaining the compatibility shims for one more release isn't really that big of a maintenance burden, especially when comparing with dozens (hundreds?) of third party libraries essentially maintaining their own. An good example of a broken package is the nose project which is no longer maintained (according to their website): the last release was in 2015. It remains a very popular test runner. According to libraries.io, it has with 3 million downloads per month, 41.7K dependent repositories and 325 dependent packages. We patched nose in Fedora to fix Python 3.5, 3.6, 3.8 and now 3.9 compatibility issues. People installing nose from PyPI with "pip install" get the unmaintained flavor which is currently completely broken on Python 3.9. Someone should take over the nose project and maintain it again, or every single project using nose should pick another tool (unittest, nose2, pytest, whatever else). Both options will take a lot of time. == Request to revert some incompatible changes == See https://docs.python.org/dev/whatsnew/3.9.html#removed Incompatible changes which require "if <python3>: (...) else: (...)" or "try: <python3 code> except (...): <python2 code>": * Removed tostring/fromstring methods in array.array and base64 modules * Removed collections aliases to ABC classes * Removed fractions.gcd() function (which is similar to math.gcd()) * Remove "U" mode of open(): having to use io.open() just for Python 2 makes the code uglier * Removed old plistlib API: 2.7 doesn't have the new API == Kept incompatible changes == Ok-ish incompatible changes (mostly only affects compatiblity libraries like six): * _dummy_thread and dummy_threading modules removed: broke six, nine and future projects. six and nine are already fixed for 3.9. OK incompatible changes (can be replaced by the same code on 2.7 and 3.9): * isAlive() method of threading.Thread has been removed: Thread.is_alive() method is available in 2.7 and 3.9 * xml.etree.ElementTree.getchildren() and xml.etree.ElementTree.getiterator() methods are removed from 3.9, but list()/iter() works in 2.7 and 3.9 == Call to check for DeprecationWarning in your own projects == You must pay attention to DeprecationWarning in Python 3.9: it will be the last "compatibility layer" release, incompatible changes will be reapplied to Python 3.10. For example, you can use the development mode to see DeprecationWarning and ResourceWarning: use the "-X dev" command line option or set the PYTHONDEVMODE=1 environment variable. Or you can use the PYTHONWARNINGS=default environment variable to see DeprecationWarning. You might even want to treat all warnings as errors to ensure that you don't miss any when you run your test suite in your CI. You can use PYTHONWARNINGS=error, and combine it with PYTHONDEVMODE=1. Warnings filters can be used to ignore warnings in third party code, see the documentation: https://docs.python.org/dev/library/warnings.html#the-warnings-filter -- Victor Stinner and Miro Hrončok for Fedora

29 65

Comments on PEP 558 (Defined semantics for locals() )
by Mark Shannon Feb. 22, 2020

Feb. 22, 2020

Hi, First of all I want to say that I'm very much in favour of the general idea behind PEP 558. Defined semantics is always better than undefined semantics :) However, I think there are a few changes needed: 1. Don't add anything to the C API, please. Frame attributes can be accessed via `PyObject_GetAttr[String]`. 2. Don't make the behaviour dependent on whether "tracing" is turned on. Doing so forces debuggers to use sys.settrace which is horribly slow. It also makes the implementation more complex, and has no benefit AFAICT. 3. Don't store write-through proxies in the frame, but make proxies retain a reference to the frame. This would reduce the size and complexity of code for handling frames. Clean up of the frame would occur naturally via reference count when all proxies have been reclaimed. The proposed implementation is hard to reason about and I am not confident that it will not introduce some new subtle bugs to replace the ones it seeks to remove. Any implementation that has functions with "Borrow" and "BreakCycles" in their names makes me nervous. A simpler conceptual model, which I believe could be made reliable, would be: No change for non-function frames (as PEP 558 currently proposes). Each access to `frame.f_locals` (for function frames) should return a new proxy object. This proxy object would have dict-like, write-through semantics for variables in the frame. For keys that do not match variable names, an exception would be raised. This means that all proxies for a single frame will have value equivalence; object equivalence is not needed. I.e. for a frame `f`, `f.f_locals == f.f_locals` would be True, even though `f.f_locals is f.f_locals` would be False. Cheers, Mark.

2 6

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: https://forms.gle/g4BXezH1Vcn7tLds5 (closes Feb 29th, 2020 AoE) *Who can attend* We welcome Python core developers, active core contributors to Python and alternative Python implementations, and anyone else who has a topic to discuss with core developers. *Who can propose a discussion topic* If you have discussion items; seeking consensus; awaiting decision on a PEP; needing help with your core dev work; or have specific questions that need answers from core developers, please submit a proposal. According to last year’s feedback, our audience prefer more discussions and shorter talks. To get an idea of past language summits, you can read past years' coverage: 2019: http://pyfound.blogspot.com/2019/05/the-2019-python-language-summit.html 2018: https://lwn.net/Articles/754152/ 2017: https://lwn.net/Articles/723251/ This year's event will be covered by A. Jesse Jiryu Davis again, and will be posted on PSF's blog. <https://us.pycon.org/2020/events/languagesummit/> Some changes to note this year: 1) We plan to start 1 hour earlier (9AM) 2) The room will have U-shaped table layout Thanks! Mariatta & Łukasz

2 3

PEP 458: Secure PyPI downloads with package signing
by Sumana Harihareswara Feb. 12, 2020

Feb. 12, 2020

Hi! I'm forwarding this on behalf of Marina Moore https://github.com/mnm678 . - Sumana Harihareswara --- PEP 458 ( https://www.python.org/dev/peps/pep-0458/ ) proposes using The Update Framework (TUF) to allow users of PyPI to verify that the packages they install originate from PyPI. Implementing this PEP would provide protection in the event of an attack on PyPI, its mirrors, or the network used to install packages. We started this PEP in 2013, and have recently revised it and restarted discussion. Recent discussion and revision of the PEP has been taking place on Discourse ( https://discuss.python.org/t/pep-458-secure-pypi-downloads-with-package-sig… ). The PEP is ready for review and I look forward to your feedback! Thanks, Marina Moore PEP 458 coauthor

1 1

extern "C" { ... } in Include/cpython/*.h
by Skip Montanaro Feb. 8, 2020

Feb. 8, 2020

(Apologies. Not sure where to ask this, and I'm not much of a C++ programmer. Maybe I should have just added a comment to the still-open issue.) I just noticed that Nick migrated the guts of Include/frameobject.h to include/cpython/frameobject.h. It's not clear to me that the latter should be #include'd directly from anywhere other than Include/frameobject.h. If that's the case, does the extern "C" stuff still need to be replicated in the lower level file? Won't the scope of the extern "C" block in Include/frameobject.h be active at the lower level? Whatever the correct answer is, I suspect the same constraints should apply to all Include/cpython/*.h files. Skip

3 2

Maintenance of multiprocessing module: there are a few stalled issues/patches
by mailer＠app.tempr.email Jan. 31, 2020

Jan. 31, 2020

Couldn't help but notice that there are quite a few stalled issues/patches, some of them for years even. :-/ So I thought, it might help to bump them here on the mailing list. https://bugs.python.org/issue28053https://github.com/python/cpython/pull/99…

2 1

Summary of Python tracker Issues
by Python tracker Jan. 31, 2020

Jan. 31, 2020

ACTIVITY SUMMARY (2020-01-24 - 2020-01-31) 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 7300 (+15) closed 43962 (+52) total 51262 (+67) Open issues with patches: 2858 Issues opened (56) ================== #36051: Drop the GIL during large bytes.join operations? https://bugs.python.org/issue36051 reopened by skip.montanaro #39350: Remove deprecated fractions.gcd() https://bugs.python.org/issue39350 reopened by mark.dickinson #39391: Nondeterministic Pydoc output on functions that have functions https://bugs.python.org/issue39391 reopened by peteroupc #39435: pickle: inconsistent arguments pickle.py vs _pickle.c vs docs https://bugs.python.org/issue39435 reopened by pitrou #39445: h5py not playing nicely with subprocess and mpirun https://bugs.python.org/issue39445 opened by Rafael Laboissière #39447: imaplib documentation claims that commands return a string, bu https://bugs.python.org/issue39447 opened by dkg #39448: Add regen-frozen makefile target https://bugs.python.org/issue39448 opened by nascheme #39450: unittest TestCase shortDescription does not strip whitespace https://bugs.python.org/issue39450 opened by scirelli #39451: enum.Enum reference count leaks https://bugs.python.org/issue39451 opened by dan.gass(a)gmail.com #39452: Improve the __main__ module documentation https://bugs.python.org/issue39452 opened by maggyero #39453: Use-after-free in list contain https://bugs.python.org/issue39453 opened by corona10 #39454: when \\u in byte_string ,byte_string.decode('raw_unicode_escap https://bugs.python.org/issue39454 opened by yayiba1223 #39456: Make IDLE calltip tests work when there are no docstrings https://bugs.python.org/issue39456 opened by terry.reedy #39457: Add an autocommit property to sqlite3.Connection with a PEP 24 https://bugs.python.org/issue39457 opened by maggyero #39460: test_zipfile: test_add_file_after_2107() sometimes fails on Fe https://bugs.python.org/issue39460 opened by vstinner #39461: [RFE] os.environ should support Path-like values, like subproc https://bugs.python.org/issue39461 opened by Antony.Lee #39462: DataClass typo-unsafe attribute creation & unexpected behaviou https://bugs.python.org/issue39462 opened by marcelpvisser #39463: ast.Constant, bytes, and ast.unparse https://bugs.python.org/issue39463 opened by Tal Ben-Nun #39464: Allow translating argparse error messages https://bugs.python.org/issue39464 opened by DjMorgul #39465: Design a subinterpreter friendly alternative to _Py_IDENTIFIER https://bugs.python.org/issue39465 opened by ncoghlan #39467: Allow to deprecate CLI arguments in argparse https://bugs.python.org/issue39467 opened by 4383 #39468: Improved the site module's permission handling while writing . https://bugs.python.org/issue39468 opened by opensource-assist #39469: Support for relative home path in pyvenv.cfg https://bugs.python.org/issue39469 opened by Jeff.Edwards #39470: Indicate that os.makedirs is equivalent to Path.mkdir https://bugs.python.org/issue39470 opened by nanjekyejoannah #39471: Meaning and clarification of PyBuffer_Release() https://bugs.python.org/issue39471 opened by seberg #39472: IDLE: improve handling of int entry in settings dialog https://bugs.python.org/issue39472 opened by terry.reedy #39473: Enable import behavior consistency option https://bugs.python.org/issue39473 opened by bluelantern #39474: col_offset for parenthesized expressions looks weird https://bugs.python.org/issue39474 opened by BTaskaya #39475: window.getmaxyx() doesn't return updated height when window is https://bugs.python.org/issue39475 opened by nova #39477: multiprocessing Pool maxtasksperchild=0 raises exception with https://bugs.python.org/issue39477 opened by jeyekomon #39479: [RFE] Add math.lcm() function: Least Common Multiple https://bugs.python.org/issue39479 opened by Ananthakrishnan #39480: referendum reference is needlessly annoying https://bugs.python.org/issue39480 opened by diziet #39481: Implement PEP 585 (Type Hinting Generics In Standard Collectio https://bugs.python.org/issue39481 opened by gvanrossum #39482: Write 2to3 fixer for collections.abc imports https://bugs.python.org/issue39482 opened by opoplawski #39483: Proposial add loop parametr to run in asyncio https://bugs.python.org/issue39483 opened by heckad #39484: time_ns() and time() cannot be compared on windows https://bugs.python.org/issue39484 opened by vxgmichel #39486: bug in %-formatting in Python, related to escaped %-characters https://bugs.python.org/issue39486 opened by Carl.Friedrich.Bolz #39488: test_largefile: TestSocketSendfile.test_it() uses too much dis https://bugs.python.org/issue39488 opened by vstinner #39489: Remove COUNT_ALLOCS special build https://bugs.python.org/issue39489 opened by vstinner #39490: Python Uninstaller fails to clean up the old path variables wh https://bugs.python.org/issue39490 opened by brucelong #39491: Import PEP 593 (Flexible function and variable annotations) su https://bugs.python.org/issue39491 opened by jstasiak #39492: reference cycle affecting Pickler instances (Python3.8+) https://bugs.python.org/issue39492 opened by pierreglaser #39495: xml.etree.ElementTree.TreeBuilder.start differs between pure P https://bugs.python.org/issue39495 opened by hauntsaninja #39496: Inelegant loops in Modules/_sqlite/cursor.c https://bugs.python.org/issue39496 opened by alex.henrie #39498: Signpost security considerations in library https://bugs.python.org/issue39498 opened by anthonypjshaw #39500: Document PyUnicode_IsIdentifier() function https://bugs.python.org/issue39500 opened by vstinner #39501: gettext's default localedir does not match documentation https://bugs.python.org/issue39501 opened by moht #39502: test_zipfile fails on AIX due to time.localtime https://bugs.python.org/issue39502 opened by EGuesnet #39503: [security][CVE-2020-8492] Denial of service in urllib.request. https://bugs.python.org/issue39503 opened by vstinner #39504: inspect.signature throws RuntimeError on select.epoll.register https://bugs.python.org/issue39504 opened by hauntsaninja #39505: redundant ‘/’ in $env:VIRTUAL_ENV when use venv in powersh https://bugs.python.org/issue39505 opened by Schwarzichet #39507: http library missing HTTP status code 418 "I'm a teapot" https://bugs.python.org/issue39507 opened by trrhodes #39508: no module curses error although i downloaded the module - wind https://bugs.python.org/issue39508 opened by haim986 #39509: Update HTTP status code to follow IANA https://bugs.python.org/issue39509 opened by corona10 #39510: use-after-free in BufferedReader.readinto() https://bugs.python.org/issue39510 opened by phg #39511: [subinterpreters] Per-interpreter singletons (None, True, Fals https://bugs.python.org/issue39511 opened by vstinner Most recent 15 issues with no replies (15) ========================================== #39510: use-after-free in BufferedReader.readinto() https://bugs.python.org/issue39510 #39508: no module curses error although i downloaded the module - wind https://bugs.python.org/issue39508 #39505: redundant ‘/’ in $env:VIRTUAL_ENV when use venv in powersh https://bugs.python.org/issue39505 #39504: inspect.signature throws RuntimeError on select.epoll.register https://bugs.python.org/issue39504 #39501: gettext's default localedir does not match documentation https://bugs.python.org/issue39501 #39498: Signpost security considerations in library https://bugs.python.org/issue39498 #39496: Inelegant loops in Modules/_sqlite/cursor.c https://bugs.python.org/issue39496 #39492: reference cycle affecting Pickler instances (Python3.8+) https://bugs.python.org/issue39492 #39491: Import PEP 593 (Flexible function and variable annotations) su https://bugs.python.org/issue39491 #39490: Python Uninstaller fails to clean up the old path variables wh https://bugs.python.org/issue39490 #39488: test_largefile: TestSocketSendfile.test_it() uses too much dis https://bugs.python.org/issue39488 #39482: Write 2to3 fixer for collections.abc imports https://bugs.python.org/issue39482 #39481: Implement PEP 585 (Type Hinting Generics In Standard Collectio https://bugs.python.org/issue39481 #39477: multiprocessing Pool maxtasksperchild=0 raises exception with https://bugs.python.org/issue39477 #39475: window.getmaxyx() doesn't return updated height when window is https://bugs.python.org/issue39475 Most recent 15 issues waiting for review (15) ============================================= #39511: [subinterpreters] Per-interpreter singletons (None, True, Fals https://bugs.python.org/issue39511 #39510: use-after-free in BufferedReader.readinto() https://bugs.python.org/issue39510 #39509: Update HTTP status code to follow IANA https://bugs.python.org/issue39509 #39507: http library missing HTTP status code 418 "I'm a teapot" https://bugs.python.org/issue39507 #39505: redundant ‘/’ in $env:VIRTUAL_ENV when use venv in powersh https://bugs.python.org/issue39505 #39503: [security][CVE-2020-8492] Denial of service in urllib.request. https://bugs.python.org/issue39503 #39502: test_zipfile fails on AIX due to time.localtime https://bugs.python.org/issue39502 #39500: Document PyUnicode_IsIdentifier() function https://bugs.python.org/issue39500 #39498: Signpost security considerations in library https://bugs.python.org/issue39498 #39496: Inelegant loops in Modules/_sqlite/cursor.c https://bugs.python.org/issue39496 #39495: xml.etree.ElementTree.TreeBuilder.start differs between pure P https://bugs.python.org/issue39495 #39492: reference cycle affecting Pickler instances (Python3.8+) https://bugs.python.org/issue39492 #39491: Import PEP 593 (Flexible function and variable annotations) su https://bugs.python.org/issue39491 #39489: Remove COUNT_ALLOCS special build https://bugs.python.org/issue39489 #39488: test_largefile: TestSocketSendfile.test_it() uses too much dis https://bugs.python.org/issue39488 Top 10 most discussed issues (10) ================================= #39460: test_zipfile: test_add_file_after_2107() sometimes fails on Fe https://bugs.python.org/issue39460 36 msgs #39479: [RFE] Add math.lcm() function: Least Common Multiple https://bugs.python.org/issue39479 22 msgs #39461: [RFE] os.environ should support Path-like values, like subproc https://bugs.python.org/issue39461 18 msgs #39502: test_zipfile fails on AIX due to time.localtime https://bugs.python.org/issue39502 14 msgs #39489: Remove COUNT_ALLOCS special build https://bugs.python.org/issue39489 9 msgs #39430: tarfile.open(mode="r") race condition when importing lzma https://bugs.python.org/issue39430 8 msgs #39483: Proposial add loop parametr to run in asyncio https://bugs.python.org/issue39483 7 msgs #18233: SSLSocket.getpeercertchain() https://bugs.python.org/issue18233 5 msgs #38792: IDLE calltips may not properly close on KeyboardInterrupt https://bugs.python.org/issue38792 5 msgs #39380: ftplib uses latin-1 as default encoding https://bugs.python.org/issue39380 5 msgs Issues closed (50) ================== #11549: Build-out an AST optimizer, moving some functionality out of t https://bugs.python.org/issue11549 closed by rhettinger #13306: Add diagnostic tools to importlib? https://bugs.python.org/issue13306 closed by brett.cannon #14715: test.support.DirsOnSysPath should be replaced by importlib.tes https://bugs.python.org/issue14715 closed by eric.smith #15243: Misleading documentation for __prepare__ https://bugs.python.org/issue15243 closed by berker.peksag #24928: mock.patch.dict spoils order of items in collections.OrderedDi https://bugs.python.org/issue24928 closed by rhettinger #25597: unittest.mock does not wrap dunder methods (__getitem__ etc) https://bugs.python.org/issue25597 closed by xtreak #30780: IDLE: configdialog - add tests for ConfigDialog GUI. https://bugs.python.org/issue30780 closed by terry.reedy #31414: IDLE: Entry tests should delete before insert. https://bugs.python.org/issue31414 closed by terry.reedy #33339: Using default encoding with `subprocess.run()` is not obvious https://bugs.python.org/issue33339 closed by eryksun #34095: [2.7] Seg fault on archlinux 32 when run tests with xvfb-run https://bugs.python.org/issue34095 closed by benjamin.peterson #36350: inspect.Signature.parameters and inspect.BoundArguments.argume https://bugs.python.org/issue36350 closed by inada.naoki #36654: Add example to tokenize.tokenize https://bugs.python.org/issue36654 closed by berker.peksag #37955: mock.patch incorrect reference to Mock https://bugs.python.org/issue37955 closed by cjw296 #38350: ./configure --with-pydebug should use -O0 rather than -Og https://bugs.python.org/issue38350 closed by vstinner #38473: AttributeError on asserting autospecced mock object added usin https://bugs.python.org/issue38473 closed by xtreak #38631: Replace Py_FatalError() with regular Python exceptions https://bugs.python.org/issue38631 closed by vstinner #38797: x86-64 High Sierra 3.x buildbot worker fails to build Python: https://bugs.python.org/issue38797 closed by vstinner #38883: Path.home() should ignore HOME env var like os.path.expanduser https://bugs.python.org/issue38883 closed by steve.dower #38932: unittest.mock.Mock.reset_mocks does not pass all arguments to https://bugs.python.org/issue38932 closed by cjw296 #39082: AsyncMock is unable to correctly patch static or class methods https://bugs.python.org/issue39082 closed by cjw296 #39153: Clarify refcounting semantics of PyDict_SetItem[String] https://bugs.python.org/issue39153 closed by corona10 #39165: Completeness and symmetry in RE, avoid `findall(...)[0]` https://bugs.python.org/issue39165 closed by rhettinger #39248: test_distutils fails on PPC64 Fedora 3.x: /tmp/subprocess.py https://bugs.python.org/issue39248 closed by vstinner #39287: Document UTF-8 mode in the using/windows. https://bugs.python.org/issue39287 closed by inada.naoki #39309: Please delete my account https://bugs.python.org/issue39309 closed by berker.peksag #39374: Key in sort -> Callable Object instead of function https://bugs.python.org/issue39374 closed by rhettinger #39388: IDLE: Changes to keybindings aren't reverted on cancel https://bugs.python.org/issue39388 closed by terry.reedy #39390: shutil.copytree - 3.8 changed argument types of the ignore cal https://bugs.python.org/issue39390 closed by giampaolo.rodola #39392: Python Turtle is not filling alternate overlapping areas of a https://bugs.python.org/issue39392 closed by terry.reedy #39393: Misleading error message upon dependent DLL resolution failure https://bugs.python.org/issue39393 closed by steve.dower #39401: [CVE-2020-8315] Unsafe dll loading in getpathp.c on Win7 https://bugs.python.org/issue39401 closed by ned.deily #39424: [easy] test_signal: test_pidfd_send_signal() uses deprecated a https://bugs.python.org/issue39424 closed by serhiy.storchaka #39434: Remove unnecessary logic of float __floordiv__ https://bugs.python.org/issue39434 closed by mark.dickinson #39443: Inhomogeneous behaviour for descriptors in between the class-i https://bugs.python.org/issue39443 closed by rhettinger #39444: Incorrect description of sorting for PrettyPrinter https://bugs.python.org/issue39444 closed by steven.daprano #39446: Documentation should reflect that all dicts are now ordered https://bugs.python.org/issue39446 closed by rhettinger #39449: New Assignment operator https://bugs.python.org/issue39449 closed by SilentGhost #39455: Update the documentation for the linecache module https://bugs.python.org/issue39455 closed by opensource-assist #39458: Multiprocessing.Pool maxtasksperchild=1 doesn't work https://bugs.python.org/issue39458 closed by Gabriel Tardif #39459: test_import: test_unwritable_module() fails on AMD64 Fedora St https://bugs.python.org/issue39459 closed by dino.viehland #39466: Spam https://bugs.python.org/issue39466 closed by xtreak #39476: Not convinced with the dynamic data type assignment https://bugs.python.org/issue39476 closed by steven.daprano #39478: can we add a median function https://bugs.python.org/issue39478 closed by vstinner #39485: Bug in mock running on PyPy3 https://bugs.python.org/issue39485 closed by cjw296 #39487: Merge duplicated _Py_IDENTIFIER identifiers in C code https://bugs.python.org/issue39487 closed by ncoghlan #39493: typing.py has an incorrect definition of closed https://bugs.python.org/issue39493 closed by gvanrossum #39494: Extra null terminators in keyword arrays in sqlite module https://bugs.python.org/issue39494 closed by berker.peksag #39497: Unused variable script_str in pysqlite_cursor_executescript https://bugs.python.org/issue39497 closed by berker.peksag #39499: ValueError using index on tuple is not showing the tuple value https://bugs.python.org/issue39499 closed by xtreak #39506: operator |= on sets does not behave like the update method https://bugs.python.org/issue39506 closed by ammar2

1 0

Limited API, MetaClasses, and ExtensionMetaClasses
by Sebastian Berg Jan. 31, 2020

Jan. 31, 2020

Hi all, I may be thinking in the wrong direction, but right now `PyType_Type.tp_new` will resolves the `metaclass` from the bases and call: type = (PyTypeObject *)metatype->tp_alloc(metatype, nslots); where `metatype` is actually resolved from the metatype of the bases. In contrast `PyType_FromSpecWithBases` immediately calls: res = (PyHeapTypeObject*)PyType_GenericAlloc(&PyType_Type, 0); So I am curious whether `PyType_FromSpecWithBases` should not do the same thing, or as to why it does not? I would also assume that it actually fails to inherit a possible MetaClass completely, but I have not checked that. That is the first question. The second, more important one, is whether ExtensionMetaClasses are a thing at all? Is it reasonable to explore them, or should I rather give up and use something more like ABCMeta, which stores information in the `HeapType->tp_dict`, plus tag on information to the actual instances as needed? Right now it seems completely fine to me, except that the creation itself is complicated (and a confusing, but its MetaClasses...). I am exploring this for NumPy. PySIDE is using such things and wrangled it into the limited API [1] (PySIDE needs to store a QT pointer additionally). When I looked the code, I was fairly sure that this only happened to work because Python allocates a slightly larger space (effectively making it `nslots+1`, or 1 above). As far as I can see, the only thing that happens if I use such an ExtensionMetaClass is that I have a HeapType with a different tp_basicsize. And I do not see why that should be any different than a normal Python object. Best, Sebastian [1] https://github.com/pyside/pyside2-setup/blob/5.11/sources/shiboken2/libshib…

1 0

PEP 613 Accepted
by Barry Warsaw Jan. 30, 2020

Jan. 30, 2020

The Steering Council has considered Guido’s request for pronouncement on PEP 613 - Explicit Type Aliases, written by Shannon Zhu and sponsored by Guido van Rossum. The Council unanimously accepts PEP 613. Congratulations! We’ll leave it to the sponsor and author to update the PEP accordingly. -Barry (on behalf of the Python Steering Council)

1 0

Static inline functions in header files, limited API and the stable ABI
by Victor Stinner Jan. 30, 2020

Jan. 30, 2020

Hi, Is it ok to add a static inline function to the limited API? Can it cause ABI issue? Or is it safer to add a regular function? For example, is it safe to add the following function to the limited API? static inline PyObject * _PyObject_CallOneArg(PyObject *func, PyObject *arg) { ... return _PyObject_VectorcallTstate(tstate, func, args, nargsf, NULL); } Or should it be an opaque definition like the following function? PyAPI_FUNC(PyObject *) PyObject_CallNoArgs(PyObject *func); I came to this question while reviewing "Make Vectorcall public" C API: https://bugs.python.org/issue39245 https://github.com/python/cpython/pull/17893 Victor -- Night gathers, and now my watch begins. It shall not end until my death.

2 1

Remove COUNT_ALLOCS special build
by Victor Stinner Jan. 29, 2020

Jan. 29, 2020

Hi, I would like to confirm that there is no user of the Python "COUNT_ALLOCS" special build, because I plan to remove it from Python 3.9. If you use it, please raise your hand and explain why other debug tools don't fit your specific use case. -- I'm always annoyed by "#ifdef COUNT_ALLOCS" code which is common in code related to reference counting (object.h, object.c, typeobject.c). It makes the code harder to read and harder to maintain. It's a 27 years old feature which always required to rebuild Python with COUNT_ALLOCS macro defined. In clear, you have to know about the feature and build your own Python binary to use it. COUNT_ALLOCS was used for 6 years (2010-2015) in the debug build of Python of the Fedora package. Sadly, C extensions provided by Fedora are only built in release mode, and so cannot be used by the debug build. python2.7-debug requires to rebuild all C extensions in debug mode. IMHO nobody ever used python2.7-debug to debug real applications. The feature was added to Fedora debug build by Dave Malcolm in 2010 to help him to debug memory leaks. Later, he wrote: "I don't think this patch ever really bought us much, and it sounds like there are better tools for this now, so feel free to drop the COUNT_ALLOC patches." So the feature was dropped from Python 3 package in 2015. I never ever used this feature. I consider that there are now way better tools to debug memory leaks in Python 3, like tracemalloc and multiple tools based on gc.get_objects(). I failed to find any user of COUNT_ALLOCS on the Internet. I'm quite sure that many core developers never heard about this special build. I proposed https://bugs.python.org/issue39489 and https://github.com/python/cpython/pull/18259 to remove the feature. My PR basically only removes code: 34 files changed, 24 insertions(+), 470 deletions(-) Do you see any reason to keep COUNT_ALLOCS in Python 3.9? If yes, please elaborate :-) Victor -- Night gathers, and now my watch begins. It shall not end until my death.

2 1

Question: how to extend standard Python library to add new functionalities?
by daniel.wangksu＠gmail.com Jan. 29, 2020

Jan. 29, 2020

Hi all, I want to add openssl engine in Python SSL library. I know that if the new functions can be added in Python we can inherit existing class (such as ssl). However, It seems the SSL module extends _SSL module which is written in C. I'm not sure how can I extend SSL module in this situation. Any help would be deeply appreciated!

2 1

Typo in Link
by onlinejudge95 Jan. 28, 2020

Jan. 28, 2020

Hi team, First of all is it a right place to ask this question? If not i would love to redirect and apologise for any inconvenience. While i was going through the wiki.python.org links, i saw that the urls( https://wiki.python.org/moin) contains *moin*, is it expected? Thanks, onlinejudge95

3 2

Re: Typo in Link
by Steve Holden Jan. 28, 2020

Jan. 28, 2020

Really webmaster(a)python.org would have been more appropriate, but I've already copied that address on my direct reply to you. The python-dev list is for discussions about the development of the language and its CPython implementation. Kind regards, Steve On Tue, Jan 28, 2020 at 7:20 PM Steve Holden <steve(a)holdenweb.com> wrote: > Hi Steve, > > I believe you will find that wiki.python.org redirects to > wiki.python.org/moin/. While https://wiki.python.org/moin/SteveHolden > exists, https://wiki.python.org/SteveHolden does not. It would therefore > appear the links should include the "/moin". > > Kind regards, > Steve > > > On Tue, Jan 28, 2020 at 3:38 PM onlinejudge95 <onlinejudge95(a)gmail.com> > wrote: > >> Hi team, >> >> First of all is it a right place to ask this question? If not i would >> love to redirect and apologise for any inconvenience. >> >> While i was going through the wiki.python.org links, i saw that the urls( >> https://wiki.python.org/moin) contains *moin*, is it expected? >> >> Thanks, >> onlinejudge95 >> >> _______________________________________________ >> 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/Y54FPSV… >> Code of Conduct: http://python.org/psf/codeofconduct/ >> >

1 0

Merge bugs.python.org accounts
by Ivan Pozdeev Jan. 28, 2020

Jan. 28, 2020

Who should I contact on subj? BPO UI doesn't have any contact information. -- Regards, Ivan

3 2

Python library for the ServiceNow REST API
by IT Canvass Jan. 28, 2020

Jan. 28, 2020

It should be compatible with modern versions of ServiceNow. If there's API breakage or new features implemented, I usually have that fixed/incorporated into pysnow in a week or two. <a href="https://itcanvass.com/"> servicenow training</a>

4 3

Are PyObject_RichCompareBool shortcuts part of Python or just CPython quirks?
by Tim Peters Jan. 26, 2020

Jan. 26, 2020

PyObject_RichCompareBool(x, y, op) has a (valuable!) shortcut: if x and y are the same object, then equality comparison returns True and inequality False. No attempt is made to execute __eq__ or __ne__ methods in those cases. This has visible consequences all over the place, but they don't appear to be documented. For example, >>> import math >>> ([math.nan] * 5).count(math.nan) 5 despite that `math.nan == math.nan` is False. It's usually clear which methods will be called, and when, but not really here. Any _context_ that calls PyObject_RichCompareBool() under the covers, for an equality or inequality test, may or may not invoke __eq__ or __ne__, depending on whether the comparands are the same object. Also any context that inlines these special cases to avoid the overhead of calling PyObject_RichCompareBool() at all. If it's intended that Python-the-language requires this, that needs to be documented. Or if it's implementation-defined, then _that_ needs to be documented. Which isn't straightforward in either case, in part because PyObject_RichCompareBool isn't a language-level concept. This came up recently when someone _noticed_ the list.count(NaN) behavior, and Victor made a PR to document it: https://github.com/python/cpython/pull/18130 I'm pushing back, because documenting it _only_ for .count() makes .count() seem unique in a way it isn't, and doesn't resolve the fundamental issue: is this language behavior, or implementation behavior? Which I don't want to argue about. But you certainly should ;-)

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[RELEASE] Python 3.9.0a3 available for testing
by Łukasz Langa Jan. 25, 2020

Jan. 25, 2020

Go get it here: https://www.python.org/downloads/release/python-390a3/ <https://www.python.org/downloads/release/python-390a3/> This is an early developer preview of Python 3.9 Python 3.9 is still in development. This releasee, 3.9.0a3 is the third of six planned alpha releases. Alpha releases are intended to make it easier to test the current state of new features and bug fixes and to test the release process. During the alpha phase, features may be added up until the start of the beta phase (2020-05-18) and, if necessary, may be modified or deleted up until the release candidate phase (2020-08-10). 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 Many new features for Python 3.9 are still being planned and written. Among the new major new features and changes so far: PEP 602 <https://www.python.org/dev/peps/pep-0602/>, Python adopts a stable annual release cadence 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; 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 of Python 3.9 will be 3.9.0a4, currently scheduled for 2020-02-17. - Ł

1 0

Summary of Python tracker Issues
by Python tracker Jan. 24, 2020

Jan. 24, 2020

ACTIVITY SUMMARY (2020-01-17 - 2020-01-24) 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 7285 (+17) closed 43910 (+55) total 51195 (+72) Open issues with patches: 2852 Issues opened (45) ================== #29258: __init__.py required for pkgutil.walk_packages in python3 https://bugs.python.org/issue29258 reopened by inada.naoki #39353: Deprecate the binhex module, binhex4 and hexbin4 standards https://bugs.python.org/issue39353 reopened by vstinner #39372: The header files in Include/ have many declarations with no de https://bugs.python.org/issue39372 reopened by pablogsal #39374: Key in sort -> Callable Object instead of function https://bugs.python.org/issue39374 opened by Carlos Segura González #39375: Document os.environ[x] = y and os.putenv() as thread unsafe https://bugs.python.org/issue39375 opened by gregory.p.smith #39376: Avoid modifying the process global environment (not thread saf https://bugs.python.org/issue39376 opened by gregory.p.smith #39378: partial of PickleState struct should be traversed. https://bugs.python.org/issue39378 opened by shihai1991 #39379: sys.path[0] is already absolute path https://bugs.python.org/issue39379 opened by ksato9700 #39380: ftplib uses latin-1 as default encoding https://bugs.python.org/issue39380 opened by SebastianGPedersen #39382: abstract_issubclass() doesn't take bases tuple item ref https://bugs.python.org/issue39382 opened by Yonatan Goldschmidt #39384: Email parser creates a message object that can't be flattened https://bugs.python.org/issue39384 opened by msapiro #39385: Add an assertNoLogs context manager to unittest TestCase https://bugs.python.org/issue39385 opened by Kit Yan Choi #39388: IDLE: Changes to keybindings aren't reverted on cancel https://bugs.python.org/issue39388 opened by cheryl.sabella #39390: shutil.copytree - 3.8 changed argument types of the ignore cal https://bugs.python.org/issue39390 opened by mbarkhau #39392: Python Turtle is not filling alternate overlapping areas of a https://bugs.python.org/issue39392 opened by lijose #39393: Misleading error message upon dependent DLL resolution failure https://bugs.python.org/issue39393 opened by plimkilde #39394: re: DeprecationWarning for `flag not at the start of expressio https://bugs.python.org/issue39394 opened by jugmac00 #39400: pydoc: Use of MANPAGER variable is incorrect https://bugs.python.org/issue39400 opened by Brocellous #39401: Unsafe dll loading in getpathp.c on Win7 https://bugs.python.org/issue39401 opened by anthonywee #39405: Using relative path as a --prefix during configure. https://bugs.python.org/issue39405 opened by Sankark #39407: Bitfield Union does not work for bit widths greater than 8 bit https://bugs.python.org/issue39407 opened by jschulte #39408: Add support for SQLCipher https://bugs.python.org/issue39408 opened by Sebastian.Noack #39409: AIX: FAIL: test_specific_values (test.test_cmath.CMathTests) https://bugs.python.org/issue39409 opened by Michael.Felt #39410: CentOS 6.10 SQLite 3.30.1 - _sqlite3 builds successfully but i https://bugs.python.org/issue39410 opened by cehovski #39411: pyclbr rewrite using AST https://bugs.python.org/issue39411 opened by Batuhan Taskaya #39413: Implement os.unsetenv() on Windows https://bugs.python.org/issue39413 opened by vstinner #39414: Multiprocessing resolving object as None https://bugs.python.org/issue39414 opened by rdil #39416: Document default numeric string formats https://bugs.python.org/issue39416 opened by kop #39417: Link to "Python Packaging User Guide: Creating and using virtu https://bugs.python.org/issue39417 opened by angelcervera #39418: str.strip() should have a means of adding to the default behav https://bugs.python.org/issue39418 opened by senji #39419: Core dump when trying to use workaround for custom warning cat https://bugs.python.org/issue39419 opened by Gerrit.Holl #39423: Process finished with exit code -1073741819 (0xC0000005) when https://bugs.python.org/issue39423 opened by mapf #39424: [easy] test_signal: test_pidfd_send_signal() uses deprecated a https://bugs.python.org/issue39424 opened by vstinner #39427: python -X options are not documented in the CLI --help https://bugs.python.org/issue39427 opened by pablogsal #39428: allow creation of "symtable entry" objects from Python https://bugs.python.org/issue39428 opened by carljm #39430: tarfile.open(mode="r") race condition when importing lzma https://bugs.python.org/issue39430 opened by Maciej Gol #39432: Distutils generates the wrong export symbol for unicode module https://bugs.python.org/issue39432 opened by da-woods #39433: curses.setupterm can raise _curses.error https://bugs.python.org/issue39433 opened by mdk #39434: Remove unnecessary logic of float __floordiv__ https://bugs.python.org/issue39434 opened by corona10 #39435: pickle: inconsistent arguments pickle.py vs _pickle.c vs docs https://bugs.python.org/issue39435 opened by crusaderky #39438: better handling of foreign signal handlers in signal.signal https://bugs.python.org/issue39438 opened by Steven G. Johnson #39441: mimetypes.guess_extension unable to get non-lowercase mimetype https://bugs.python.org/issue39441 opened by Inkhey #39442: from __future__ import annotations makes dataclasses.Field.typ https://bugs.python.org/issue39442 opened by lopek #39443: Inhomogeneous behaviour for descriptors in between the class-i https://bugs.python.org/issue39443 opened by Hugo Ricateau #39444: Incorrect description of sorting for PrettyPrinter https://bugs.python.org/issue39444 opened by TextGeek Most recent 15 issues with no replies (15) ========================================== #39443: Inhomogeneous behaviour for descriptors in between the class-i https://bugs.python.org/issue39443 #39441: mimetypes.guess_extension unable to get non-lowercase mimetype https://bugs.python.org/issue39441 #39438: better handling of foreign signal handlers in signal.signal https://bugs.python.org/issue39438 #39435: pickle: inconsistent arguments pickle.py vs _pickle.c vs docs https://bugs.python.org/issue39435 #39432: Distutils generates the wrong export symbol for unicode module https://bugs.python.org/issue39432 #39428: allow creation of "symtable entry" objects from Python https://bugs.python.org/issue39428 #39424: [easy] test_signal: test_pidfd_send_signal() uses deprecated a https://bugs.python.org/issue39424 #39419: Core dump when trying to use workaround for custom warning cat https://bugs.python.org/issue39419 #39407: Bitfield Union does not work for bit widths greater than 8 bit https://bugs.python.org/issue39407 #39405: Using relative path as a --prefix during configure. https://bugs.python.org/issue39405 #39392: Python Turtle is not filling alternate overlapping areas of a https://bugs.python.org/issue39392 #39388: IDLE: Changes to keybindings aren't reverted on cancel https://bugs.python.org/issue39388 #39385: Add an assertNoLogs context manager to unittest TestCase https://bugs.python.org/issue39385 #39382: abstract_issubclass() doesn't take bases tuple item ref https://bugs.python.org/issue39382 #39378: partial of PickleState struct should be traversed. https://bugs.python.org/issue39378 Most recent 15 issues waiting for review (15) ============================================= #39435: pickle: inconsistent arguments pickle.py vs _pickle.c vs docs https://bugs.python.org/issue39435 #39434: Remove unnecessary logic of float __floordiv__ https://bugs.python.org/issue39434 #39432: Distutils generates the wrong export symbol for unicode module https://bugs.python.org/issue39432 #39430: tarfile.open(mode="r") race condition when importing lzma https://bugs.python.org/issue39430 #39427: python -X options are not documented in the CLI --help https://bugs.python.org/issue39427 #39416: Document default numeric string formats https://bugs.python.org/issue39416 #39413: Implement os.unsetenv() on Windows https://bugs.python.org/issue39413 #39411: pyclbr rewrite using AST https://bugs.python.org/issue39411 #39400: pydoc: Use of MANPAGER variable is incorrect https://bugs.python.org/issue39400 #39393: Misleading error message upon dependent DLL resolution failure https://bugs.python.org/issue39393 #39390: shutil.copytree - 3.8 changed argument types of the ignore cal https://bugs.python.org/issue39390 #39388: IDLE: Changes to keybindings aren't reverted on cancel https://bugs.python.org/issue39388 #39385: Add an assertNoLogs context manager to unittest TestCase https://bugs.python.org/issue39385 #39384: Email parser creates a message object that can't be flattened https://bugs.python.org/issue39384 #39382: abstract_issubclass() doesn't take bases tuple item ref https://bugs.python.org/issue39382 Top 10 most discussed issues (10) ================================= #39390: shutil.copytree - 3.8 changed argument types of the ignore cal https://bugs.python.org/issue39390 12 msgs #38076: Make struct module PEP-384 compatible https://bugs.python.org/issue38076 9 msgs #39413: Implement os.unsetenv() on Windows https://bugs.python.org/issue39413 9 msgs #39430: tarfile.open(mode="r") race condition when importing lzma https://bugs.python.org/issue39430 9 msgs #39353: Deprecate the binhex module, binhex4 and hexbin4 standards https://bugs.python.org/issue39353 7 msgs #39408: Add support for SQLCipher https://bugs.python.org/issue39408 6 msgs #39434: Remove unnecessary logic of float __floordiv__ https://bugs.python.org/issue39434 6 msgs #39372: The header files in Include/ have many declarations with no de https://bugs.python.org/issue39372 5 msgs #39418: str.strip() should have a means of adding to the default behav https://bugs.python.org/issue39418 5 msgs #17005: Add a topological sort algorithm https://bugs.python.org/issue17005 4 msgs Issues closed (54) ================== #18091: Remove PyNoArgsFunction https://bugs.python.org/issue18091 closed by serhiy.storchaka #18842: Add float.is_finite is_nan is_infinite to match Decimal method https://bugs.python.org/issue18842 closed by corona10 #21600: mock.patch.stopall doesn't work with patch.dict https://bugs.python.org/issue21600 closed by cjw296 #24658: open().write() and .read() fails on 2 GB+ data (OS X) https://bugs.python.org/issue24658 closed by zach.ware #29435: Allow to pass fileobj to is_tarfile https://bugs.python.org/issue29435 closed by ethan.furman #32989: IDLE: Fix pyparse.find_good_parse_start https://bugs.python.org/issue32989 closed by terry.reedy #34145: uuid3 and uuid5 hard to use portably between Python 2 and 3 https://bugs.python.org/issue34145 closed by zach.ware #34834: test_ssl.test_options does not correctly account for built-in https://bugs.python.org/issue34834 closed by zach.ware #35182: Popen.communicate() breaks when child closes its side of pipe https://bugs.python.org/issue35182 closed by gregory.p.smith #35561: Valgrind reports Syscall param epoll_ctl(event) points to unin https://bugs.python.org/issue35561 closed by vstinner #36417: unicode.isdecimal bug in online Python 2 documentation https://bugs.python.org/issue36417 closed by zach.ware #37669: Make mock_open return per-file content https://bugs.python.org/issue37669 closed by cjw296 #38536: Trailing space in formatted currency with international=True a https://bugs.python.org/issue38536 closed by inada.naoki #39035: Travis CI fail on backports: pyvenv not installed https://bugs.python.org/issue39035 closed by vstinner #39146: too much memory consumption in re.compile unicode https://bugs.python.org/issue39146 closed by zach.ware #39197: argparse: title and description for mutually exclusive arg gro https://bugs.python.org/issue39197 closed by paul.j3 #39295: usage of bitfields in ctypes structures changed between 3.7.5 https://bugs.python.org/issue39295 closed by vinay.sajip #39331: 2to3 mishandles indented imports https://bugs.python.org/issue39331 closed by cheryl.sabella #39336: Immutable module type can't be used as package in custom loade https://bugs.python.org/issue39336 closed by dino.viehland #39343: Travis CI: documentation job fails in library/nntplib.rst with https://bugs.python.org/issue39343 closed by vstinner #39361: [C API] Document PyTypeObject.tp_print removal in What's New I https://bugs.python.org/issue39361 closed by vstinner #39365: Support (SEEK_END/SEEK_CUR) relative seeking in StringIO https://bugs.python.org/issue39365 closed by serhiy.storchaka #39366: Remove deprecated nntplib method https://bugs.python.org/issue39366 closed by berker.peksag #39370: askopenfilename is missing from the Tkinter filedialog library https://bugs.python.org/issue39370 closed by ned.deily #39373: -- https://bugs.python.org/issue39373 closed by zach.ware #39377: json.loads encoding parameter deprecation removal in Python 3. https://bugs.python.org/issue39377 closed by inada.naoki #39381: Fix get_event_loop documentation https://bugs.python.org/issue39381 closed by asvetlov #39383: Mention Darwin as a potential value for platform.system() https://bugs.python.org/issue39383 closed by ned.deily #39386: Prevent double awaiting of async iterator https://bugs.python.org/issue39386 closed by asvetlov #39387: configparser read_file() with variable https://bugs.python.org/issue39387 closed by Mattia Verga #39389: gzip metadata fails to reflect compresslevel https://bugs.python.org/issue39389 closed by serhiy.storchaka #39391: Nondeterministic Pydoc output on functions that have functions https://bugs.python.org/issue39391 closed by serhiy.storchaka #39395: The os module should unset() environment variable at exit https://bugs.python.org/issue39395 closed by vstinner #39396: AIX: self.assertEqualSign(math.nextafter(-0.0, +0.0), +0.0) te https://bugs.python.org/issue39396 closed by vstinner #39397: Mac : fail to launch Python 3.8 https://bugs.python.org/issue39397 closed by inada.naoki #39398: AMD64 Fedora Rawhide Clang 3.x: C compiler cannot create execu https://bugs.python.org/issue39398 closed by vstinner #39399: Cross compilation using different libc is broken https://bugs.python.org/issue39399 closed by ned.deily #39402: Consistent use of terms https://bugs.python.org/issue39402 closed by rhettinger #39403: Objects equal (assertEqual return True) but behave differently https://bugs.python.org/issue39403 closed by zach.ware #39404: Pexpect : setwinsize() not working in SLES 12.4 kernel 4.12.14 https://bugs.python.org/issue39404 closed by archi-pandey #39406: Implement os.putenv() with setenv() if available https://bugs.python.org/issue39406 closed by vstinner #39412: Install launcher for all users https://bugs.python.org/issue39412 closed by steve.dower #39415: Remove unused code from longobject.c complexobject.c floatobje https://bugs.python.org/issue39415 closed by benjamin.peterson #39420: Windows: convertenviron() doesn't parse environment variables https://bugs.python.org/issue39420 closed by vstinner #39421: Use-after-free in heappushpop() of heapq module https://bugs.python.org/issue39421 closed by pablogsal #39422: datetime.datetime.strptime incorrectly interpretting format '% https://bugs.python.org/issue39422 closed by SilentGhost #39425: list.count performance regression https://bugs.python.org/issue39425 closed by pablogsal #39426: Pickler docstring misstates default and highest protocols https://bugs.python.org/issue39426 closed by pitrou #39429: Add a new "Python Development Mode" page to the documentation https://bugs.python.org/issue39429 closed by vstinner #39431: Mention nonlocal too in assignment quirk https://bugs.python.org/issue39431 closed by terry.reedy #39436: Strange behavior of comparing int and float numbers https://bugs.python.org/issue39436 closed by mrabarnett #39437: collections.Counter support multiplication https://bugs.python.org/issue39437 closed by ammar2 #39439: Windows Multiprocessing in Virtualenv: sys.prefix is incorrect https://bugs.python.org/issue39439 closed by eryksun #39440: Use PyNumber_InPlaceAdd in sum() for the second iteration onwa https://bugs.python.org/issue39440 closed by edk

1 0

Re: SWIFT Confirmation and request for Updated Statement for DEC invoice
by ron＠ronstruckandauto.com Jan. 24, 2020

Jan. 24, 2020

Sir, Please note that and we are Transferring payment again to your Designated bank As advised earlier. Kindly see attached covering letter with Bank Swift for follow up with your bank. Also see below specification Of payment breakdown. USD 3,146.05 USD 28,550.00 Please kindly confirm the attached swifts and Send Updated Statement of Account for our records Purpose. Regards Brian Alex Head Of Finance Treasury Department. Address: ul. 327 Abdrakhmanova (Bayalinov lane) +996 312 37 67 70

1 0

Comparing UUID objects to strings: why not?
by Michael Anckaert Jan. 23, 2020

Jan. 23, 2020

Hello everyone I have a usecase where I'm comparing a UUID instance with string quite often. A case where I have to convert the UUID instance to a string using str(uuid_obj), leading to redundant code: if str(uuid_obj) == uuid: # do stuff... In my experience I can't find a case where you wouldn't want the implicit conversion to string before comparing a UUID with string. So I would like to propose improving the __eq__ method of UUID to: def __eq__(self, other): if isinstance(other, UUID): return self.int == other.int elif isinstance(other, str): return str(self) == other return NotImplemented Based on my testing and experience I don't think this is a breaking change and would be a meaningful change to the way UUID works. Of course please don't hesitate to change my view or point out any flaws in my reasoning. If other people support this change I'd start the work of creating an issue and PR to get this change implemented. -- Michael Anckaert +32 474 066 467 https://www.sinax.be

4 4

Re: Documenting Python's float.__str__()
by Vedran Čačić Jan. 22, 2020

Jan. 22, 2020

> ints print the same in just about every single programming language that uses base ten Arabic-Hindu digits 0...9. It's kind of a universal. Not actually true: C64's Basic V2 printed positive numbers with space in front. -- Vedran Čačić

1 0

Documenting Python's float.__str__()
by Karl O. Pinc Jan. 22, 2020

Jan. 22, 2020

Hello, There appears to be extremely minimal documentation on how floats are formatted on output. All I really see is that float.__str__() is float.__repr__(). So that means that float->str->float does not result in a different value. It would be nice if the output format for float was documented, to the extent this is possible. #python suggested that I propose a patch, but I see no way to write a documentation patch without having any clue about what Python promises, whether in the CPython implementation or as part of a specification for Python. What are the promises Python makes about the str() of a float? Will it produce 1.0 today and 1.0e0 or +1.0 tomorrow? When is the result in exponential notation and when not? Does any of this depend on the underlying OS or hardware or Python implementation? Etc. I'm guessing that Python is consistent with an IEEE 754 "external character sequence", but don't know what the IEEE specification says or whether python conforms. I don't really care whether there's documentation for __str__() or __repr__() or something else. I'm just thinking that there should be some way to guarantee a well defined "useful" float output formatting. By "useful" I mean in exponential notation when non-exponential notation is over-long. I am writing a program that sometimes prints python floats and want to be able to document what is printed. Right now I can't truly guarantee anything, other than the nan and inf and -inf representations. (I feel comfortable with nan and the like because I don't see it likely that their representations will change.) Of course I could always re-implement Python's float.__repr__() in Python so as to have full control, but this should be pointless. Python's output representation is unlikely to change and Python should be able to make sufficient promises about its existing float representation. I suppose there are similar issues with integers, but the varieties of floating point number implementations and the existence of both exponential and non-exponential representations make float particularly problematic and representations potentially mercurial. I also don't know if documentation changes with regard to external representations would require a PEP. I have found the following related information: Use shorter float repr when possible https://bugs.python.org/issue1580 https://github.com/python/cpython/blob/master/Python/pystrtod.c#L831 String conversion and formatting https://docs.python.org/3/c-api/conversion.html sys.float_repr_style https://docs.python.org/3/library/sys.html#sys.float_repr_style object.__str__(self) https://docs.python.org/3/reference/datamodel.html#object.__str__ At the end of the day I don't _really_ care. But having put thought into the matter I care enough to write this email and ask the question. Regards, Karl <kop(a)karlpinc.com> Free Software: "You don't pay back, you pay forward." -- Robert A. Heinlein

6 13

PEP 587
by Zak Mabbott Jan. 21, 2020

Jan. 21, 2020

I am really confused on writing python and what app I need to write it in any tips or any ideas for apps??

2 1

About "python-porting" mail list
by Facundo Batista Jan. 20, 2020

Jan. 20, 2020

Hello! This list (which I co-admin, with Georg) is getting less and less traffic as months pass by. See: https://mail.python.org/pipermail/python-porting/ The interwebs has been collecting ton of resources about porting py2 to 3 during these years. Any not-yet-answered question surely can be done in a list with more participants. Can we kill this list? Thanks! Regards, -- . Facundo Blog: http://www.taniquetil.com.ar/plog/ PyAr: http://www.python.org.ar/ Twitter: @facundobatista

4 7

Re: Questions about CPython's behavior on addition operator -- binary_op1 (abstract.c) and nb_add (typeobject.c)
by Raphaël Monat Jan. 20, 2020

Jan. 20, 2020

> I'm also keen to understand this and think I can elucidate a little, > from my study of the code. The perspective of someone who *didn't* > write it might help, but I defer to the authors' version when it appears. > Thank you! I'd be happy to know the authors' opinion as well. > A crucial observation is that there is only one nb_add slot in a type > definition. Think about adding a int(1) + float(2). Where it lands in > long_add (v->ob_type->tp_as_number->nb_add) will return > NotImplemented, because it does not understand the float right-hand > argument, but float_add (w->ob_type->tp_as_number->nb_add) is able to > give an answer, since it can float the int, behaving as > float.__radd__(f, i). So the slots have to implement both __add__ and > __radd__. > I agree. And by default, this is done by expanding the macro "SLOT1BIN(slot_nb_add, nb_add, "__add__", "__radd__")". > The logic is the same as binary_op1, but the function has to deal with > the possibility that one or other type may already provide a special > function wrapper function in its nb_add slot, which is what the test > tp_as_number->SLOTNAME == TESTFUNC is about. TESTFUNC is nearly always > the same as FUNCNAME. Then it also deals with quite a complex decision > in method_is_overloaded(). > I have overlooked this test, and now I'm confused by it. In the definition of slot_nb_add, it seems to check that tp_as_number->nb_add == slot_nb_add. Is it (a convoluted way) to check that tp_as_number->nb_add != NULL? Otherwise, I guess this always hold for standard library modules, but someone may change tp_as_number->nb_add for another function? > The partial repetition of the logic, which I think is now nested > (because binary_op1() may have called slot_nb_add) is necessary to > insert the more complex version into the decision tree. But this is > roughly where my ability to visualise the paths runs out. > I have an hypothesis: when binary_op1(v, w, ...) is called: 1) either slotv (v->ob_type->tp_as_number->nb_add) is defined. This calls v's slot_nb_add. This slot_nb_add may then call either v's "__add__" or w's "__radd__" using the calls to vectorcall_maybe. 2) or slotv is not defined. In that case we start the whole process using w's slot_nb_add, which should be stored in w->ob_type->tp_as_number->nb_add. In particular, does this mean that if slotv is defined, the if(slotw) <https://github.com/python/cpython/blob/3.8/Objects/abstract.c#L813> will never be reached (meaning this if could be changed by an else if)? Letting the case where w is a subtype of v aside for now, this would mean that some tests may be performed twice, but only one slot_nb_add will be called? (of course, this slot_nb_add will be able to call either its __add__ or the __radd__ of the other) > I would not say they are "defined" by the slot_nb_add function. > Rather, if one or other has been defined (in Python), v.__add__ or > w.__radd__ is called by the single function slot_nb_add. They cannot > be called directly from C, but call_maybe() supplies the mechanism. > > A confusing factor is that for types defined in C and filling the > nb_add slot, the slot function (float_add, or whatever) has to be > wrapped by two descriptors that can then sit in the type's dictionary > as "__add__" and "__radd__". In that case these *are* defined by a > wrapped C function, but that function is the function in the > implementation of the type (float_add, say), not slot_nb_add. There > are two kinds of wrapper: one used "Python-side out", so > Python-calling "__add__" leads to nb_add's behaviour, and one "C-side > out" so C-calling via nb_add leads to "__add__". > This makes sense. Thank you! > I *think* it is changed to contain slot_nb_add as defined by the macro. > And then slot_nb_add is able to dispatch to __add__ or __radd__ with vectorcall_maybe. Thanks! When this is all clearer (and hopefully accurate), I'll wrap it up in a blog post or something. -- Raphaël

1 0

Remove formatter module from Python 3.9, deprecated for 7 years (Python 3.4)
by Victor Stinner Jan. 17, 2020

Jan. 17, 2020

Hi, I proposed https://bugs.python.org/issue39352 to remove the formatter module. It's deprecated since Python 3.4. The main reason why it's still around is the PEP 4 rule: "In order to facilitate writing code that works in both Python 2 & 3 simultaneously, any module that exists in both Python 3.5 and Python 2.7 will not be removed from the standard library until Python 2.7 is no longer supported as specified by PEP 373." https://www.python.org/dev/peps/pep-0004/#for-modules-existing-in-both-pyth… Python 2.7 is not longer supported. So can we now remove the formatter module? The module has no test, I failed to find any user in a dummy GitHub code search and I didn't know that this module even existed. We can still revert the module before 3.9.0 final release if someone shows up and asks to keep it for one more cycle. My intent here is to reduce the size of the Python standard library to reduce the maintenance burden. Python became quite large and it's more and more expensive to maintain it. Wait... I'm not asking to remove all modules of the standard library :-) The decision must be taken on a case by case basis, for each module. Here I'm only taking about the formatter module. Victor -- Night gathers, and now my watch begins. It shall not end until my death.

3 3

Summary of Python tracker Issues
by Python tracker Jan. 17, 2020

Jan. 17, 2020

ACTIVITY SUMMARY (2020-01-10 - 2020-01-17) 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 7268 (+17) closed 43855 (+63) total 51123 (+80) Open issues with patches: 2847 Issues opened (54) ================== #16576: ctypes: structure with bitfields as argument https://bugs.python.org/issue16576 reopened by vinay.sajip #37751: In codecs, function 'normalizestring' should convert both spa https://bugs.python.org/issue37751 reopened by vstinner #38076: Make struct module PEP-384 compatible https://bugs.python.org/issue38076 reopened by pablogsal #39293: Windows 10 64-bit needs reboot https://bugs.python.org/issue39293 opened by ToKa #39294: zipfile.ZipInfo objects contain invalid 'extra' fields. https://bugs.python.org/issue39294 opened by Bram Stolk #39295: usage of bitfields in ctypes structures changed between 3.7.5 https://bugs.python.org/issue39295 opened by Matthew Newville #39296: Windows register keys https://bugs.python.org/issue39296 opened by ToKa #39298: add BLAKE3 to hashlib https://bugs.python.org/issue39298 opened by larry #39299: Improve test coverage for mimetypes module https://bugs.python.org/issue39299 opened by xtreak #39301: Specification of bitshift on integers should clearly state flo https://bugs.python.org/issue39301 opened by ncoghlan #39302: Language reference does not clearly describe modern operand co https://bugs.python.org/issue39302 opened by ncoghlan #39305: Merge nntplib._NNTPBase and nntplib.NNTP https://bugs.python.org/issue39305 opened by corona10 #39306: Lib/configparser.py - RawConfigParser.set does not pass non-tr https://bugs.python.org/issue39306 opened by Strijker #39309: Please delete my account https://bugs.python.org/issue39309 opened by sfjwlejfawnf #39314: Autofill the closing paraenthesis during auto-completion for f https://bugs.python.org/issue39314 opened by opensource-assist #39316: settrace skips lines when chaining methods without arguments https://bugs.python.org/issue39316 opened by alexmojaki #39318: NamedTemporaryFile could cause double-close on an fd if _Tempo https://bugs.python.org/issue39318 opened by nneonneo #39320: Handle unpacking of */** arguments and rvalues in the compiler https://bugs.python.org/issue39320 opened by Mark.Shannon #39323: Add test for imghdr cli https://bugs.python.org/issue39323 opened by xtreak #39324: Add mimetype for extension .md (markdown) https://bugs.python.org/issue39324 opened by Ryan Batchelder #39325: Original window focus when opening IDLE by double clicking Pyt https://bugs.python.org/issue39325 opened by IrvKalb #39326: Python-3.8.1 "test_importlib" failed https://bugs.python.org/issue39326 opened by Divyansh_tiwari #39327: shutil.rmtree using vagrant synched folder fails https://bugs.python.org/issue39327 opened by PeterFS #39328: Allow filename mismatch in local and central directories in zi https://bugs.python.org/issue39328 opened by cheryl.sabella #39331: 2to3 mishandles indented imports https://bugs.python.org/issue39331 opened by galun.guy #39334: python specific index directives in our doc has been deprecate https://bugs.python.org/issue39334 opened by mdk #39336: Immutable module type can't be used as package in custom loade https://bugs.python.org/issue39336 opened by dino.viehland #39337: codecs.lookup() ignores non-ASCII characters, whereas encoding https://bugs.python.org/issue39337 opened by vstinner #39339: ProcessPoolExecutor() Exception in thread QueueManagerThread https://bugs.python.org/issue39339 opened by pythonpython #39340: shutil.rmtree and write protected files https://bugs.python.org/issue39340 opened by PeterFS #39341: [security] zipfile: ZIP Bomb vulnerability, don't check announ https://bugs.python.org/issue39341 opened by vstinner #39342: Expose X509_V_FLAG_ALLOW_PROXY_CERTS in ssl https://bugs.python.org/issue39342 opened by chrisburr #39343: Travis CI: documentation job fails in library/nntplib.rst with https://bugs.python.org/issue39343 opened by vstinner #39344: Getting error while importing ssl " import _ssl # if we can't https://bugs.python.org/issue39344 opened by Ajaya #39345: Py_Initialize Hangs on Windows 10 https://bugs.python.org/issue39345 opened by dhamilton #39346: gzip module only supports half of possible read/write scenario https://bugs.python.org/issue39346 opened by ddevault #39347: Use of argument clinic like parsing and `METH_FASTCALL` suppor https://bugs.python.org/issue39347 opened by seberg #39349: Add "cancel_futures" parameter to concurrent.futures.Executor. https://bugs.python.org/issue39349 opened by aeros #39352: Remove the formatter module, deprecated since Python 3.4 https://bugs.python.org/issue39352 opened by vstinner #39353: Deprecate the binhex module, binhex4 and hexbin4 standards https://bugs.python.org/issue39353 opened by vstinner #39355: The Python library will not compile with a C++2020 compiler be https://bugs.python.org/issue39355 opened by aCuria #39358: test_code.CoExtra leads to double-free when ce_size >1 https://bugs.python.org/issue39358 opened by slebedev #39359: zipfile: add missing "pwd: expected bytes, got str" exception https://bugs.python.org/issue39359 opened by dhillier #39360: python3.8 regression - ThreadPool join via __del__ hangs forev https://bugs.python.org/issue39360 opened by gaborbernat #39361: [C API] Document PyTypeObject.tp_print removal in What's New I https://bugs.python.org/issue39361 opened by vstinner #39362: add option to make chunksize adaptive for multiprocessing.pool https://bugs.python.org/issue39362 opened by fgregg #39363: zipfile with multiprocessing: zipfile.BadZipFile https://bugs.python.org/issue39363 opened by maxime-lemonnier #39364: Automatically tabulate module contents in the docs https://bugs.python.org/issue39364 opened by alexchandel #39365: Support (SEEK_END/SEEK_CUR) relative seeking in StringIO https://bugs.python.org/issue39365 opened by random832 #39366: Remove deprecated nntplib method https://bugs.python.org/issue39366 opened by corona10 #39369: Doc: Update mmap readline method documentation https://bugs.python.org/issue39369 opened by wellpardim #39370: askopenfilename is missing from the Tkinter filedialog library https://bugs.python.org/issue39370 opened by rdnielsen #39371: http.client.HTTPResponse raises IncompleteRead on chunked enco https://bugs.python.org/issue39371 opened by Arden #39372: The header files in Include/ have many declarations with no de https://bugs.python.org/issue39372 opened by pablogsal Most recent 15 issues with no replies (15) ========================================== #39372: The header files in Include/ have many declarations with no de https://bugs.python.org/issue39372 #39370: askopenfilename is missing from the Tkinter filedialog library https://bugs.python.org/issue39370 #39369: Doc: Update mmap readline method documentation https://bugs.python.org/issue39369 #39365: Support (SEEK_END/SEEK_CUR) relative seeking in StringIO https://bugs.python.org/issue39365 #39364: Automatically tabulate module contents in the docs https://bugs.python.org/issue39364 #39362: add option to make chunksize adaptive for multiprocessing.pool https://bugs.python.org/issue39362 #39361: [C API] Document PyTypeObject.tp_print removal in What's New I https://bugs.python.org/issue39361 #39359: zipfile: add missing "pwd: expected bytes, got str" exception https://bugs.python.org/issue39359 #39358: test_code.CoExtra leads to double-free when ce_size >1 https://bugs.python.org/issue39358 #39347: Use of argument clinic like parsing and `METH_FASTCALL` suppor https://bugs.python.org/issue39347 #39346: gzip module only supports half of possible read/write scenario https://bugs.python.org/issue39346 #39345: Py_Initialize Hangs on Windows 10 https://bugs.python.org/issue39345 #39342: Expose X509_V_FLAG_ALLOW_PROXY_CERTS in ssl https://bugs.python.org/issue39342 #39339: ProcessPoolExecutor() Exception in thread QueueManagerThread https://bugs.python.org/issue39339 #39337: codecs.lookup() ignores non-ASCII characters, whereas encoding https://bugs.python.org/issue39337 Most recent 15 issues waiting for review (15) ============================================= #39372: The header files in Include/ have many declarations with no de https://bugs.python.org/issue39372 #39366: Remove deprecated nntplib method https://bugs.python.org/issue39366 #39359: zipfile: add missing "pwd: expected bytes, got str" exception https://bugs.python.org/issue39359 #39353: Deprecate the binhex module, binhex4 and hexbin4 standards https://bugs.python.org/issue39353 #39352: Remove the formatter module, deprecated since Python 3.4 https://bugs.python.org/issue39352 #39343: Travis CI: documentation job fails in library/nntplib.rst with https://bugs.python.org/issue39343 #39342: Expose X509_V_FLAG_ALLOW_PROXY_CERTS in ssl https://bugs.python.org/issue39342 #39336: Immutable module type can't be used as package in custom loade https://bugs.python.org/issue39336 #39334: python specific index directives in our doc has been deprecate https://bugs.python.org/issue39334 #39324: Add mimetype for extension .md (markdown) https://bugs.python.org/issue39324 #39323: Add test for imghdr cli https://bugs.python.org/issue39323 #39320: Handle unpacking of */** arguments and rvalues in the compiler https://bugs.python.org/issue39320 #39318: NamedTemporaryFile could cause double-close on an fd if _Tempo https://bugs.python.org/issue39318 #39299: Improve test coverage for mimetypes module https://bugs.python.org/issue39299 #39298: add BLAKE3 to hashlib https://bugs.python.org/issue39298 Top 10 most discussed issues (10) ================================= #39318: NamedTemporaryFile could cause double-close on an fd if _Tempo https://bugs.python.org/issue39318 10 msgs #39295: usage of bitfields in ctypes structures changed between 3.7.5 https://bugs.python.org/issue39295 8 msgs #17005: Add a topological sort algorithm https://bugs.python.org/issue17005 7 msgs #37751: In codecs, function 'normalizestring' should convert both spa https://bugs.python.org/issue37751 6 msgs #39343: Travis CI: documentation job fails in library/nntplib.rst with https://bugs.python.org/issue39343 6 msgs #39353: Deprecate the binhex module, binhex4 and hexbin4 standards https://bugs.python.org/issue39353 6 msgs #29282: Fused multiply-add: proposal to add math.fma() https://bugs.python.org/issue29282 5 msgs #38076: Make struct module PEP-384 compatible https://bugs.python.org/issue38076 5 msgs #39207: concurrent.futures.ProcessPoolExecutor does not properly reap https://bugs.python.org/issue39207 5 msgs #39296: Windows register keys https://bugs.python.org/issue39296 5 msgs Issues closed (65) ================== #17718: boolop constant checking for if/while https://bugs.python.org/issue17718 closed by benjamin.peterson #19557: ast - docs for every node type are missing https://bugs.python.org/issue19557 closed by cheryl.sabella #27195: Crash when RawIOBase.write(b) evaluates b.format https://bugs.python.org/issue27195 closed by cheryl.sabella #31031: Unify duplicate bits_in_digit and bit_length https://bugs.python.org/issue31031 closed by vstinner #32021: Brotli encoding is not recognized by mimetypes https://bugs.python.org/issue32021 closed by maxking #32524: Python 2.7 leaks a packages __init__.py module object on Synta https://bugs.python.org/issue32524 closed by cheryl.sabella #32615: Inconsistent behavior if globals is a dict subclass https://bugs.python.org/issue32615 closed by vstinner #33471: string format with 'n' failling with french locales https://bugs.python.org/issue33471 closed by cheryl.sabella #34922: hashlib segmentation fault https://bugs.python.org/issue34922 closed by ned.deily #36556: Trashcan causing duplicated __del__ calls https://bugs.python.org/issue36556 closed by cheryl.sabella #36710: Pass _PyRuntimeState as an argument rather than using the _PyR https://bugs.python.org/issue36710 closed by vstinner #36746: Create test for fcntl.lockf() https://bugs.python.org/issue36746 closed by vstinner #37958: Adding get_profile_dict to pstats https://bugs.python.org/issue37958 closed by gregory.p.smith #38293: Deepcopying property objects results in unexpected TypeError https://bugs.python.org/issue38293 closed by cheryl.sabella #38330: httplib specifies content-length when transfer-encoding presen https://bugs.python.org/issue38330 closed by cheryl.sabella #38356: test_asyncio: SubprocessThreadedWatcherTests leaks threads https://bugs.python.org/issue38356 closed by asvetlov #38361: syslog: Default "ident" in syslog.openlog() shouldn't contain https://bugs.python.org/issue38361 closed by brandtbucher #38630: subprocess.Popen.send_signal() should poll the process https://bugs.python.org/issue38630 closed by vstinner #38901: [venv] Add a CLI flag to venv to use the pwd basename as the p https://bugs.python.org/issue38901 closed by vinay.sajip #38903: #if 0 block on parsetok.c https://bugs.python.org/issue38903 closed by pablogsal #39033: zipimport raises NameError: name '_boostrap_external' is not d https://bugs.python.org/issue39033 closed by petr.viktorin #39048: Look up __aenter__ before __aexit__ in the async with statemen https://bugs.python.org/issue39048 closed by ncoghlan #39156: Break up COMPARE_OP into logically distinct operations. https://bugs.python.org/issue39156 closed by Mark.Shannon #39160: ./configure --help has inconsistencies in style https://bugs.python.org/issue39160 closed by ned.deily #39164: Add private _PyErr_GetExcInfo() function which accepts a tstat https://bugs.python.org/issue39164 closed by vstinner #39179: pandas tz_convert() seems to report incorrect date conversion https://bugs.python.org/issue39179 closed by cheryl.sabella #39200: Fix inaccurate TypeError messages when calling with insufficie https://bugs.python.org/issue39200 closed by vstinner #39233: glossary entry for parameter out-of-date for positional-only p https://bugs.python.org/issue39233 closed by mark.dickinson #39249: difflib SequenceMatcher 200 char length limitation for ratio c https://bugs.python.org/issue39249 closed by terry.reedy #39259: poplib.POP3/POP3_SSL should reject timeout = 0 (non-blocking m https://bugs.python.org/issue39259 closed by vstinner #39275: Traceback off by one line when https://bugs.python.org/issue39275 closed by facundobatista #39288: Add math.nextafter(a, b) https://bugs.python.org/issue39288 closed by vstinner #39289: crypt.crypt fail with OSError "[Errno 22] Invalid argument" on https://bugs.python.org/issue39289 closed by vinay.sajip #39291: "pathlib.Path.link_to()" and "pathlib.Path.symlink_to()" have https://bugs.python.org/issue39291 closed by pitrou #39292: syslog constants behind rfc https://bugs.python.org/issue39292 closed by vinay.sajip #39297: Synchronize importlib.metadata with importlib_metadata 1.4 https://bugs.python.org/issue39297 closed by jaraco #39300: dataclasses non-default argument follows default argument https://bugs.python.org/issue39300 closed by eric.smith #39303: Refactor cmd module https://bugs.python.org/issue39303 closed by cheryl.sabella #39304: Don't accept a negative number for the count argument in str.r https://bugs.python.org/issue39304 closed by rhettinger #39307: Memory leak in parsetok https://bugs.python.org/issue39307 closed by pablogsal #39308: Literal[True] prints as Literal[1] in some cases https://bugs.python.org/issue39308 closed by gvanrossum #39310: Add math.ulp(x): unit in the last place https://bugs.python.org/issue39310 closed by vstinner #39311: difflib pathlike support for {unified,context}_diff() {from,to https://bugs.python.org/issue39311 closed by rhettinger #39312: Expose placeholder reparse points in Windows https://bugs.python.org/issue39312 closed by steve.dower #39313: lib2to3 provide a way to use exec as a function in Refactoring https://bugs.python.org/issue39313 closed by pablogsal #39315: Lists of objects containing lists https://bugs.python.org/issue39315 closed by hmathers #39317: This new feature or bug about operator "- -"? https://bugs.python.org/issue39317 closed by rhettinger #39319: ntpath module must not be available on POSIX platforms https://bugs.python.org/issue39319 closed by eryksun #39321: AMD64 FreeBSD Non-Debug 3.x: main regrtest process killed by S https://bugs.python.org/issue39321 closed by vstinner #39322: Add gc.is_finalized to check if an object has been finalised b https://bugs.python.org/issue39322 closed by pablogsal #39329: smtplib.LMTP needs timeout parameter https://bugs.python.org/issue39329 closed by vstinner #39330: Way to build without IDLE https://bugs.python.org/issue39330 closed by zach.ware #39332: Python 3.6 compiler protections from Ubuntu distros https://bugs.python.org/issue39332 closed by benjamin.peterson #39333: argparse should offer an alternative to SystemExit in case a p https://bugs.python.org/issue39333 closed by geophile #39335: round Decimal edge case https://bugs.python.org/issue39335 closed by benjamin.peterson #39338: Data lost randomly from dictionary after creating the dictiona https://bugs.python.org/issue39338 closed by zach.ware #39348: wrong rst syntax in socket.rst https://bugs.python.org/issue39348 closed by Mariatta #39350: Remove deprecated fractions.gcd() https://bugs.python.org/issue39350 closed by vstinner #39351: Remove base64.encodestring() and base64.decodestring() aliases https://bugs.python.org/issue39351 closed by vstinner #39354: collections.UserString format and format_map return a string https://bugs.python.org/issue39354 closed by rhettinger #39356: zipfile suprising "except DeprecationWarning:" block https://bugs.python.org/issue39356 closed by vstinner #39357: bz2: Remove deprecated buffering parameter of bz2.BZ2File https://bugs.python.org/issue39357 closed by vstinner #39367: readline module core dumps Python 3.8.1 when calling exit() https://bugs.python.org/issue39367 closed by vstinner #39368: A matrix (list of lists) behaves differently, depending how it https://bugs.python.org/issue39368 closed by ezio.melotti #1531415: parsetok.c emits warnings by writing to stderr https://bugs.python.org/issue1531415 closed by pablogsal

1 0

Questions about CPython's behavior on addition operator -- binary_op1 (abstract.c) and nb_add (typeobject.c)
by Raphaël Monat Jan. 17, 2020

Jan. 17, 2020

Hi all, I'm looking at CPython's behavior when an addition is called. From what I understand, binary_op1 <https://github.com/python/cpython/blob/3.8/Objects/abstract.c#L786> is eventually called, and it calls either slotv or slotw, which seems to be the binaryfunc defined as nb_add in the field tp_as_number of respectively v / w. I have a few questions: 1) In the default case, tp_as_number->nb_add is defined by the function slot_nb_add <https://github.com/python/cpython/blob/3.8/Objects/typeobject.c#L6312> itself stemming from the macro expansion SLOT1BINFULL <https://github.com/python/cpython/blob/3.8/Objects/typeobject.c#L6140> defined in typeobject.c. Both binary_op1(v, w) and slot_nb_add(v, w) appear to perform similar checks (if their second argument is a subtype of the first, etc), to decide if v's add or w's reverse add must be called and in which order. I find this repetition weird, and I guess I'm missing something... Any ideas? 2) From the SLOT1BINFULL macro, both __add__ and __radd__ are defined by the slot_nb_add function (with some argument swapping done by wrap_binaryfunc_l / wrap_binaryfunc_r). If I want to define a different behavior for the reverse operator during a definition with a PyTypeObject, I guess I should add an "__radd__" method? 3) If I create a user-defined class A, having different methods __add__ and __radd__, these methods are added in A's dictionary. From what I understand, the function update_one_slot <https://github.com/python/cpython/blob/3.8/Objects/typeobject.c#L7209> is then called to change A's tp_as_number->nb_add to point to the methods defined by __add__ and __radd__? From the code documentation, I think that "a wrapper for the special methods is installed". Where exactly is this wrapper applied, and how does it know when to dispatch to __add__ or __radd__? Kind regards, Raphaël

2 1

Windows - rebuilding grammar files
by Abdur-Rahmaan Janhangeer Jan. 14, 2020

Jan. 14, 2020

Greetings list, On windows i want to play with the grammar file, but according to this article <https://realpython.com/cpython-source-code-guide/>: > For Windows, there is no officially supported way of running pgen. However, you can clone my fork <https://github.com/tonybaloney/cpython/tree/pcbuildregen> and run build.bat --regen from within the PCBuild directory. But i don't want to work from his fork. Is there an official way of regenerating the files? I just want to have my own keywords. As far as i've understood, rebuilding won't do it. Yours, Abdur-Rahmaan Janhangeer Mauritius

2 2

Why doesn't venv also install python3*-config?
by Musbur Jan. 13, 2020

Jan. 13, 2020

Hello, I'm experimenting with package development on different versions of Python in different virtualenvs. After running "make" I don't do "make install", but rather I set up virtualenvs by running /path/to/source/python -m venv env_dir. This works for as long as I don't need to compile extensions. Once I do that I'm running into trouble because there is no python3-config binary in the venv, so it uses the "system" python3-config which of course returns results for the /usr(/local)/.... tree. This seems to go against the idea of an encapsulated and self-contained environment. And the venv created straight from the "not-installed" source tree works so well that having a venv/bin/python3-config whose output points into the source tree seems a logical step. Is this an omission or is there a rationale for not doing it? Of course I can "properly" install different Python versions by using different "configure --prefix" directories. But I like the venv so much in general that this rubs me the wrong way. Thanks!

10 15

Should we pass tstate in the VECTORCALL calling convention before making it public?
by Victor Stinner Jan. 11, 2020

Jan. 11, 2020

Hi, I started to modify Python internals to pass explicitly the Python thread state ("tstate") to internal C a functions: https://vstinner.github.io/cpython-pass-tstate.html Until subinterpreters will be fully implemented, it's unclear if getting the current Python thread state using _PyThreadState_GET() macro (which uses an atomic read) will remain efficient. For example, right now, the "GIL state" API doesn't support subinterpreters: fixing this may require to add a lock somewhere which may make _PyThreadState_GET() less efficient. Sorry, I don't have numbers, since I didn't experiment to implement these changes yet: I was blocked by other issues. We can only guess at this point. To me, it sounds like a good practice to pass the current Python thread state to internal C functions. It seems like most core developers agreed with that in my previous python-dev thread "Pass the Python thread state to internal C functions": https://mail.python.org/archives/list/python-dev@python.org/thread/PQBGECVG… The question is now if we should "propagate" tstate to function calls in the latest VECTORCALL calling convention (which is currently private). Petr Viktorin plans to make VECTORCALL APIs public in Python 3.9, as planned in the PEP 590: https://bugs.python.org/issue39245 I added explicitly Stefan Behnel in copy, since Cython should be directly impacted by such change. Cython is the kind of project which may benefit of having tstate accessible directly. I started to move more and more things from "globals" to "per interpreter". For example, the garbage collector is now "per interpreter" (lives in PyThreadState). Small integer singletons are now also "per singleton": int("1") are now different objects in each interpreter, whereas they were shared previously. Later, even "None" singleton (and all other singletons) should be made "per interpreter". Getting a "per interpreter" object requires to state from the Python thread state: call _PyThreadState_GET(). Avoiding _PyThreadState_GET() calls reduces any risk of making Python slower with incoming subinterpreter changes. For the long term, the goal is that each subinterpreter has its own isolated world: no Python object should be shared, no state should be shared. The intent is to avoid any need of locking, to maximize performance when running interpreters in parallel. Obviously, each interpreter will have its own private GIL ;-) Py_INCREF() and Py_DECREF() would require slow atomic operations if Python objects are shared. If objects are not shared between interpreters, Py_INCREF() and Py_DECREF() can remain as fast as they are today. Any additional locking may kill performance. Victor -- Night gathers, and now my watch begins. It shall not end until my death.

6 11

Object deallocation during the finalization of Python program
by Pau Freixes Jan. 11, 2020

Jan. 11, 2020

Hi, Recently I've been facing a really weird bug where a Python program was randomly segfaulting during the finalization, the program was using some C extensions via Cython. Debugging the issue I realized that during the deallocation of one of the Python objects the deallocation function was trying to release a pointer that was surprisingly assigned to NULL. The pointer was at the same time held by another Python object that was an attribute of the Python object that had the deallocation function, something like this: class Foo: my_type * value class Bar def __cinit__: self._foo = Foo() self._foo->value = initialize() def __dealloc__: destroy(self._foo->value) Seems that randomly the instance of the object Foo held by the Bar object was deallocated by the CPython interpreter before the Foo deallocation, so after being deallocated - and zeroing the memory space of the instance of Foo - the execution of the `destroy(self._foo->value)` was in fact given as a parameter a NULL address and raising a segfault. It was a surprise for me, If I'm not missing something the deallocation of the Foo instance happened even though there was still an active reference held by the Bar object. As a kind of double-checking I changed the program for making an explicit `gc.collect()` before the last line of the Python program. As a result, I couldn't reproduce the segfault, which theoretically would mean that objects were deallocated "in order". So my question would be, could CPython deallocate the objects during the finalization step without considering the dependencies between objects? If this is not the right list to make this kind of questions, just let me know what would be the best place for making this kind of questions Thanks in advance, -- --pau

3 3

Requesting PR review on locale module
by Cédric Krier Jan. 11, 2020

Jan. 11, 2020

Hi, Few months ago, I submitted a PR [1] for the bpo [2] about locale.format casting Decimal into float. Has someone some times to finish the review? This change is blocking a bugfix on Tryton [3]. [1] https://github.com/python/cpython/pull/15275 [2] https://bugs.python.org/issue34311 [3] https://bugs.tryton.org/issue8574 Thanks, -- Cédric Krier - B2CK SPRL Email/Jabber: cedric.krier(a)b2ck.com Tel: +32 472 54 46 59 Website: http://www.b2ck.com/

4 4

Is anyone aware of any existing tests for ternary_op in abstract.c?
by Nick Coghlan Jan. 11, 2020

Jan. 11, 2020

[Note: I don't think this is a high priority issue, as it only relates to doing mixed-type modular exponentiation, and that seems like an inherently bad idea anyway. But I'm also curious if anyone is able to explain the current behaviour, as I haven't come up with a better explanation than "It doesn't actually work, but nobody needs it enough to complain about it not working"] While writing up bpo-39302 [1], I tried experimenting at the REPL to see if I could get __pow__ to ever exercise the code paths where 3-argument pow() is handled by the exponent or the modulus (as described in the source code and PEP 208), rather than the usual case where it is handled by the base. I failed - the only time I could get my custom __pow__ implementation to run was when it was the base, never when it was the modulus or exponent. This means that, as far as I'm able to tell, ternary_op in abstract.c isn't actually working as intended, or at least, it doesn't work in combination with the way the `nb_power` slot wrapper is implemented in typeobject.c. That slot wrapper only ever calls the Python level function provided by the first operand, even though ternary_op calls 3 different slot implementations, they all ultimately get resolved as attempts to call the same python level function (the `__pow__` implementation on the base). I couldn't find any test cases that exercise this functionality, so even though PEP 208 describes the expected semantics, it isn't clear whether or not the implementation has ever achieved them. This is the session where I tried to see if I could get it to work the way I expected it to work based on the comments in ternary_op: [py3.7]> class _PowArgsMixin: ... def __pow__(*args): ... return tuple(map(type, args)) ... [py3.7]> class NoPow: ... pass ... [py3.7]> class NotImplementedPow: ... def __pow__(*args): ... return NotImplemented ... [py3.7]> class UnrelatedPow(_PowArgsMixin): ... pass ... [py3.7]> class ChildOfNoPow(_PowArgsMixin, NoPow): ... pass ... [py3.7]> class ChildOfNotImplementedPow(_PowArgsMixin, NotImplementedPow): ... pass ... [py3.7]> no_pow = NoPow() [py3.7]> ni_pow = NotImplementedPow() [py3.7]> has_pow = UnrelatedPow() [py3.7]> child_no = ChildOfNoPow() [py3.7]> child_ni = ChildOfNotImplementedPow() [py3.7]> # They all give the expected result as the base ... pow(has_pow, no_pow, no_pow) (<class '__main__.UnrelatedPow'>, <class '__main__.NoPow'>, <class '__main__.NoPow'>) [py3.7]> pow(has_pow, ni_pow, ni_pow) (<class '__main__.UnrelatedPow'>, <class '__main__.NotImplementedPow'>, <class '__main__.NotImplementedPow'>) [py3.7]> pow(child_no, no_pow, no_pow) (<class '__main__.ChildOfNoPow'>, <class '__main__.NoPow'>, <class '__main__.NoPow'>) [py3.7]> pow(child_ni, ni_pow, ni_pow) (<class '__main__.ChildOfNotImplementedPow'>, <class '__main__.NotImplementedPow'>, <class '__main__.NotImplementedPow'>) [py3.7]> # But none of them work when given as the exponent ... pow(no_pow, has_pow, no_pow) Traceback (most recent call last): File "<stdin>", line 2, in <module> TypeError: unsupported operand type(s) for pow(): 'NoPow', 'UnrelatedPow', 'NoPow' [py3.7]> pow(ni_pow, has_pow, ni_pow) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: unsupported operand type(s) for pow(): 'NotImplementedPow', 'UnrelatedPow', 'NotImplementedPow' [py3.7]> pow(no_pow, child_no, no_pow) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: unsupported operand type(s) for pow(): 'NoPow', 'ChildOfNoPow', 'NoPow' [py3.7]> pow(ni_pow, child_ni, ni_pow) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: unsupported operand type(s) for pow(): 'NotImplementedPow', 'ChildOfNotImplementedPow', 'NotImplementedPow' [py3.7]> # And none of them work when given as the modulus either ... pow(no_pow, no_pow, has_pow) Traceback (most recent call last): File "<stdin>", line 2, in <module> TypeError: unsupported operand type(s) for pow(): 'NoPow', 'NoPow', 'UnrelatedPow' [py3.7]> pow(ni_pow, ni_pow, has_pow) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: unsupported operand type(s) for pow(): 'NotImplementedPow', 'NotImplementedPow', 'UnrelatedPow' [py3.7]> pow(no_pow, no_pow, child_no) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: unsupported operand type(s) for pow(): 'NoPow', 'NoPow', 'ChildOfNoPow' [py3.7]> pow(ni_pow, ni_pow, child_ni) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: unsupported operand type(s) for pow(): 'NotImplementedPow', 'NotImplementedPow', 'ChildOfNotImplementedPow' [1] https://bugs.python.org/issue39302 -- Nick Coghlan | ncoghlan(a)gmail.com | Brisbane, Australia

1 0

Summary of Python tracker Issues
by Python tracker Jan. 10, 2020

Jan. 10, 2020

ACTIVITY SUMMARY (2020-01-03 - 2020-01-10) 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 7251 (+24) closed 43792 (+66) total 51043 (+90) Open issues with patches: 2846 Issues opened (63) ================== #25872: multithreading traceback KeyError when modifying file https://bugs.python.org/issue25872 reopened by xtreak #27657: urlparse fails if the path is numeric https://bugs.python.org/issue27657 reopened by orsenthil #29778: _Py_CheckPython3 uses uninitialized dllpath when embedder sets https://bugs.python.org/issue29778 reopened by vstinner #39158: ast.literal_eval() doesn't support empty sets https://bugs.python.org/issue39158 reopened by pablogsal #39204: Automate adding Type Annotations to Documentation https://bugs.python.org/issue39204 opened by cooperlees #39205: Hang when interpreter exits after ProcessPoolExecutor.shutdown https://bugs.python.org/issue39205 opened by bquinlan #39206: Modulefinder does not consider source file encoding https://bugs.python.org/issue39206 opened by Nicholas Feix #39207: concurrent.futures.ProcessPoolExecutor does not properly reap https://bugs.python.org/issue39207 opened by yus2047889 #39210: Sorting falls back to use __gt__ when __lt__ is not present https://bugs.python.org/issue39210 opened by yanmitrofanov #39212: Show qualified function name when giving arguments error https://bugs.python.org/issue39212 opened by cool-RR #39213: cmd should have a hook in the finally block of cmdloop https://bugs.python.org/issue39213 opened by Joseph Sible #39214: Add curses.window.in_wch https://bugs.python.org/issue39214 opened by Anthony Sottile #39217: GC of a ctypes object causes application crash https://bugs.python.org/issue39217 opened by Kevin Schlossser #39218: Assertion failure when calling statistics.variance() on a floa https://bugs.python.org/issue39218 opened by reed #39219: Fix attributes of syntax errors raized in the tokenizer https://bugs.python.org/issue39219 opened by serhiy.storchaka #39220: constant folding affects annotations despite 'from __future__ https://bugs.python.org/issue39220 opened by Carl.Friedrich.Bolz #39221: Cross compiled python installed wrong version of lib2to3/Gramm https://bugs.python.org/issue39221 opened by puchenyaka #39222: unittest.mock.Mock.parent is broken or undocumented https://bugs.python.org/issue39222 opened by florian.brucker #39224: HTTPConnection.timeout None support https://bugs.python.org/issue39224 opened by Daniel Farley #39228: traceback.FrameSummary does not handle exceptions from `repr() https://bugs.python.org/issue39228 opened by blueyed #39229: library/functions.rst causes translated builds to fail https://bugs.python.org/issue39229 opened by rffontenelle #39231: Mistaken notion in tutorial https://bugs.python.org/issue39231 opened by r0b #39232: asyncio crashes when tearing down the proactor event loop https://bugs.python.org/issue39232 opened by mikeshardmind #39233: glossary entry for parameter out-of-date for positional-only p https://bugs.python.org/issue39233 opened by mark.dickinson #39236: [venv] Adding a .gitignore file to virtual environments https://bugs.python.org/issue39236 opened by brett.cannon #39238: test_asyncio: test_cancel_make_subprocess_transport_exec() han https://bugs.python.org/issue39238 opened by vstinner #39241: Popen of python3.6 hangs on os.read(errpipe_read, 50000) https://bugs.python.org/issue39241 opened by liuxu1005 #39243: CDLL __init__ no longer supports name being passed as None whe https://bugs.python.org/issue39243 opened by David Heffernan #39244: multiprocessing.get_all_start_methods() wrong default on macOS https://bugs.python.org/issue39244 opened by stefanholek #39245: Public API for Vectorcall (PEP 590) https://bugs.python.org/issue39245 opened by petr.viktorin #39247: dataclass defaults and property don't work together https://bugs.python.org/issue39247 opened by Michael Robellard #39248: test_distutils fails on PPC64 Fedora 3.x: /tmp/subprocess.py https://bugs.python.org/issue39248 opened by vstinner #39249: difflib SequenceMatcher 200 char length limitation for ratio c https://bugs.python.org/issue39249 opened by Daniel Pezoa #39252: email.contentmanager.raw_data_manager bytes handler breaks on https://bugs.python.org/issue39252 opened by rmccampbell7 #39253: Running the test suite with --junit-xml and -R incorrectly rep https://bugs.python.org/issue39253 opened by pablogsal #39254: python shebang in python3 tarball files https://bugs.python.org/issue39254 opened by arekm #39257: contextvars.Context.run hangs forever in ProccessPoolExecutor https://bugs.python.org/issue39257 opened by ronserruya #39259: poplib.POP3/POP3_SSL should reject timeout = 0 (non-blocking m https://bugs.python.org/issue39259 opened by corona10 #39260: distutils.spawn: find_executable() Fails To Find Many Executab https://bugs.python.org/issue39260 opened by tbpassin #39263: Windows Installer can't select TargetDir in UI? https://bugs.python.org/issue39263 opened by Jameson Nash #39264: Fix UserDict.get to account for __missing__ https://bugs.python.org/issue39264 opened by bar.harel #39266: [2.7] test_bsddb3 leaked [1, 1, 1] file descriptors on AMD64 R https://bugs.python.org/issue39266 opened by vstinner #39267: Fix dict's __missing__ documentation https://bugs.python.org/issue39267 opened by bar.harel #39268: test_asyncio: test_create_server_ssl_verified() failed on AMD6 https://bugs.python.org/issue39268 opened by vstinner #39273: ncurses does not include BUTTON5_* constants https://bugs.python.org/issue39273 opened by michael.yoo(a)akunacapital.com #39274: Conversion from fractions.Fraction to bool https://bugs.python.org/issue39274 opened by francois-durand #39275: Traceback off by one line when https://bugs.python.org/issue39275 opened by facundobatista #39276: type() cause segmentation fault in callback function called f https://bugs.python.org/issue39276 opened by karczex #39277: _PyTime_FromDouble() fails to detect an integer overflow when https://bugs.python.org/issue39277 opened by graingert #39278: add docstrings to functions in pdb module https://bugs.python.org/issue39278 opened by carlbordum #39279: Don't allow non-Ascii digits in platform.py https://bugs.python.org/issue39279 opened by cool-RR #39280: Don't allow datetime parsing to accept non-Ascii digits https://bugs.python.org/issue39280 opened by cool-RR #39281: The CO_NESTED flag is associated with a significant performanc https://bugs.python.org/issue39281 opened by bup #39282: python-config --embed documentation https://bugs.python.org/issue39282 opened by M.Kerr #39283: Add ability to inherit unittest arguement parser https://bugs.python.org/issue39283 opened by atb00ker #39285: PurePath.match indicates case-sensitive nature and presents a https://bugs.python.org/issue39285 opened by xtreak #39286: Configure includes LIBS but does not pass it to distutils https://bugs.python.org/issue39286 opened by Alex Grund #39287: Document UTF-8 mode in the using/windows. https://bugs.python.org/issue39287 opened by inada.naoki #39288: Add math.nextafter(a, b) https://bugs.python.org/issue39288 opened by vstinner #39289: crypt.crypt fail with OSError "[Errno 22] Invalid argument" on https://bugs.python.org/issue39289 opened by vinay.sajip #39290: lib2to3.fixes.fix_import: support imports_as_name in traverse_ https://bugs.python.org/issue39290 opened by BTaskaya #39291: "pathlib.Path.link_to()" and "pathlib.Path.symlink_to()" have https://bugs.python.org/issue39291 opened by Rockmizu #39292: syslog constants behind rfc https://bugs.python.org/issue39292 opened by tryanunderwood(a)gmail.com Most recent 15 issues with no replies (15) ========================================== #39292: syslog constants behind rfc https://bugs.python.org/issue39292 #39291: "pathlib.Path.link_to()" and "pathlib.Path.symlink_to()" have https://bugs.python.org/issue39291 #39290: lib2to3.fixes.fix_import: support imports_as_name in traverse_ https://bugs.python.org/issue39290 #39288: Add math.nextafter(a, b) https://bugs.python.org/issue39288 #39287: Document UTF-8 mode in the using/windows. https://bugs.python.org/issue39287 #39286: Configure includes LIBS but does not pass it to distutils https://bugs.python.org/issue39286 #39285: PurePath.match indicates case-sensitive nature and presents a https://bugs.python.org/issue39285 #39282: python-config --embed documentation https://bugs.python.org/issue39282 #39281: The CO_NESTED flag is associated with a significant performanc https://bugs.python.org/issue39281 #39278: add docstrings to functions in pdb module https://bugs.python.org/issue39278 #39276: type() cause segmentation fault in callback function called f https://bugs.python.org/issue39276 #39273: ncurses does not include BUTTON5_* constants https://bugs.python.org/issue39273 #39268: test_asyncio: test_create_server_ssl_verified() failed on AMD6 https://bugs.python.org/issue39268 #39267: Fix dict's __missing__ documentation https://bugs.python.org/issue39267 #39266: [2.7] test_bsddb3 leaked [1, 1, 1] file descriptors on AMD64 R https://bugs.python.org/issue39266 Most recent 15 issues waiting for review (15) ============================================= #39290: lib2to3.fixes.fix_import: support imports_as_name in traverse_ https://bugs.python.org/issue39290 #39288: Add math.nextafter(a, b) https://bugs.python.org/issue39288 #39287: Document UTF-8 mode in the using/windows. https://bugs.python.org/issue39287 #39280: Don't allow datetime parsing to accept non-Ascii digits https://bugs.python.org/issue39280 #39279: Don't allow non-Ascii digits in platform.py https://bugs.python.org/issue39279 #39278: add docstrings to functions in pdb module https://bugs.python.org/issue39278 #39277: _PyTime_FromDouble() fails to detect an integer overflow when https://bugs.python.org/issue39277 #39267: Fix dict's __missing__ documentation https://bugs.python.org/issue39267 #39264: Fix UserDict.get to account for __missing__ https://bugs.python.org/issue39264 #39259: poplib.POP3/POP3_SSL should reject timeout = 0 (non-blocking m https://bugs.python.org/issue39259 #39245: Public API for Vectorcall (PEP 590) https://bugs.python.org/issue39245 #39233: glossary entry for parameter out-of-date for positional-only p https://bugs.python.org/issue39233 #39229: library/functions.rst causes translated builds to fail https://bugs.python.org/issue39229 #39228: traceback.FrameSummary does not handle exceptions from `repr() https://bugs.python.org/issue39228 #39224: HTTPConnection.timeout None support https://bugs.python.org/issue39224 Top 10 most discussed issues (10) ================================= #38623: Python documentation should mention how to find site-packages https://bugs.python.org/issue38623 12 msgs #29778: _Py_CheckPython3 uses uninitialized dllpath when embedder sets https://bugs.python.org/issue29778 9 msgs #39253: Running the test suite with --junit-xml and -R incorrectly rep https://bugs.python.org/issue39253 8 msgs #39029: TestMaildir.test_clean fails randomly under parallel tests https://bugs.python.org/issue39029 7 msgs #39158: ast.literal_eval() doesn't support empty sets https://bugs.python.org/issue39158 7 msgs #39280: Don't allow datetime parsing to accept non-Ascii digits https://bugs.python.org/issue39280 7 msgs #30717: Add unicode grapheme cluster break algorithm https://bugs.python.org/issue30717 6 msgs #39200: Fix inaccurate TypeError messages when calling with insufficie https://bugs.python.org/issue39200 6 msgs #39210: Sorting falls back to use __gt__ when __lt__ is not present https://bugs.python.org/issue39210 6 msgs #39243: CDLL __init__ no longer supports name being passed as None whe https://bugs.python.org/issue39243 6 msgs Issues closed (68) ================== #16806: col_offset is -1 and lineno is wrong for multiline string expr https://bugs.python.org/issue16806 closed by pablogsal #18930: os.spawnXX functions terminates process if second argument is https://bugs.python.org/issue18930 closed by pablogsal #18969: test suite: enable faulthandler timeout in assert_python https://bugs.python.org/issue18969 closed by vstinner #22606: Inconsistency between Python 2 and PyPy regarding future impor https://bugs.python.org/issue22606 closed by benjamin.peterson #23147: Possible error in _header_value_parser.py https://bugs.python.org/issue23147 closed by r.david.murray #24554: GC should happen when a subinterpreter is destroyed https://bugs.python.org/issue24554 closed by vstinner #24817: IDLE: disable format menu items when not applicable https://bugs.python.org/issue24817 closed by terry.reedy #28143: ASDL compatibility with Python 3 system interpreter https://bugs.python.org/issue28143 closed by cheryl.sabella #28367: Add more standard baud rate constants to "termios" https://bugs.python.org/issue28367 closed by twouters #28617: Why isn't "in" called a comparison operation? https://bugs.python.org/issue28617 closed by wim.glenn #31829: Portability issues with pickle https://bugs.python.org/issue31829 closed by cheryl.sabella #33095: Cross-reference isolated mode from relevant locations https://bugs.python.org/issue33095 closed by xtreak #33255: json.dumps has different behaviour if encoding='utf-8' or enco https://bugs.python.org/issue33255 closed by cheryl.sabella #34110: cPickle may raise AttributeError when loading concurrently in https://bugs.python.org/issue34110 closed by cheryl.sabella #34946: inspect.getcallargs is marked as deprecated in documentation, https://bugs.python.org/issue34946 closed by anthonypjshaw #35292: Make SimpleHTTPRequestHandler load mimetypes lazily https://bugs.python.org/issue35292 closed by steve.dower #36761: Extended slice assignment + iterable unpacking https://bugs.python.org/issue36761 closed by wim.glenn #37537: Compute allocated blocks in _Py_GetAllocatedBlocks() https://bugs.python.org/issue37537 closed by inada.naoki #38209: Simplify dataclasses.InitVar by using __class_getitem__() https://bugs.python.org/issue38209 closed by eric.smith #38502: regrtest: use process groups https://bugs.python.org/issue38502 closed by vstinner #38615: imaplib has no timeout setting https://bugs.python.org/issue38615 closed by vstinner #38871: lib2to3 generates invalid code with filter and ternary operato https://bugs.python.org/issue38871 closed by vstinner #38907: http.server (command) fails to bind dual-stack on Windows https://bugs.python.org/issue38907 closed by jaraco #38973: Shared Memory List Returns 0 Length https://bugs.python.org/issue38973 closed by HugeAckmen #39055: base64.b64decode() with validate=True does not raise for a tra https://bugs.python.org/issue39055 closed by serhiy.storchaka #39056: Issues with handling the -W option https://bugs.python.org/issue39056 closed by serhiy.storchaka #39057: Issues with urllib.request.proxy_bypass_environment https://bugs.python.org/issue39057 closed by serhiy.storchaka #39074: Threading memory leak in _shutdown_locks for non-daemon thread https://bugs.python.org/issue39074 closed by vstinner #39141: IDLE: system clear function returns 256 on Mac OS Catalina https://bugs.python.org/issue39141 closed by terry.reedy #39152: Faulty override of tkinter.Misc.configure in tkinter.ttk.Scale https://bugs.python.org/issue39152 closed by terry.reedy #39161: Py_NewInterpreter docs need updating for multi-phase initializ https://bugs.python.org/issue39161 closed by petr.viktorin #39166: Python 3.9.0a2 changed how "async for" traces its final iterat https://bugs.python.org/issue39166 closed by Mark.Shannon #39174: unicodedata.normalize failing with NFD and NFKD for some chara https://bugs.python.org/issue39174 closed by Lee Collins #39191: Coroutine is awaited despite an exception in run_until_complet https://bugs.python.org/issue39191 closed by asvetlov #39196: json fails to encode dictionary view types https://bugs.python.org/issue39196 closed by inada.naoki #39198: Lock may not be released in Logger.isEnabledFor https://bugs.python.org/issue39198 closed by vinay.sajip #39201: Threading.timer leaks memory in 3.8.0/3.8.1 https://bugs.python.org/issue39201 closed by vstinner #39203: python3 time module misses attributes in Mac installers https://bugs.python.org/issue39203 closed by ned.deily #39208: PDB pm function throws exception without sys import https://bugs.python.org/issue39208 closed by zach.ware #39209: Crash on REPL mode with long text copy and paste https://bugs.python.org/issue39209 closed by pablogsal #39211: Change in http.server default IP behavior? https://bugs.python.org/issue39211 closed by jaraco #39215: Type Annotation of nested function with positional only argume https://bugs.python.org/issue39215 closed by pablogsal #39216: ast_opt.c -- missing posonlyargs? https://bugs.python.org/issue39216 closed by pablogsal #39223: Fold constant slicing with slices https://bugs.python.org/issue39223 closed by serhiy.storchaka #39225: Python should warn when a global/local has the same name as a https://bugs.python.org/issue39225 closed by brett.cannon #39226: venv does not include pythonXX.lib https://bugs.python.org/issue39226 closed by Antonio Vázquez Blanco #39227: OverflowError in len(range(2**63)) https://bugs.python.org/issue39227 closed by rhettinger #39230: fail on datetime import if _datetime.py exists in PATH https://bugs.python.org/issue39230 closed by vstinner #39234: `enum.auto()` incrementation value not specified. https://bugs.python.org/issue39234 closed by eric.smith #39235: Generator expression has wrong line/col info when inside a Cal https://bugs.python.org/issue39235 closed by serhiy.storchaka #39237: Redundant call to round in delta_new https://bugs.python.org/issue39237 closed by vstinner #39239: select.epoll.unregister(fd) should not ignore EBADF https://bugs.python.org/issue39239 closed by vstinner #39240: keyerror in string format https://bugs.python.org/issue39240 closed by eric.smith #39242: Update news.gmane.org to news.gmane.io https://bugs.python.org/issue39242 closed by vstinner #39246: shutil.rmtree is inefficient because of using os.scandir inste https://bugs.python.org/issue39246 closed by Felipe A. Hernandez #39250: os.path.commonpath() not so common https://bugs.python.org/issue39250 closed by zach.ware #39251: outdated windows store links in WindowsApps folder https://bugs.python.org/issue39251 closed by steve.dower #39255: Windows and Unix run-time differences https://bugs.python.org/issue39255 closed by eryksun #39256: Exception handler set by set_exception_handler is called only https://bugs.python.org/issue39256 closed by asvetlov #39258: json serialiser errors with numpy int64 https://bugs.python.org/issue39258 closed by xtreak #39261: Dead assignment in pyinit_config https://bugs.python.org/issue39261 closed by benjamin.peterson #39262: Unused error message in _sharedexception_bind https://bugs.python.org/issue39262 closed by benjamin.peterson #39265: test_ssl failed on AMD64 RHEL8 Refleaks 2.7 https://bugs.python.org/issue39265 closed by vstinner #39269: Descriptor how-to guide wanting update for 3.6+ features https://bugs.python.org/issue39269 closed by rhettinger #39270: Dead assignment in config_init_module_search_paths https://bugs.python.org/issue39270 closed by vstinner #39271: Dead assignment in pattern_subx https://bugs.python.org/issue39271 closed by serhiy.storchaka #39272: Dead assignment in _ssl__SSLContext_load_verify_locations_impl https://bugs.python.org/issue39272 closed by vstinner #39284: Flexible indentation https://bugs.python.org/issue39284 closed by eric.smith

1 0

Differences in what lint (e.g., mypy, flake8, etc) require from new code and what Cpython uses/returns - e.g., strings with single/double quotes.
by Michael Jan. 9, 2020

Jan. 9, 2020

Hi all, Last year I was struggling to get some code to pass CI in pypa/packaging. There were other issues, but one that suprised me most was learning to ALWAYS use double quotes (") to get the code to pass the lint check (type checking). Anything using single quotes (') as string delimiters were not accepted as a STRING type. I am not questioning the demands of the lint checker - rather - I am offering my services (aka time) to work through core to make CPython pass it's own (I assume) PEP recommendations or guidelines. Again, this is not a bug-report - but an offer to assist with what I see as an inconsistency. If my assistance in this area is appreciated/desired I would appreciate one or more core developers to assist me with managing the PR process. Not for speed, but I would not want to burden just one core developer. My approach would entail opening a number of related 'issues' for different pieces: e.g., Lib, Modules, Python, Documentation where some Lib|Modules|Python pieces might need to be individual 'issues' due to size and/or complexity. I do not see this as happening 'overnight'. so-called simple things to fix: In Documentation: The return value is the result of the evaluated expression. Syntax errors are reported as exceptions. Example: x = 1 eval('x+1') 2 Change the text above to state eval("x+1") - assuming the lint process would no longer accept eval('x+1') as proper typed syntax. And, then, hoping this is still regarded as 'simple' make sure code such as ctypes.util.find_library() is consistent, returning strings terminated by double quotes rather than the single quotes as of now. >>> import ctypes.util >>> ctypes.util.find_library("c") >>> 'libc.a(shr.o)' >>> ctypes.util.find_library("ssl") >>> 'libssl.a(libssl.so)' Something more "complex" may be the list of names dir() returns: >>> >>> import sysconfig >>> dir(sysconfig)) ['_BASE_EXEC_PREFIX', '_BASE_PREFIX', '_CONFIG_VARS', '_EXEC_PREFIX', '_INSTALL_SCHEMES', '_PREFIX', '_PROJECT_BASE', '_PYTHON_BUILD', '_PY_VERSION', '_PY_VERSION_SHORT', '_PY_VERSION_SHORT_NO_DOT', '_SCHEME_KEYS', '_USER_BASE', '__all__', '__builtins__', '__cached__', '__doc__', '__file__', '__loader__', '__name__', '__package__', '__spec__', '_expand_vars', '_extend_dict', '_generate_posix_vars', '_get_default_scheme', '_get_sysconfigdata_name', '_getuserbase', '_init_non_posix', '_init_posix', '_is_python_source_dir', '_main', '_parse_makefile', '_print_dict', '_safe_realpath', '_subst_vars', '_sys_home', 'get_config_h_filename', 'get_config_var', 'get_config_vars', 'get_makefile_filename', 'get_path', 'get_path_names', 'get_paths', 'get_platform', 'get_python_version', 'get_scheme_names', 'is_python_build', 'os', 'pardir', 'parse_config_h', 'realpath', 'scheme', 'sys'] >>> Regards, Michael

3 3

Dict __missing__ consistency issues.
by Bar Harel Jan. 9, 2020

Jan. 9, 2020

Hey guys, I was just about to fix dict's get() to call __missing__ if a key doesn't exist (before returning the default value) but realized that although small, that patch can cause future issues. Right now there's an inconsistency: >>> from collections import UserDict >>> class A(dict): ... def __missing__(self, key): ... print(key) ... >>> class B(UserDict): ... def __missing__(self, key): ... print("UserDict", key) ... >>> a = A() >>> b = B() >>> a.get(123) >>> b.get(123) UserDict 123 >>> a.get(123, "abc") 'abc' >>> b.get(123, "abc") UserDict 123 The reason for this inconsistency is because the Mapping abc and dict behave differently. Dict's get doesn't call __getitem__ which causes the call not to route to __missing__. MutableMapping's get calls __getitem__, which UserDict implements as a check to __missing__ as well. According to the doc, the specification requires dict's __getitem__ to call __missing__. It doesn't say anything about get(). Should get() call __missing__? If it does, things like defaultdict.get() might break. It will however be more consistent with dict's specification. If it doesn't, we expect Mapping to not care about __missing__ as it's only a dict thing, which will require UserDict to override get(). Dict's get() will need to receive a doc update as well stating __missing__ is not called. Second question is: Is __missing__ only a dict thing, or is it part of the Mapping ABC? I would expect it to be a part of the Mapping ABC, with subclasses not having to implement it. Right now it's not. Looking forward for your inputs, Bar Harel

3 8

Re: Dict __missing__ consistency issues.
by Bar Harel Jan. 8, 2020

Jan. 8, 2020

> > [Bar Harel] > > As for get(). Current implementation of UserDict returns the default > value > > for get() if __missing__() raises KeyError. Which sounds reasonable to > me. > > After all, you would logically expect __missing__ to be called for get() > > as you tried to get a non-existing value. > > > [Ethan Furman] > I disagree. My understanding of the purpose behind get() is to get a value > or return the default specified in the get() call, not to create a new key > (which the default __missing__ does). > There is no default __missing__. That's what the __missing__ at defaultdict does. Like I said before: The fact __missing__ is not called for missing values is a bit funny in my opinion, but it doesn't actually matter cause we can't do anything about it without breaking lots of stuff (e.g. making defaultdict.get worthless).

1 0

Dict __missing__ consistency issues
by Bar Harel Jan. 8, 2020

Jan. 8, 2020

Hey guys, I was just about to fix dict's get() to call __missing__ if a key doesn't exist (before returning the default value) but realized that although small, that patch can cause future issues. Right now there's an inconsistency: >>> from collections import UserDict >>> class A(dict): ... def __missing__(self, key): ... print(key) ... >>> class B(UserDict): ... def __missing__(self, key): ... print("UserDict", key) ... >>> a = A() >>> b = B() >>> a.get(123) >>> b.get(123) UserDict 123 >>> a.get(123, "abc") 'abc' >>> b.get(123, "abc") UserDict 123 The reason for this inconsistency is because the Mapping abc and dict behave differently. Dict's get doesn't call __getitem__ which causes the call not to route to __missing__. MutableMapping's get calls __getitem__, which UserDict implements as a check to __missing__ as well. According to the doc, the specification requires dict's __getitem__ to call __missing__. It doesn't say anything about get(). Should get() call __missing__? If it does, things like defaultdict.get() might break. It will however be more consistent with dict's specification. If it doesn't, we expect Mapping to not care about __missing__ as it's only a dict thing, which will require UserDict to override get(). Dict's get() will need to receive a doc update as well stating __missing__ is not called. Second question is: Is __missing__ only a dict thing, or is it part of the Mapping ABC? I would expect it to be a part of the Mapping ABC, with subclasses not having to implement it. Right now it's not. Looking forward for your inputs, Bar Harel

1 0

Should set objects maintain insertion order too?
by Larry Hastings Jan. 8, 2020

Jan. 8, 2020

As of 3.7, dict objects are guaranteed to maintain insertion order. But set objects make no such guarantee, and AFAIK in practice they don't maintain insertion order either. Should they? I do have a use case for this. In one project I maintain a "ready" list of jobs; I need to iterate over it, but I also want fast lookup because I soemtimes remove jobs when they're subsequently marked "not ready". The existing set object would work fine here, except that it doesn't maintain insertion order. That means multiple runs of the program with the same inputs may result in running jobs in different orders, and this instability makes debugging more difficult. I've therefore switched from a set to a dict with all keys mapped to None, which provides all the set-like functionality I need. ISTM that all the reasons why dicts should maintain insertion order also apply to sets, and so I think we should probably do this. Your thoughts? //arry/ p.s. My dim recollection is that the original set object was a hacked-up copy of the dict object removing the ability to store values. So there's some precedent for dicts and sets behaving similarly. (Note: non-pejorative use of "hacked-up" here, that was a fine way to start.)

26 79

Python Documentation and AIX specifics - how to proceed?
by Michael Jan. 7, 2020

Jan. 7, 2020

First - best wishes all for a happy and healthy 2020! As my nickname implies - my primary means to contribute to Python is with regard to AIX. One of the things I recently came across is Misc/README.AIX which was last updated sometime between 2010 and 2014. I am thinking a facelift is in order. Assuming 2010-2011 as the original date - much has changed and many of the comments are no longer accurate. Before saying so, I would like to check here that - having all tests pass on the 3.8 bot implies that there are no outstanding issues. As to the historical issues in the current document - these could either be deleted, or a short text describing when they were resolved (e.g., Python 3.7, or just resolved, but noone knows exactly how or when - whether it was a Python change, or a platform (AIX) change. What I see as being more relevant is the description re: how to build Python for AIX - for the "do it youself"-ers. So, besides the direct question re: what to say about the old "known issues" and whether there are no known issues aka, no issues identified via the standard tests - I would appreciate feedback on what is considered appropriate - anno 2020 - for any Misc/README.platform text. Additionally, I am willing to work on other areas of the standard documentation where it is either needed or considered appropriate for platform specific details and/or examples. This is not something I would try to get done in a single PR, Instead I am thinking a single -longer term- issue - and multiple PR's to work through corrections and additions during 2020. Focus on Python 3.9 and beyond yet where appropriate backlevel to Python 3.8 or even 3.7. Sincerely, Michael

3 3

Python-dev mailing lis archives earlier than late April 1999?
by Skip Montanaro Jan. 7, 2020

Jan. 7, 2020

I could swear python-dev was older than late April 1999, yet that's as far back as the MM3 archives go. As evidence, here's an email from Jack Jansen on 28 April 1999 which was a reply to an earlier message not present in the current archive: https://mail.python.org/archives/list/python-dev@python.org/thread/EMH62JYF… Any pointers to older messages appreciated... Skip

5 16

Steering Council Update (November through December)
by Ewa Jodlowska Jan. 6, 2020

Jan. 6, 2020

Hello! Below is an update from the Steering Council. It covers November and December. The update has been added to the Steering Council repo: https://github.com/python/steering-council/blob/master/updates/2020-01-06-s… (added to README as well). ------------------------------------------------------------------------ # Steering Council Community Update for November - December 2019 ## November recap: - Steering Council assigned one another tasks to check-in on and clean up 29 open PEPs in November (Nov 5 and Nov 12 meetings). See [PEP repo]( https://github.com/python/peps/) for details. - Steering Council decided that going forward, only one person will need to approve the minutes and the group will try to rotate that responsibility. Additionally, to keep meetings efficient we will: - 1. have a person responsible for the agenda to make sure the agenda is accurate and timed appropriately - 2. have a person run the actual meeting to make sure we stay on topic and cut discussions when topics go over time. - Steering Council discussed ideas on how to lower the count of PRs. It was decided that Brett would start a discussion on Discourse with the idea to close enhancement PRs. This has been done [here]( https://discuss.python.org/t/automatically-close-all-enhancement-prs-for-co…). At a later time, it was decided the idea would be shut down since many folks did not approve. - Steering Council discussed how a hiring plan can coincide with the Vision Deck and how it would work with sponsor/corporate collaborations. The Vision Deck is an overview document the Steering Council is drafting, which will help develop Python's roadmap for the next 5 years. Goal is to have the Vision Deck complete by PyCon 2020. - Steering Council had a brief discussion about encouraging more candidates to run for the next steering council and that everyone would work on raising awareness for this. ## December recap: - The Steering Council reviewed [PEP 584]( https://www.python.org/dev/peps/pep-0584/) (“Add + and += operators to the built-in dict class”) and decided that Guido would let the PEP authors know | and |= was preferred and that the PEP needed some editing. [This was done]( https://mail.python.org/archives/list/python-ideas@python.org/message/P46F7…). At a later time it was decided that Guido will be BDFL-Delegate. - The Steering Council decided it would meet after the 2020 Steering Council vote ended. The Steering Council will meet December 10 and December 17th. The hand-off meeting will happen the first week of January. Ewa will send out a Doodle for the first full week of January once the new Steering Council members are known. It was decided that on January 8th, 2020 the Steering Council will have a hand-off meeting between the 2019 team and 2020 team. - Steering Council decided that we would send out ballots to Marc-Andre Lemburg, Alex Martelli, and Kurt B. Kaiser. [Brett responded to thread]( https://mail.python.org/archives/list/python-committers@python.org/message/…) noting this decision and future plans for [PEP 13]( https://www.python.org/dev/peps/pep-0013/). - Steering Council discussed [PEP 611]( https://www.python.org/dev/peps/pep-0611/). Barry [emailed the python-dev@ list]( https://mail.python.org/archives/list/python-dev@python.org/message/KY46EXG…) with the outcome of the discussion. - Steering Council discussed PyPI’s typosquatting issues. - Group discussed the status of the GitHub migration plan. Ewa drafted a job description for the Project Manager role to help with the GitHub migration for the Dec 17th SC meeting. The Steering Council reviewed it and Ewa scheduled a call with the GitHub team for late January for next steps. - Steering Council decided to keep Zulip since the Packaging-wg plans on using it. We will re-evaluate usage next year. Guido informed the [Discourse thread]( https://discuss.python.org/t/should-we-continue-using-zulip/2816/7). Brett [posted an announcement]( https://python.zulipchat.com/#narrow/stream/116742-core.2Fhelp/topic/Engage…) in Zulip. Thank you, Ewa ----------------------- *As a non-profit organization, the PSF depends on sponsorships and donations to support the Python community. Check out our Annual Impact Report for more details: https://www.python.org/psf/annual-report/2019/ <https://www.python.org/psf/annual-report/2019/>* *Please contribute to PSF; we can't continue our work without your support! https://www.python.org/psf/donations/ <https://www.python.org/psf/donations/>*

1 0

Adding a scarier warning to object.__del__?
by Yonatan Zunger Jan. 5, 2020

Jan. 5, 2020

Hey everyone, I just encountered yet another reason to beware of __del__: when it's called during interpreter shutdown, for reasons which are kind of obvious in retrospect, if it calls notify() on a threading.Condition, the waiting thread may or may not ever actually receive it, and so if it does that and then tries to join() the thread the interpreter may hang in a hard-to-debug way. This isn't something that can reasonably be fixed, and (like in most cases involving __del__) there's a very simple fix of using weakref.finalize instead. My question for the dev list: How would people feel about changing the documentation for the method <https://docs.python.org/3/reference/datamodel.html#object.__del__> to more bluntly warn people against using it, and refer them to weakref.finalize and/or atexit.register as an alternative? The text already has an undertone of "lasciate ogni speranza, voi ch'entrate" but it may be helpful to be more explicit to avoid people getting caught in unexpected pitfalls. Yonatan

10 16

Summary of Python tracker Issues
by Python tracker Jan. 3, 2020

Jan. 3, 2020

ACTIVITY SUMMARY (2019-12-27 - 2020-01-03) 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 7227 (+24) closed 43726 (+38) total 50953 (+62) Open issues with patches: 2842 Issues opened (48) ================== #27973: urllib.urlretrieve() fails on second ftp transfer https://bugs.python.org/issue27973 reopened by pablogsal #39114: Python 3.9.0a2 changed how finally/return is traced https://bugs.python.org/issue39114 reopened by nedbat #39141: IDLE Clear function returns 256 on Mac OS Catalina https://bugs.python.org/issue39141 opened by twister68(a)gmail.com #39143: Implementing sub-generation steps in the gc https://bugs.python.org/issue39143 opened by pablogsal #39146: too much memory consumption in re.compile unicode https://bugs.python.org/issue39146 opened by Zhipeng Xie #39147: using zipfile with root privilege shows FileNotFoundError https://bugs.python.org/issue39147 opened by Patrick Liu #39148: DatagramProtocol + IPv6 does not work with ProactorEventLoop https://bugs.python.org/issue39148 opened by alex.gronholm #39150: See if PyToken_OneChar would be faster as a lookup table https://bugs.python.org/issue39150 opened by petdance #39151: Simplify the deep-first-search of the assembler https://bugs.python.org/issue39151 opened by pablogsal #39152: Faulty override of tkinter.Misc.configure in tkinter.ttk.Scale https://bugs.python.org/issue39152 opened by glombardo #39153: Clarify refcounting semantics of PyDict_SetItem[String] https://bugs.python.org/issue39153 opened by ncoghlan #39154: "utf8" not always a synonym for "utf-8" in lib2to3 https://bugs.python.org/issue39154 opened by Peter Ludemann #39155: "utf8-sig" missing from codecs (inconsistency) https://bugs.python.org/issue39155 opened by Peter Ludemann #39156: Break up COMPARE_OP into logically distinct operations. https://bugs.python.org/issue39156 opened by Mark.Shannon #39157: test_pidfd_send_signal can fail on some systems with Permissio https://bugs.python.org/issue39157 opened by pablogsal #39159: Ideas for making ast.literal_eval() usable https://bugs.python.org/issue39159 opened by rhettinger #39160: ./configure --help has inconsistencies in style https://bugs.python.org/issue39160 opened by anthony shaw #39161: Py_NewInterpreter docs need updating for multi-phase initializ https://bugs.python.org/issue39161 opened by ncoghlan #39162: setup.py not picking up tkinter headers https://bugs.python.org/issue39162 opened by anthonypjshaw #39164: PyErr_GetExcInfo does not allow to retrieve for an arbitrary t https://bugs.python.org/issue39164 opened by jd #39165: Completeness and symmetry in RE, avoid `findall(...)[0]` https://bugs.python.org/issue39165 opened by apalala #39166: Python 3.9.0a2 changed how "async for" traces its final iterat https://bugs.python.org/issue39166 opened by nedbat #39168: Generic type subscription is a huge toll on Python performance https://bugs.python.org/issue39168 opened by Ruslan Dautkhanov #39169: TypeError: 'int' object is not callable if the signal handler https://bugs.python.org/issue39169 opened by Ronald Li #39170: Sqlite3 row_factory for attribute access: NamedRow https://bugs.python.org/issue39170 opened by jidn #39171: Missing default root in tkinter simpledialog.py https://bugs.python.org/issue39171 opened by dominic108 #39173: _AttributeHolder of argparse should support the sort function https://bugs.python.org/issue39173 opened by shihai1991 #39174: unicodedata.normalize failing with NFD and NFKD for some chara https://bugs.python.org/issue39174 opened by Lee Collins #39177: In tkinter, simple dialogs, askstrings, etc. with flexible coo https://bugs.python.org/issue39177 opened by dominic108 #39179: pandas tz_convert() seems to report incorrect date conversion https://bugs.python.org/issue39179 opened by Seeking.that #39180: Missing getlines func documentation from linecache module https://bugs.python.org/issue39180 opened by khalidmammadov #39181: Add `os.makedirs()` as `Path.mkdir()` equivalent in correspond https://bugs.python.org/issue39181 opened by jack1142 #39182: sys.addaudithook(hook) loops indefinitely on mismatch for hook https://bugs.python.org/issue39182 opened by Dutcho #39184: Many command execution functions are not raising auditing even https://bugs.python.org/issue39184 opened by Saiyang Gou #39185: Add quiet and detailed verbosity levels to build.bat https://bugs.python.org/issue39185 opened by anthonypjshaw #39187: urllib.robotparser does not respect the longest match for the https://bugs.python.org/issue39187 opened by gallicrooster #39188: recent change when passing a Union to a function https://bugs.python.org/issue39188 opened by Kevin Schlossser #39189: Use io.DEFAULT_BUFFER_SIZE for filecmp BUFSIZE variable https://bugs.python.org/issue39189 opened by Bahram Aghaei #39190: _result_handler dies on raised exceptions [multiprocessing] https://bugs.python.org/issue39190 opened by sindrig #39191: Coroutine is awaited despite an exception in run_until_complet https://bugs.python.org/issue39191 opened by dkaveshnikov #39194: asyncio.open_connection returns a closed client when server fa https://bugs.python.org/issue39194 opened by Jonathan Martin #39196: json fails to encode dictionary view types https://bugs.python.org/issue39196 opened by jogo #39197: Support the title and description arguments for mutually exclu https://bugs.python.org/issue39197 opened by signing_agreement #39198: Lock may not be released in Logger.isEnabledFor https://bugs.python.org/issue39198 opened by derektbrown #39199: Improve the AST documentation https://bugs.python.org/issue39199 opened by pablogsal #39200: Fix inaccurate TypeError messages when calling with insufficie https://bugs.python.org/issue39200 opened by jferard #39201: Threading.timer leaks memory in 3.8.0/3.8.1 https://bugs.python.org/issue39201 opened by mneerup #39202: Python shelve __del__ ignored exception https://bugs.python.org/issue39202 opened by libbkmz Most recent 15 issues with no replies (15) ========================================== #39202: Python shelve __del__ ignored exception https://bugs.python.org/issue39202 #39199: Improve the AST documentation https://bugs.python.org/issue39199 #39197: Support the title and description arguments for mutually exclu https://bugs.python.org/issue39197 #39194: asyncio.open_connection returns a closed client when server fa https://bugs.python.org/issue39194 #39190: _result_handler dies on raised exceptions [multiprocessing] https://bugs.python.org/issue39190 #39189: Use io.DEFAULT_BUFFER_SIZE for filecmp BUFSIZE variable https://bugs.python.org/issue39189 #39188: recent change when passing a Union to a function https://bugs.python.org/issue39188 #39185: Add quiet and detailed verbosity levels to build.bat https://bugs.python.org/issue39185 #39184: Many command execution functions are not raising auditing even https://bugs.python.org/issue39184 #39182: sys.addaudithook(hook) loops indefinitely on mismatch for hook https://bugs.python.org/issue39182 #39181: Add `os.makedirs()` as `Path.mkdir()` equivalent in correspond https://bugs.python.org/issue39181 #39180: Missing getlines func documentation from linecache module https://bugs.python.org/issue39180 #39177: In tkinter, simple dialogs, askstrings, etc. with flexible coo https://bugs.python.org/issue39177 #39170: Sqlite3 row_factory for attribute access: NamedRow https://bugs.python.org/issue39170 #39169: TypeError: 'int' object is not callable if the signal handler https://bugs.python.org/issue39169 Most recent 15 issues waiting for review (15) ============================================= #39200: Fix inaccurate TypeError messages when calling with insufficie https://bugs.python.org/issue39200 #39199: Improve the AST documentation https://bugs.python.org/issue39199 #39198: Lock may not be released in Logger.isEnabledFor https://bugs.python.org/issue39198 #39191: Coroutine is awaited despite an exception in run_until_complet https://bugs.python.org/issue39191 #39190: _result_handler dies on raised exceptions [multiprocessing] https://bugs.python.org/issue39190 #39187: urllib.robotparser does not respect the longest match for the https://bugs.python.org/issue39187 #39185: Add quiet and detailed verbosity levels to build.bat https://bugs.python.org/issue39185 #39180: Missing getlines func documentation from linecache module https://bugs.python.org/issue39180 #39171: Missing default root in tkinter simpledialog.py https://bugs.python.org/issue39171 #39170: Sqlite3 row_factory for attribute access: NamedRow https://bugs.python.org/issue39170 #39166: Python 3.9.0a2 changed how "async for" traces its final iterat https://bugs.python.org/issue39166 #39164: PyErr_GetExcInfo does not allow to retrieve for an arbitrary t https://bugs.python.org/issue39164 #39162: setup.py not picking up tkinter headers https://bugs.python.org/issue39162 #39160: ./configure --help has inconsistencies in style https://bugs.python.org/issue39160 #39157: test_pidfd_send_signal can fail on some systems with Permissio https://bugs.python.org/issue39157 Top 10 most discussed issues (10) ================================= #39143: Implementing sub-generation steps in the gc https://bugs.python.org/issue39143 15 msgs #39168: Generic type subscription is a huge toll on Python performance https://bugs.python.org/issue39168 12 msgs #36051: Drop the GIL during large bytes.join operations? https://bugs.python.org/issue36051 10 msgs #32615: Inconsistent behavior if globals is a dict subclass https://bugs.python.org/issue32615 9 msgs #27973: urllib.urlretrieve() fails on second ftp transfer https://bugs.python.org/issue27973 8 msgs #39114: Python 3.9.0a2 changed how finally/return is traced https://bugs.python.org/issue39114 6 msgs #39134: can't construct dataclass as ABC (or runtime check as data pro https://bugs.python.org/issue39134 6 msgs #39166: Python 3.9.0a2 changed how "async for" traces its final iterat https://bugs.python.org/issue39166 6 msgs #34118: Fix some class entries in 'Built-in Functions' https://bugs.python.org/issue34118 5 msgs #39156: Break up COMPARE_OP into logically distinct operations. https://bugs.python.org/issue39156 5 msgs Issues closed (38) ================== #5851: Add a stream parameter to gc.set_debug https://bugs.python.org/issue5851 closed by pablogsal #13601: sys.stderr should be line-buffered when stderr is not a TTY https://bugs.python.org/issue13601 closed by pitrou #15273: Remove unnecessarily random behavior from test_unparse.py https://bugs.python.org/issue15273 closed by pablogsal #15723: Python breaks OS' append guarantee on file writes https://bugs.python.org/issue15723 closed by gvanrossum #18858: dummy_threading lacks threading.get_ident() equivalent https://bugs.python.org/issue18858 closed by inada.naoki #20443: __code__. co_filename should always be an absolute path https://bugs.python.org/issue20443 closed by ncoghlan #24174: Python crash on exit https://bugs.python.org/issue24174 closed by SilentGhost #25087: Type variable substitution in type instances https://bugs.python.org/issue25087 closed by gvanrossum #30427: isinstance checks in os.path.normcase redundant with os.fspath https://bugs.python.org/issue30427 closed by brett.cannon #32438: PyLong_ API cleanup https://bugs.python.org/issue32438 closed by mark.dickinson #33387: Simplify bytecodes for try-finally, try-except and with blocks https://bugs.python.org/issue33387 closed by Mark.Shannon #33777: dummy_threading: .is_alive method returns True after execution https://bugs.python.org/issue33777 closed by inada.naoki #35143: `from __future__ import annotations` has no effect inside `ast https://bugs.python.org/issue35143 closed by eric.smith #36220: LOAD_NAME and LOAD_GLOBAL, STORE_GLOBAL handle dict subclasses https://bugs.python.org/issue36220 closed by pablogsal #37446: Undefined behavior in Python/hamt.c https://bugs.python.org/issue37446 closed by benjamin.peterson #38532: Missing decrefs in the _ctypes module https://bugs.python.org/issue38532 closed by twouters #38588: Use-after-free in dict/list https://bugs.python.org/issue38588 closed by pablogsal #38610: use-after-free in list object function https://bugs.python.org/issue38610 closed by pablogsal #38879: Reordered error checking in PyArena_New(). https://bugs.python.org/issue38879 closed by pitrou #39037: Fix the trial order of the __exit__ and __enter__ methods in t https://bugs.python.org/issue39037 closed by maggyero #39112: Misleading documentation for tuple https://bugs.python.org/issue39112 closed by terry.reedy #39136: Typos in whatsnew file and docs https://bugs.python.org/issue39136 closed by terry.reedy #39142: logging.config.dictConfig will convert namedtuple to Convertin https://bugs.python.org/issue39142 closed by vinay.sajip #39144: Align ctags and etags targets and include Python stdlib https://bugs.python.org/issue39144 closed by pablogsal #39145: Innocuous parent class changes multiple inheritance MRO https://bugs.python.org/issue39145 closed by steven.daprano #39149: False positive using operator 'AND' while checking keys on dic https://bugs.python.org/issue39149 closed by serhiy.storchaka #39158: ast.literal_eval() doesn't support empty sets https://bugs.python.org/issue39158 closed by rhettinger #39163: spam https://bugs.python.org/issue39163 closed by xtreak #39167: argparse boolean type bug https://bugs.python.org/issue39167 closed by josh.r #39172: Transformation of "string.find('asd', 'sd')" to Python 3 using https://bugs.python.org/issue39172 closed by serhiy.storchaka #39175: Funkness with issubset https://bugs.python.org/issue39175 closed by rhettinger #39176: Syntax error message uses strange term: "named assignment" https://bugs.python.org/issue39176 closed by rhettinger #39178: Should we make dict not accept a sequence of sets? https://bugs.python.org/issue39178 closed by steven.daprano #39183: Text divided in two strings due to wrong formatting https://bugs.python.org/issue39183 closed by rffontenelle #39186: Windows installer instructions refer to mercurial https://bugs.python.org/issue39186 closed by zach.ware #39192: relationlist module https://bugs.python.org/issue39192 closed by mark.dickinson #39193: Out-of-bound write in ceval.c:_PyEval_EvalFrameDefault https://bugs.python.org/issue39193 closed by pablogsal #39195: re._compile should check if the argument is a compiled pattern https://bugs.python.org/issue39195 closed by Recursing

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PEP 558: Defined semantics for locals() (December 2019 edition)
by Nick Coghlan Jan. 2, 2020

Jan. 2, 2020

Hi folks, I've finally updated PEP 558 and it's reference implementation based on Nathaniel's feedback back in May. The latest version of the PEP can now be found at https://www.python.org/dev/peps/pep-0558/, and I've created a discussion thread on Discourse: https://discuss.python.org/t/pep-558-defined-semantics-for-locals/2936 The latest version implements Nathaniel's "independent snapshot" proposal, and I like how that has turned out. The one thing that changed from the May discussion thread is that the refcount semantics of PyEval_GetLocals() (it returns a borrowed reference) meant that it had to keep the old behaviour of returning a reference to the internal dynamically updated shared "snapshot" at function scope, with a new API, PyEval_GetPyLocals(), providing the C equivalent of the locals() builtin. Cheers, Nick. -- Nick Coghlan | ncoghlan(a)gmail.com | Brisbane, Australia

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Use of AT_SECURE on Linux
by Max Mazurov Jan. 1, 2020

Jan. 1, 2020

Hello, list. I noticed that CPython does not sanitize environment when transition between SELinux contexts or AppArmor profiles happens, which I think is a good thing to do in cases when one sandboxed application runs a Python script with different (potentially less strict) sandbox configuration. On Linux, such transition is indicated by LSMs (SELinux, AppArmor) using the AT_SECURE bit in the aux. vector. Consult getauxval(3) in the glibc manual for details. Here is the paragraph describing AT_SECURE: > Has a nonzero value if this executable should be treated securely. Most > commonly, a nonzero value indicates that the process is executing a > set-user-ID or set-group-ID binary (so that its real and effective UIDs or > GIDs differ from one another), or that it gained capabilities by executing a > binary file that has capabilities (see capabilities(7)). Alternatively, a > nonzero value may be triggered by a Linux Security Module. When this value is > nonzero, the dynamic linker disables the use of certain environment variables > (see ld-linux.so(8)) and glibc changes other aspects of its behavior. (See > also secure_getenv(3).) set-user-ID and capabilities are not directly relevant to Python since it is not possible to apply setuid bit or file capabilities to the script (with #!). Though, it might be relevant for other applications embedding CPython. The case with LSMs is directly relevant for standalone scripts since both SELinux and AppArmor allow applying per-script restrictions. There is the -I flag for the CPython interpreter that in my opinion does exactly what should be done when AT_SECURE bit is set. Since isolated flag is already checked by all relevant code paths in CPython and standard library, I believe it is a good idea to simply make AT_SECURE imply -I. Though I am not sure whether the behavior for other applications embedding CPython should be same. I can put together a patch to implement that if there is an interest and somebody can point me to an appropriate place to change. -- Cheers, Max Mazurov https://foxcpp.dev

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