Mailman 3 August 2016 - Python-Dev

Re: [Python-Dev] PEP487: Simpler customization of class creation
by Sylvain Corlay Aug. 11, 2016

Aug. 11, 2016

Hello, This is my first post on python-dev and I hope that I am not breaking any rule. I wanted to react on the discussion regarding PEP487. This year, we have been working on a refactoring of the `traitlets` library, an implementation of the descriptor pattern that is used in Project Jupyter / IPython. The motivations for the refactoring was similar to those of this PEP: having a more generic metaclass allowing more flexibility in terms of types of descriptors, in order to avoid conflicts between meta classes. We ended up with: - A metaclass called MetaHasDescriptor - A base class of meta MetaHasDescriptor named HasDescriptors Usage: class MyClass(HasDescriptors): attr = DesType() DesType inherits from a base Descriptor type. The key is that their initialization is done in three stages - the main DesType.__init__ - the part of the initialization of DesType that depends on the definition of MyClass DesType.class_init(self, cls, name) which is called from MetaHasDescriptors.__new__ - a method of DesType that depends on the definition of instances of MyClass DesType.instance_init(self, obj) which is called from HasDescriptors.__new__. instance_init, may make modifications on the HasDescriptors instance. My understanding is that the proposed __set_name__ in PEP487 exactly corresponds to our class_init, although interestingly we often do much more in class_init than setting the name of the descriptor, such as setting a this_class attribute or calling class_init on contained descriptors. Therefore I do not think that the names __set_name__ or __set_owner__ are appropriate for this use case. In a way, the long-form explicit names for our class_init and instance_init methods would be something like __init_fom_owner_class__, and __touch_instance__. Thanks, Sylvain PS: thanks to Neil Girdhar for the heads up on the traitlets repo.

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Rewrite @contextlib.contextmanager in C
by Giampaolo Rodola' Aug. 10, 2016

Aug. 10, 2016

import timeit import contextlib @contextlib.contextmanager def ctx1(): yield class ctx2: def __enter__(self): pass def __exit__(self, *args): pass t1 = timeit.timeit("with ctx1(): pass", setup="from __main__ import ctx1") t2 = timeit.timeit("with ctx2(): pass", setup="from __main__ import ctx2") print("%.3f secs" % t1) print("%.3f secs" % t2) print("slowdown: -%.2fx" % (t1 / t2)) ...with Python 3.5: 1.938 secs 0.443 secs slowdown: -4.37x I wanted to give it a try rewriting this in C but since @contextmanager has a lot of magic I wanted to ask first whether this 1) is technically possible 2) is desirable. Thoughts? -- Giampaolo - http://grodola.blogspot.com

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Re: [Python-Dev] [python-committers] Failed to build select
by Ned Deily Aug. 8, 2016

Aug. 8, 2016

On Aug 8, 2016, at 02:45, Steven D'Aprano <steve(a)pearwood.info> wrote: > On Mon, Aug 08, 2016 at 12:17:21AM -0400, Ned Deily wrote: >> Also, try without setting PYTHONHOME. I'm not sure what you're trying to do by setting that but you shouldn't need to. > I didn't think I needed to either, but when I try without it, I get: > > Could not find platform dependent libraries <exec_prefix> > Consider setting $PYTHONHOME to <prefix>[:<exec_prefix>] > Could not find platform dependent libraries <exec_prefix> > Consider setting $PYTHONHOME to <prefix>[:<exec_prefix>] On Aug 8, 2016, at 03:25, Chris Jerdonek <chris.jerdonek(a)gmail.com> wrote: > FWIW, I would be interested in learning more about the above warning > (its significance, how it can be addressed, whether it can be ignored, > etc). I also get this message when installing 3.5.2 from source on > Ubuntu 14.04. Those messages are harmless and are generated by the Makefile steps that update Importlib's bootstrap files, Python/importlib_external.h and Python/importlib_external.h. See http://bugs.python.org/issue14928 for the origins of this. It should be possible to fix the Makefile to suppress those messages. I suggest you open an issue about it. -- Ned Deily nad(a)python.org -- []

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Review request: issue 10910, pyport.h causes trouble for C++ extensions on BSDs
by tdsmith Aug. 8, 2016

Aug. 8, 2016

Hi python-dev! I'm a maintainer for Homebrew, a third-party package manager for OS X, where I'm the resident parseltongue. Issue 10910 is related to problems building CPython extension modules with C++ code on BSDs. As I understand it, pyport.h has some code specific to BSD and friends, including OS X, which causes conflicts with the C++ stdlib. We've been carrying the patch Ronald Oussoren wrote in 2011 [2] against Python 2.7 since olden times. We were recently prompted to add the patch to our 3.5 package as well [3] because the bug was causing build problems in the wild. [4] We strive to apply as few patches as possible in Homebrew and we (I) would love to see a fix for this deployed upstream. Can I do anything to help code get checked in? Thanks, Tim [1] https://bugs.python.org/issue10910 [2] https://bugs.python.org/issue10910#msg135414 [3] https://github.com/Homebrew/homebrew-core/pull/3396 [4] https://github.com/IntelPNI/brainiak/pull/82 -- Tim Smith Freenode: tdsmith, #machomebrew https://tds.xyz, https://github.com/tdsmith

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libmpdec already uses and compiles with -std=c99 -pedantic everywhere
by Stefan Krah Aug. 7, 2016

Aug. 7, 2016

The following C99 features are supported by any buildbot compiler (including obscure ones on snakebite): - stdint.h - static inline functions in header files - extern inline functions (not really necessary for CPython) - variadic macros I'd like to add: - standard conforming C99 spelling of the "struct hack" (supported by gcc since I can remember). Our current way leads to problems for some analyzers. Some people (not me) would like: - variable declarations everywhere (rather than only at the beginning of blocks). I think this would probably be enough for the start. Obviously things like variable-length arrays should never be used anyway. Stefan Krah

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Re: [Python-Dev] C99
by Hugh Fisher Aug. 7, 2016

Aug. 7, 2016

> Message: 2 > Date: Sat, 6 Aug 2016 14:27:15 +0900 > From: INADA Naoki <songofacandy(a)gmail.com> > To: Guido van Rossum <guido(a)python.org> > Cc: Ned Deily <nad(a)python.org>, Python-Dev <python-dev(a)python.org> > Subject: Re: [Python-Dev] C99 > Message-ID: > <CAEfz+Twc9t2pO4zzO3yyfvAPN0aWWV99YnvSjuPSq1=v3Lkt1Q(a)mail.gmail.com> > Content-Type: text/plain; charset=UTF-8 > > I think these features may improve C code readability. > (Easy feature first). > > * // one line comment > > * inline function > static inline function can be used instead of may macros. > It is more readable, and type safe. My experience from a few months ago with some cross-platform code is that clang, GCC and MSVC have different ideas about how inline functions in C work. Are they static or extern? Do you need provide an implementation body somewhere? There are also differences between the C++ and C99 definitions. Probably all solvable with build settings, but not as easy as one line comments. -- cheers, Hugh Fisher

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Summary of Python tracker Issues
by Python tracker Aug. 5, 2016

Aug. 5, 2016

ACTIVITY SUMMARY (2016-07-29 - 2016-08-05) Python tracker at http://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 5589 ( +1) closed 33862 (+44) total 39451 (+45) Open issues with patches: 2445 Issues opened (26) ================== #27650: Implement `__repr__` methods for logging.Logger and others http://bugs.python.org/issue27650 opened by cool-RR #27653: [Patch] Also disable the use of <netinet/tcp.h> on CloudABI http://bugs.python.org/issue27653 opened by EdSchouten #27654: [Patch] Use arc4random_buf() on CloudABI http://bugs.python.org/issue27654 opened by EdSchouten #27655: [Patch] Don't require presence of POLLPRI http://bugs.python.org/issue27655 opened by EdSchouten #27657: urlparse fails if the path is numeric http://bugs.python.org/issue27657 opened by Björn.Lindqvist #27658: python 3.5.2 built from source fails to install completely on http://bugs.python.org/issue27658 opened by Mario Grgic #27659: Check for the existence of crypt() http://bugs.python.org/issue27659 opened by Chi Hsuan Yen #27660: Replace size_t with Py_ssize_t as the type of local variable i http://bugs.python.org/issue27660 opened by xiang.zhang #27662: Check against PY_SSIZE_T_MAX instead of PY_SIZE_MAX in List_Ne http://bugs.python.org/issue27662 opened by xiang.zhang #27664: Allow specifying prefix for thread name in concurrent.futures. http://bugs.python.org/issue27664 opened by durin42 #27665: Make create_server able to listen on several ports http://bugs.python.org/issue27665 opened by bayandin #27666: "stack smashing detected" in PyCursesWindow_Box http://bugs.python.org/issue27666 opened by Steve Fink #27671: FAQ: len() is still function for good reason. http://bugs.python.org/issue27671 opened by methane #27674: Quote mark breaks cookie processing http://bugs.python.org/issue27674 opened by Artur Smęt #27675: IDLE file completion has 2 bugs depending on open quote used http://bugs.python.org/issue27675 opened by egerosa #27679: set_bitfields() unused in _ctypes_test http://bugs.python.org/issue27679 opened by martin.panter #27680: Reduce Github pull request rate http://bugs.python.org/issue27680 opened by holdenweb #27681: readline: consecutive rl_kill_word do not append http://bugs.python.org/issue27681 opened by qsantos #27682: Windows Error 10053, ConnectionAbortedError: [WinError 10053] http://bugs.python.org/issue27682 opened by SG #27683: ipaddress subnet slicing iterator malfunction http://bugs.python.org/issue27683 opened by tklausmann #27687: Linux shutil.move between mountpoints as root does not retain http://bugs.python.org/issue27687 opened by jort.bloem #27688: Expand documentation about Any in the typing module http://bugs.python.org/issue27688 opened by michael0x2a #27689: Add documentation for typing.Generator http://bugs.python.org/issue27689 opened by michael0x2a #27691: X509 cert with GEN_RID subject alt name causes SytemError http://bugs.python.org/issue27691 opened by christian.heimes #27692: Clean serveral unnecessary NULL checks in exceptions.c http://bugs.python.org/issue27692 opened by xiang.zhang #27693: curses.textpad.Textbox(win).edit() won't edit last character http://bugs.python.org/issue27693 opened by Dietmar Schindler Most recent 15 issues with no replies (15) ========================================== #27693: curses.textpad.Textbox(win).edit() won't edit last character http://bugs.python.org/issue27693 #27691: X509 cert with GEN_RID subject alt name causes SytemError http://bugs.python.org/issue27691 #27689: Add documentation for typing.Generator http://bugs.python.org/issue27689 #27688: Expand documentation about Any in the typing module http://bugs.python.org/issue27688 #27687: Linux shutil.move between mountpoints as root does not retain http://bugs.python.org/issue27687 #27679: set_bitfields() unused in _ctypes_test http://bugs.python.org/issue27679 #27671: FAQ: len() is still function for good reason. http://bugs.python.org/issue27671 #27666: "stack smashing detected" in PyCursesWindow_Box http://bugs.python.org/issue27666 #27664: Allow specifying prefix for thread name in concurrent.futures. http://bugs.python.org/issue27664 #27654: [Patch] Use arc4random_buf() on CloudABI http://bugs.python.org/issue27654 #27653: [Patch] Also disable the use of <netinet/tcp.h> on CloudABI http://bugs.python.org/issue27653 #27646: yield from expression can be any iterable http://bugs.python.org/issue27646 #27636: Refactor IDLE htest http://bugs.python.org/issue27636 #27635: pickle documentation says that unpickling may not call __new__ http://bugs.python.org/issue27635 #27599: Buffer overrun in binascii http://bugs.python.org/issue27599 Most recent 15 issues waiting for review (15) ============================================= #27692: Clean serveral unnecessary NULL checks in exceptions.c http://bugs.python.org/issue27692 #27691: X509 cert with GEN_RID subject alt name causes SytemError http://bugs.python.org/issue27691 #27689: Add documentation for typing.Generator http://bugs.python.org/issue27689 #27688: Expand documentation about Any in the typing module http://bugs.python.org/issue27688 #27683: ipaddress subnet slicing iterator malfunction http://bugs.python.org/issue27683 #27680: Reduce Github pull request rate http://bugs.python.org/issue27680 #27665: Make create_server able to listen on several ports http://bugs.python.org/issue27665 #27664: Allow specifying prefix for thread name in concurrent.futures. http://bugs.python.org/issue27664 #27662: Check against PY_SSIZE_T_MAX instead of PY_SIZE_MAX in List_Ne http://bugs.python.org/issue27662 #27660: Replace size_t with Py_ssize_t as the type of local variable i http://bugs.python.org/issue27660 #27659: Check for the existence of crypt() http://bugs.python.org/issue27659 #27655: [Patch] Don't require presence of POLLPRI http://bugs.python.org/issue27655 #27650: Implement `__repr__` methods for logging.Logger and others http://bugs.python.org/issue27650 #27646: yield from expression can be any iterable http://bugs.python.org/issue27646 #27645: Supporting native backup facility of SQLite http://bugs.python.org/issue27645 Top 10 most discussed issues (10) ================================= #20767: Some python extensions can't be compiled with clang 3.4 http://bugs.python.org/issue20767 11 msgs #27604: More details about `-O` flag http://bugs.python.org/issue27604 10 msgs #27621: Finish IDLE Query dialog appearance and behavior. http://bugs.python.org/issue27621 10 msgs #27660: Replace size_t with Py_ssize_t as the type of local variable i http://bugs.python.org/issue27660 10 msgs #1621: Do not assume signed integer overflow behavior http://bugs.python.org/issue1621 8 msgs #20160: broken ctypes calling convention on MSVC / 64-bit Windows (lar http://bugs.python.org/issue20160 8 msgs #27683: ipaddress subnet slicing iterator malfunction http://bugs.python.org/issue27683 8 msgs #19660: decorator syntax: allow testlist instead of just dotted_name http://bugs.python.org/issue19660 7 msgs #27682: Windows Error 10053, ConnectionAbortedError: [WinError 10053] http://bugs.python.org/issue27682 7 msgs #27657: urlparse fails if the path is numeric http://bugs.python.org/issue27657 6 msgs Issues closed (41) ================== #6926: socket module missing IPPROTO_IPV6, IPPROTO_IPV4 http://bugs.python.org/issue6926 closed by berker.peksag #8418: Crash 0xc0000417 STATUS_INVALID_CRUNTIME_PARAMETER on program http://bugs.python.org/issue8418 closed by berker.peksag #13651: Improve redirection in urllib http://bugs.python.org/issue13651 closed by martin.panter #17310: Ctypes callbacks shows problem on Windows Python (64bit) http://bugs.python.org/issue17310 closed by vinay.sajip #17599: mingw: detect REPARSE_DATA_BUFFER http://bugs.python.org/issue17599 closed by martin.panter #23710: C API doc for PyObject_HEAD is outdated http://bugs.python.org/issue23710 closed by berker.peksag #24082: Obsolete note in argument parsing (c-api/arg.rst) http://bugs.python.org/issue24082 closed by martin.panter #24278: Docs on Parsing arguments should say something about mem mgmt http://bugs.python.org/issue24278 closed by martin.panter #24672: shutil.rmtree fails on non ascii filenames http://bugs.python.org/issue24672 closed by r.david.murray #26109: _Py_DumpTraceback should be PyAPI_FUNC http://bugs.python.org/issue26109 closed by berker.peksag #26462: Patch to enhance literal block language declaration http://bugs.python.org/issue26462 closed by martin.panter #26576: Tweak wording of decorator docos http://bugs.python.org/issue26576 closed by berker.peksag #27241: Catch exceptions raised in pstats add (repl) http://bugs.python.org/issue27241 closed by skrah #27366: PEP487: Simpler customization of class creation http://bugs.python.org/issue27366 closed by ncoghlan #27389: When a TypeError is raised due to invalid arguments to a metho http://bugs.python.org/issue27389 closed by Steven.Barker #27424: Failures in test.test_logging http://bugs.python.org/issue27424 closed by vinay.sajip #27453: $CPP invocation in configure must use $CPPFLAGS http://bugs.python.org/issue27453 closed by xdegaye #27568: "HTTPoxy", use of HTTP_PROXY flag supplied by attacker in CGI http://bugs.python.org/issue27568 closed by orsenthil #27638: int.to_bytes() and int.from_bytes() should support 'net' and ' http://bugs.python.org/issue27638 closed by rhettinger #27641: Do not build Programs/_freeze_importlib when cross-compiling http://bugs.python.org/issue27641 closed by martin.panter #27644: Expand documentation about type aliases and NewType in the typ http://bugs.python.org/issue27644 closed by gvanrossum #27651: bytearray changes when function mutates it http://bugs.python.org/issue27651 closed by SilentGhost #27652: Make use of non-standard error number ESHUTDOWN optional http://bugs.python.org/issue27652 closed by berker.peksag #27656: [Patch] Make presence of SCHED_* optional http://bugs.python.org/issue27656 closed by python-dev #27661: Add tzinfo= argument to datetime.combine http://bugs.python.org/issue27661 closed by python-dev #27663: Inconsistent CSV Writer Behaviour http://bugs.python.org/issue27663 closed by SilentGhost #27667: subprocess32 unable to be installed via pip and python install http://bugs.python.org/issue27667 closed by berker.peksag #27668: list illogical affectation http://bugs.python.org/issue27668 closed by SilentGhost #27669: Bug in re.fullmatch() specific to Windows XP http://bugs.python.org/issue27669 closed by zach.ware #27670: Use https instead of http in the PYTHON_VERSION constant http://bugs.python.org/issue27670 closed by python-dev #27672: x fromat of % operator broken in Python 3.5.2 http://bugs.python.org/issue27672 closed by SilentGhost #27673: lambda function in loop http://bugs.python.org/issue27673 closed by ebarry #27676: comports() failing due to internal 4G module http://bugs.python.org/issue27676 closed by zach.ware #27677: Reopening issue 20930 http://bugs.python.org/issue27677 closed by SilentGhost #27678: itertools.permutations/.combinations should have len http://bugs.python.org/issue27678 closed by r.david.murray #27684: Incorrect exception message of ImportError constructor http://bugs.python.org/issue27684 closed by berker.peksag #27685: altinstall with --enable-shared showing incorrect behaviour http://bugs.python.org/issue27685 closed by ubehera #27686: Spam http://bugs.python.org/issue27686 closed by zach.ware #27690: os.path.normcase broken. http://bugs.python.org/issue27690 closed by serhiy.storchaka #27694: Socket incorrectly states IP address that start with a zero af http://bugs.python.org/issue27694 closed by martin.panter #1521950: shlex.split() does not tokenize like the shell http://bugs.python.org/issue1521950 closed by python-dev

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Status of the Argument Clinic DSL
by Alexander Belopolsky Aug. 5, 2016

Aug. 5, 2016

What is the current status of the Argument Clinic DSL? The clinic preprocessor was released [1] with Python 3.4 with a promise [2] "that signature metadata for programmatic introspection will be added to additional callables implemented in C as part of Python 3.4 maintenance releases." We are now close to 3.6 beta and clinic coverage in stdlib is sparse at best. For example, the math module makes no use of the clinic (but interestingly a few methods in cmath do). The documentation is very sparse as well. While one would expect PEP 436 to serve as *the* documentation while clinic is being developed, but the PEP has the "Draft" status and has not been updated since 2013. Furthermore, the 3.4 release notes contain a warning saying "The Argument Clinic PEP is not fully up to date with the state of the implementation." It does not look like this situation has improved since. The practical question is: does it make sense to invest time in learning the clinic DSL and converting more modules (e.g. datetime) to it or it is likely that the whole approach will be revised in the future? [1] http://bugs.python.org/issue16612 [2] https://docs.python.org/3.6/whatsnew/3.4.html?highlight=clinic#pep-436-argu…

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Method signatures in the datetime module documentation
by Alexander Belopolsky Aug. 4, 2016

Aug. 4, 2016

I have started [1] writing documentation for the new PEP 495 (Local Time Disambiguation) features and ran into the following problem. The current documentation is rather inconsistent in presenting the method signatures. For example: date.replace(year, month, day) [2], but datetime.replace([year[, month[, day[, hour[, minute[, second[, microsecond[, tzinfo]]]]]]]]) [3]. The new signature for datetime.replace in the Python implementation is def replace(self, hour=None, minute=None, second=None, microsecond=None, tzinfo=True, *, fold=None): but the C implementation does not accept True for tzinfo or None for the other arguments. The defaults in the Python implementation are really just sentinels to detect which arguments are not provided. How should I present the signature of the new replace method in the documentation? [1]: http://bugs.python.org/issue27595 [2]: https://docs.python.org/3/library/datetime.html#datetime.date.replace [3]: https://docs.python.org/3/library/datetime.html#datetime.datetime.replace

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stuck issue 26826
by Marcos Dione Aug. 4, 2016

Aug. 4, 2016

Hi pythonistas. A couple of moths ago I opened an issue in the bug tracker for adding a new syscall to the os module. It's based on new developments in the Linux kernel. Here's the link: https://bugs.python.org/issue26826 After two months and a half I managed to create a nice patch with unit tests and documentation (yay!), but then the issue went cold. I would like to know how to proceed to get the issue going again. Cheers, -- Marcos. -- (Not so) Random fortune: Terrorism isn't a crime against people or property. It's a crime against our minds, using the death of innocents and destruction of property to make us fearful. -- Bruce Schneier

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