Python-Dev July 2016

python-dev@python.org

57 participants
40 discussions

congrats on 3.5! Alas, windows 7 users are having problems installing it

by Laura Creighton

webmaster has already heard from 4 people who cannot install it. I sent them to the bug tracker or to python-list but they seem not to have gone either place. Is there some guide I should be sending them to, 'how to debug installation problems'? Laura

9 months, 3 weeks

Debugging Python scripts with GDB on OSX

by Alexandru Croitor

Hello, I'm interested to find out if debugging Python scripts with GDB is supported on OSX at all? I'm referring to the functionality described on https://wiki.python.org/moin/DebuggingWithGdb and on http://fedoraproject.org/wiki/Features/EasierPythonDebugging. I've tried so far various combinations of pre-compiled GDB from the homebrew package manager, locally-compiled GDB from homebrew, as well as locally compiled GDB from MacPorts, together with a pre-compiled Python 2.7, homebrew-compiled 2.7, and custom compiled Python 2.7 from the official source tarball. My results so far were not successful. The legacy GDB commands to show a python stack trace or the local variables - do not work. And the new GDB commands (referenced on the Fedora project page) are not present at all in any of the GDB versions. I've checked the python CI build bot tests, and it seems the new GDB commands are only successfully tested on Linux machines, and are skipped on FreeBSD, OS X, and Solaris machines. Are the new python <-> GDB commands specific to Linux? Are there any considerations to take in regards to debug symbols for Python / GDB on OSX? Has anyone attempted what I'm trying to do? I would be grateful for any advice. And I apologize if my choice of the mailing lists is not the best. Regards, Alex.

3 years, 8 months

C99

by Benjamin Peterson

PEP 7 requires CPython to use C code conforming to the venerable C89 standard. Traditionally, we've been stuck with C89 due to poor C support in MSVC. However, MSVC 2013 and 2015 implement the key features of C99. C99 does not offer anything earth-shattering; here are the features I think we'd find most interesting: - Variable declarations can be on any line: removes possibly the most annoying limitation of C89. - Inline functions: We can make Py_DECREF and Py_INCREF inline functions rather than unpleasant macros. - C++-style line comments: Not an killer feature but commonly used. - Booleans In summary, some niceties that would make CPython hacking a little more fun. So, what say you to updating PEP 7 to allow C99 features for Python 3.6 (in so much as GCC and MSVC support them)? Regards, Benjamin

3 years, 9 months

Python parser performance optimizations

by Artyom Skrobov

Hello, Back in March, I've posted a patch at http://bugs.python.org/issue26526 -- "In parsermodule.c, replace over 2KLOC of hand-crafted validation code, with a DFA". The motivation for this patch was to enable a memory footprint optimization, discussed at http://bugs.python.org/issue26415 My proposed optimization reduces the memory footprint by up to 30% on the standard benchmarks, and by 200% on a degenerate case which sparked the discussion. The run time stays unaffected by this optimization. Python Developer's Guide says: "If you don't get a response within a few days after pinging the issue, then you can try emailing python-dev(a)python.org<mailto:python-dev@python.org> asking for someone to review your patch." So, here I am. IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you.

3 years, 9 months

RFC: PEP 509: Add a private version to dict

by Victor Stinner

Hi, I updated my PEP 509 to make the dictionary version globally unique. With *two* use cases of this PEP (Yury's method call patch and my FAT Python project), I think that the PEP is now ready to be accepted. Globally unique identifier is a requirement for Yury's patch optimizing method calls ( https://bugs.python.org/issue26110 ). It allows to check for free if the dictionary was replaced. I also renamed the ma_version field to ma_version_tag. HTML version: https://www.python.org/dev/peps/pep-0509/ Victor PEP: 509 Title: Add a private version to dict Version: $Revision$ Last-Modified: $Date$ Author: Victor Stinner <victor.stinner(a)gmail.com> Status: Draft Type: Standards Track Content-Type: text/x-rst Created: 4-January-2016 Python-Version: 3.6 Abstract ======== Add a new private version to the builtin ``dict`` type, incremented at each dictionary creation and at each dictionary change, to implement fast guards on namespaces. Rationale ========= In Python, the builtin ``dict`` type is used by many instructions. For example, the ``LOAD_GLOBAL`` instruction searchs for a variable in the global namespace, or in the builtins namespace (two dict lookups). Python uses ``dict`` for the builtins namespace, globals namespace, type namespaces, instance namespaces, etc. The local namespace (namespace of a function) is usually optimized to an array, but it can be a dict too. Python is hard to optimize because almost everything is mutable: builtin functions, function code, global variables, local variables, ... can be modified at runtime. Implementing optimizations respecting the Python semantics requires to detect when "something changes": we will call these checks "guards". The speedup of optimizations depends on the speed of guard checks. This PEP proposes to add a version to dictionaries to implement fast guards on namespaces. Dictionary lookups can be skipped if the version does not change which is the common case for most namespaces. Since the version is globally unique, the version is also enough to check if the namespace dictionary was not replaced with a new dictionary. The performance of a guard does not depend on the number of watched dictionary entries, complexity of O(1), if the dictionary version does not change. Example of optimization: copy the value of a global variable to function constants. This optimization requires a guard on the global variable to check if it was modified. If the variable is modified, the variable must be loaded at runtime when the function is called, instead of using the constant. See the `PEP 510 -- Specialized functions with guards <https://www.python.org/dev/peps/pep-0510/>`_ for the concrete usage of guards to specialize functions and for the rationale on Python static optimizers. Guard example ============= Pseudo-code of an fast guard to check if a dictionary entry was modified (created, updated or deleted) using an hypothetical ``dict_get_version(dict)`` function:: UNSET = object() class GuardDictKey: def __init__(self, dict, key): self.dict = dict self.key = key self.value = dict.get(key, UNSET) self.version = dict_get_version(dict) def check(self): """Return True if the dictionary entry did not changed and the dictionary was not replaced.""" # read the version of the dict structure version = dict_get_version(self.dict) if version == self.version: # Fast-path: dictionary lookup avoided return True # lookup in the dictionary value = self.dict.get(self.key, UNSET) if value is self.value: # another key was modified: # cache the new dictionary version self.version = version return True # the key was modified return False Usage of the dict version ========================= Speedup method calls 1.2x ------------------------- Yury Selivanov wrote a `patch to optimize method calls <https://bugs.python.org/issue26110>`_. The patch depends on the `implement per-opcode cache in ceval <https://bugs.python.org/issue26219>`_ patch which requires dictionary versions to invalidate the cache if the globals dictionary or the builtins dictionary has been modified. The cache also requires that the dictionary version is globally unique. It is possible to define a function in a namespace and call it in a different namespace: using ``exec()`` with the *globals* parameter for example. In this case, the globals dictionary was changed and the cache must be invalidated. Specialized functions using guards ---------------------------------- The `PEP 510 -- Specialized functions with guards <https://www.python.org/dev/peps/pep-0510/>`_ proposes an API to support specialized functions with guards. It allows to implement static optimizers for Python without breaking the Python semantics. Example of a static Python optimizer: the `fatoptimizer <http://fatoptimizer.readthedocs.org/>`_ of the `FAT Python <http://faster-cpython.readthedocs.org/fat_python.html>`_ project implements many optimizations which require guards on namespaces. Examples: * Call pure builtins: to replace ``len("abc")`` with ``3``, guards on ``builtins.__dict__['len']`` and ``globals()['len']`` are required * Loop unrolling: to unroll the loop ``for i in range(...): ...``, guards on ``builtins.__dict__['range']`` and ``globals()['range']`` are required Pyjion ------ According of Brett Cannon, one of the two main developers of Pyjion, Pyjion can also benefit from dictionary version to implement optimizations. Pyjion is a JIT compiler for Python based upon CoreCLR (Microsoft .NET Core runtime). Unladen Swallow --------------- Even if dictionary version was not explicitly mentioned, optimizing globals and builtins lookup was part of the Unladen Swallow plan: "Implement one of the several proposed schemes for speeding lookups of globals and builtins." Source: `Unladen Swallow ProjectPlan <https://code.google.com/p/unladen-swallow/wiki/ProjectPlan>`_. Unladen Swallow is a fork of CPython 2.6.1 adding a JIT compiler implemented with LLVM. The project stopped in 2011: `Unladen Swallow Retrospective <http://qinsb.blogspot.com.au/2011/03/unladen-swallow-retrospective.html>`_. Changes ======= Add a ``ma_version_tag`` field to the ``PyDictObject`` structure with the C type ``PY_INT64_T``, 64-bit unsigned integer. Add also a global dictionary version. Each time a dictionary is created, the global version is incremented and the dictionary version is initialized to the global version. The global version is also incremented and copied to the dictionary version at each dictionary change: * ``clear()`` if the dict was non-empty * ``pop(key)`` if the key exists * ``popitem()`` if the dict is non-empty * ``setdefault(key, value)`` if the `key` does not exist * ``__detitem__(key)`` if the key exists * ``__setitem__(key, value)`` if the `key` doesn't exist or if the value is not ``dict[key]`` * ``update(...)`` if new values are different than existing values: values are compared by identity, not by their content; the version can be incremented multiple times The ``PyDictObject`` structure is not part of the stable ABI. The field is called ``ma_version_tag`` rather than ``ma_version`` to suggest to compare it using ``version_tag == old_version_tag`` rather than ``version <= old_version`` which makes the integer overflow much likely. Example using an hypothetical ``dict_get_version(dict)`` function:: >>> d = {} >>> dict_get_version(d) 100 >>> d['key'] = 'value' >>> dict_get_version(d) 101 >>> d['key'] = 'new value' >>> dict_get_version(d) 102 >>> del d['key'] >>> dict_get_version(d) 103 The version is not incremented if an existing key is set to the same value. For efficiency, values are compared by their identity: ``new_value is old_value``, not by their content: ``new_value == old_value``. Example:: >>> d = {} >>> value = object() >>> d['key'] = value >>> dict_get_version(d) 40 >>> d['key'] = value >>> dict_get_version(d) 40 .. note:: CPython uses some singleton like integers in the range [-5; 257], empty tuple, empty strings, Unicode strings of a single character in the range [U+0000; U+00FF], etc. When a key is set twice to the same singleton, the version is not modified. Implementation and Performance ============================== The `issue #26058: PEP 509: Add ma_version_tag to PyDictObject <https://bugs.python.org/issue26058>`_ contains a patch implementing this PEP. On pybench and timeit microbenchmarks, the patch does not seem to add any overhead on dictionary operations. When the version does not change, ``PyDict_GetItem()`` takes 14.8 ns for a dictionary lookup, whereas a guard check only takes 3.8 ns. Moreover, a guard can watch for multiple keys. For example, for an optimization using 10 global variables in a function, 10 dictionary lookups costs 148 ns, whereas the guard still only costs 3.8 ns when the version does not change (39x as fast). The `fat module <http://fatoptimizer.readthedocs.org/en/latest/fat.html>`_ implements such guards: ``fat.GuardDict`` is based on the dictionary version. Integer overflow ================ The implementation uses the C type ``PY_UINT64_T`` to store the version: a 64 bits unsigned integer. The C code uses ``version++``. On integer overflow, the version is wrapped to ``0`` (and then continue to be incremented) according to the C standard. After an integer overflow, a guard can succeed whereas the watched dictionary key was modified. The bug only occurs at a guard check if there are exaclty ``2 ** 64`` dictionary creations or modifications since the previous guard check. If a dictionary is modified every nanosecond, ``2 ** 64`` modifications takes longer than 584 years. Using a 32-bit version, it only takes 4 seconds. That's why a 64-bit unsigned type is also used on 32-bit systems. A dictionary lookup at the C level takes 14.8 ns. A risk of a bug every 584 years is acceptable. Alternatives ============ Expose the version at Python level as a read-only __version__ property ---------------------------------------------------------------------- The first version of the PEP proposed to expose the dictionary version as a read-only ``__version__`` property at Python level, and also to add the property to ``collections.UserDict`` (since this type must mimick the ``dict`` API). There are multiple issues: * To be consistent and avoid bad surprises, the version must be added to all mapping types. Implementing a new mapping type would require extra work for no benefit, since the version is only required on the ``dict`` type in practice. * All Python implementations must implement this new property, it gives more work to other implementations, whereas they may not use the dictionary version at all. * Exposing the dictionary version at Python level can lead the false assumption on performances. Checking ``dict.__version__`` at the Python level is not faster than a dictionary lookup. A dictionary lookup has a cost of 48.7 ns and checking a guard has a cost of 47.5 ns, the difference is only 1.2 ns (3%):: $ ./python -m timeit -s 'd = {str(i):i for i in range(100)}' 'd["33"] == 33' 10000000 loops, best of 3: 0.0487 usec per loop $ ./python -m timeit -s 'd = {str(i):i for i in range(100)}' 'd.__version__ == 100' 10000000 loops, best of 3: 0.0475 usec per loop * The ``__version__`` can be wrapped on integer overflow. It is error prone: using ``dict.__version__ <= guard_version`` is wrong, ``dict.__version__ == guard_version`` must be used instead to reduce the risk of bug on integer overflow (even if the integer overflow is unlikely in practice). Mandatory bikeshedding on the property name: * ``__cache_token__``: name proposed by Nick Coghlan, name coming from `abc.get_cache_token() <https://docs.python.org/3/library/abc.html#abc.get_cache_token>`_. * ``__version__`` * ``__timestamp__`` Add a version to each dict entry -------------------------------- A single version per dictionary requires to keep a strong reference to the value which can keep the value alive longer than expected. If we add also a version per dictionary entry, the guard can only store the entry version to avoid the strong reference to the value (only strong references to the dictionary and to the key are needed). Changes: add a ``me_version`` field to the ``PyDictKeyEntry`` structure, the field has the C type ``PY_INT64_T``. When a key is created or modified, the entry version is set to the dictionary version which is incremented at any change (create, modify, delete). Pseudo-code of an fast guard to check if a dictionary key was modified using hypothetical ``dict_get_version(dict)`` ``dict_get_entry_version(dict)`` functions:: UNSET = object() class GuardDictKey: def __init__(self, dict, key): self.dict = dict self.key = key self.dict_version = dict_get_version(dict) self.entry_version = dict_get_entry_version(dict, key) def check(self): """Return True if the dictionary entry did not changed and the dictionary was not replaced.""" # read the version of the dict structure dict_version = dict_get_version(self.dict) if dict_version == self.version: # Fast-path: dictionary lookup avoided return True # lookup in the dictionary entry_version = get_dict_key_version(dict, key) if entry_version == self.entry_version: # another key was modified: # cache the new dictionary version self.dict_version = dict_version return True # the key was modified return False The main drawback of this option is the impact on the memory footprint. It increases the size of each dictionary entry, so the overhead depends on the number of buckets (dictionary entries, used or unused yet). For example, it increases the size of each dictionary entry by 8 bytes on 64-bit system. In Python, the memory footprint matters and the trend is to reduce it. Examples: * `PEP 393 -- Flexible String Representation <https://www.python.org/dev/peps/pep-0393/>`_ * `PEP 412 -- Key-Sharing Dictionary <https://www.python.org/dev/peps/pep-0412/>`_ Add a new dict subtype ---------------------- Add a new ``verdict`` type, subtype of ``dict``. When guards are needed, use the ``verdict`` for namespaces (module namespace, type namespace, instance namespace, etc.) instead of ``dict``. Leave the ``dict`` type unchanged to not add any overhead (memory footprint) when guards are not needed. Technical issue: a lot of C code in the wild, including CPython core, expecting the exact ``dict`` type. Issues: * ``exec()`` requires a ``dict`` for globals and locals. A lot of code use ``globals={}``. It is not possible to cast the ``dict`` to a ``dict`` subtype because the caller expects the ``globals`` parameter to be modified (``dict`` is mutable). * Functions call directly ``PyDict_xxx()`` functions, instead of calling ``PyObject_xxx()`` if the object is a ``dict`` subtype * ``PyDict_CheckExact()`` check fails on ``dict`` subtype, whereas some functions require the exact ``dict`` type. * ``Python/ceval.c`` does not completely supports dict subtypes for namespaces The ``exec()`` issue is a blocker issue. Other issues: * The garbage collector has a special code to "untrack" ``dict`` instances. If a ``dict`` subtype is used for namespaces, the garbage collector can be unable to break some reference cycles. * Some functions have a fast-path for ``dict`` which would not be taken for ``dict`` subtypes, and so it would make Python a little bit slower. Prior Art ========= Method cache and type version tag --------------------------------- In 2007, Armin Rigo wrote a patch to to implement a cache of methods. It was merged into Python 2.6. The patch adds a "type attribute cache version tag" (``tp_version_tag``) and a "valid version tag" flag to types (the ``PyTypeObject`` structure). The type version tag is not available at the Python level. The version tag has the C type ``unsigned int``. The cache is a global hash table of 4096 entries, shared by all types. The cache is global to "make it fast, have a deterministic and low memory footprint, and be easy to invalidate". Each cache entry has a version tag. A global version tag is used to create the next version tag, it also has the C type ``unsigned int``. By default, a type has its "valid version tag" flag cleared to indicate that the version tag is invalid. When the first method of the type is cached, the version tag and the "valid version tag" flag are set. When a type is modified, the "valid version tag" flag of the type and its subclasses is cleared. Later, when a cache entry of these types is used, the entry is removed because its version tag is outdated. On integer overflow, the whole cache is cleared and the global version tag is reset to ``0``. See `Method cache (issue #1685986) <https://bugs.python.org/issue1685986>`_ and `Armin's method cache optimization updated for Python 2.6 (issue #1700288) <https://bugs.python.org/issue1700288>`_. Globals / builtins cache ------------------------ In 2010, Antoine Pitrou proposed a `Globals / builtins cache (issue #10401) <http://bugs.python.org/issue10401>`_ which adds a private ``ma_version`` field to the ``PyDictObject`` structure (``dict`` type), the field has the C type ``Py_ssize_t``. The patch adds a "global and builtin cache" to functions and frames, and changes ``LOAD_GLOBAL`` and ``STORE_GLOBAL`` instructions to use the cache. The change on the ``PyDictObject`` structure is very similar to this PEP. Cached globals+builtins lookup ------------------------------ In 2006, Andrea Griffini proposed a patch implementing a `Cached globals+builtins lookup optimization <https://bugs.python.org/issue1616125>`_. The patch adds a private ``timestamp`` field to the ``PyDictObject`` structure (``dict`` type), the field has the C type ``size_t``. Thread on python-dev: `About dictionary lookup caching <https://mail.python.org/pipermail/python-dev/2006-December/070348.html>`_. Guard against changing dict during iteration -------------------------------------------- In 2013, Serhiy Storchaka proposed `Guard against changing dict during iteration (issue #19332) <https://bugs.python.org/issue19332>`_ which adds a ``ma_count`` field to the ``PyDictObject`` structure (``dict`` type), the field has the C type ``size_t``. This field is incremented when the dictionary is modified, and so is very similar to the proposed dictionary version. Sadly, the dictionary version proposed in this PEP doesn't help to detect dictionary mutation. The dictionary version changes when values are replaced, whereas modifying dictionary values while iterating on dictionary keys is legit in Python. PySizer ------- `PySizer <http://pysizer.8325.org/>`_: a memory profiler for Python, Google Summer of Code 2005 project by Nick Smallbone. This project has a patch for CPython 2.4 which adds ``key_time`` and ``value_time`` fields to dictionary entries. It uses a global process-wide counter for dictionaries, incremented each time that a dictionary is modified. The times are used to decide when child objects first appeared in their parent objects. Discussion ========== Thread on the mailing lists: * python-dev: `PEP 509: Add a private version to dict <https://mail.python.org/pipermail/python-dev/2016-January/142685.html>`_ (january 2016) * python-ideas: `RFC: PEP: Add dict.__version__ <https://mail.python.org/pipermail/python-ideas/2016-January/037702.html>`_ (january 2016) Copyright ========= This document has been placed in the public domain.

3 years, 10 months

PEP 447: Add __getdescriptor__ to metaclasses

by Ronald Oussoren

Hi, It’s getting a tradition for me to work on PEP 447 during the EuroPython sprints and disappear afterwards. Hopefully I can manage to avoid the latter step this year… Last year the conclusion appeared to be that this is an acceptable PEP, but Mark Shannon had a concern about a default implementation for __getdescriptor__ on type in <https://mail.python.org/pipermail/python-dev/2015-July/140938.html> (follow the link for more context): > "__getdescriptor__" is fundamentally different from "__getattribute__" in that > is defined in terms of itself. > > object.__getattribute__ is defined in terms of type.__getattribute__, but > type.__getattribute__ just does > dictionary lookups. However defining type.__getattribute__ in terms of > __descriptor__ causes a circularity as > __descriptor__ has to be looked up on a type. > > So, not only must the cycle be broken by special casing "type", but that > "__getdescriptor__" can be defined > not only by a subclass, but also a metaclass that uses "__getdescriptor__" to > define "__getdescriptor__" on the class. > (and so on for meta-meta classes, etc.) My reaction that year is in <https://mail.python.org/pipermail/python-dev/2015-August/141114.html>. As I wrote there I did not fully understand the concerns Mark has, probably because I’m focussed too much on the implementation in CPython. If removing type.__getdescriptor__ and leaving this special method as an optional hook for subclasses of type fixes the conceptual concerns then that’s fine by me. I used type.__getdescriptor__ as the default implementation both because it appears to be cleaner to me and because this gives subclasses an easy way to access the default implementation. The implementation of the PEP in issue 18181 <http://bugs.python.org/issue18181> does special-case type.__getdescriptor__ but only as an optimisation, the code would work just as well without that special casing because the normal attribute lookup machinery is not used when accessing special methods written in C. That is, the implementation of object.__getattribute__ directly accesses fields of the type struct at the C level. Some magic behavior appears to be necessary even without the addition of __getdescriptor__ (type is a subclass of itself, object.__getattribute__ has direct access to dict.__getitem__, …). I’m currently working on getting the patch in 18181 up-to-date w.r.t. the current trunk, the patch in the issue no longer applies cleanly. After that I’ll try to think up some tests that seriously try to break the new behaviour, and I want to update a patch I have for PyObjC to make use of the new functionality to make sure that the PEP actually fixes the issues I had w.r.t. builtin.super’s behavior. What is the best way forward after that? As before this is a change in behavior that, unsurprisingly, few core devs appear to be comfortable with evaluating, combined with new functionality that will likely see little use beyond PyObjC (although my opinions of that shouldn’t carry much weight, I thought that decorators would have limited appeal when those where introduced and couldn’t have been more wrong about that). Ronald P.S. The PEP itself: <https://www.python.org/dev/peps/pep-0447>

3 years, 10 months

Re: [Python-Dev] PEP487: Simpler customization of class creation

by Sylvain Corlay

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.

3 years, 11 months

Method signatures in the datetime module documentation

by Alexander Belopolsky

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

3 years, 11 months

The devguide is now hosted on GitHub

by Brett Cannon

https://github.com/python/devguide I have also moved all issues over as well and hooked up Read The Docs so that there's a mirror which is always up-to-date (vs. docs.python.org/devguide which is on a cronjob).

3 years, 11 months

Summary of Python tracker Issues

by Python tracker

ACTIVITY SUMMARY (2016-07-22 - 2016-07-29) 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 5588 ( +2) closed 33818 (+56) total 39406 (+58) Open issues with patches: 2442 Issues opened (41) ================== #24773: Implement PEP 495 (Local Time Disambiguation) http://bugs.python.org/issue24773 reopened by martin.panter #27593: Deprecate sys._mercurial and create sys._git http://bugs.python.org/issue27593 opened by brett.cannon #27594: Assertion failure when running "test_ast" tests with coverage. http://bugs.python.org/issue27594 opened by ap #27595: Document PEP 495 (Local Time Disambiguation) features http://bugs.python.org/issue27595 opened by belopolsky #27596: Build failure with Xcode 8 beta on OSX 10.11 http://bugs.python.org/issue27596 opened by ronaldoussoren #27597: Add usage examples for TracebackException, StackSummary and Fr http://bugs.python.org/issue27597 opened by cool-RR #27598: Add SizedIterable to collections.abc and typing http://bugs.python.org/issue27598 opened by brett.cannon #27599: Buffer overrun in binascii http://bugs.python.org/issue27599 opened by serhiy.storchaka #27602: Enable py launcher to launch repository Python. http://bugs.python.org/issue27602 opened by terry.reedy #27603: Migrate IDLE context menu items to shell extension http://bugs.python.org/issue27603 opened by steve.dower #27604: More details about `-O` flag http://bugs.python.org/issue27604 opened by cool-RR #27605: Inconsistent calls to __eq__ from built-in __contains__ http://bugs.python.org/issue27605 opened by vfaronov #27606: Android cross-built for armv5te with clang and '-mthumb' crash http://bugs.python.org/issue27606 opened by xdegaye #27607: Importing the main module twice leads to two incompatible inst http://bugs.python.org/issue27607 opened by SylvieLorxu #27609: IDLE completions: format, factor, and fix http://bugs.python.org/issue27609 opened by terry.reedy #27611: test_tix cannot import _default_root after test_idle http://bugs.python.org/issue27611 opened by martin.panter #27612: socket.gethostbyname resolving octal IP addresses incorrectly http://bugs.python.org/issue27612 opened by mattrobenolt #27613: Empty iterator is rendered as a single bracket ] when using js http://bugs.python.org/issue27613 opened by altvod #27614: Race in test_docxmlrpc.py http://bugs.python.org/issue27614 opened by earl.chew #27618: docs for threading.Lock claim it's a class (since 3.3), but it http://bugs.python.org/issue27618 opened by gvanrossum #27619: getopt should strip whitespace from long arguments http://bugs.python.org/issue27619 opened by steven.daprano #27620: IDLE: Add keyboard equivalents for mouse actions. http://bugs.python.org/issue27620 opened by terry.reedy #27621: Finish IDLE Query dialog appearance and behavior. http://bugs.python.org/issue27621 opened by serhiy.storchaka #27623: int.to_bytes() and int.from_bytes(): raise ValueError when byt http://bugs.python.org/issue27623 opened by mmarkk #27627: clang fails to build ctypes on Android armv7 http://bugs.python.org/issue27627 opened by xdegaye #27628: ipaddress incompatibility with ipaddr: __contains__ between ne http://bugs.python.org/issue27628 opened by lukasz.langa #27629: Cannot create ssl.SSLSocket without existing socket http://bugs.python.org/issue27629 opened by nemunaire #27630: Generator._encoded_EMTPY misspelling in email package http://bugs.python.org/issue27630 opened by martin.panter #27632: build on AIX fails when builddir != srcdir, more than bad path http://bugs.python.org/issue27632 opened by Michael.Felt #27635: pickle documentation says that unpickling may not call __new__ http://bugs.python.org/issue27635 opened by july #27636: Refactor IDLE htest http://bugs.python.org/issue27636 opened by terry.reedy #27637: int.to_bytes(-1, ...) should automatically choose required cou http://bugs.python.org/issue27637 opened by mmarkk #27638: int.to_bytes() and int.from_bytes() should support 'net' and ' http://bugs.python.org/issue27638 opened by mmarkk #27639: UserList.__getitem__ doesn't account for slices http://bugs.python.org/issue27639 opened by staticshock #27640: add the '--disable-test-suite' option to configure http://bugs.python.org/issue27640 opened by xdegaye #27641: Do not build Programs/_freeze_importlib when cross-compiling http://bugs.python.org/issue27641 opened by thomas.perl #27643: test_ctypes fails on AIX with xlc http://bugs.python.org/issue27643 opened by Michael.Felt #27644: Expand documentation about type aliases and NewType in the typ http://bugs.python.org/issue27644 opened by michael0x2a #27645: Supporting native backup facility of SQLite http://bugs.python.org/issue27645 opened by lelit #27646: yield from expression can be any iterable http://bugs.python.org/issue27646 opened by terry.reedy #27647: Update Windows build to Tcl/Tk 8.6.6 http://bugs.python.org/issue27647 opened by serhiy.storchaka Most recent 15 issues with no replies (15) ========================================== #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 #27632: build on AIX fails when builddir != srcdir, more than bad path http://bugs.python.org/issue27632 #27599: Buffer overrun in binascii http://bugs.python.org/issue27599 #27597: Add usage examples for TracebackException, StackSummary and Fr http://bugs.python.org/issue27597 #27595: Document PEP 495 (Local Time Disambiguation) features http://bugs.python.org/issue27595 #27594: Assertion failure when running "test_ast" tests with coverage. http://bugs.python.org/issue27594 #27593: Deprecate sys._mercurial and create sys._git http://bugs.python.org/issue27593 #27589: asyncio doc: issue in as_completed() doc http://bugs.python.org/issue27589 #27584: New addition of vSockets to the python socket module http://bugs.python.org/issue27584 #27566: Tools/freeze/winmakemakefile.py clean target should use 'del' http://bugs.python.org/issue27566 #27565: Offer error context manager for code.interact http://bugs.python.org/issue27565 #27534: IDLE: Reduce number and time for user process imports http://bugs.python.org/issue27534 #27530: Non-Critical Compiler WARNING: Python Embedding C++11 does not http://bugs.python.org/issue27530 Most recent 15 issues waiting for review (15) ============================================= #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 #27644: Expand documentation about type aliases and NewType in the typ http://bugs.python.org/issue27644 #27641: Do not build Programs/_freeze_importlib when cross-compiling http://bugs.python.org/issue27641 #27640: add the '--disable-test-suite' option to configure http://bugs.python.org/issue27640 #27639: UserList.__getitem__ doesn't account for slices http://bugs.python.org/issue27639 #27629: Cannot create ssl.SSLSocket without existing socket http://bugs.python.org/issue27629 #27623: int.to_bytes() and int.from_bytes(): raise ValueError when byt http://bugs.python.org/issue27623 #27621: Finish IDLE Query dialog appearance and behavior. http://bugs.python.org/issue27621 #27619: getopt should strip whitespace from long arguments http://bugs.python.org/issue27619 #27614: Race in test_docxmlrpc.py http://bugs.python.org/issue27614 #27611: test_tix cannot import _default_root after test_idle http://bugs.python.org/issue27611 #27604: More details about `-O` flag http://bugs.python.org/issue27604 #27587: Issues, reported by PVS-Studio static analyzer http://bugs.python.org/issue27587 #27584: New addition of vSockets to the python socket module http://bugs.python.org/issue27584 Top 10 most discussed issues (10) ================================= #24773: Implement PEP 495 (Local Time Disambiguation) http://bugs.python.org/issue24773 29 msgs #26462: Patch to enhance literal block language declaration http://bugs.python.org/issue26462 23 msgs #27612: socket.gethostbyname resolving octal IP addresses incorrectly http://bugs.python.org/issue27612 18 msgs #26852: add the '--enable-sourceless-distribution' option to configure http://bugs.python.org/issue26852 14 msgs #27546: Integrate tkinter and asyncio (and async) http://bugs.python.org/issue27546 13 msgs #27607: Importing the main module twice leads to two incompatible inst http://bugs.python.org/issue27607 13 msgs #27604: More details about `-O` flag http://bugs.python.org/issue27604 12 msgs #26851: android compilation and link flags http://bugs.python.org/issue26851 11 msgs #27619: getopt should strip whitespace from long arguments http://bugs.python.org/issue27619 11 msgs #27623: int.to_bytes() and int.from_bytes(): raise ValueError when byt http://bugs.python.org/issue27623 11 msgs Issues closed (54) ================== #7063: Memory errors in array.array http://bugs.python.org/issue7063 closed by martin.panter #8623: Aliasing warnings in socketmodule.c http://bugs.python.org/issue8623 closed by martin.panter #10036: compiler warnings for various modules on Linux buildslaves http://bugs.python.org/issue10036 closed by martin.panter #10965: dev task of documenting undocumented APIs http://bugs.python.org/issue10965 closed by brett.cannon #11048: "import ctypes" causes segfault on read-only filesystem http://bugs.python.org/issue11048 closed by haypo #13849: Add tests for NUL checking in certain strs http://bugs.python.org/issue13849 closed by berker.peksag #14218: include rendered output in addition to markup http://bugs.python.org/issue14218 closed by brett.cannon #15661: OS X installer packages should be signed for OS X 10.8 Gatekee http://bugs.python.org/issue15661 closed by ned.deily #16930: mention limitations and/or alternatives to hg graft http://bugs.python.org/issue16930 closed by brett.cannon #16931: mention work-around to create diffs in default/non-git mode http://bugs.python.org/issue16931 closed by brett.cannon #17227: devguide: buggy heading numbers http://bugs.python.org/issue17227 closed by brett.cannon #17596: mingw: add wincrypt.h in Python/random.c http://bugs.python.org/issue17596 closed by martin.panter #18041: mention issues with code churn in the devguide http://bugs.python.org/issue18041 closed by brett.cannon #20851: Update devguide to cover testing from a tarball http://bugs.python.org/issue20851 closed by brett.cannon #22645: Unable to install Python 3.4.2 amd64 on Windows 8.1 Update 1 http://bugs.python.org/issue22645 closed by berker.peksag #23320: devguide should mention rules about "paragraph reflow" in the http://bugs.python.org/issue23320 closed by brett.cannon #23951: Update devguide style to use a similar theme as Docs http://bugs.python.org/issue23951 closed by brett.cannon #24016: Add a Sprints organization/preparation section to devguide http://bugs.python.org/issue24016 closed by brett.cannon #24682: Add Quick Start: Communications section to devguide http://bugs.python.org/issue24682 closed by brett.cannon #24689: Add tips for effective online communication to devguide http://bugs.python.org/issue24689 closed by brett.cannon #25431: implement address in network in ipaddress module http://bugs.python.org/issue25431 closed by berker.peksag #25966: Bug in asyncio.corotuines._format_coroutine http://bugs.python.org/issue25966 closed by berker.peksag #26152: A non-breaking space in a source http://bugs.python.org/issue26152 closed by ncoghlan #26662: configure/Makefile doesn't check if "python" command works, ne http://bugs.python.org/issue26662 closed by xdegaye #26974: Crash in Decimal.from_float http://bugs.python.org/issue26974 closed by skrah #27130: zlib: OverflowError while trying to compress 2^32 bytes or mor http://bugs.python.org/issue27130 closed by martin.panter #27131: Unit test random shuffle http://bugs.python.org/issue27131 closed by rhettinger #27250: Add os.urandom_block() http://bugs.python.org/issue27250 closed by haypo #27266: Always use getrandom() in os.random() on Linux and add block=F http://bugs.python.org/issue27266 closed by haypo #27404: Misc/NEWS: add [Security] prefix to Python 3.5.2 changelog http://bugs.python.org/issue27404 closed by haypo #27454: PyUnicode_InternInPlace can use PyDict_SetDefault http://bugs.python.org/issue27454 closed by berker.peksag #27490: Do not run pgen when it is not going to be used (cross-compili http://bugs.python.org/issue27490 closed by martin.panter #27493: logging module fails with unclear error when supplied a (Posix http://bugs.python.org/issue27493 closed by python-dev #27579: Add a tutorial for AsyncIO in the documentation http://bugs.python.org/issue27579 closed by haypo #27581: Fix overflow check in PySequence_Tuple http://bugs.python.org/issue27581 closed by martin.panter #27591: multiprocessing: Possible uninitialized pointer use in Windows http://bugs.python.org/issue27591 closed by berker.peksag #27592: FIPS_mode() and FIPS_mode_set() functions in Python (ssl) http://bugs.python.org/issue27592 closed by r.david.murray #27600: Spam http://bugs.python.org/issue27600 closed by ebarry #27601: Minor inaccuracy in hash documentation http://bugs.python.org/issue27601 closed by magniff #27608: Something wrong with str.upper().lower() chain? http://bugs.python.org/issue27608 closed by magniff #27610: Add PEP 514 metadata to Windows installer http://bugs.python.org/issue27610 closed by steve.dower #27615: IDLE's debugger steps into PyShell.py for calls to print() et http://bugs.python.org/issue27615 closed by terry.reedy #27616: filedialog.askdirectory inconsistent on Windows between return http://bugs.python.org/issue27616 closed by serhiy.storchaka #27617: Compiled bdist_wininst missing from embedded distribution http://bugs.python.org/issue27617 closed by steve.dower #27622: int.to_bytes(): docstring is not precise http://bugs.python.org/issue27622 closed by mmarkk #27624: unclear documentation on Queue.qsize() http://bugs.python.org/issue27624 closed by rhettinger #27625: "make install" fails when no zlib support available http://bugs.python.org/issue27625 closed by SilentGhost #27626: Spelling fixes http://bugs.python.org/issue27626 closed by martin.panter #27631: .exe is appended to python executable based on filesystem case http://bugs.python.org/issue27631 closed by ammar2 #27633: Doc: Add missing version info to email.parser http://bugs.python.org/issue27633 closed by berker.peksag #27634: selectors.SelectSelectors fails if select.select was patched http://bugs.python.org/issue27634 closed by brett.cannon #27642: import and __import__() fails silently without a ImportError a http://bugs.python.org/issue27642 closed by ebarry #27648: Message of webbrowser.py something wrong. http://bugs.python.org/issue27648 closed by r.david.murray #27649: multiprocessing on Windows does not properly manage class attr http://bugs.python.org/issue27649 closed by r.david.murray

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Python-Dev July 2016