Mailman 3 September 2019 - docs

[issue15088] PyGen_NeedsFinalizing is public, but undocumented
by STINNER Victor Sept. 6, 2019

Sept. 6, 2019

STINNER Victor <vstinner(a)python.org> added the comment: New changeset 74b662cf202753d224d82d5503974cce881f7436 by Victor Stinner (Joannah Nanjekye) in branch 'master': bpo-15088 : Remove PyGen_NeedsFinalizing() (GH-15702) https://github.com/python/cpython/commit/74b662cf202753d224d82d5503974cce88… ---------- _______________________________________ Python tracker <report(a)bugs.python.org> <https://bugs.python.org/issue15088> _______________________________________

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Documentation bug: struct library, endian format chars are reversed
by Tom Belpasso Sept. 5, 2019

Sept. 5, 2019

Dear Python Docs: The struct library has table with format values for pack and unpack. In section: 7.1.2.1. Byte Order, Size, and Alignment The big endian and little endian characters are reversed in the table. '>' should be little endian, just like the character looks. '<' should be big endian, just like the character. I have verified that this is the correct behavior after use the wrong one in my program and wondering why I was seeing so many large fluctuations in my plots. I had … [View More]

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[issue15088] PyGen_NeedsFinalizing is public, but undocumented
by STINNER Victor Sept. 5, 2019

Sept. 5, 2019

STINNER Victor <vstinner(a)python.org> added the comment: The function is not documented nor tested. I searched for usage of PyGen_NeedsFinalizing() in C code in GitHub: https://github.com/search?l=C&p=1&q=PyGen_NeedsFinalizing&type=Code I only found copies of the CPython code source: PyGen_NeedsFinalizing() definition in genobject.h. IHMO we can safely remove the function right now. If someone complains, we can reintroduce it later. We just have to document clearly its … [View More]

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[issue15088] PyGen_NeedsFinalizing is public, but undocumented
by STINNER Victor Sept. 5, 2019

Sept. 5, 2019

STINNER Victor <vstinner(a)python.org> added the comment: PyGen_NeedsFinalizing() was added by: commit 49fd7fa4431da299196d74087df4a04f99f9c46f Author: Thomas Wouters <thomas(a)python.org> Date: Fri Apr 21 10:40:58 2006 +0000 Merge p3yk branch with the trunk up to revision 45595. This breaks a fair number of tests, all because of the codecs/_multibytecodecs issue described here (it's not a Py3K issue, just something Py3K discovers): http://mail.python.org/… [View More]pipermail/python-dev/2006-April/064051.html Hye-Shik Chang promised to look for a fix, so no need to fix it here. The tests that are expected to break are: test_codecencodings_cn test_codecencodings_hk test_codecencodings_jp test_codecencodings_kr test_codecencodings_tw test_codecs test_multibytecodec This merge fixes an actual test failure (test_weakref) in this branch, though, so I believe merging is the right thing to do anyway. It was used in this gcmodule.c function: /* Return true if object has a finalization method. * CAUTION: An instance of an old-style class has to be checked for a *__del__ method, and earlier versions of this used to call PyObject_HasAttr, * which in turn could call the class's __getattr__ hook (if any). That * could invoke arbitrary Python code, mutating the object graph in arbitrary * ways, and that was the source of some excruciatingly subtle bugs. */ static int has_finalizer(PyObject *op) { if (PyInstance_Check(op)) { assert(delstr != NULL); return _PyInstance_Lookup(op, delstr) != NULL; } else if (PyType_HasFeature(op->ob_type, Py_TPFLAGS_HEAPTYPE)) return op->ob_type->tp_del != NULL; else if (PyGen_CheckExact(op)) return PyGen_NeedsFinalizing((PyGenObject *)op); else return 0; } (2) The PEP 442 implementation made PyGen_NeedsFinalizing() useless: commit 796564c27b8f2e32b9fbc034bbdda75f9507ca43 Author: Antoine Pitrou <solipsis(a)pitrou.net> Date: Tue Jul 30 19:59:21 2013 +0200 Issue #18112: PEP 442 implementation (safe object finalization). Replaced: /* Return true if object has a finalization method. */ static int has_finalizer(PyObject *op) { if (PyGen_CheckExact(op)) return PyGen_NeedsFinalizing((PyGenObject *)op); else return op->ob_type->tp_del != NULL; } with: /* Return true if object has a pre-PEP 442 finalization method. */ static int has_legacy_finalizer(PyObject *op) { return op->ob_type->tp_del != NULL; } -- The last reference to PyGen_NeedsFinalizing() can be found in ceval.c: case TARGET(SETUP_FINALLY): { /* NOTE: If you add any new block-setup opcodes that are not try/except/finally handlers, you may need to update the PyGen_NeedsFinalizing() function. */ PyFrame_BlockSetup(f, SETUP_FINALLY, INSTR_OFFSET() + oparg, STACK_LEVEL()); DISPATCH(); } ---------- nosy: +vstinner _______________________________________ Python tracker <report(a)bugs.python.org> <https://bugs.python.org/issue15088> _______________________________________ [View Less]

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[issue15088] PyGen_NeedsFinalizing is public, but undocumented
by Joannah Nanjekye Sept. 5, 2019

Sept. 5, 2019

Joannah Nanjekye <nanjekyejoannah(a)gmail.com> added the comment: My searches show references to this function in CPython cloned repositories. From @pitrous's views, I think it is better to deprecate it with a removal notice for a later release. I have deprecated the Function instead and will be removed in the next release in this PR https://github.com/python/cpython/pull/15702 . ---------- nosy: +nanjekyejoannah _______________________________________ Python tracker <report(a)bugs.… [View More]

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[issue15088] PyGen_NeedsFinalizing is public, but undocumented
by Joannah Nanjekye Sept. 5, 2019

Sept. 5, 2019

Change by Joannah Nanjekye <nanjekyejoannah(a)gmail.com>: ---------- pull_requests: +15356 stage: -> patch review pull_request: https://github.com/python/cpython/pull/15702 _______________________________________ Python tracker <report(a)bugs.python.org> <https://bugs.python.org/issue15088> _______________________________________

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[issue37934] Docs: Clarify NotImplemented use cases
by Kyle Stanley Sept. 5, 2019

Sept. 5, 2019

New submission from Kyle Stanley <aeros167(a)gmail.com>: In the documentation for the NotImplemented constant (https://docs.python.org/3/library/constants.html#NotImplemented), the only use case mentioned is for binary special methods, (such as object.__eq__(other)). However, based on a conversation in a recent PR (https://github.com/python/cpython/pull/15327#discussion_r316561140), there seems be several other use cases as well. It's quite useful to utilize when it's desired to express … [View More]

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Can't open bugs tracker from Russia, had to use a VPN
by Anastasia Karchevskaya Sept. 4, 2019

Sept. 4, 2019

Good day, I have all of a sudden encountered rather unusual issue: If I try opening https://bugs.python.org <https://bugs.python.org/> without the VPN, I can’t open the page. I have to use VPN and that comes only at that page, all the other pages work well. Please, do somewhat. Many thx, BR, Ana

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Inadequate documentation on re.sub()
by Malik Rumi Sept. 4, 2019

Sept. 4, 2019

1. I am aware of issues 34304 and 28450. I am writing because I think those fixes are inadequate. This is my proposed language change to https://docs.python.org/3/library/re.html#re.sub re.sub(pattern, repl, string, count=0, flags=0) Return the string obtained by replacing the leftmost non-overlapping occurrences of pattern in string by the replacement repl. If the pattern isn’t found, string is returned unchanged. repl can be a string or a function; if it is a string, any backslash escapes in … [View More]

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Incorrect description of != involving NaN operands
by Robert Gamble Sept. 3, 2019

Sept. 3, 2019

In 6.10.1. Value comparisons <https://docs.python.org/3/reference/expressions.html#value-comparisons>, the following paragraph appears (emphasis mine): The not-a-number values float('NaN') and decimal.Decimal('NaN') are special. Any ordered comparison of a number to a not-a-number value is false. A counter-intuitive implication is that *not-a-number values are not equal to themselves*. For example, if x = float('NaN'), 3 < x, x < 3, x ==x , *x != x* are all false. This behavior is … [View More]

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