Mailman 3 February 2020 - docs

[issue39096] Description of "Format Specification Mini-Language" not accurate for Decimal
by Michael Amrhein Dec. 18, 2020

Dec. 18, 2020

New submission from Michael Amrhein <michael(a)adrhinum.de>: The description of the "Format Specification Mini-Language" states for float and Decimal regarding presentation type 'f': "The default precision is 6." Regarding presentation type None it reads: "Similar to 'g', except that fixed-point notation, when used, has at least one digit past the decimal point." While both statements are accurate for float, they don't hold for Decimal. In order to preserve the information about the decimal exponent, in both cases Decimal formatting displays as many fractional digits as dictated by it's exponent. ---------- assignee: docs@python components: Documentation messages: 358667 nosy: docs@python, mamrhein priority: normal severity: normal status: open title: Description of "Format Specification Mini-Language" not accurate for Decimal type: behavior versions: Python 3.6, Python 3.7, Python 3.8, Python 3.9 _______________________________________ Python tracker <report(a)bugs.python.org> <https://bugs.python.org/issue39096> _______________________________________

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[issue39416] Document default numeric string formats
by Karl O. Pinc Dec. 16, 2020

Dec. 16, 2020

New submission from Karl O. Pinc <kop(a)karlpinc.com>: Seems sane to put _some_ restrictions on the string representations of the Numeric classes. This would be a change to the Python language specification. Suggestions made in a pull request. See the email thread: Subject: Documenting Python's float.__str__() https://mail.python.org/archives/list/python-dev@python.org/thread/FV22TKT3… ---------- assignee: docs@python components: Documentation messages: 360442 nosy: docs@python, kop priority: normal severity: normal status: open title: Document default numeric string formats _______________________________________ Python tracker <report(a)bugs.python.org> <https://bugs.python.org/issue39416> _______________________________________

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[issue14586] TypeError: truncate() takes no keyword arguments
by Guy Taylor Dec. 15, 2020

Dec. 15, 2020

New submission from Guy Taylor <thebigguy.co.uk(a)gmail.com>: The Python docs suggest that io.IOBase.truncate' should take a keyword argument of 'size'. However this causes a 'TypeError': TypeError: truncate() takes no keyword arguments Suggest that the docs are changed to 'truncate(size)' or CPython is changed to allow the keyword. http://docs.python.org/py3k/library/io.html?highlight=truncate#io.IOBase.tr… http://docs.python.org/library/io.html?highlight=truncate#io.IOBase.truncate ---------- assignee: docs@python components: Documentation, Interpreter Core files: test.py messages: 158308 nosy: TheBiggerGuy, docs@python priority: normal severity: normal status: open title: TypeError: truncate() takes no keyword arguments type: behavior versions: Python 2.7, Python 3.2 Added file: http://bugs.python.org/file25219/test.py _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue14586> _______________________________________

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[issue26515] Update extending/embedding docs to new way to build modules in C
by Brett Cannon Dec. 15, 2020

Dec. 15, 2020

New submission from Brett Cannon: https://docs.python.org/3/extending/extending.html#a-simple-example uses PyModule_Create() instead of PyModuleDef_Init(). ---------- assignee: docs@python components: Documentation messages: 261398 nosy: brett.cannon, docs@python, eric.snow, ncoghlan priority: normal severity: normal stage: needs patch status: open title: Update extending/embedding docs to new way to build modules in C versions: Python 3.5, Python 3.6 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue26515> _______________________________________

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[issue35083] Fix documentation for __instancecheck__
by Joy Diamond Dec. 15, 2020

Dec. 15, 2020

New submission from Joy Diamond <python.gem(a)gmail.com>: This is a request to fix the documentation for __instancecheck__. Please add the following: """ (Note that any object `x` is always considered to be an instance of `type(x)`, and this cannot be overridden.) """ Consider the following program: class M(type): def __instancecheck__(m, t): print('instancecheck(%s, %s)' % (m, t)) return False # LIE! Test = M('Test', ((object,)), {}) something = Test() print('Does *NOT* call __instancecheck__:') print('isinstance(something, Test): %s' % isinstance(something, Test)) print() print('Does call __instancecheck__:') print('isinstance(0, Test): %s' % isinstance(0, Test)) Under python 2, python 3, and pypy, in all cases, the first examples does *NOT* call __instancecheck__. You can see the optimization here: https://github.com/python/cpython/blob/master/Objects/abstract.c#L2397-L2405 Which reads: int PyObject_IsInstance(PyObject *inst, PyObject *cls) { _Py_IDENTIFIER(__instancecheck__); PyObject *checker; /* Quick test for an exact match */ if (Py_TYPE(inst) == (PyTypeObject *)cls) return 1; I'm fine with the optimization -- I am not suggesting to get rid of it. I just want the documentation to match the actual implementation. The following documentation needs to be fixed: https://docs.python.org/2/reference/datamodel.html https://docs.python.org/3/reference/datamodel.html https://www.python.org/dev/peps/pep-3119/ It took me half an hour to figure out why my version of __instancecheck__ was not working, as I tried to test it using the super simple code above ... One of the best things about python is how accurate and consistent the documentation is. This request is to keep these high standards. ---------- assignee: docs@python components: Documentation messages: 328658 nosy: docs@python, joydiamond priority: normal severity: normal status: open title: Fix documentation for __instancecheck__ type: enhancement versions: Python 2.7, Python 3.8 _______________________________________ Python tracker <report(a)bugs.python.org> <https://bugs.python.org/issue35083> _______________________________________

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[issue26451] CSV documentation doesn't open with an example
by Alex LordThorsen Dec. 13, 2020

Dec. 13, 2020

New submission from Alex LordThorsen: Had a friend get stuck on the CSV documentation. They didn't know what a CSV was (to start with) and couldn't find an example that made sense to them. they went to other sources to figure out how to read CSV files in the end. I made this patch in the hope that starting out with a very minimal example file format followed by an example python read will make landing on the CSV docs easier to follow for new programmers. ---------- assignee: docs@python components: Documentation files: csv_documentation.patch keywords: patch messages: 260960 nosy: Alex.LordThorsen, docs@python priority: normal severity: normal status: open title: CSV documentation doesn't open with an example versions: Python 3.6 Added file: http://bugs.python.org/file42040/csv_documentation.patch _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue26451> _______________________________________

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[issue24110] zipfile.ZipFile.write() does not accept bytes arcname
by July Tikhonov Dec. 8, 2020

Dec. 8, 2020

New submission from July Tikhonov: In documentation of zipfile.ZipFile.write() there is following notice: "There is no official file name encoding for ZIP files. If you have unicode file names, you must convert them to byte strings in your desired encoding before passing them to write()." I understand it as that 'arcname' argument to write() shouldn't be of type str, but rather bytes. But it is str that works, and bytes that does not: $ ./python Python 3.5.0a4+ (default:6f6e78931875, May 1 2015, 23:18:40) [GCC 4.8.4] on linux Type "help", "copyright", "credits" or "license" for more information. >>> import zipfile >>> zf = zipfile.ZipFile('foo.zip', 'w') >>> zf.write('python', 'a') >>> zf.write('python', b'b') Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/home/july/source/python/Lib/zipfile.py", line 1442, in write zinfo = ZipInfo(arcname, date_time) File "/home/july/source/python/Lib/zipfile.py", line 322, in __init__ null_byte = filename.find(chr(0)) TypeError: a bytes-like object is required, not 'str' (ZipInfo ostensibly attempts to find a zero byte in the filename, but searches instead for a unicode character chr(0). There are several other places in ZipInfo class that assume filename being str rather than bytes.) I consider this a documentation issue: the notice is misleading. Although maybe there is someone who wants to fix the behavior of ZipInfo to allow bytes filename. ---------- assignee: docs@python components: Documentation messages: 242355 nosy: docs@python, july priority: normal severity: normal status: open title: zipfile.ZipFile.write() does not accept bytes arcname type: behavior versions: Python 3.4, Python 3.5, Python 3.6 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue24110> _______________________________________

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[issue25573] traceback documentation example is lying about FrameSummary repr()
by Alexandre Macabies Dec. 8, 2020

Dec. 8, 2020

New submission from Alexandre Macabies: https://docs.python.org/3.5/library/traceback.html#traceback-examples See second code sample and its sample output. According to the docs, the call: print(repr(traceback.extract_tb(exc_traceback))) is supposed to print something that looks like an array with only strings; that is what the doc sample output states: [('<doctest...>', 10, '<module>', 'lumberjack()'), But actually, in 3.5+, this call outputs the repr() of a list of FrameSummary instances that do not go further in repr()esenting their state: [<FrameSummary file <ipython-input-61-3e63d7daea82>, line 10 in <module>>, By looking at the docs I thought I was able to get a nice string representation of a FrameSummary. I actually have to format it myself. It should be reflected in the doc sample output. ---------- assignee: docs@python components: Documentation messages: 254224 nosy: Alexandre Macabies, docs@python priority: normal severity: normal status: open title: traceback documentation example is lying about FrameSummary repr() versions: Python 3.5, Python 3.6 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue25573> _______________________________________

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[issue38843] Document argparse behaviour when custom namespace object already has the field set
by Ivan Kurnosov Dec. 7, 2020

Dec. 7, 2020

New submission from Ivan Kurnosov <zerkms(a)zerkms.com>: At this moment it's impossible to explain the behaviour of this script using documentation. Given it was explicitly coded to behave like that - it should be somehow noted in the documentation, that as long as a `CliArgs.foo` field has a default value set already - it won't be overwritten with a default argparse argument value. ``` import argparse class CliArgs(object): foo: str = 'not touched' parser = argparse.ArgumentParser() parser.add_argument('--foo', default='bar') args = CliArgs() parser.parse_args(namespace=args) print(args.foo) # 'not touched' print(parser.parse_args()) # 'bar' ``` ---------- assignee: docs@python components: Documentation messages: 356939 nosy: docs@python, zerkms priority: normal severity: normal status: open title: Document argparse behaviour when custom namespace object already has the field set _______________________________________ Python tracker <report(a)bugs.python.org> <https://bugs.python.org/issue38843> _______________________________________

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[issue26582] asyncio documentation links to wrong CancelledError
by awilfox Dec. 4, 2020

Dec. 4, 2020

New submission from awilfox: In the 3.5 and 3.6a0 documentation for asyncio, "CancelledError" is linked to the concurrent.futures.CancelledError. This led me to try catching that exception and finding that it did not work correctly at all. Only after searching for asyncio example code and seeing how other people caught asyncio.CancelledError did I realise the issue. The fact asyncio.CancelledError even exists isn't actually documented, and I believe that is why the :exc: reference is linking to the wrong module. ---------- assignee: docs@python components: Documentation messages: 261911 nosy: awilfox, docs@python priority: normal severity: normal status: open title: asyncio documentation links to wrong CancelledError versions: Python 3.5, Python 3.6 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue26582> _______________________________________

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