Mailman 3 August 2017 - docs

[issue22401] argparse: 'resolve' conflict handler damages the actions of the parent parser
by paul j3 27 Jan '21

27 Jan '21

New submission from paul j3: When there's a conflict involving an argument that was added via 'parents', and the conflict handler is 'resolve', the action in the parent parser may be damaged, rendering that parent unsuitable for further use. In this example, 2 parents have the same '--config' argument: parent1 = argparse.ArgumentParser(add_help=False) parent1.add_argument('--config') parent2 = argparse.ArgumentParser(add_help=False) parent2.add_argument('--config') parser = argparse.ArgumentParser(parents=[parent1,parent2], conflict_handler='resolve') The actions of the 3 parsers are (from the ._actions list): (id, dest, option_strings) parent1: [(3077384012L, 'config', [])] # empty option_strings parent2: [(3076863628L, 'config', ['--config'])] parser: [(3076864428L, 'help', ['-h', '--help']), (3076863628L, 'config', ['--config'])] # same id The 'config' Action from 'parent1' is first copied to 'parser' by reference (this is important). When 'config' from 'parent2' is copied, there's a conflict. '_handle_conflict_resolve()' attempts to remove the first Action, so it can add the second. But in the process it ends up deleting the 'option_strings' values from the original action. So now 'parent1' has an action in its 'optionals' argument group with an empty option_strings list. It would display as an 'optionals' but parse as a 'positionals'. 'parent1' can no longer be safely used as a parent for another (sub)parser, nor used as a parser itself. The same sort of thing would happen, if, as suggested in the documentation: "Sometimes (e.g. when using parents_) it may be useful to simply override any older arguments with the same option string." In test_argparse.py, 'resolve' is only tested once, with a simple case of two 'add_argument' statements. The 'parents' class tests a couple of cases of conflicting actions (for positionals and optionals), but does nothing with the 'resolve' handler. ------------------------------ Possible fixes: - change the documentation to warn against reusing such a parent parser - test the 'resolve' conflict handler more thoroughly - rewrite this conflict handler so it does not modify the action in the parent - possibly change the 'parents' mechanism so it does a deep copy of actions. References: http://stackoverflow.com/questions/25818651/argparse-conflict-resolver-for-… http://bugs.python.org/issue15271 argparse: repeatedly specifying the same argument ignores the previous ones http://bugs.python.org/issue19462 Add remove_argument() method to argparse.ArgumentParser http://bugs.python.org/issue15428 add "Name Collision" section to argparse docs ---------- assignee: docs@python components: Documentation, Library (Lib), Tests messages: 226862 nosy: docs@python, paul.j3 priority: normal severity: normal status: open title: argparse: 'resolve' conflict handler damages the actions of the parent parser type: behavior versions: Python 3.5 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue22401> _______________________________________

3 15

[issue24711] Document getpass.getpass behavior on ^C
by Markus Unterwaditzer 11 Jan '21

11 Jan '21

New submission from Markus Unterwaditzer: getpass.getpass doesn't enter a newline when the user aborts input with ^C, while input/raw_input does. This behavior is surprising and can lead to mis-formatting of subsequent output. However, since this behavior exists since 2.7 and applications may have started to rely on it, I'd add a note to the documentation. ---------- assignee: docs@python components: Documentation messages: 247302 nosy: docs@python, untitaker priority: normal severity: normal status: open title: Document getpass.getpass behavior on ^C versions: Python 2.7, Python 3.2, Python 3.3, Python 3.4, Python 3.5, Python 3.6 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue24711> _______________________________________

2 2

[issue8595] Unexpected default timeout in http-client-related libraries
by Julian 29 Dec '20

29 Dec '20

New submission from Julian <python_org(a)somethinkodd.com>: Since Python 2.6, httplib has offered a timeout parameter for fetches. As the documentation explains, if this parameter is not provided, it uses the global default. What the document doesn't explain is httplib builds on top of the socket library. The socket library has a default timeout of None (i.e. forever). This may be an appropriate default for general sockets, but it is a poor default for httplib; typical http clients would use a timeout in the 2-10 second range. This problem is propagated up to urllib2, which sits on httplib, and further obscures that the default might be unsuitable. >From an inspection of the manuals, Python 3.0.1 suffers from the same problem except, the names have changed. urllib.response sits on http.client. I, for one, made a brutal mistake of assuming that the "global default" would be some reasonable default for fetching web pages; I didn't have any specific timeout in mind, and was happy for the library to take care of it. Several million successful http downloads later, my server application thread froze waiting forever when talking to a recalcitrant web-server. I imagine others have fallen for the same trap. While an ideal solution would be for httplib and http.client to use a more generally acceptable default, I can see it might be far too late to make such a change without breaking existing applications. Failing that, I would recommend that the documentation for httplib, urllib, urllib2, http.client and urllib.request (+ any other similar libraries sitting on socket? FTP, SMTP?) be changed to highlight that the default global timeout, sans deliberate override, is to wait a surprisingly long time. ---------- assignee: docs@python components: Documentation, Library (Lib) messages: 104763 nosy: docs@python, oddthinking priority: normal severity: normal status: open title: Unexpected default timeout in http-client-related libraries type: behavior versions: Python 2.6, Python 2.7, Python 3.1 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue8595> _______________________________________

5 8

[issue8822] datetime naive and aware types should have a well-defined definition that can be cross-referenced
by anatoly techtonik 29 Dec '20

29 Dec '20

New submission from anatoly techtonik <techtonik(a)gmail.com>: 'naive' and 'aware' are key datetime types - they need a proper definition and anchor for crossrefences. If you take a look at http://docs.python.org/library/datetime.html - the definition of distinction between them is too vague and this seeds of uncertainty grow through the rest of the doc. It is not said how to make non-naive object, how to detect if object of naive or aware. All this stuff is very important for troubleshooting datetims issues in Python projects. It needs a proper documentation. ---------- assignee: docs@python components: Documentation messages: 106524 nosy: docs@python, techtonik priority: normal severity: normal status: open title: datetime naive and aware types should have a well-defined definition that can be cross-referenced _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue8822> _______________________________________

6 15

[issue23522] Misleading note in Statistics module documentation
by Jake 19 Dec '20

19 Dec '20

New submission from Jake: In the statistics module documentation, there is a note that states that "The mean is strongly affected by outliers and is not a robust estimator for central location: the mean is not necessarily a typical example of the data points. For more robust, although less efficient, measures of central location, see median() and mode()" https://docs.python.org/3/library/statistics.html While I appreciate the intention, this is quite misleading. The implication is that the mean, median and mode are different ways to estimate one "central location", however, in reality they are very different things (albeit which refer to a similar notion). The sample mean is an unbiased estimator of the true mean but it need not be unbiased as an estimator of the true median or modes and vice versa for the median and mode. To make this clearer I would rephrase to "The mean is strongly affected by outliers and is not necessarily representative of the central tendency of the data. For cases with large outliers or very low sample size, see median() and mode()" Apologies if this is seen as frivolous, but statistics can be hard enough to remain very clear about even when the words are used precisely. ---------- assignee: docs@python components: Documentation messages: 236612 nosy: Journeyman08, docs@python priority: normal severity: normal status: open title: Misleading note in Statistics module documentation type: enhancement versions: Python 3.4 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue23522> _______________________________________

5 11

[issue14586] TypeError: truncate() takes no keyword arguments
by Guy Taylor 15 Dec '20

15 Dec '20

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> _______________________________________

6 15

[issue26515] Update extending/embedding docs to new way to build modules in C
by Brett Cannon 15 Dec '20

15 Dec '20

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> _______________________________________

5 7

[issue26451] CSV documentation doesn't open with an example
by Alex LordThorsen 13 Dec '20

13 Dec '20

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> _______________________________________

2 2

[issue24110] zipfile.ZipFile.write() does not accept bytes arcname
by July Tikhonov 08 Dec '20

08 Dec '20

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> _______________________________________

6 9

[issue25573] traceback documentation example is lying about FrameSummary repr()
by Alexandre Macabies 08 Dec '20

08 Dec '20

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> _______________________________________

7 16