Mailman 3 April 2018 - docs

[issue19950] Document that unittest.TestCase.__init__ is called once per test
by Claudiu.Popa 19 May '18

19 May '18

New submission from Claudiu.Popa: I was surprised that in the following __init__ is actually called once per test function, although nothing in documentation implied so. a.py ------ import unittest class A(unittest.TestCase): def __init__(self, *args, **kwargs): print('called only once!') super().__init__(*args, **kwargs) def test(self): self.assertEqual(1, 1) def test2(self): self.assertEqual(2, 2) if __name__ == '__main__': unittest.main() $ python a.py called only once! called only once! .. ---------------------------------------------------------------------- Ran 2 tests in 0.001s OK The attached patch adds a note regarding this behaviour for the TestCase class. ---------- assignee: docs@python components: Documentation files: unittest_init.patch keywords: patch messages: 205864 nosy: Claudiu.Popa, docs@python, michael.foord priority: normal severity: normal status: open title: Document that unittest.TestCase.__init__ is called once per test type: enhancement versions: Python 3.4 Added file: http://bugs.python.org/file33086/unittest_init.patch _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue19950> _______________________________________

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[issue32216] Document PEP 557 Data Classes
by Eric V. Smith 16 May '18

16 May '18

New submission from Eric V. Smith <eric(a)trueblade.com>: The documentation needs to be added. ---------- assignee: docs@python components: Documentation messages: 307614 nosy: docs@python, eric.smith priority: high severity: normal status: open title: Document PEP 557 Data Classes versions: Python 3.7 _______________________________________ Python tracker <report(a)bugs.python.org> <https://bugs.python.org/issue32216> _______________________________________

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[issue26701] Documentation for int constructor mentions __int__ but not __trunc__
by Robert Smallshire 10 May '18

10 May '18

New submission from Robert Smallshire: The documentation for the int(x) constructor explains that if possible, it delegates to x.__int__(). The documentation does not explain that there is a fallback to x.__trunc__() if x.__int__() is not available. The only mention of __trunc__ in the Python documentation is in the entry for math.trunc; the documentation for the numbers module does not describe the underlying special methods. Given that all Real numbers are required to implement __trunc__ but only Integral subclasses are required to implement __int__ this could be important to implementers of other Real types, although in practice I imagine that most Real types will implement __int__ as float does. ---------- assignee: docs@python components: Documentation messages: 262941 nosy: Robert Smallshire2, docs@python priority: normal severity: normal status: open title: Documentation for int constructor mentions __int__ but not __trunc__ type: enhancement versions: Python 3.5 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue26701> _______________________________________

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[issue32288] Inconsistent behavior with slice assignment?
by Massimiliano Culpo 10 May '18

10 May '18

New submission from Massimiliano Culpo <massimiliano.culpo(a)googlemail.com>: I am not really sure if what I am reporting is to be considered a bug in the interpreter (slice built-in), a lack in documentation or if it is just me not finding the proper references (in which case feel free to close this and sorry for the noise). Anyhow, while trying to code a class that mimics built-in lists, I noticed a few seemingly inconsistent behaviors in the use of slices to set items. This can be reduced down to this very simple example: ``` Python 3.6.2 (default, Jul 29 2017, 00:00:00) [GCC 4.8.4] on linux # 1. Slice has start and stop, step is defaulted to None >>> a = [1, 2, 3, 4] >>> a[1:3] = [11, 22, 33, 44] >>> a [1, 11, 22, 33, 44, 4] # 2. Same as above setting explicitly step == 1 >>> a = [1, 2, 3, 4] >>> a[1:3:1] = [11, 22, 33, 44] >>> a [1, 11, 22, 33, 44, 4] # 3. Trying to do the same thing with step == -1 # (I naively expected either [1, 44, 33, 22, 11, 4] or 2. to fail like 3.) >>> a = [1, 2, 3, 4] >>> a[3:1:-1] = [11, 22, 33, 44] Traceback (most recent call last): File "<input>", line 1, in <module> ValueError: attempt to assign sequence of size 4 to extended slice of size 2 ``` Now, the first issue: I tried to search what an "extended slice" is exactly, but found nothing in the docs. What is written here https://docs.python.org/3/library/functions.html#slice seems to suggest that an "extended slice" is a slice where `step is not None`, but then I would expect case 2. to behave the same as case 3. So to me it appears as either lack of documentation on the behavior, or a bug in 2. Second issue: in the same page in the docs it's written > slice objects are also generated when extended indexing syntax is used. For example: a[start:stop:step] or a[start:stop, i] I wasn't aware of the second syntax, and tried to use it: ``` >>> a = [1, 2, 3, 4] >>> a[1:3:1] [2, 3] >>> a[1:3, 1] Traceback (most recent call last): File "<input>", line 1, in <module> TypeError: list indices must be integers or slices, not tuple ``` I guess that's not the result one would expect... Third issue: slightly related, but here https://docs.python.org/3/library/stdtypes.html#mutable-sequence-types I see that the documentation of `insert` reads: > inserts x into s at the index given by i (same as s[i:i] = [x]) and from the interpreter: ``` help(list.insert) Help on method_descriptor: insert(...) L.insert(index, object) -- insert object before index ``` Here the fact is that `insert` really behaves like `s[i:i] = [x]`, but in my understanding it doesn't keep the promise to `insert object before index`. ``` # "Out of bounds" on the right >>> a = [1, 2, 3, 4] >>> a.insert(101, 11) >>> a [1, 2, 3, 4, 11] # "Out of bounds" on the left >>> a.insert(-101, 11) >>> a [11, 1, 2, 3, 4] ``` I don't know honestly if docs are not clear here, or if it is just me, but I didn't expect this behavior and thought it was worth reporting. Let me know if you need more information. ---------- assignee: docs@python components: Documentation, Interpreter Core messages: 308120 nosy: Massimiliano Culpo, docs@python priority: normal severity: normal status: open title: Inconsistent behavior with slice assignment? type: behavior versions: Python 2.7, Python 3.4, Python 3.5, Python 3.6 _______________________________________ Python tracker <report(a)bugs.python.org> <https://bugs.python.org/issue32288> _______________________________________

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[issue13525] Tutorial: Example of Source Code Encoding triggers error
by Nicolas Goutte 09 May '18

09 May '18

New submission from Nicolas Goutte <nicolas.goutte(a)extragroup.de>: Current Behaviour The tutorial of Python 3.2.x has an example to set an encoding in a source file: http://docs.python.org/py3k/tutorial/interpreter.html#source-code-encoding It explains to set the following line at the start of the source code: # -*- coding: cp-1252 -*- However when done exactly so, Python raises the following exception: SyntaxError: encoding problem: with BOM The problem seems to be that Python knows Windows codepage 1252 as windows-1252 (its IANA charset name, see http://www.iana.org/assignments/charset-reg/windows-1252 ) or alternatively as cp1252 (without dash) but not as cp-1252 (with dash). As this is an example in the tutorial is particularly problematic, as users might not understand how to do it correctly. This is still the case in the tutorial of Python 3.3 alpha: http://docs.python.org/dev/tutorial/interpreter.html#source-code-encoding Expected Behaviour The tutorial should give a correct example, for example with: # -*- coding: windows-1252 -*- Alternatively a totally other example as for Python 2.7 would be nice too: http://docs.python.org/tutorial/interpreter.html#source-code-encoding Notes: I have tested this with following Python implementations: - Python 3.2.1 (openSUSE 12.1) on Linux - Python 3.2.2 on Windows 7 SP1 64 Bits - Python 3.2.2 on MacOS 10.5.8 (Always on the command line; I have not tested in IDLE.) ---------- assignee: docs@python components: Documentation files: cp_1252broken.py messages: 148798 nosy: docs@python, nicolasg priority: normal severity: normal status: open title: Tutorial: Example of Source Code Encoding triggers error versions: Python 3.2 Added file: http://bugs.python.org/file23840/cp_1252broken.py _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue13525> _______________________________________

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[issue32362] multiprocessing.connection.Connection misdocumented as multiprocessing.Connection
by Mark 05 May '18

05 May '18

New submission from Mark <markamery(a)btinternet.com>: https://docs.python.org/3/library/multiprocessing.html#multiprocessing.Conn… purports to document the multiprocessing.Connection class. There's no such thing: Python 3.6.1 (v3.6.1:69c0db5050, Mar 21 2017, 01:21:04) [GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin Type "help", "copyright", "credits" or "license" for more information. >>> import multiprocessing >>> multiprocessing.Connection Traceback (most recent call last): File "<stdin>", line 1, in <module> AttributeError: module 'multiprocessing' has no attribute 'Connection' I think it should be multiprocessing.connection.Connection? ---------- assignee: docs@python components: Documentation messages: 308539 nosy: Amery, docs@python priority: normal severity: normal status: open title: multiprocessing.connection.Connection misdocumented as multiprocessing.Connection versions: Python 2.7, Python 3.4, Python 3.5, Python 3.6, Python 3.7, Python 3.8 _______________________________________ Python tracker <report(a)bugs.python.org> <https://bugs.python.org/issue32362> _______________________________________

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[issue20722] newline is (partially) independent of universal newlines; needs to be made more clear in docs
by Devin Jeanpierre 03 May '18

03 May '18

New submission from Devin Jeanpierre: http://docs.python.org/3.4/library/functions.html#open says "newline controls how universal newlines mode works (it only applies to text mode)." My reading of this when I saw it was that newline= doesn't do anything unless universal newlines mode is enabled. This is untrue, and you can infer it's untrue from the following lines, but then the docs appear to contradict themselves. Please fix to say something more along the lines of "newline controls how newlines are read and written. It only applies to text mode." The interactions with universal newlines mode are explained in the following text, so they don't need to be called out upfront. newline does more than just that. ---------- assignee: docs@python components: Documentation messages: 211854 nosy: Devin Jeanpierre, docs@python priority: normal severity: normal status: open title: newline is (partially) independent of universal newlines; needs to be made more clear in docs versions: Python 3.4 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue20722> _______________________________________

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[issue32790] Keep trailing zeros in precision for string format option g
by Bharat Chhabra 28 Apr '18

28 Apr '18

Change by Bharat Chhabra <bchhabra2490(a)gmail.com>: ---------- keywords: +patch pull_requests: +6320 stage: needs patch -> patch review _______________________________________ Python tracker <report(a)bugs.python.org> <https://bugs.python.org/issue32790> _______________________________________

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[issue33366] `contextvars` documentation incorrectly refers to "non-local state".
by Tom Christie 28 Apr '18

28 Apr '18

New submission from Tom Christie <tom(a)tomchristie.com>: The `contextvars` documentation, at https://docs.python.org/3.7/library/contextvars.html starts with the following: "This module provides APIs to manage, store, and access non-local state." I assume that must be a documentation bug, right. The module isn't for managing non-local state, it's for managing state that *is* local. I'd assume it ought to read... "This module provides APIs to manage, store, and access context-local state." (ie. for managing state that is transparently either thread-local or task-local depending on the current execution context.) ---------- assignee: docs@python components: Documentation, asyncio messages: 315792 nosy: asvetlov, docs@python, tomchristie, yselivanov priority: normal severity: normal status: open title: `contextvars` documentation incorrectly refers to "non-local state". type: enhancement versions: Python 3.7, Python 3.8 _______________________________________ Python tracker <report(a)bugs.python.org> <https://bugs.python.org/issue33366> _______________________________________

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[issue33339] Using default encoding with `subprocess.run()` is not obvious
by Terry J. Reedy 27 Apr '18

27 Apr '18

Change by Terry J. Reedy <tjreedy(a)udel.edu>: ---------- assignee: -> docs@python components: +Documentation nosy: +docs@python stage: -> needs patch type: -> enhancement versions: +Python 2.7, Python 3.6, Python 3.7, Python 3.8 _______________________________________ Python tracker <report(a)bugs.python.org> <https://bugs.python.org/issue33339> _______________________________________

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