Mailman 3 June 2018 - docs

[issue30969] Docs should say that `x is z or x == z` is used for `x in y` in containers that do not implement `__contains__`
by Antti Haapala May 30, 2019

May 30, 2019

New submission from Antti Haapala: The doc reference/expressions.srt says that > For user-defined classes which do not define __contains__() but do > define __iter__(), x in y is True if some value z with x == z is > produced while iterating over y. If an exception is raised during the > iteration, it is as if in raised that exception. and > Lastly, the old-style iteration protocol is tried: if a class defines > __getitem__(), x in y is True if and only if there is a non-negative > integer index i such that x == y[i], and all lower integer indices do > not raise IndexError exception. (If any other exception is raised, it > is as if in raised that exception). The documentation doesn't match the implementation, which clearly does `x is y or x == y` to check if `x` is the element `y` from a container. Both the `__iter__` and the index-iteration method test the elements using `is` first. While the document says that `x is x` means that `x == x` should be true, it is not true for example in the case of `nan`: ---------- assignee: docs@python components: Documentation messages: 298671 nosy: docs@python, ztane priority: normal severity: normal status: open title: Docs should say that `x is z or x == z` is used for `x in y` in containers that do not implement `__contains__` type: enhancement _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue30969> _______________________________________

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[issue33006] docstring of filter function is incorrect
by Pierre Thibault May 29, 2019

May 29, 2019

New submission from Pierre Thibault <pierre.thibault1.dev(a)gmail.com>: > help(filter) Help on built-in function filter in module __builtin__: filter(...) filter(function or None, sequence) -> list, tuple, or string Return those items of sequence for which function(item) is true. If function is None, return the items that are true. If sequence is a tuple or string, return the same type, else return a list. (END) The second argument can be an iterable. Suggestion: Replace the docstring with the definition found at https://docs.python.org/2/library/functions.html#filter. ---------- assignee: docs@python components: Documentation messages: 313302 nosy: Pierre Thibault, docs@python priority: normal severity: normal status: open title: docstring of filter function is incorrect versions: Python 2.7 _______________________________________ Python tracker <report(a)bugs.python.org> <https://bugs.python.org/issue33006> _______________________________________

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[issue22865] Allow pty.spawn to ignore data to copy
by Geoff Shannon May 21, 2019

May 21, 2019

New submission from Geoff Shannon: While using the pty.py module I had cause to want to be able to silently eat characters from the input stream. I discovered that because of the check for end of file being "if not data" that there was no way to do this. Since the default function used by spawn and _copy is a thin wrapper on os.read, I figured that it would be useful to interpret None as a sentinel value meaning "this is not EOF, but there's nothing I actually want to copy over." ---------- assignee: docs@python components: Documentation, Library (Lib) files: pty.patch keywords: patch messages: 231126 nosy: RadicalZephyr, docs@python priority: normal severity: normal status: open title: Allow pty.spawn to ignore data to copy type: enhancement versions: Python 2.7, Python 3.2, Python 3.3, Python 3.4, Python 3.5, Python 3.6 Added file: http://bugs.python.org/file37189/pty.patch _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue22865> _______________________________________

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[issue19175] Erroneous reference to "integer" in format string grammar
by David Chambers May 17, 2019

May 17, 2019

New submission from David Chambers: I first raised this issue on Stack Overflow: http://stackoverflow.com/questions/19203194 The [replacement field grammar][1] states that an [integer][2] is a valid field_name, but this is inaccurate: >>> '{0}'.format('zero') 'zero' >>> '{0x0}.format('zero') KeyError: '0x0' >>> '{0o0}.format('zero') KeyError: '0o0' >>> '{0b0}.format('zero') KeyError: '0b0' This [comment][3] by Eric Smith suggests that the above is the intended behaviour: > get_integer uses the narrowest possible definition for integer indexes, > in order to pass all other strings to mappings. The documentation should be updated to match the actual behaviour. abarnert on Stack Overflow suggested the following change: -arg_name ::= [identifier | integer] +arg_name ::= [identifier | digit+] [1]: http://docs.python.org/2/library/string.html#format-string-syntax [2]: http://docs.python.org/2/reference/lexical_analysis.html#grammar-token-inte… [3]: http://bugs.python.org/issue8985#msg107705 ---------- assignee: docs@python components: Documentation messages: 199024 nosy: davidchambers, docs@python priority: normal severity: normal status: open title: Erroneous reference to "integer" in format string grammar versions: Python 2.6, Python 2.7, Python 3.1, Python 3.2, Python 3.3, Python 3.4 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue19175> _______________________________________

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[issue21202] Naming a file` io.py` causes cryptic error message
by Madison May May 15, 2019

May 15, 2019

New submission from Madison May: Naming a file `io.py` in the root directory of a project causes the following error on 2.7: AttributeError: 'module' object has no attribute 'BufferedIOBase' Similar issues arise on 3.x., although the error message is a bit more useful: Fatal Python error: Py_Initialize: can't initialize sys standard streams AttributeError: 'module' object has no attribute 'OpenWrapper' At the very least we should ensure that the error message is a bit more straightforward and clear, as I imagine its not all that uncommon to cause this kind of conflict. ---------- assignee: docs@python components: Documentation, IO messages: 215940 nosy: docs@python, madison.may priority: normal severity: normal status: open title: Naming a file` io.py` causes cryptic error message versions: Python 2.7 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue21202> _______________________________________

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[issue18478] Class bodies: when does a name become local?
by Terry J. Reedy May 14, 2019

May 14, 2019

New submission from Terry J. Reedy: http://docs.python.org/3/reference/executionmodel.html#naming-and-binding says "The following are blocks: ... a class definition." and "If a name binding operation occurs anywhere within a code block, all uses of the name within the block are treated as references to the current block. This can lead to errors when a name is used within a block before it is bound. ..." This is definitely true for functions, but not for classes: foo = 'bar' class C: foo = foo print(C().foo) # bar This is the same for 3.3 and 2.7 with and without '(object)' added. Unless the code is considered to be buggy (probably since forever), the doc should be modified to change 'code block' to 'function code block' or maybe 'module or function code block'. (At near as I can think, the statement is true for modules, but only because globals() == locals(), so that part of the issue does not arise.) ---------- assignee: docs@python components: Documentation messages: 193205 nosy: docs@python, terry.reedy priority: normal severity: normal stage: needs patch status: open title: Class bodies: when does a name become local? type: behavior versions: Python 2.7, Python 3.3, Python 3.4 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue18478> _______________________________________

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[issue32995] Add a glossary entry for context variables
by Serhiy Storchaka May 14, 2019

May 14, 2019

New submission from Serhiy Storchaka <storchaka+cpython(a)gmail.com>: I think the term context variable is worth adding into the glossary. ---------- assignee: docs@python components: Documentation messages: 313241 nosy: docs@python, serhiy.storchaka, yselivanov priority: normal severity: normal status: open title: Add a glossary entry for context variables type: enhancement versions: Python 3.7, Python 3.8 _______________________________________ Python tracker <report(a)bugs.python.org> <https://bugs.python.org/issue32995> _______________________________________

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[issue30535] Warn that meta_path is not empty
by Xavier Morel May 14, 2019

May 14, 2019

New submission from Xavier Morel: Encountered this issue porting Python 2 code manipulating meta_path to Python 3. In Python 2, meta_path is empty by default and its documentation specifically notes that: > sys.meta_path is searched before any implicit default finders or sys.path. As a result, sys.meta_path.append() works perfectly well and is overwhelmingly common[0]. In Python 3, this note was removed but the documentation does not specifically state default finders are present in meta_path, and the old code using sys.meta_path.append may now break as the default finders will silently take precedence on the custom ones if they believe they can do the job. I'd like to add a warning to the Python 3 documentation (3.5+?) noting the presence of existing default loaders, and to the Python 2 documentation suggesting `sys.meta_path.insert(0, finder)` for future-proofing, would there be objections or issues? [0] https://github.com/search?q=meta_path.append&type=Code&utf8=✓ ---------- assignee: docs@python components: Documentation messages: 294919 nosy: docs@python, xmorel priority: normal severity: normal status: open title: Warn that meta_path is not empty type: behavior versions: Python 2.7, Python 3.5, Python 3.6 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue30535> _______________________________________

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[issue13286] PEP 3151 breaks backward compatibility: it should be documented
by STINNER Victor May 13, 2019

May 13, 2019

New submission from STINNER Victor <victor.stinner(a)haypocalc.com>: The following example works on Python 2.7 and 3.2, but fails on Python 3.3: ----------- import errno import os try: os.rmdir("testdir") except: pass os.mkdir("testdir") try: try: os.mkdir("testdir") except IOError as exc: # If can't get proper access, then just forget about writing # the data. if exc.errno == errno.EACCES: pass else: raise except OSError as exc: # Probably another Python process already created the dir. if exc.errno == errno.EEXIST: pass else: raise except Exception: print("PEP 3151 broke backward compatibility on such pattern!") ----------- I noticed the problem while reading the changeset e4d44c2e8e81. ---------- assignee: docs@python components: Documentation messages: 146562 nosy: docs@python, flox, haypo, pitrou priority: normal severity: normal status: open title: PEP 3151 breaks backward compatibility: it should be documented versions: Python 3.3 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue13286> _______________________________________

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[issue33882] doc Mention breakpoint() in debugger-related FAQ
by Andrés Delfino May 13, 2019

May 13, 2019

New submission from Andrés Delfino <adelfino(a)gmail.com>: IMHO, it's a good opportunity to advertise the convenience of breakpoint(). PR adds a mention. ---------- assignee: docs@python components: Documentation messages: 319796 nosy: adelfino, docs@python priority: normal severity: normal status: open title: doc Mention breakpoint() in debugger-related FAQ type: enhancement versions: Python 3.7, Python 3.8 _______________________________________ Python tracker <report(a)bugs.python.org> <https://bugs.python.org/issue33882> _______________________________________

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