docs May 2014

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55 participants
555 discussions

[issue13828] Further improve casefold documentation
by Jim Jewett 24 Aug '20

24 Aug '20

New submission from Jim Jewett <jimjjewett(a)gmail.com>: > http://hg.python.org/cpython/rev/0b5ce36a7a24 > changeset: 74515:0b5ce36a7a24 > + Casefolding is similar to lowercasing but more aggressive because it is > + intended to remove all case distinctions in a string. For example, the German > + lowercase letter ``'ß'`` is equivalent to ``"ss"``. Since it is already > + lowercase, :meth:`lower` would do nothing to ``'ß'``; :meth:`casefold` > + converts it to ``"ss"``. Perhaps add the recommendation to canonicalize as well. A complete, but possibly too long, try is below: Casefolding is similar to lowercasing but more aggressive because it is intended to remove all case distinctions in a string. For example, the German lowercase letter ``'ß'`` is equivalent to ``"ss"``. Since it is already lowercase, :meth:`lower` would do nothing to ``'ß'``; :meth:`casefold` converts it to ``"ss"``. Note that most case-insensitive matches should also match compatibility equivalent characters. The casefolding algorithm is described in section 3.13 of the Unicode Standard. Per D146, a compatibility caseless match can be achieved by from unicodedata import normalize def caseless_compat(string): nfd_string = normalize("NFD", string) nfkd1_string = normalize("NFKD", nfd_string.casefold()) return normalize("NFKD", nfkd1_string.casefold()) ---------- assignee: docs@python components: Documentation messages: 151644 nosy: Jim.Jewett, benjamin.peterson, docs@python priority: normal severity: normal status: open title: Further improve casefold documentation versions: Python 3.3 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue13828> _______________________________________

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[issue21333] Document recommended exception for objects that shouldn't be pickled
by Stefan Schwarzer 05 Jul '20

05 Jul '20

New submission from Stefan Schwarzer: I recently was confused whether to raise a `PicklingError` or `TypeError` in `__getstate__` if objects of my class can't and shouldn't be pickled. [1] Terry Reedy advised I should use `TypeError`. [2] I wonder if the `pickle` module documention should explicitly recommend using `TypeError` if a class wants to say that its objects can't be pickled. What do you think? [1] https://mail.python.org/pipermail/python-list/2014-April/670987.html [2] https://mail.python.org/pipermail/python-list/2014-April/671002.html ---------- assignee: docs@python components: Documentation messages: 217054 nosy: docs@python, sschwarzer priority: normal severity: normal status: open title: Document recommended exception for objects that shouldn't be pickled type: enhancement versions: Python 3.5 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue21333> _______________________________________

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[issue17805] No such class: multiprocessing.pool.AsyncResult
by Takafumi Arakaki 03 Jul '20

03 Jul '20

New submission from Takafumi Arakaki: Document mentions AsyncResult but there is no such class. http://docs.python.org/2/library/multiprocessing.html#multiprocessing.pool.… You can check it by simply running: python -c 'from multiprocessing.pool import AsyncResult' I think it means ApplyResult so I made a patch (attached). Note that there managers.py also uses name 'AsyncResult': % hg grep AsyncResult Doc/library/multiprocessing.rst:83232:.. class:: AsyncResult Lib/multiprocessing/managers.py:81039: 'apply_async': 'AsyncResult', Lib/multiprocessing/managers.py:81039: 'map_async': 'AsyncResult', Lib/multiprocessing/managers.py:81039: 'starmap_async': 'AsyncResult', Lib/multiprocessing/managers.py:81039:SyncManager.register('AsyncResult', create_method=False) Probably renaming them would be better? ---------- assignee: docs@python components: Documentation files: ApplyResult.patch keywords: patch messages: 187466 nosy: docs@python, tkf priority: normal severity: normal status: open title: No such class: multiprocessing.pool.AsyncResult versions: Python 2.6, Python 2.7, Python 3.1, Python 3.2, Python 3.3, Python 3.4, Python 3.5 Added file: http://bugs.python.org/file29954/ApplyResult.patch _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue17805> _______________________________________

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[issue17589] Make documentation about macros in C API explicit about rvalue vs statement
by Larry Hastings 25 Jun '20

25 Jun '20

New submission from Larry Hastings: CPython API "functions" implemented as macros can expand into either rvalues or statements. Most expand into statements (often using the do {} while (0) syntactic sugar trick), but occasionally they're legal as rvalues. As of this writing Py_INCREF works as an rvalue. But discussion on another tracker issue (#17206) proposes changing the implementation in such a way that it will only be usable as a statement. Although it's mildly unlikely, it's certainly possible that this will break somebody's code. I propose that the documentation make an explicit ruling on whether macros are usable as rvalues or as statements. Perhaps a blanket statement would suffice, "all macros are only supported for use as statements except where explicitly noted", then annotate specific macros that are supported for use as rvalues. Though that raises the question of acknowledging in the documentation that some things are macros--I think the documentation glosses over that fact right now. Note: I added you three (Georg, Mark, Martin) as I thought you might have an opinion on this one way or the other. If you're not interested, my apologies. ---------- assignee: docs@python components: Documentation messages: 185646 nosy: Mark.Shannon, docs@python, georg.brandl, larry, loewis priority: normal severity: normal stage: needs patch status: open title: Make documentation about macros in C API explicit about rvalue vs statement type: enhancement versions: Python 3.4 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue17589> _______________________________________

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[issue21508] C API PyArg_ParseTuple doc is innacurate
by Steve 25 Jun '20

25 Jun '20

New submission from Steve: PyArg_ParseTuple is defined as returning an "int", but the documentation talks about returning a true/false value, and failling on false. In addition to being inaccurate, considering that most other functions fail on !=0 ("true"), it can lead to confusion. Doc: int PyArg_ParseTuple(PyObject *args, const char *format, ...) Parse the parameters of a function that takes only positional parameters into local variables. Returns true on success; on failure, it returns false and raises the appropriate exception. ---------- assignee: docs@python components: Documentation messages: 218536 nosy: Banger, docs@python priority: normal severity: normal status: open title: C API PyArg_ParseTuple doc is innacurate type: enhancement versions: Python 3.3, Python 3.4, Python 3.5 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue21508> _______________________________________

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[issue20224] C API docs need a clear "defining custom extension types" section
by Nick Coghlan 25 Jun '20

25 Jun '20

New submission from Nick Coghlan: The main C API docs don't clearly explain how to define new types, so people almost always cargo cult an existing legacy type definition instead (I know I do). The extending and embedding docs have a guide (http://docs.python.org/3/extending/newtypes.html), but that describes the old legacy method based on static type declarations. New code should instead use the dynamic mechanism defined in PEP 384 (http://www.python.org/dev/peps/pep-0384/#type-objects). See also http://docs.python.org/3/c-api/type.html#PyType_FromSpec Note that PyType_Spec isn't defined in the C API docs *at all*. ---------- assignee: docs@python components: Documentation messages: 207927 nosy: docs@python, ncoghlan priority: normal severity: normal stage: needs patch status: open title: C API docs need a clear "defining custom extension types" section type: enhancement versions: Python 3.3, Python 3.4, Python 3.5 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue20224> _______________________________________

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[issue17110] sys.argv docs should explaining how to handle encoding issues
by Nick Coghlan 18 Jun '20

18 Jun '20

New submission from Nick Coghlan: The sys.argv docs [1] currently contain no mention of the fact that they are Unicode strings decoded from bytes provided by the OS. They also don't explain how to correct a decoding error by reversing Python's implicit conversion and redoing it based on the application's knowledge of the correct encoding, as described at [2] [1] http://docs.python.org/3/library/sys#sys.argv [2] http://stackoverflow.com/questions/6981594/sys-argv-as-bytes-in-python-3k/ ---------- assignee: docs@python components: Documentation, Unicode messages: 181239 nosy: docs@python, ezio.melotti, ncoghlan priority: normal severity: normal stage: needs patch status: open title: sys.argv docs should explaining how to handle encoding issues type: enhancement versions: Python 3.2, Python 3.3, Python 3.4 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue17110> _______________________________________

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[issue16891] Fix docs about module search order
by Dmitry Mugtasimov 31 May '20

31 May '20

New submission from Dmitry Mugtasimov: http://docs.python.org/2/tutorial/modules.html should be rewritten. AS IS 6.1.2. The Module Search Path When a module named spam is imported, the interpreter first searches for a built-in module with that name. If not found, it then searches for a file named spam.py in a list of directories given by the variable sys.path. sys.path is initialized from these locations: TO BE 6.1.2. The Module Search Path When a module named spam is imported, the interpreter first searches for a built-in module with that name. If not found, it looks in the containing package (the package of which the current module is a submodule). If not found, it then searches for a file named spam.py in a list of directories given by the variable sys.path. sys.path is initialized from these locations: ------ Note that now "6.1.2. The Module Search Path" and "6.4.2. Intra-package References" are contradictary since in 6.4.2 it is said: "In fact, such references are so common that the import statement first looks in the containing package before looking in the standard module search path.", but this is not reflected in 6.1.2. ------ EXAMPLE (for more information see http://stackoverflow.com/questions/14183541/why-python-finds-module-instead… ): /home/dmugtasimov/tmp/name-res3/xyz __init__.py a.py b.py t.py xyz.py Files init.py, b.py and xyz.py are empty File a.py: import os, sys ROOT_DIRECTORY = os.path.abspath(os.path.join(os.path.dirname(__file__), '..')) if not sys.path or ROOT_DIRECTORY not in sys.path: print 'sys.path is modified in a.py' sys.path.insert(0, ROOT_DIRECTORY) else: print 'sys.path is NOT modified in a.py' print 'sys.path:', sys.path print 'BEFORE import xyz.b' import xyz.b print 'AFTER import xyz.b' File t.py: import os, sys ROOT_DIRECTORY = os.path.abspath(os.path.join(os.path.dirname(__file__), '..')) if not sys.path or ROOT_DIRECTORY not in sys.path: print 'sys.path is modified in t.py' sys.path.insert(0, ROOT_DIRECTORY) else: print 'sys.path is NOT modified in t.py' import xyz.a Run: python a.py Output: sys.path is modified in a.py sys.path: ['/home/dmugtasimov/tmp/name-res3', '/home/dmugtasimov/tmp/name-res3/xyz', '/usr/local/lib/python2.7/dist-packages/tornado-2.3-py2.7.egg', '/home/dmugtasimov/tmp/name-res3/xyz', '/usr/lib/python2.7', '/usr/lib/python2.7/plat-linux2', '/usr/lib/python2.7/lib-tk', '/usr/lib/python2.7/lib-old', '/usr/lib/python2.7/lib-dynload', '/usr/local/lib/python2.7/dist-packages', '/usr/local/lib/python2.7/dist-packages/setuptools-0.6c11-py2.7.egg-info', '/usr/lib/python2.7/dist-packages', '/usr/lib/python2.7/dist-packages/PIL', '/usr/lib/python2.7/dist-packages/gst-0.10', '/usr/lib/python2.7/dist-packages/gtk-2.0', '/usr/lib/python2.7/dist-packages/ubuntu-sso-client'] BEFORE import xyz.b AFTER import xyz.b Run: python -vv a.py Output: import xyz # directory /home/dmugtasimov/tmp/name-res3/xyz # trying /home/dmugtasimov/tmp/name-res3/xyz/__init__.so # trying /home/dmugtasimov/tmp/name-res3/xyz/__init__module.so # trying /home/dmugtasimov/tmp/name-res3/xyz/__init__.py # /home/dmugtasimov/tmp/name-res3/xyz/__init__.pyc matches /home/dmugtasimov/tmp/name-res3/xyz/__init__.py import xyz # precompiled from /home/dmugtasimov/tmp/name-res3/xyz/__init__.pyc # trying /home/dmugtasimov/tmp/name-res3/xyz/b.so # trying /home/dmugtasimov/tmp/name-res3/xyz/bmodule.so # trying /home/dmugtasimov/tmp/name-res3/xyz/b.py # /home/dmugtasimov/tmp/name-res3/xyz/b.pyc matches /home/dmugtasimov/tmp/name-res3/xyz/b.py import xyz.b # precompiled from /home/dmugtasimov/tmp/name-res3/xyz/b.pyc Run: python t.py Output: sys.path is modified in t.py sys.path is NOT modified in a.py sys.path: ['/home/dmugtasimov/tmp/name-res3', '/home/dmugtasimov/tmp/name-res3/xyz', '/usr/local/lib/python2.7/dist-packages/tornado-2.3-py2.7.egg', '/home/dmugtasimov/tmp/name-res3/xyz', '/usr/lib/python2.7', '/usr/lib/python2.7/plat-linux2', '/usr/lib/python2.7/lib-tk', '/usr/lib/python2.7/lib-old', '/usr/lib/python2.7/lib-dynload', '/usr/local/lib/python2.7/dist-packages', '/usr/local/lib/python2.7/dist-packages/setuptools-0.6c11-py2.7.egg-info', '/usr/lib/python2.7/dist-packages', '/usr/lib/python2.7/dist-packages/PIL', '/usr/lib/python2.7/dist-packages/gst-0.10', '/usr/lib/python2.7/dist-packages/gtk-2.0', '/usr/lib/python2.7/dist-packages/ubuntu-sso-client'] BEFORE import xyz.b Traceback (most recent call last): File "t.py", line 9, in <module> import xyz.a File "/home/dmugtasimov/tmp/name-res3/xyz/a.py", line 11, in <module> import xyz.b ImportError: No module named b Run: python -vv t.py Output: import xyz # directory /home/dmugtasimov/tmp/name-res3/xyz # trying /home/dmugtasimov/tmp/name-res3/xyz/__init__.so # trying /home/dmugtasimov/tmp/name-res3/xyz/__init__module.so # trying /home/dmugtasimov/tmp/name-res3/xyz/__init__.py # /home/dmugtasimov/tmp/name-res3/xyz/__init__.pyc matches /home/dmugtasimov/tmp/name-res3/xyz/__init__.py import xyz # precompiled from /home/dmugtasimov/tmp/name-res3/xyz/__init__.pyc # trying /home/dmugtasimov/tmp/name-res3/xyz/a.so # trying /home/dmugtasimov/tmp/name-res3/xyz/amodule.so # trying /home/dmugtasimov/tmp/name-res3/xyz/a.py # /home/dmugtasimov/tmp/name-res3/xyz/a.pyc matches /home/dmugtasimov/tmp/name-res3/xyz/a.py import xyz.a # precompiled from /home/dmugtasimov/tmp/name-res3/xyz/a.pyc # trying /home/dmugtasimov/tmp/name-res3/xyz/os.so # trying /home/dmugtasimov/tmp/name-res3/xyz/osmodule.so # trying /home/dmugtasimov/tmp/name-res3/xyz/os.py # trying /home/dmugtasimov/tmp/name-res3/xyz/os.pyc # trying /home/dmugtasimov/tmp/name-res3/xyz/sys.so # trying /home/dmugtasimov/tmp/name-res3/xyz/sysmodule.so # trying /home/dmugtasimov/tmp/name-res3/xyz/sys.py # trying /home/dmugtasimov/tmp/name-res3/xyz/sys.pyc # trying /home/dmugtasimov/tmp/name-res3/xyz/xyz.so # trying /home/dmugtasimov/tmp/name-res3/xyz/xyzmodule.so # trying /home/dmugtasimov/tmp/name-res3/xyz/xyz.py # /home/dmugtasimov/tmp/name-res3/xyz/xyz.pyc matches /home/dmugtasimov/tmp/name-res3/xyz/xyz.py import xyz.xyz # precompiled from /home/dmugtasimov/tmp/name-res3/xyz/xyz.pyc # clear[2] __file__ # clear[2] __package__ # clear[2] sys # clear[2] ROOT_DIRECTORY # clear[2] __name__ # clear[2] os sys.path is modified in t.py sys.path is NOT modified in a.py sys.path: ['/home/dmugtasimov/tmp/name-res3', '/home/dmugtasimov/tmp/name-res3/xyz', '/usr/local/lib/python2.7/dist-packages/tornado-2.3-py2.7.egg', '/home/dmugtasimov/tmp/name-res3/xyz', '/usr/lib/python2.7', '/usr/lib/python2.7/plat-linux2', '/usr/lib/python2.7/lib-tk', '/usr/lib/python2.7/lib-old', '/usr/lib/python2.7/lib-dynload', '/usr/local/lib/python2.7/dist-packages', '/usr/local/lib/python2.7/dist-packages/setuptools-0.6c11-py2.7.egg-info', '/usr/lib/python2.7/dist-packages', '/usr/lib/python2.7/dist-packages/PIL', '/usr/lib/python2.7/dist-packages/gst-0.10', '/usr/lib/python2.7/dist-packages/gtk-2.0', '/usr/lib/python2.7/dist-packages/ubuntu-sso-client'] BEFORE import xyz.b Traceback (most recent call last): File "t.py", line 9, in <module> import xyz.a File "/home/dmugtasimov/tmp/name-res3/xyz/a.py", line 11, in <module> import xyz.b ImportError: No module named b As you see sys.path is the same for both cases: sys.path: ['/home/dmugtasimov/tmp/name-res3', '/home/dmugtasimov/tmp/name-res3/xyz', '/usr/local/lib/python2.7/dist-packages/tornado-2.3-py2.7.egg', '/home/dmugtasimov/tmp/name-res3/xyz', '/usr/lib/python2.7', '/usr/lib/python2.7/plat-linux2', '/usr/lib/python2.7/lib-tk', '/usr/lib/python2.7/lib-old', '/usr/lib/python2.7/lib-dynload', '/usr/local/lib/python2.7/dist-packages', '/usr/local/lib/python2.7/dist-packages/setuptools-0.6c11-py2.7.egg-info', '/usr/lib/python2.7/dist-packages', '/usr/lib/python2.7/dist-packages/PIL', '/usr/lib/python2.7/dist-packages/gst-0.10', '/usr/lib/python2.7/dist-packages/gtk-2.0', '/usr/lib/python2.7/dist-packages/ubuntu-sso-client'] But the behaviour is different. For a.py python searches for package xyz first, and them for module b in it: import xyz # directory /home/dmugtasimov/tmp/name-res3/xyz # trying /home/dmugtasimov/tmp/name-res3/xyz/__init__.so # trying /home/dmugtasimov/tmp/name-res3/xyz/__init__module.so # trying /home/dmugtasimov/tmp/name-res3/xyz/__init__.py # /home/dmugtasimov/tmp/name-res3/xyz/__init__.pyc matches /home/dmugtasimov/tmp/name-res3/xyz/__init__.py import xyz # precompiled from /home/dmugtasimov/tmp/name-res3/xyz/__init__.pyc # trying /home/dmugtasimov/tmp/name-res3/xyz/b.so # trying /home/dmugtasimov/tmp/name-res3/xyz/bmodule.so # trying /home/dmugtasimov/tmp/name-res3/xyz/b.py # /home/dmugtasimov/tmp/name-res3/xyz/b.pyc matches /home/dmugtasimov/tmp/name-res3/xyz/b.py import xyz.b # precompiled from /home/dmugtasimov/tmp/name-res3/xyz/b.pyc In other words: Search PACKAGE xyz in directory sys.path[0] -> FOUND Search module b in PACKAGE xyz -> FOUND Continue execution For t.py it searches for moduel xyz in the same directory as a.py itself and then fails to find module b in module xyz: # trying /home/dmugtasimov/tmp/name-res3/xyz/xyz.so # trying /home/dmugtasimov/tmp/name-res3/xyz/xyzmodule.so # trying /home/dmugtasimov/tmp/name-res3/xyz/xyz.py # /home/dmugtasimov/tmp/name-res3/xyz/xyz.pyc matches /home/dmugtasimov/tmp/name-res3/xyz/xyz.py import xyz.xyz # precompiled from /home/dmugtasimov/tmp/name-res3/xyz/xyz.pyc In other words: Search MODULE xyz in directory in the same directory as a.py (or sys.path[1] ?) -> FOUND Search MODULE b in MODULE xyz -> NOT FOUND ImportError So it looks like if "import xyz.b" bahaves different depending on how a.py was initially loaded as a script or imported from another module. ---------- assignee: docs@python components: Documentation messages: 179321 nosy: dmugtasimov, docs@python priority: normal severity: normal status: open title: Fix docs about module search order type: behavior versions: Python 2.7 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue16891> _______________________________________

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[issue13649] termios.ICANON is not documented
by anatoly techtonik 31 May '20

31 May '20

New submission from anatoly techtonik <techtonik(a)gmail.com>: http://docs.python.org/library/termios.html is missing documentation for ICANON flag used to put terminal to "raw" mode. It is also worth to place `termios` raw/canonical mode equivalent on `tty` pages, so that people porting C code to Python could understand the hidden magic. ---------- assignee: docs@python components: Documentation, IO, Library (Lib) messages: 150098 nosy: docs@python, techtonik priority: normal severity: normal status: open title: termios.ICANON is not documented versions: Python 2.7 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue13649> _______________________________________

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[issue16700] Document that bytes OS API can returns unusable results on Windows
by Serhiy Storchaka 31 May '20

31 May '20

New submission from Serhiy Storchaka: Some OS functions which returns bytes (os.environb, os.getenvb(), os.getcwdb(), os.listdir(), os.readlink(), os.walk(), os.path.abspath(), os.path.expanduser(), os.path.expandvars(), os.path.realpath() and may be other) can return unusable result on Windows (see for example issue13247 and issue16656). The documentation should contains strong warnings about this. ---------- assignee: docs@python components: Documentation, Windows messages: 177613 nosy: docs@python, serhiy.storchaka priority: normal severity: normal stage: needs patch status: open title: Document that bytes OS API can returns unusable results on Windows type: enhancement versions: Python 2.7, Python 3.2, Python 3.3, Python 3.4 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue16700> _______________________________________

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