docs September 2013

docs@python.org

33 participants
522 discussions

[issue15097] Improving wording on the thread-safeness of import

by Merlijn van Deen

New submission from Merlijn van Deen <valhallasw(a)gmail.com>: http://docs.python.org/library/threading.html#importing-in-threaded-code Currently, the documentation states "Firstly, other than in the main module, an import should not have the side effect of spawning a new thread and then waiting for that thread in any way. Failing to abide by this restriction can lead to a deadlock if the spawned thread directly or indirectly attempts to import a module." which, I think, fails to make the main point: a call to import acquires the import lock. A call to import from a second thread will thus block. As such, I would suggest rephrasing it to something like: "Firstly, an import acquires the import lock for that thread. Therefore, the import should not have the side effect of waiting for a different thread in any way, as this can lead to a deadlock if that thread directly or indirectly attempts to import a module." There are two additional points that might be interesting to note: (1) Any module can be imported. If the import causes a deadlock, that is a bad thing. Every module *will* be imported by tools such as nosetests. (1b) so: never, ever, have code that causes locks in a different thread in module level code witout 'if __name__=="__main__" ' blocks? (2) The lock is also acquired if a module has already been imported. For instance, in import sys # (1) def f(): import sys # (2) the import lock is acquired in (1) /and/ (2). Adding example code and/or a flow diagram might be a bit too much, but it does clarify how easy it is to make this mistake. See the attached for an example (both a simple example script, as well as a flow diagram explaining what happens). ---------- assignee: docs@python components: Documentation files: deadlock.py messages: 163068 nosy: docs@python, valhallasw priority: normal severity: normal status: open title: Improving wording on the thread-safeness of import type: enhancement Added file: http://bugs.python.org/file26037/deadlock.py _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue15097> _______________________________________

2 weeks, 3 days

[issue8595] Unexpected default timeout in http-client-related libraries

by Julian

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> _______________________________________

2 weeks, 5 days

[issue8822] datetime naive and aware types should have a well-defined definition that can be cross-referenced

by anatoly techtonik

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> _______________________________________

2 weeks, 5 days

[issue14586] TypeError: truncate() takes no keyword arguments

by Guy Taylor

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> _______________________________________

1 month

[issue15104] abusive language in __name__ description

by anatoly techtonik

New submission from anatoly techtonik <techtonik(a)gmail.com>: http://docs.python.org/library/__main__.html "It is this environment in which the idiomatic “conditional script” stanza causes a script to run" ?!? ---------- assignee: docs@python components: Documentation messages: 163140 nosy: docs@python, techtonik priority: normal severity: normal status: open title: abusive language in __name__ description _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue15104> _______________________________________

1 month, 2 weeks

[issue13341] Incorrect documentation for "u" PyArg_Parse format unit

by Ilya Novoselov

New submission from Ilya Novoselov <ilya.novoselov(a)gmail.com>: Documentation states that u format unit returns "buffer of 16-bit Unicode (UTF-16) data" while it returns pointer to internal buffer of unicode data, which is either UCS-16 or UCS-32 http://docs.python.org/c-api/arg.html ---------- assignee: docs@python components: Documentation, Unicode messages: 147002 nosy: Ilya.Novoselov, docs@python, ezio.melotti priority: normal severity: normal status: open title: Incorrect documentation for "u" PyArg_Parse format unit type: behavior versions: Python 2.7 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue13341> _______________________________________

1 month, 2 weeks

[issue17576] PyNumber_Index() is not int-subclass friendly

by Barry A. Warsaw

New submission from Barry A. Warsaw: operator.index() is just a thin wrapper around PyNumber_Index(). The documentation for operator.index() claims that it is equivalent to calling obj.__index__() but for subclasses of int, this is not true. In fact, PyNumber_Index() first does (e.g. in Python 3.3) a PyLong_Check() and if that succeeds, the original object is returned *without* doing the moral equivalent in C of calling obj.__index__(). An example: class myint(int): def __index__(self): return int(self) + 1 >>> x = myint(7) >>> x.__index__() 8 >>> from operator import index >>> index(x) 7 The C API documents PyNumber_Index() as: "Returns the o converted to a Python int on success or NULL with a TypeError exception raised on failure." Because this has been the behavior of PyNumber_Index() since at least 2.7 (I didn't check farther back), this probably cannot be classified as a bug deserving to be fixed in the code for older Pythons. It might be worth fixing for Python 3.4, i.e. by moving the index check before the type check. In the meantime, this is probably a documentation bug. The C API implies, but should be clearer that if o is an int subtype (int and long in Python 2), it is returned unchanged. The operator.index() documentation should be amended to describe this behavior for int/long subclasses. A different alternative would be to leave PyNumber_Index() unchanged, but with the doco fix, and to augment operator.index() to do the PyIndex_Check() first, before calling PyNumber_Index(). That's a little more redundant, but would provide the documented behavior without changing the C API. ---------- assignee: docs@python components: Documentation messages: 185522 nosy: barry, docs@python priority: normal severity: normal status: open title: PyNumber_Index() is not int-subclass friendly type: behavior versions: 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/issue17576> _______________________________________

1 month, 3 weeks

[issue17854] symmetric difference operation applicable to more than two sets

by Amit Saha

New submission from Amit Saha: The description of the symmetric difference operation implies that it cannot be applied to more than two sets (http://docs.python.org/3/library/stdtypes.html#set.symmetric_difference). However, this is certainly possible: >>> s={1,2} >>> t={2,3} >>> u={3,4} >>> s^t^u {1, 4} >>> s.symmetric_difference(t).symmetric_difference(u) {1, 4} I am not sure how much of a "semantic" sense that makes, given that symmetric difference is by definition for two sets. (http://en.wikipedia.org/wiki/Symmetric_difference). So, either the operator should be fixed to allow only two sets or the description be updated. ---------- assignee: docs@python components: Documentation messages: 187899 nosy: Amit.Saha, docs@python priority: normal severity: normal status: open title: symmetric difference operation applicable to more than two sets type: behavior versions: Python 3.3 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue17854> _______________________________________

2 months

[issue17887] docs: summary page - generator vs iterator vs iterable

by anatoly techtonik

New submission from anatoly techtonik: Docs lack a good summary page comparing three concepts. The main question is how do I tell if something is a sequence, generator, iterator or iterable? I found myself puzzled that range() is neither generator or iterator. ---------- assignee: docs@python components: Documentation messages: 188203 nosy: docs@python, techtonik priority: normal severity: normal status: open title: docs: summary page - generator vs iterator vs iterable _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue17887> _______________________________________

2 months

[issue13875] cmd: no user documentation

by anatoly techtonik

New submission from anatoly techtonik <techtonik(a)gmail.com>: http://docs.python.org/library/cmd.html# Documentation for cmd module is poor to explain the value of this module to users. Intro is too abstract - phrase "simple framework for writing line-oriented command interpreters" doesn't mean much. Perhaps word "interactive" is missing? So, there is no part explaining the what cmd does exactly (intro fails) and no part explaining the main principle - How exactly does this framework allows to do this in a simple way? (I guess reference part under 'Cmd objects -> Cmd.cmdloop([intro]) -> p[4]` does that, but it is not the place you'd usually expect this info. At the very least what could be done is a link to Doug's tutorial http://www.doughellmann.com/PyMOTW/cmd/ ---------- assignee: docs@python components: Documentation messages: 152010 nosy: docs@python, techtonik priority: normal severity: normal status: open title: cmd: no user documentation _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue13875> _______________________________________

2 months

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docs September 2013