docs November 2012

docs@python.org

41 participants
517 discussions

[issue14189] Documentation for some C APIs is missing clear specification of the type of reference they return

by Baruch Sterin

New submission from Baruch Sterin <python(a)bsterin.com>: In addition to the description text, most C API functions have a one-line, emphasized specification whether they return a new or a borrowed reference. (e.g. 'Return value: New reference.'). The following API functions are missing that. Some of them, like PyMemoryView_FromBuffer(), have descriptions that are clear, but it would still be nice to have an unambiguous statement like most other API functions have. The list has been generated automatically, so it might contain some errors. Doc/c-api/arg.rst: Py_VaBuildValue Doc/c-api/buffer.rst: PyMemoryView_FromBuffer Doc/c-api/buffer.rst: PyMemoryView_FromObject Doc/c-api/buffer.rst: PyMemoryView_GetContiguous Doc/c-api/bytearray.rst: PyByteArray_Concat Doc/c-api/bytearray.rst: PyByteArray_FromObject Doc/c-api/bytearray.rst: PyByteArray_FromStringAndSize Doc/c-api/code.rst: PyCode_New Doc/c-api/codec.rst: PyCodec_BackslashReplaceErrors Doc/c-api/codec.rst: PyCodec_Decode Doc/c-api/codec.rst: PyCodec_Decoder Doc/c-api/codec.rst: PyCodec_Encode Doc/c-api/codec.rst: PyCodec_Encoder Doc/c-api/codec.rst: PyCodec_IgnoreErrors Doc/c-api/codec.rst: PyCodec_IncrementalDecoder Doc/c-api/codec.rst: PyCodec_IncrementalEncoder Doc/c-api/codec.rst: PyCodec_LookupError Doc/c-api/codec.rst: PyCodec_ReplaceErrors Doc/c-api/codec.rst: PyCodec_StreamReader Doc/c-api/codec.rst: PyCodec_StreamWriter Doc/c-api/codec.rst: PyCodec_StrictErrors Doc/c-api/codec.rst: PyCodec_XMLCharRefReplaceErrors Doc/c-api/exceptions.rst: PyUnicodeDecodeError_Create Doc/c-api/exceptions.rst: PyUnicodeDecodeError_GetEncoding Doc/c-api/exceptions.rst: PyUnicodeDecodeError_GetObject Doc/c-api/exceptions.rst: PyUnicodeDecodeError_GetReason Doc/c-api/exceptions.rst: PyUnicodeEncodeError_Create Doc/c-api/exceptions.rst: PyUnicodeTranslateError_Create Doc/c-api/float.rst: PyFloat_GetInfo Doc/c-api/import.rst: PyImport_GetImporter Doc/c-api/import.rst: PyImport_ImportModuleNoBlock Doc/c-api/import.rst: _PyImport_FindExtension Doc/c-api/import.rst: _PyImport_FixupExtension Doc/c-api/init.rst: PyEval_GetCallStats Doc/c-api/int.rst: PyInt_FromSize_t Doc/c-api/long.rst: PyLong_FromSize_t Doc/c-api/long.rst: PyLong_FromSsize_t Doc/c-api/number.rst: PyNumber_Index Doc/c-api/number.rst: PyNumber_ToBase Doc/c-api/object.rst: PyObject_Bytes Doc/c-api/object.rst: PyObject_GenericGetAttr Doc/c-api/unicode.rst: PyUnicode_AsUTF32String Doc/c-api/unicode.rst: PyUnicode_DecodeMBCSStateful Doc/c-api/unicode.rst: PyUnicode_DecodeUTF32 Doc/c-api/unicode.rst: PyUnicode_DecodeUTF32Stateful Doc/c-api/unicode.rst: PyUnicode_DecodeUTF7 Doc/c-api/unicode.rst: PyUnicode_DecodeUTF7Stateful Doc/c-api/unicode.rst: PyUnicode_EncodeUTF32 Doc/c-api/unicode.rst: PyUnicode_EncodeUTF7 Doc/c-api/veryhigh.rst: PyEval_EvalCodeEx Doc/c-api/veryhigh.rst: PyEval_EvalFrame Doc/c-api/veryhigh.rst: PyEval_EvalFrameEx ---------- assignee: docs@python components: Documentation messages: 154877 nosy: baruch.sterin, docs@python priority: normal severity: normal status: open title: Documentation for some C APIs is missing clear specification of the type of reference they return type: behavior versions: Python 2.7 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue14189> _______________________________________

3 weeks, 4 days

[issue15533] subprocess.Popen(cwd) documentation

by Chris Jerdonek

New submission from Chris Jerdonek: The sentence describing Popen()'s cwd argument in the subprocess documentation seems reversed to me: http://docs.python.org/dev/library/subprocess.html#subprocess.Popen It says, "If cwd is not None, the child’s current directory will be changed to cwd before it is executed. Note that this directory is not considered when searching the executable, so you can’t specify the program’s path relative to cwd." However, when cwd is not None, it seems like you *must* specify the program's path relative to cwd. For example, when running a script containing the following using `./python.exe` from a source checkout-- p = Popen(['./python.exe', '-V'], stdout=PIPE, stderr=PIPE, cwd='temp') you get an: "OSError: [Errno 2] No such file or directory." In contrast, when you *do* specify the program's path relative to cwd, it works-- p = Popen(['../python.exe', '-V'], stdout=PIPE, stderr=PIPE, cwd='temp') Issue 6374 seems to have made the same point in its second bullet, but the issue was closed without addressing that part of it. ---------- assignee: docs@python components: Documentation keywords: easy messages: 167194 nosy: cjerdonek, docs@python priority: normal severity: normal status: open title: subprocess.Popen(cwd) documentation versions: Python 2.7, Python 3.3 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue15533> _______________________________________

4 weeks, 1 day

[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> _______________________________________

1 month, 1 week

[issue8557] subprocess portability issue

by Dave Abrahams

New submission from Dave Abrahams <dave(a)boostpro.com>: On POSIX systems, the PATH environment variable is always used to look up directory-less executable names passed as the first argument to Popen(...), but on Windows, PATH is only considered when shell=True is also passed. Actually I think it may be slightly weirder than that when shell=False, because the following holds for me: C:\>rem ##### Prepare minimal PATH ##### C:\>set "PATH=C:\Python26\Scripts;C:\Python26;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem" C:\>rem ##### Prepare a minimal, clean environment ##### C:\>virtualenv --no-site-packages e:\zzz New python executable in e:\zzz\Scripts\python.exe Installing setuptools................done. C:\>rem ##### Show that shell=True makes the difference in determining whether PATH is respected ##### C:\>python Python 2.6.5 (r265:79096, Mar 19 2010, 18:02:59) [MSC v.1500 64 bit (AMD64)] on win32 Type "help", "copyright", "credits" or "license" for more information. >>> import subprocess >>> subprocess.Popen(['python', '-c', 'import sys; print sys.executable']) <subprocess.Popen object at 0x0000000001DBE080> >>> C:\Python26\python.exe >>> subprocess.Popen(['python', '-c', 'import sys; print sys.executable'], env={'PATH':r'e:\zzz\Scripts'}) <subprocess.Popen object at 0x0000000001F05A90> >>> C:\Python26\python.exe >>> subprocess.Popen(['python', '-c', 'import sys; print sys.executable'], env={'PATH':r'e:\zzz\Scripts'}, shell=True) <subprocess.Popen object at 0x0000000001F05B00> >>> e:\zzz\Scripts\python.exe That is, it looks like the environment at the time Python is invoked is what counts unless I pass shell=True. I don't even seem to be able to override this behavior by changing os.environ: you can clear() it and pass env={} and subprocess.Popen(['python']) still succeeds. This is a very important problem for portable code and one that took me hours to suss out. I think: a) the current behavior needs to be documented b) it needs to be fixed if possible c) otherwise, shell=True should be the default ---------- assignee: docs@python components: Documentation messages: 104422 nosy: dabrahams, docs@python priority: normal severity: normal status: open title: subprocess portability issue type: behavior versions: Python 2.6 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue8557> _______________________________________

1 month, 1 week

[issue16272] C-API documentation clarification for tp_dictoffset

by Chris Colbert

New submission from Chris Colbert: The documentation of the tp_dictoffset is a bit unclear when describing the responsibilities of a base type with a nonzero tp_dictoffset. http://docs.python.org/c-api/typeobj.html I feel there should some statement to the effect of: """ If a type defines a nonzero tp_dictoffset, that type is responsible for defining a `__dict__` slot as part of the tp_getset structures. Failure to do so will result in the dict being inaccesible from Python via `obj.__dict__` from instances of the type or subtypes. """ The reasoning is twofold: 1) `PyType_Ready` does not add the default getset members like `type_new` does. This prevents the instances of the type itself from retrieving `obj.__dict__` 2) `type_new` will provide the default `subtype_dict` getset member for subclasses, but this calls `get_builtin_base_with_dict` which will resolve to the most base type which is not heap allocated; in this case, the C type. Since this type has no `__dict__` getset member, the lookup fails. Adding a bit of verbage about this "gotcha" would likely save some headaches in the future. ---------- assignee: docs@python components: Documentation messages: 173222 nosy: Chris.Colbert, docs@python priority: normal severity: normal status: open title: C-API documentation clarification for tp_dictoffset versions: Python 2.6, Python 2.7, Python 3.1, Python 3.2, Python 3.3, Python 3.4, Python 3.5 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue16272> _______________________________________

1 month, 1 week

[issue12594] Docs for py3k still refer to "MacPython 2.5 folder"

by Christoph Schindler

New submission from Christoph Schindler <hop(a)30hopsmax.at>: In http://docs.python.org/py3k/using/mac.html#getting-and-installing-macpython and http://docs.python.org/py3k/using/mac.html#distributing-python-applications… . ---------- assignee: docs@python components: Documentation messages: 140744 nosy: docs@python, hop priority: normal severity: normal status: open title: Docs for py3k still refer to "MacPython 2.5 folder" versions: Python 3.1, Python 3.2 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue12594> _______________________________________

1 month, 1 week

[issue13368] Possible problem in documentation of module subprocess, method send_signal

by Eli Bendersky

New submission from Eli Bendersky <eliben(a)gmail.com>: docs@ list report by Daniel Dieterle: in the documentation (http://docs.python.org/library/subprocess.html#subprocess.Popen.send_signal) is a bug. CTRL_C_EVENT can not be sent to processes started with a creationflags parameter which includes CREATE_NEW_PROCESS_GROUP. Why can be read in the msdn documentation http://msdn.microsoft.com/en-us/library/windows/desktop/ms683155%28v=vs.85%… . A workaround using CTRL_C_EVENT nevertheless is described here: http://stackoverflow.com/questions/7085604/sending-c-to-python-subprocess-o… -- I do not know why the subprocess.CREATE_NEW_PROCESS_GROUP parameter was introduced. But it is useless for terminating a process with os.kill() in combination with signal.SIGTERM, which corresponds to a CTRL-C-EVENT. A CTRL-C-EVENT is only forwarded to the process if the process group is zero. Therefore the Note in the documentation on Popen.send_signal() is wrong. ---------- assignee: docs@python components: Documentation messages: 147272 nosy: docs@python, eli.bendersky priority: normal severity: normal status: open title: Possible problem in documentation of module subprocess, method send_signal versions: Python 2.7 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue13368> _______________________________________

1 month, 2 weeks

[issue13433] String format documentation contains error regarding %g

by Christian Iversen

New submission from Christian Iversen <ci(a)sikkerhed.org>: The documentation for string format options state that both %f, %g and %e default to 6 digits after the decimal point. In fact, %g always seems to use 5 digits by default: >>> "%g" % 2.1234567 '2.12346' >>> "%f" % 2.1234567 '2.123457' >>> "%e" % 2.1234567 '2.123457e+00' But something much more insidious is wrong, because even when explicitly told how many digits to have, %g is one off: >>> "%.6g" % 2.1234567 '2.12346' >>> "%.6f" % 2.1234567 '2.123457' >>> "%.6e" % 2.1234567 '2.123457e+00' This can't be right? ---------- assignee: docs@python components: Documentation messages: 147940 nosy: Christian.Iversen, docs@python priority: normal severity: normal status: open title: String format documentation contains error regarding %g type: behavior versions: Python 2.6, Python 2.7 _______________________________________ Python tracker <report(a)bugs.python.org> <http://bugs.python.org/issue13433> _______________________________________

1 month, 3 weeks

[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> _______________________________________

3 months, 2 weeks

[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> _______________________________________

3 months, 2 weeks

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