Mailman 3 January 2014 - Python-Dev

Python 3 marketing document?
by Dan Stromberg 25 Jan '14

25 Jan '14

Has anyone published a web page or wiki page about what's great about Python 3.x?

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Summary of Python tracker Issues
by Python tracker 25 Jan '14

25 Jan '14

ACTIVITY SUMMARY (2014-01-17 - 2014-01-24) Python tracker at http://bugs.python.org/ To view or respond to any of the issues listed below, click on the issue. Do NOT respond to this message. Issues counts and deltas: open 4475 (+38) closed 27678 (+54) total 32153 (+92) Open issues with patches: 2039 Issues opened (70) ================== #17390: display python version on idle title bar http://bugs.python.org/issue17390 reopened by ezio.melotti #18147: SSL: diagnostic functions to list loaded CA certs http://bugs.python.org/issue18147 reopened by r.david.murray #19081: zipimport behaves badly when the zip file changes while the pr http://bugs.python.org/issue19081 reopened by gregory.p.smith #20290: inspect module bug for modules with same filename http://bugs.python.org/issue20290 opened by cqxz #20291: Argument Clinic should understand *args and **kwargs parameter http://bugs.python.org/issue20291 opened by larry #20293: pydoc fails with the "unspecified" default value http://bugs.python.org/issue20293 opened by serhiy.storchaka #20295: imghdr add openexr support http://bugs.python.org/issue20295 opened by mvignali #20296: PyArg_ParseTuple 2.X docs mention int for "t#", but "Py_ssize_ http://bugs.python.org/issue20296 opened by rlb #20297: concurrent.futures.as_completed() installs waiters for already http://bugs.python.org/issue20297 opened by glangford #20303: Argument Clinic: optional groups http://bugs.python.org/issue20303 opened by serhiy.storchaka #20304: Argument Clinic: char convertor should use default values of t http://bugs.python.org/issue20304 opened by taleinat #20305: Android's incomplete locale.h implementation prevents cross-co http://bugs.python.org/issue20305 opened by shiz #20306: Lack of pw_gecos field in Android's struct passwd causes cross http://bugs.python.org/issue20306 opened by shiz #20307: Android's failure to expose SYS_* system call constants causes http://bugs.python.org/issue20307 opened by shiz #20308: inspect.Signature doesn't support user classes without __init_ http://bugs.python.org/issue20308 opened by larry #20309: Not all method descriptors are callable http://bugs.python.org/issue20309 opened by larry #20311: epoll.poll(timeout) and PollSelector.select(timeout) must roun http://bugs.python.org/issue20311 opened by haypo #20314: Potentially confusing formulation in 6.1.4. Template strings http://bugs.python.org/issue20314 opened by Gerrit.Holl #20317: ExitStack hang if enough nested exceptions http://bugs.python.org/issue20317 opened by jcflack #20318: subprocess.Popen can hang in threaded applications http://bugs.python.org/issue20318 opened by Andrew.Lutomirski #20319: concurrent.futures.wait() can block forever even if Futures ha http://bugs.python.org/issue20319 opened by glangford #20320: select.select(timeout) and select.kqueue.control(timeout) must http://bugs.python.org/issue20320 opened by haypo #20322: Upgrade ensurepip's pip and setuptools http://bugs.python.org/issue20322 opened by dstufft #20323: Argument Clinic: docstring_prototype output causes build failu http://bugs.python.org/issue20323 opened by zach.ware #20325: Argument Clinic: self converters are not preserved when clonin http://bugs.python.org/issue20325 opened by taleinat #20326: Argument Clinic should use a non-error-prone syntax to mark te http://bugs.python.org/issue20326 opened by larry #20328: mailbox: http://bugs.python.org/issue20328 opened by jmtd #20329: zipfile.extractall fails in Posix shell with utf-8 filename http://bugs.python.org/issue20329 opened by Laurent.Mazuel #20330: PEP 342 is outdated http://bugs.python.org/issue20330 opened by msmhrt #20331: Fix various fd leaks http://bugs.python.org/issue20331 opened by serhiy.storchaka #20333: argparse subparser usage message hides main parser usage http://bugs.python.org/issue20333 opened by Martin.d'Anjou #20334: make inspect Signature hashable http://bugs.python.org/issue20334 opened by yselivanov #20335: bytes constructor accepts more than one argument even if the f http://bugs.python.org/issue20335 opened by rndblnch #20336: test_asyncio: relax timings even more http://bugs.python.org/issue20336 opened by skrah #20337: bdist_rpm should support %config(noreplace) http://bugs.python.org/issue20337 opened by kv #20338: Idle: increase max calltip width http://bugs.python.org/issue20338 opened by terry.reedy #20339: Make bytes() use tp_as_buffer for cmp http://bugs.python.org/issue20339 opened by nascheme #20341: Argument Clinic: add "nullable ints" http://bugs.python.org/issue20341 opened by larry #20342: Endianness not detected correctly due to AC_RUN_IFELSE macros http://bugs.python.org/issue20342 opened by zaytsev #20344: subprocess.check_output() docs misrepresent what shell=True do http://bugs.python.org/issue20344 opened by klausman #20345: Better logging defaults http://bugs.python.org/issue20345 opened by ArneBab #20346: Argument Clinic: missing entry in table mapping legacy convert http://bugs.python.org/issue20346 opened by taleinat #20348: Argument Clinic HOWTO listed multiple times in HOWTO index http://bugs.python.org/issue20348 opened by brett.cannon #20349: Argument Clinic: error on __new__ or __init__ with no argument http://bugs.python.org/issue20349 opened by taleinat #20350: Replace tkapp.split() to tkapp.splitlist() http://bugs.python.org/issue20350 opened by serhiy.storchaka #20351: Add doc examples for DictReader and DictWriter http://bugs.python.org/issue20351 opened by charlax #20352: Add support for AUTH command to poplib http://bugs.python.org/issue20352 opened by dveeden #20353: Hanging bug with multiprocessing + sqlite3 + tkinter (OS X 10. http://bugs.python.org/issue20353 opened by Craig.Silverstein #20354: tracemalloc causes segfault in "make profile-opt" http://bugs.python.org/issue20354 opened by matejcik #20355: -W command line options should have higher priority than PYTHO http://bugs.python.org/issue20355 opened by Arfrever #20356: fix formatting of positional-only parameters in inspect.Signat http://bugs.python.org/issue20356 opened by yselivanov #20357: Mention buildbots in the core dev section of the devguide http://bugs.python.org/issue20357 opened by ncoghlan #20358: test_curses is failing http://bugs.python.org/issue20358 opened by larry #20360: inspect.Signature could provide readable expressions for defau http://bugs.python.org/issue20360 opened by larry #20361: -W command line options and PYTHONWARNINGS environmental varia http://bugs.python.org/issue20361 opened by Arfrever #20362: longMessage attribute is ignored in unittest.TestCase.assertRe http://bugs.python.org/issue20362 opened by Dhara #20363: BytesWarnings triggerred by test suite http://bugs.python.org/issue20363 opened by Arfrever #20364: Rename & explain sqlite3.Cursor.execute 'parameters' param http://bugs.python.org/issue20364 opened by terry.reedy #20366: SQLite FTS (full text search) http://bugs.python.org/issue20366 opened by mark #20367: concurrent.futures.as_completed() fails when given duplicate F http://bugs.python.org/issue20367 opened by glangford #20368: Tkinter: handle the null character http://bugs.python.org/issue20368 opened by serhiy.storchaka #20369: concurrent.futures.wait() blocks forever when given duplicate http://bugs.python.org/issue20369 opened by glangford #20371: datetime.datetime.replace bypasses a subclass's __new__ http://bugs.python.org/issue20371 opened by Andrew.Lutomirski #20372: inspect.getfile should raise a TypeError if C object does not http://bugs.python.org/issue20372 opened by yselivanov #20373: Use test.script_helper.assert_python_ok() instead of subproces http://bugs.python.org/issue20373 opened by Arfrever #20375: ElementTree: Document handling processing instructions http://bugs.python.org/issue20375 opened by nikolaus.rath #20376: Argument Clinic: backslashes in docstrings are not escaped http://bugs.python.org/issue20376 opened by serhiy.storchaka #20378: Implement `Signature.__repr__` http://bugs.python.org/issue20378 opened by cool-RR #20379: help(bound_builtin_class) does not display self http://bugs.python.org/issue20379 opened by larry #20381: Argument Clinic: expression default arguments broken http://bugs.python.org/issue20381 opened by zach.ware Most recent 15 issues with no replies (15) ========================================== #20381: Argument Clinic: expression default arguments broken http://bugs.python.org/issue20381 #20379: help(bound_builtin_class) does not display self http://bugs.python.org/issue20379 #20378: Implement `Signature.__repr__` http://bugs.python.org/issue20378 #20375: ElementTree: Document handling processing instructions http://bugs.python.org/issue20375 #20373: Use test.script_helper.assert_python_ok() instead of subproces http://bugs.python.org/issue20373 #20372: inspect.getfile should raise a TypeError if C object does not http://bugs.python.org/issue20372 #20368: Tkinter: handle the null character http://bugs.python.org/issue20368 #20366: SQLite FTS (full text search) http://bugs.python.org/issue20366 #20362: longMessage attribute is ignored in unittest.TestCase.assertRe http://bugs.python.org/issue20362 #20357: Mention buildbots in the core dev section of the devguide http://bugs.python.org/issue20357 #20351: Add doc examples for DictReader and DictWriter http://bugs.python.org/issue20351 #20350: Replace tkapp.split() to tkapp.splitlist() http://bugs.python.org/issue20350 #20349: Argument Clinic: error on __new__ or __init__ with no argument http://bugs.python.org/issue20349 #20346: Argument Clinic: missing entry in table mapping legacy convert http://bugs.python.org/issue20346 #20339: Make bytes() use tp_as_buffer for cmp http://bugs.python.org/issue20339 Most recent 15 issues waiting for review (15) ============================================= #20375: ElementTree: Document handling processing instructions http://bugs.python.org/issue20375 #20373: Use test.script_helper.assert_python_ok() instead of subproces http://bugs.python.org/issue20373 #20372: inspect.getfile should raise a TypeError if C object does not http://bugs.python.org/issue20372 #20369: concurrent.futures.wait() blocks forever when given duplicate http://bugs.python.org/issue20369 #20368: Tkinter: handle the null character http://bugs.python.org/issue20368 #20367: concurrent.futures.as_completed() fails when given duplicate F http://bugs.python.org/issue20367 #20364: Rename & explain sqlite3.Cursor.execute 'parameters' param http://bugs.python.org/issue20364 #20363: BytesWarnings triggerred by test suite http://bugs.python.org/issue20363 #20361: -W command line options and PYTHONWARNINGS environmental varia http://bugs.python.org/issue20361 #20356: fix formatting of positional-only parameters in inspect.Signat http://bugs.python.org/issue20356 #20355: -W command line options should have higher priority than PYTHO http://bugs.python.org/issue20355 #20354: tracemalloc causes segfault in "make profile-opt" http://bugs.python.org/issue20354 #20352: Add support for AUTH command to poplib http://bugs.python.org/issue20352 #20351: Add doc examples for DictReader and DictWriter http://bugs.python.org/issue20351 #20350: Replace tkapp.split() to tkapp.splitlist() http://bugs.python.org/issue20350 Top 10 most discussed issues (10) ================================= #20341: Argument Clinic: add "nullable ints" http://bugs.python.org/issue20341 30 msgs #20218: Add `pathlib.Path.write` and `pathlib.Path.read` http://bugs.python.org/issue20218 26 msgs #20311: epoll.poll(timeout) and PollSelector.select(timeout) must roun http://bugs.python.org/issue20311 26 msgs #17481: inspect.getfullargspec should use __signature__ http://bugs.python.org/issue17481 23 msgs #20180: Derby #11: Convert 50 sites to Argument Clinic across 9 files http://bugs.python.org/issue20180 14 msgs #20293: pydoc fails with the "unspecified" default value http://bugs.python.org/issue20293 12 msgs #20338: Idle: increase max calltip width http://bugs.python.org/issue20338 12 msgs #20308: inspect.Signature doesn't support user classes without __init_ http://bugs.python.org/issue20308 10 msgs #20177: Derby #8: Convert 28 sites to Argument Clinic across 2 files http://bugs.python.org/issue20177 9 msgs #20185: Derby #17: Convert 49 sites to Argument Clinic across 13 files http://bugs.python.org/issue20185 9 msgs Issues closed (55) ================== #7883: CallTips.py _find_constructor does not work http://bugs.python.org/issue7883 closed by terry.reedy #16630: IDLE: Calltip fails if __getattr__ raises exception http://bugs.python.org/issue16630 closed by terry.reedy #16638: support multi-line docstring signatures in IDLE calltips http://bugs.python.org/issue16638 closed by terry.reedy #16655: IDLE list.append calltips test failures http://bugs.python.org/issue16655 closed by terry.reedy #17811: Improve os.readv() and os.writev() documentation and docstring http://bugs.python.org/issue17811 closed by python-dev #17814: Popen.stdin/stdout/stderr documentation should mention object http://bugs.python.org/issue17814 closed by python-dev #18574: BaseHTTPRequestHandler.handle_expect_100() sends invalid respo http://bugs.python.org/issue18574 closed by python-dev #19020: Regression: Windows-tkinter-idle, unicode, and 0xxx filename http://bugs.python.org/issue19020 closed by terry.reedy #19036: setlocale fails due to locale.h being wrapped up in LANGINFO c http://bugs.python.org/issue19036 closed by skrah #19291: Add docs for asyncio package (Tulip, PEP 3156) http://bugs.python.org/issue19291 closed by haypo #19584: IDLE fails - Python V2.7.6 - 64b on Win7 64b http://bugs.python.org/issue19584 closed by terry.reedy #19936: Executable permissions of Python source files http://bugs.python.org/issue19936 closed by serhiy.storchaka #20024: Py_BuildValue() can call Python code with an exception set http://bugs.python.org/issue20024 closed by haypo #20122: Move CallTips tests to idle_tests http://bugs.python.org/issue20122 closed by terry.reedy #20165: unittest TestResult wasSuccessful returns True when there are http://bugs.python.org/issue20165 closed by gregory.p.smith #20189: inspect.Signature doesn't recognize all builtin types http://bugs.python.org/issue20189 closed by larry #20194: Add :deprecated: marker to formatter module docs http://bugs.python.org/issue20194 closed by brett.cannon #20195: Add :deprecated: marker to imp docs http://bugs.python.org/issue20195 closed by brett.cannon #20222: unittest.mock-examples doc uses builtin file which is removed http://bugs.python.org/issue20222 closed by terry.reedy #20238: Incomplete gzip output with tarfile.open(fileobj=..., mode="w: http://bugs.python.org/issue20238 closed by serhiy.storchaka #20243: ReadError when open a tarfile for writing http://bugs.python.org/issue20243 closed by serhiy.storchaka #20244: Possible resources leak in tarfile.open() http://bugs.python.org/issue20244 closed by serhiy.storchaka #20245: Check empty mode in TarFile.*open() http://bugs.python.org/issue20245 closed by serhiy.storchaka #20252: Argument Clinic howto: small typo in y# translation http://bugs.python.org/issue20252 closed by rmsr #20262: Convert some debugging prints in zipfile to warnings http://bugs.python.org/issue20262 closed by serhiy.storchaka #20270: urllib.parse doesn't work with empty port http://bugs.python.org/issue20270 closed by serhiy.storchaka #20275: asyncio: remove debug code from BaseEventLoop http://bugs.python.org/issue20275 closed by python-dev #20280: add "predicate" to the glossary http://bugs.python.org/issue20280 closed by flox #20282: Argument Clinic: int with boolean default http://bugs.python.org/issue20282 closed by larry #20287: Argument Clinic: support diverting output to buffer, external http://bugs.python.org/issue20287 closed by larry #20292: clinic.py str_converter with encoding throws exception http://bugs.python.org/issue20292 closed by larry #20294: Argument Clinic: add support for __init__ http://bugs.python.org/issue20294 closed by larry #20298: json library needs a non-strict option to decode single-quoted http://bugs.python.org/issue20298 closed by rhettinger #20299: Argument Clinic CConverter.__init__() overrides c_default and http://bugs.python.org/issue20299 closed by larry #20300: Argument Clinic raises exception for custom converter with def http://bugs.python.org/issue20300 closed by larry #20301: Correct docs for default access argument for DeleteKeyEx http://bugs.python.org/issue20301 closed by zach.ware #20302: Argument Clinic: meaningful names for group flags http://bugs.python.org/issue20302 closed by larry #20310: Recommend using pprint for deterministic doctest http://bugs.python.org/issue20310 closed by r.david.murray #20312: A missing link to Python-3.4.0b2.tar.bz2 in the download page. http://bugs.python.org/issue20312 closed by georg.brandl #20313: inspect.signature should raise ValueError for builtins with no http://bugs.python.org/issue20313 closed by larry #20315: Remove old compatibility code http://bugs.python.org/issue20315 closed by serhiy.storchaka #20316: Byte-compiled files should be absent in tarballs http://bugs.python.org/issue20316 closed by benjamin.peterson #20321: ImportError when a module is created after a catched ImportErr http://bugs.python.org/issue20321 closed by brett.cannon #20324: gcc-4.2.4 support on python-3.3 (libmpdec) http://bugs.python.org/issue20324 closed by georg.brandl #20327: Argument Clinic: setting internal variable names for parsed ar http://bugs.python.org/issue20327 closed by zach.ware #20332: Argument Clinic docs do not list support for the 'l' format http://bugs.python.org/issue20332 closed by larry #20340: -bb option does not have different behavior than -b option http://bugs.python.org/issue20340 closed by Arfrever #20343: zipfile truncates extracted files http://bugs.python.org/issue20343 closed by serhiy.storchaka #20347: dir(__future__) gives segfault on OS X in 3.2 and 3.3 http://bugs.python.org/issue20347 closed by r.david.murray #20359: Having escape sequences (like color codes) in the sys.ps1 mess http://bugs.python.org/issue20359 closed by georg.brandl #20365: test_asyncio.test_read_pty_output() fails on "AMD64 Snow Leop http://bugs.python.org/issue20365 closed by python-dev #20370: Docs error in Library reference-17.1.3 threading.Lock.acquire( http://bugs.python.org/issue20370 closed by yonoho #20374: Failure to compile with readline-6.3-rc1 http://bugs.python.org/issue20374 closed by python-dev #20377: Argument Clinic: get rid of the "_impl" suffix http://bugs.python.org/issue20377 closed by larry #20380: __defaults__ changed by *args http://bugs.python.org/issue20380 closed by larry

1 0

Enable Hostname and Certificate Chain Validation
by Donald Stufft 24 Jan '14

24 Jan '14

I would like to propose that a backwards incompatible change be made to Python to make verification of hostname and certificate chain the default instead of requiring it to be opt in. Python 3.4 has made great strides in making it easier for applications to simply turn on these settings, however many people are not aware at all that they need to opt into this. Most assume that it will operate similarly to their browser, curl, wget, etc and validate by default and in the typical style of security related issues it will appear to work just fine however be grossly insecure. In the real world “opt in security” typically translates to just plain old insecure for the bulk of applications/libraries. I believe that Python has a responsibility to do the right thing by default here and it is in the best position to do so. The alternative requires every Python developer who wants to access a secure resource to be educated on the fact that they need to flip some switch to do what most of them would expect. ----------------- Donald Stufft PGP: 0x6E3CBCE93372DCFA // 7C6B 7C5D 5E2B 6356 A926 F04F 6E3C BCE9 3372 DCFA

22 77

Wrong keyword parameter name in regex pattern methods
by Serhiy Storchaka 24 Jan '14

24 Jan '14

Currently there is a mismatch between documented parameter names in some methods of regex pattern object. match(), search(), and fullmatch() (the last was added in 3.4) document first arguments as "string": match(string[, pos[, endpos]]) search(string[, pos[, endpos]]) fullmatch(string[, pos[, endpos]]) But actually they don't accept the "string" keyword parameter, by mistake it is named as "pattern" in the code. findall() and split() document first arguments as "string": findall(string[, pos[, endpos]]) -> list split(string[, maxsplit = 0]) But actually they don't accept the "string" keyword parameter, it is named as "source" in the code. The scanner() method is not documented and also has the "source" parameter. All other methods accepts the "string" argument as documented. The match object returned by match(), search(), fullmatch(), and finditer() methods and generated by the scanner, has the "string" attribute which is equivalent to the argument of these methods. Module level functions which corresponds to these methods have the "string" parameter. Due to all these facts I think that parameter names "pattern" and "source" are accidental mistakes and should be renamed to expected "string". Because this parameter is mandatory, apparently it is always used as positional parameter, and this error was not discovered long time. http://bugs.python.org/issue20283

2 1

.clinic.c vs .c.clinic
by Serhiy Storchaka 23 Jan '14

23 Jan '14

After the latest Argument Clinic updates my patches began to look much better. Thank you Larry. Now Argument Clinic supports output to side file (this is not default, you should specify "output preset file" at the start of first clinic declaration). I already wrote about this here, but it seems my post got lost in the heart of one of the numerous threads and was not noticed. So I repeat it as a separate thread. Now generated files have suffixes .clinic.c. I think it will be better, if they will end at special suffix (.c.clinic or even just .clinic). My reasons: 1. I very very often use global search in sources. It's my way of navigation and it's my way of investigations. I don't want to get false results in generated files. And it is much easy to specify mask '*.[ch]' or '*.c,*.h' (depending on tool) than specify a mask and negative mask. The latter is even not always possible, I can write cumbersome expression for the find command, but Midnight Commander doesn't support negative masks at all (and perhaps your favorite IDE doesn't support them too). 2. I'm not use any IDE, but if you use, it can be important for you. If IDE shows sources tree, unlikely you want to see generated *.clinic.c files in them. This will increase the list of sources almost twice. 3. Pathname expansion works better with unique endings, You can open all Modules/_io/*.c files, but unlikely you so interested in *.clinic.c files which are matched by former pattern. 4. .c suffix at the end lies. This is not compilable C source file. This file should be included in other C source file. This will confuse accidental user and other tools. Including Argument Clinic itself, this is why it inserts the "preserve" directive at the start of generated file. But other tools have no such sign. My attempt to convince Larry on IRC failed. He agreed to change his opinion only if other core developers persuade him. I ask you to help me convince Larry.

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Using argument clinic to replace timemodule.c:parse_time_t_args()
by Nikolaus Rath 22 Jan '14

22 Jan '14

Hello, I'm trying to convert functions using parse_time_t_args() (from timemodule.c) for argument parsing to argument clinic. The function is defined as: ,---- | static int | parse_time_t_args(PyObject *args, char *format, time_t *pwhen) | { | PyObject *ot = NULL; | time_t whent; | | if (!PyArg_ParseTuple(args, format, &ot)) | return 0; | if (ot == NULL || ot == Py_None) { | whent = time(NULL); | } | else { | if (_PyTime_ObjectToTime_t(ot, &whent) == -1) | return 0; | } | *pwhen = whent; | return 1; | } `---- and used like this: ,---- | static PyObject * | time_localtime(PyObject *self, PyObject *args) | { | time_t when; | struct tm buf; | | if (!parse_time_t_args(args, "|O:localtime", &when)) | return NULL; | if (pylocaltime(&when, &buf) == -1) | return NULL; | return tmtotuple(&buf); | } `---- In other words, if any Python object is passed to it, it calls _PyTime_ObjectToTime_t on it to convert it to time_t, and otherwise uses time(NULL) as the default value. May first attempt to implement something similar in argument clinic was: ,---- | /*[python input] | class time_t_converter(CConverter): | type = 'time_t' | converter = 'time_t_converter' | default = None | py_default = 'None' | c_default = 'time(NULL)' | converter = '_PyTime_ObjectToTime_t' | [python start generated code]*/ | | /*[clinic input] | time.localtime | | seconds: time_t | / | | bla. | [clinic start generated code]*/ `---- However, running clinic.py on this file gives: ,---- | $ Tools/clinic/clinic.py Modules/timemodule.c | Error in file "Modules/timemodule.c" on line 529: | Exception raised during parsing: | Traceback (most recent call last): | File "Tools/clinic/clinic.py", line 1445, in parse | parser.parse(block) | File "Tools/clinic/clinic.py", line 2738, in parse | self.state(None) | File "Tools/clinic/clinic.py", line 3468, in state_terminal | self.function.docstring = self.format_docstring() | File "Tools/clinic/clinic.py", line 3344, in format_docstring | s += "".join(a) | TypeError: sequence item 2: expected str instance, NoneType found `---- What am I doing wrong? Best, Nikolaus -- Encrypted emails preferred. PGP fingerprint: 5B93 61F8 4EA2 E279 ABF6 02CF A9AD B7F8 AE4E 425C »Time flies like an arrow, fruit flies like a Banana.«

4 17

Re: [Python-Dev] Using argument clinic to replace timemodule.c:parse_time_t_args()
by Larry Hastings 22 Jan '14

22 Jan '14

Yes, I meant in the definition of the convertor class. You can fix c_default in converter_init. On Jan 21, 2014 7:19 PM, Nikolaus Rath <Nikolaus(a)rath.org> wrote: > > Larry Hastings <larry(a)hastings.org> writes: > > A comment on your approach so far: I'm very much against giving > > "default" a default value in the constructor. > > You mean in the definition of the custom converter class? > > > I realize that hack saves you having to say "= NULL" in a lot of > > places. But explicit is better than implicit, and we're going to read > > these signatures a lot more often than we write them, and I want > > Clinic signatures to be easy to read at first glance. > [....] > > All is not lost! What follows is rough pseudo-C code, hopefully you > > can take it from here. > > > > typedef struct { > > int set; > > time_t when; > > } clinic_time_t; > > #define DEFAULT_CLINIC_TIME_T {0, 0} > > > [...] > > > > /*[python input] > > class clinic_time_t_converter(CConverter): > > type = 'clinic_time_t' > > converter = 'parse_clinic_time_t' > > c_default = 'DEFAULT_CLINIC_TIME_T' > > [python start generated code]*/ > > /*[python end generated code: checksum=...]*/ > > > > Now you can use clinic_time_t. Parameters declared clinic_time_t can > > be required, or they can be optional; if they're optional give them a > > default value of None. > > That doesn't work. If the default value is declared for the function > rather than in the converter definition, it overwrites the C default: > > /*[clinic input] > time.gmtime > > seconds: clinic_time_t=None > / > */ > > gives: > > static PyObject * > time_gmtime(PyModuleDef *module, PyObject *args) > { > PyObject *return_value = NULL; > clinic_time_t seconds = Py_None; > > if (!PyArg_ParseTuple(args, > "|O&:gmtime", > parse_clinic_time_t, &seconds)) > goto exit; > return_value = time_gmtime_impl(module, seconds); > > so the default for seconds is now Py_None instead of > DEFAULT_CLINIC_TIME_T'. > > Best, > Nikolaus > > -- > Encrypted emails preferred. > PGP fingerprint: 5B93 61F8 4EA2 E279 ABF6 02CF A9AD B7F8 AE4E 425C > > »Time flies like an arrow, fruit flies like a Banana.« > _______________________________________________ > Python-Dev mailing list > Python-Dev(a)python.org > https://mail.python.org/mailman/listinfo/python-dev > Unsubscribe: https://mail.python.org/mailman/options/python-dev/larry%40hastings.org

1 0

Formatting of positional-only parameters in signatures
by Yury Selivanov 22 Jan '14

22 Jan '14

There is one more, hopefully last, open urgent question with the signature object. At the time we were working on the PEP 362, PEP 457 didn’t exist. Nor did we have any function with real positonal-only parameters, since there was no Argument Clinic yet. However, I implemented rudimentary support for them: “Parameter.POSITIONAL_ONLY” constant; “Signature.bind” and “Signature.bind_partial” fully support functions with positional-only parameters; “Signature.__str__” renders them distinctively from other kinds. The last point is the troublesome now. "Signature.__str__” renders positional-only parameters in ‘<>’ brackets, so in: foo(<ham>, <spam>, baz) “ham” and “spam” are positional-only. The choice of angle brackets was unfortunate, as, first of all, this wasn’t really discussed on python-dev, and second, it’s easy to think that those parameters are optional. Now, with the AC landing in 3.4, we need to decide how positional-only parameters will look like. Without starting a new discussion similar to what we had prior to PEP 457, I think we have three options: 1. Leave it as is. Obviously, the downside is the potential confusion with “optional” notation. 2. Adopt PEP 457 style: using “/“ to separate positional-only parameters from the rest. 3. Don’t use any notation, just render them as plain arguments: "foo(ham, spam, baz)". The downside here is that the users will be confused, and might try passing those parameters with keywords, or binding them with keywords. Thoughts? Yury

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PEP 461 - Adding % and {} formatting to bytes
by Ethan Furman 22 Jan '14

22 Jan '14

This PEP goes a but further than PEP 460 does, and hopefully spells things out in enough detail so there is no confusion as to what is meant. -- ~Ethan~

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signature.object, argument clinic and grouped parameters
by Yury Selivanov 21 Jan '14

21 Jan '14

In the midst of work on the issue #17481, it became apparent that we need a way of specifying optional/grouped parameters. One good example of grouped parameters in python is the `type` function. Basically, it has two different signatures: * type(name, bases, dict) * type(object) Which we can combine in one, if we define a notion of grouped parameters: * type(object_or_name, [bases, dict]) Another good example, is 'itertools.repeat'. Its signature is "(elem[, n])". If "n" argument is passed, then it's how many times the "elem" will be repeated, and if it is not passed at all, then "elem" will be repeated endlessly. One way of emulating this behavior in pure python is to define a special private marker object and use it as a default value: _optional = object() def repeat(elem, n=_optional): if n is _optional: # `n` wasn't passed, repeat indefinitely else: # we have something for `n` One of the problems with the above approach is how to represent its signature, how to document it clearly. Another one, is that there is no common marker, so whenever this is needed, a new marker is invented. Now, the more I think about having a concept of grouped parameters, the more different things to consider and take care of appear: * In issue #17481 Larry proposed that parameters will have a group id (arbitrary), and perhaps parent group id, to make it possible to have nested groups. * API for retrieving grouped parameters for the Signature objects. Something akin to what we have for ``regex.Match`` objects, probably. * An accepted and documented method of declaring groups for pure python function would be a nice thing to have. * Will we have groups for keyword-only parameters? Can we combine ``*args`` and a keyword-only parameter in a group? etc. That seems to be a lot of work (some of it is maybe enough for a PEP.) So before committing to the parameters groups idea, I'd like to propose somewhat simpler, but powerful enough to solve our todays problems solution. What if we add a notion of "optional" parameters? * ``Parameter.__init__ `` will receive one more keyword-only argument: ``optional``, ``False`` by default. * We add a special marker ``Parameter.optional`` (or some other name, like ``inspect.optional`` or ``functools.optional``), and teach ``inspect.signature`` to recognize it. So for pure-python functions, if you want to define an optional parameter, you would write: ``def mytype(name_or_obj, bases=Parameter.optional, dict=Parameter.optional)`` * Argument Clinic may get a new syntax for specifying if parameter is optional. * We standardize how optional parameters should look like in documentation and ``Signature.__str__``. In PEP 362 we used <optional> notation for optional parameters: ``foo(param=<optional>)``, but we also can use square brackets for that: ``bar([spam][, ham])``. With this approach, a signature of the ``type`` function would look like: ``type(object_or_name[, bases][, dict])``. The main downside is that it's not immediately apparent, that you can only pass either one argument "(object)", or all three arguments "(name, bases, dict)". But that's something, that a good documentation (and meaningful exceptions) could help with. The advantages if this approach, is that it works for all types of parameters, and that the implementation is going to be simpler than groups (and we will need fewer new APIs). Yury

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