Mailman 3 May 2003 - Python-Dev

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26 May '03

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RELEASED Python 2.2.3c1
by Barry Warsaw 25 May '03

25 May '03

I'm happy to announce the release of Python 2.2.3c1 (release candidate 1). This is a bug fix release for the stable Python 2.2 code line. Barring any critical issues, we expect to release Python 2.2.3 final by this time next week. We encourage those with an interest in a solid 2.2.3 release to download this candidate and test it on their code. The new release is available here: http://www.python.org/2.2.3/ Python 2.2.3 has a large number of bug fixes and memory leak patches. For full details, see the release notes at http://www.python.org/2.2.3/NEWS.txt There are a small number of minor incompatibilities with Python 2.2.2; for details see: http://www.python.org/2.2.3/bugs.html Perhaps the most important is that the Bastion.py and rexec.py modules have been disabled, since we do not deem them to be safe. As usual, a Windows installer and a Unix/Linux source tarball are made available, as well as tarballs of the documentation in various forms. At the moment, no Mac version or Linux RPMs are available, although I expect them to appear soon after 2.2.3 final is released. On behalf of Guido, I'd like to thank everyone who contributed to this release, and who continue to ensure Python's success. Enjoy, -Barry

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RE: [Python-checkins] python/dist/src/Lib weakref.py,1.19,1.20
by Tim Peters 25 May '03

25 May '03

[redirected to python-dev] [Tim] >> Someone review this, please! Final releases are getting close, Fred >> (the weakref guy) won't be around until Tuesday, and the pre-patch >> code can indeed raise spurious RuntimeErrors in the presence of >> threads or mutating comparison functions. >> >> See the bug report for my confusions: I can't see any reason for why >> __delitem__ iterated over the keys. [Raymond Hettinger] > Until reading the note on threads, I didn't see the error and thought > the original code was valid because it returned after the deletion > instead of continuing to loop through iterkeys. Note that one of the new tests I checked in provoked RuntimeError without threads. >> The new one-liner implementation is much faster, can't raise >> RuntimeError, and should be> better-behaved in all respects wrt threads. > Yes, that solves the OP's problem. >> Bugfix candidate for 2.2.3 too, if someone else agrees with this >> patch. > The original code does its contortions to avoid raising a KeyError > whenever the dictionary entry might have disappeared due to the > ref count falling to zero and then a new, equal key was formed later. Sorry, I can't picture what you're trying to say. Show some code? If in a weak-keyed dict d I do d[k1] = v del k1 # last reference, so the dict mutation went away del d[k2] # where k2 happens to be compare equal to what k1 was then I claim that *should* raise KeyError, and pretty obviously so. Note that the other new test I checked in showed that del d[whatever] never raised KeyError before; I can't see how that can be called a feature, and if someone thinks it was they neglected to document it, or write a test that failed when I changed the behavior <wink>. > If the data disappeared, then, I think ref(key) will return None No, ref(x) never returns None, regardless of what x may be. It may raise TypeError if x is not of a weakly referencable type, and it may raise MemoryError if we don't have enough memory left to construct a weakref, but those are the only things that can go wrong. w = ref(x) followed later by w() will return None, iff x has gone away in the meantime -- maybe that's what you're thinking of. > which is a bummer because that is then used (in your patch) > as a lookup key. If x and y are two weakly-referencable objects (not necessarily distinct) that compare equal, then ref(x) == ref(y) and hash(ref(x)) == hash(ref(y)) so long as both ref(x)() and ref(y)() don't return None (i.e., so long as x and y are both still alive). Soo when I map del d[k1] to del d.data[ref(k1)] it will succeed if and only if d.data has a key for a still-live object, and that key compares equal to k1; else it will raise KeyError (or maybe TypeError if k1 is a silly key to test in a weak-keyed dict, or MemoryError if we run out of memory). That's what I believe it should do. > The safest approach (until Fred re-appears) is to keep the original > approach but use keys() instead of iterkeys(). Then, wrap the > actual deletion in a try / except KeyError to handle a thread > race to delete the same weakref object. I'm not clear on what that means. By "delete the same weakref object", do you mean that both threads try to do del d[k] with the same k and the same weak-valued dict d? If so, then I think one of them *should* see KeyError, exactly the same as if they tried pulling this trick with a regular dict. > I'm sure there is a better way and will take another look tomorrow. Thanks for trying, but I still don't get it. It would help if you could show specific code that you believe worked correctly before but is broken now. I added two new tests showing what I believe to be code that was broken before but works now, and no changes to the existing tests were needed.

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Weekly Python Bug/Patch Summary
by Skip Montanaro 25 May '03

25 May '03

Bug/Patch Summary ----------------- 372 open / 3658 total bugs (-30) 151 open / 2173 total patches (+12) New Bugs -------- IMAP4_SSL broken (2003-05-19) http://python.org/sf/739909 re.finditer() listed as new in 2.2.? (2003-05-19) http://python.org/sf/740026 test/build-failures on FreeBSD stable/current (2003-05-19) http://python.org/sf/740234 Can't browse methods and Classes (2003-05-20) http://python.org/sf/740407 MacPython-OS9 distutils breaks on OSX (2003-05-20) http://python.org/sf/740424 HTMLParser -- possible bug in handle_comment (2003-05-21) http://python.org/sf/741029 Configure does NOT set properly *FLAGS for thread support (2003-05-21) http://python.org/sf/741307 test_long failure (2003-05-22) http://python.org/sf/741806 curses support on Python-2.3b1/Tru64Unix 5.1A (2003-05-22) http://python.org/sf/741843 Python crashes if recursively reloading modules (2003-05-23) http://python.org/sf/742342 WeakKeyDictionary __delitem__ uses iterkeys (2003-05-24) http://python.org/sf/742860 Memory fault on complex weakref/weakkeydict delete (2003-05-24) http://python.org/sf/742911 New Patches ----------- inspect.getargspec: None instead of () (2002-11-12) http://python.org/sf/637217 zlib.decompressobj under-described. (2002-11-18) http://python.org/sf/640236 Several objects don't decref tmp on failure in subtype_new (2003-03-14) http://python.org/sf/703666 strange warnings messages in interpreter (2003-03-14) http://python.org/sf/703779 build of html docs broken (liboptparse.tex) (2003-05-04) http://python.org/sf/732174 HP-UX support for unixccompiler.py (2003-05-20) http://python.org/sf/740301 add urldecode() method to urllib (2003-05-20) http://python.org/sf/740827 unicode "support" for shlex.py (2003-05-23) http://python.org/sf/742290 SocketServer timeout, zombies (2003-05-23) http://python.org/sf/742598 ast-branch: msvc project sync (2003-05-23) http://python.org/sf/742621 check for true in diffrent paths, -pthread support (2003-05-24) http://python.org/sf/742741 Ordering of handlers in urllib2 (2003-05-24) http://python.org/sf/742823 Closed Bugs ----------- crash in shelve module (2001-03-13) http://python.org/sf/408271 maximum recursion limit exceeded (2.1) (2001-04-24) http://python.org/sf/418626 raw-unicode-escape codec fails roundtrip (2001-07-25) http://python.org/sf/444514 strange IRIX test_re/test_sre failure (2001-08-28) http://python.org/sf/456398 New httplib lacks documentation (2001-09-04) http://python.org/sf/458447 maximum recursion limit exceeded in match (2001-12-14) http://python.org/sf/493252 inconsistent behavior of __getslice__ (2002-05-24) http://python.org/sf/560064 Mixing framework and static Pythons (2002-06-19) http://python.org/sf/571343 inheriting from property and docstrings (2002-07-03) http://python.org/sf/576990 unittest.py, better error message (2002-07-30) http://python.org/sf/588825 installation errors (2002-08-07) http://python.org/sf/592161 test_nis test fails on TRU64 5.1 (2002-08-14) http://python.org/sf/594998 non greedy match bug (2002-08-30) http://python.org/sf/602444 cgitb tracebacks not accessible (2002-08-31) http://python.org/sf/602893 faster [None]*n or []*n (2002-09-04) http://python.org/sf/604716 Max recursion limit with "*?" pattern (2002-10-08) http://python.org/sf/620412 cStringIO().write TypeError (2002-11-08) http://python.org/sf/635814 inspect.getargspec: None instead of () (2002-11-12) http://python.org/sf/637217 zlib.decompressobj under-described. (2002-11-18) http://python.org/sf/640236 Poor error message for augmented assign (2002-11-26) http://python.org/sf/644345 gettext.py crash on bogus preamble (2002-12-24) http://python.org/sf/658233 BoundaryError: multipart message with no defined boundary (2003-01-14) http://python.org/sf/667931 bsddb doc error (2003-01-28) http://python.org/sf/676233 test_logging fails (2003-01-31) http://python.org/sf/678217 new.function() leads to segfault (2003-02-25) http://python.org/sf/692776 Python 2.3a2 Build fails on HP-UX11i (2003-02-27) http://python.org/sf/694431 Several objects don't decref tmp on failure in subtype_new (2003-03-14) http://python.org/sf/703666 strange warnings messages in interpreter (2003-03-14) http://python.org/sf/703779 Assertion failed, python aborts (2003-03-17) http://python.org/sf/705231 Error when using PyZipFile to create archive (2003-03-17) http://python.org/sf/705295 Minor nested scopes doc issues (2003-04-06) http://python.org/sf/716168 Uthread problem - Pipe left open (2003-04-08) http://python.org/sf/717614 Mac OS X painless compilation (2003-04-11) http://python.org/sf/719549 runtime_library_dirs broken under OS X (2003-04-17) http://python.org/sf/723495 email/quopriMIME.py exception on int (lstrip) (2003-04-20) http://python.org/sf/724621 Possible OSX module location bug (2003-04-21) http://python.org/sf/725026 comparing versions - one a float (2003-04-28) http://python.org/sf/729317 Lambda functions in list comprehensions (2003-05-08) http://python.org/sf/734869 FILEMODE not honoured (2003-05-09) http://python.org/sf/735274 Command line timeit.py sets sys.path badly (2003-05-09) http://python.org/sf/735293 csv.Sniffer docs need updating (2003-05-15) http://python.org/sf/738471 On Windows, os.listdir() throws incorrect exception (2003-05-15) http://python.org/sf/738617 array.insert and negative indices (2003-05-17) http://python.org/sf/739313 Closed Patches -------------- Optional output streams for dis (2003-02-08) http://python.org/sf/683074 Add copyrange method to array. (2003-04-14) http://python.org/sf/721061

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urllib2 proxy support broken?
by Gustavo Niemeyer 24 May '03

24 May '03

I've just tried to use the proxy support in urllib2, and was surprised by the fact that it seems to be broken, at least in 2.2 and 2.3. Can somebody please confirm that it's really broken, so that I can prepare a patch? If I understood it correctly, that's how the proxy support is supposed to work: import urllib2 proxy_support = urllib2.ProxyHandler({"http":"http://ahad-haam:3128"}) opener = urllib2.build_opener(proxy_support) urllib2.install_opener(opener) f = urllib2.urlopen('http://www.python.org/') OTOH, code in build_opener() does this: # Remove default handler if a custom handler was provided for klass in default_classes: for check in handlers: if inspect.isclass(check): if issubclass(check, klass): skip.append(klass) elif isinstance(check, klass): skip.append(klass) for klass in skip: default_classes.remove(klass) # Instantiate default handler and append them for klass in default_classes: opener.add_handler(klass()) # Instantiate custom handler and append them for h in handlers: if inspect.isclass(h): h = h() opener.add_handler(h) Notice that default handlers are added *before* custom handlers, so HTTPHandler.http_open() ends up being called before ProxyHandler.http_open(), and the later doesn't work. To make the first snippet work, one would have to use the unobvious version: import urllib2 proxy_support = urllib2.ProxyHandler({"http":"http://ahad-haam:3128"}) http_support = urllib2.HTTPHandler() opener = urllib2.build_opener(proxy_support, http_support) urllib2.install_opener(opener) f = urllib2.urlopen('http://www.python.org/') Is this really broken, or perhaps it's a known "feature" which should be left as is to avoid side effects (and I should patch the documentation instead)? -- Gustavo Niemeyer [ 2AAC 7928 0FBF 0299 5EB5 60E2 2253 B29A 6664 3A0C ]

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24 May '03

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Need advice, maybe support
by Christian Tismer 23 May '03

23 May '03

Hi Guido, all, In the last months, I made very much progress with Stackless 3.0 . Finally, I was able to make much more of Python stackless (which means, does not use recursive interpreter calls) than I could achive with 1.0 . There is one drawback with this, and I need advice: Compared to older Python versions, Py 2.2.2 and up uses more indirection through C function pointers than ever. This blocked my implementation of stackless versions, in the first place. Then the idea hit me like a blizzard: Most problems simply vanish if I add another slot to the PyMethodDef structure, which is NULL by default: ml_meth_nr is a function pointer with the same semantics as ml_meth, but it tries to perform its action without doing a recursive call. It tries instead to push a frame and to return Py_UnwindToken. Doing this change made Stackless crystal clear and simple: A C extension not aware of Stackless does what it does all the time: call ml_meth. Stackless aware C code (like my modified ceval.c code) calls the ml_meth_nr slots, instead, which either defaults to the ml_meth code, or has a special version which avoids recursive interpreter calls. I also added a tp_call_nr slot to typeobject, for similar reasons. While this is just great for me, yielding complete source code compatability, it is a slight drawback, since almost all extension modules make use of the PyMethodDef structure. Therefore, binary compatability of Stackless has degraded, dramatically. I'm now in some kind of dilemma: On the one side, I'm happy with this solution (while I have to admit that it is not too inexpensive, but well, all the new descriptor objects are also not cheap, but just great), on the other hand, simply replacing python22.dll is no longer sufficient. You need to re-compile everything, which might be a hard thing on Windows (win32 extensions, wxPython). Sure, I would stand this, if there is no alternative, I would have to supply a complete replacement package of everything. Do you (does anybody) have an alternative suggestion how to efficiently maintain a "normal" and a "non-recursive" version of a method without changing the PyMethodDef struc? Alternatively, would it be reasonable to ask the Python core developers, if they would accept to augment PyMethodDef and PyTypeObject with an extra field (default NULL, no maintenance), just for me and Stackless? Many thanks for any reply - sincerely -- chris -- Christian Tismer :^) <mailto:tismer@tismer.com> Mission Impossible 5oftware : Have a break! Take a ride on Python's Johannes-Niemeyer-Weg 9a : *Starship* http://starship.python.net/ 14109 Berlin : PGP key -> http://wwwkeys.pgp.net/ work +49 30 89 09 53 34 home +49 30 802 86 56 pager +49 173 24 18 776 PGP 0x57F3BF04 9064 F4E1 D754 C2FF 1619 305B C09C 5A3B 57F3 BF04 whom do you want to sponsor today? http://www.stackless.com/

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Introduction
by Jeffery Roberts 23 May '03

23 May '03

Hello all ! I'm new to the list and thought I would quickly introduce myself. My name is Jeff and I am a university student [4th year] living in Toronto. I would love to be able to help with Python-dev in some way. I'm especially interested in issues directly related to the interpreter itself. I have gained some compiler development experience while at the university and would love to continue working in this area. If anyone has any thoughts or suggestions on how best I could proceed in this direction, I would love to hear them. Thanks ! Jeff Roberts

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Descriptor API
by Gonçalo Rodrigues 23 May '03

23 May '03

I was doing some tricks with metaclasses and descriptors in Python 2.2 and stumbled on the following: >>> class test(object): ... a = property(lambda: 1) ... >>> print test.a <property object at 0x01504D20> >>> print test.a.__set__ <method-wrapper object at 0x01517220> >>> print test.a.fset None What this means in practice, is that if I want to test if a descriptor is read-only I have to have two tests: One for custom descriptors, checking that getting __set__ does not barf and another for property, checking that fset returns None. So, why doesn't getting __set__ raise AttributeError in the above case? Is this a bug? If it's not, it sure is a (minor) feature request from my part :-) With my best regards, G. Rodrigues

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Of what use is commands.getstatus()
by Skip Montanaro 23 May '03

23 May '03

I was reading the docs for the commands module and noticed getstatus() seems to be completely unrelated to getstatusoutput() and getoutput(). I thought, "I'll correct the docs. They must be wrong." Then I looked at commands.py and saw the docs are correct. It's the function definition which is weird. Of what use is it to return 'ls -ld file'? Based on its name I would have guessed its function was def getoutput(cmd): """Return status of executing cmd in a shell.""" return getstatusoutput(cmd)[0] This particular function dates from 1990, so it clearly can't just be deleted, but it seems completely superfluous to me, especially given the existence of os.stat, os.listdir, etc. Should it be deprecated or modified to do (what I think is) the obvious thing? Skip

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