Mailman 3 September 2002 - Python-Dev

Unicode regexp problem
by Florent Guillaume 17 Sep '02

17 Sep '02

I've got the following problem, in python 2.1, 2.2 and 2.3a0 (Debian): >>> import re >>> re.compile(r'\w+', re.U).sub('X', u'hello caf\xe9') u'X X' >>> re.compile(r'\w{1}', re.U).sub('X', u'hello caf\xe9') u'XXXXX XXXX' >>> re.compile(r'\w', re.U).sub('X', u'hello caf\xe9') u'XXXXX XXX\xe9' The first two results are ok, but the third is not. Thanks, Florent PS: I'd appreciate a Cc on answers. -- Florent Guillaume, Nuxeo (Paris, France) +33 1 40 33 79 87 http://nuxeo.com mailto:fg@nuxeo.com

2 1

Python-dev summary for 2002-09-01 to 2002-09-15
by Brett Cannon 17 Sep '02

17 Sep '02

Since posting here first before posting to c.l.py worked out rather nicely last time, I am going to do it again. Basically everyone gets 24 hours to reply an corrections for this summary. Now please note that the links that point to where I am going to keep the summaries are not up yet (but they will be by the time I post to c.l.py). Enjoy. ============================== This is a summary of traffic on the `python-dev mailing list`_ between September 01, 2002 and September 15, 2002 (exclusive). It is intended to inform the wider Python community of ongoing developments on the list; everything from new features of the language to how to handle discovered bugs that might affect the general Python programmer. To comment on anything mentioned here, just post to python-list(a)python.org or comp.lang.python in the usual way. Give your posting a meaningful subject line, and if it's about a PEP, include the PEP number (e.g. Subject: PEP 201 - Lockstep iteration) All python-dev members are interested in seeing ideas discussed by the community, so don't hesitate to take a stance on a PEP (or anything else for that matter) if you have an opinion. :: This is the second summary written by Brett Cannon (hopefully my sophomoric performance will be better then most sophomore music albums). Summaries by me (2002-09-15 to ... when I burn out) are archived at http://www.ocf.berkeley.edu/~bac/python-dev/summaries/index.php . You can find summaries by Michael Hudson (2002-02-01 to 2001-07-05) at http://starship.python.net/crew/mwh/summaries/index.html . Summaries by A.M. Kuchling (2000-12-01 to 2001-01-31) are at http://www.amk.ca/python/dev/ . Please note that this summary is written using reST_ which can be found at http://docutils.sourceforge.net/rst.html . If there is some markup in the summary that seems odd, chances are it is because of reST. Also, I am considering keeping a list of names that people are often referred to in emails. This would serve a dual purpose: allows people who read emails from the list to have a reference to be able to figure out who is who and makes the summaries easier for me because I reference these people in my head by their nicknames. =) Any comments on that idea are appreciated. .. _python-dev mailing list: http://mail.python.org/mailman/listinfo/python-dev ============================ `To commit or not commit`_ ============================ Walter Dorwald asked if there were "any objections against committing the patch" for implementing `PEP 293`_ (Codec Error Handling Callbacks). Guido asked what Martin V. Lowis and M.A. Lemburg had to say about it. MAL responded that he was +1 on the patch. Martin was "concerned about the massive amounts of C code, most of which could be expressed way more compact in Python code", but "Walter convinced [MvL] that this does have a real performance impact for real data" so he would live with it. In the end he gave it his vote. Walter said he would check it in (and he has). The PEP has now been moved to the finished PEP list. .. _To commit or not commit: http://mail.python.org/pipermail/python-dev/2002-September/028502.html .. _PEP 293: http://www.python.org/peps/pep-0293.html ======================================= `Proposed Mixins for Wide Interfaces`_ ======================================= Raymond Hettinger suggested adding mixin classes that automatically implement magic methods when certain basic magic methods were already implemented (e.g., "given an __eq__ method in a subclass, adds a __ne__ method"). David Abrahams said that he thought "these are a great idea, *in the context of* an understanding of what we want interfaces to be, say, and do." Guido brought up some points about the initial suggestions Raymond made. He then said that he thought that there wasn't "enough here to warrant putting this into the standard library"; the issue will be revisited when a standard type or interface hierarchy is added to Python (not in 2.3). .. _Proposed Mixins for Wide Interfaces: http://mail.python.org/pipermail/python-dev/2002-September/028543.html =================================== `mysterious hangs in socket code`_ =================================== Jeremy Hylton wrote some threaded code to fetch some web pages that hung when performing a slow DNS operation. Apparently, in Python 2.1 "it produces a steady stream of output -- urls and the time it took to load them". In Python 2.2 and 2.3, though, "it produces little bursts of output, then pauses for a long time, then repeats". Jeremy guessed that it *might* have something to do with Linux's getaddrinfo() being thread-safe by allowing only a single lookup at a time. Aahz said that "gethostbyname() IIRC has frequently been non-reentrant". Skip ran the code in question under strace and said that "it seems mostly to be sitting in select() calls and rt_sigsuspend() which [Skip] guess[es] is a wrapper around sigsuspend()." .. _mysterious hangs in socket code: http://mail.python.org/pipermail/python-dev/2002-September/028555.html ======================================== `Two random and nearly unrelated ideas`_ ======================================== Skip Montanaro had two ideas; one was to make the info in `Misc/NEWS`_ (which is a summary of what has been changed in Python for each release) and "to get rid of the ticker altogether in systems with proper signal support" (see the `2002-08-16 - 2002-09-01 summary`_ for an explanation of what the ticker is). That would get rid of the polling of the ticker and thus reduce the overhead on threads. For the first idea, Guido asked Skip to try seeing what it would look like with reST_ markup and what the resulting page would look like. In response to the second idea, Oren Tirosh said it couldn't be done until "all Python I/O calls are converted to be EINTR-safe" (EINTER-safe means to be able to handle the EINTER signal which what is raised "When an I/O operation is interrupted by an unmasked signal"). That "requires a lot of work in some of the hairiest places in the Python codebase." Fredrik Lundh said that this "sounds like a good topic for a "here's what I learned when trying to fix this problem" PEP. This is most likely in reference to Skip writing the patch to make the ticker global instead of a per-thread issue. Guido said, in terms of signals, to "just say no"; "it is impossible to write correct code in the presense of signals". Guido, in a later email, gave this whole idea a vote of -1,000,000; so it ain't ever going to happen. Some discussion on signals ensued, but Guido never budged from his position. Oren pointed out that if some C code used signals and people didn't handle it in their Python code by checking if IOError was caused by EINTER (as shown below by Oren's code):: while 1: try: <code> except IOError, exc: if exc.errno == errno.EINTR: continue else: raise , it would not restart properly even though there was no reason for it to have stopped. Oren said that Python could add the loop in the C code of the core where EINTR might be raised ("Only low-level functions like os.read_ and os.write_ that map directly to stdio functions should ever return EINTR"). The proposed idea was to wrap functions that might raise this that can be re-entered safely. .. _Two random and nearly unrelated ideas: http://mail.python.org/pipermail/python-dev/2002-September/028555.html .. _Misc/NEWS: http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/python/python/dist/src/Misc/… .. _2002-08-16 - 2002-09-01 summary: http://www.ocf.berkeley.edu/~bac/python-dev/summaries/2002-08-16--2002-09-0… .. _reST: http://docutils.sourceforge.net/rst.html .. _os.read: .. _os.write: http://www.python.org/dev/doc/devel/lib/os-fd-ops.html ================================================ `Should KeyError use repr() on its arguments?`_ ================================================ Originally, when an exception was raised and you passed in an optional object to act as a description of why the exception was raised (such as ``KeyError("there is no spoon")`` where ``there is now spoon`` is the optional argument bound to ``<exception>.args``), it just returned what args was bound to when you called; ``str(<exception>) == <exception>.args``. Now it calls repr() on what args is bound to; ``str(<exception>) == str(<exception>.args)``. Much better. =) .. _Should KeyError use repr() on its arguments?: http://mail.python.org/pipermail/python-dev/2002-September/028545.html ========================================== `New 'spambayes' project on SourceForge`_ ========================================== Thanks to great work done by Tim Peters and several other contributors, Barry Warsaw started an SF project to host the spambayes code. It can be found at http://sf.net/projects/spambayes . There are two mailing lists: http://mail.python.org/mailman-21/listinfo/spambayes and http://mail.python.org/mailman-21/listinfo/spambaye-checkins (yes, that is Mailman 2.1, and yes, you will "help be a guinea pig for Mailman 2.1"). .. _New 'spambayes' project on SourceForge: http://mail.python.org/pipermail/python-dev/2002-September/028626.html ========================= `Subsecond time stamps`_ ========================= Martin V. Lowis wanted to introduce subsecond timestamps on platforms that supported it. He suggested adding another field to stat, create a new type, or make st_mtime a floating point. The first one option is easy, the second has the usual problems of defining a new type, and the third does not guarantee enough accuracy. Paul Svensson and Guido said that the last option (turning st_mtime into a float) was the most Pythonic. MvL agreed, but worried about breaking code that expected an int. Guido then suggested that maybe the new field is the way to go; define something like st_mtimef that will contain the float if available or contain an int otherwise. Tim Peters also weighed in with his `IEEE 754`_ voodoo about how a float can hold enough info to be accurate up to 100 nanoseconds if you only span a single year; issues start to come up once you try to go past a year's worth of seconds. But then MvL discovered that st_mtime was already a float on the Mac; had that caused issues? Jack Jansen of course chimed in on this by saying that it caused him a headache about once a year in the form of a failing test (other issues caused by timestamps is the Classic Macs having the epoch at 1904 and not using UTC time). He said he would prefer to see the timestamp as a cookie that was passed into a function that spit out "something guaranteed to be of your liking". To address the other issues that Jack mentioned, Guido suggested that all timestamps be converted to UTC time with the epoch at 1970. MvL has `SF patch 606592`_ up on SF that has already been closed that makes all the relevant changes to have timestamps return floats. .. _Subsecond time stamps: http://mail.python.org/pipermail/python-dev/2002-September/028648.html .. _IEEE 754: http://grouper.ieee.org/groups/754/ .. _SF patch 606592: http://www.python.org/sf/606592 ================================= `64-bit process optimization 1`_ ================================= Bob Ledwith posted a simple patch for `Include/object.h`_ that changed the order of certain parts of the PyObject_HEAD macros, affecting PyObject and PyVarObject. This was for a 64-bit platform performance boost (40% for large data sets according to Bob). The reordering eliminated some padding in the struct and allows more Python objects to fit in the L2 cache, or at least that is what Bob thinks is going on. Guido pointed out that this would save 8 bytes per object; he thought all of this was "Interesting!". But alas, using this patch would break binary compatibility. Guido was not sure, though, whether it had been broken yet between Python 2.2 and 2.3 and thus he might be "being too conservative here" in terms of saying that it should be held back for now. A problem Guido pointed out for 64-bit systems, is that theoretically the reference count for an object could go negative with enough references as things stand now. Guido then suggested that perhaps refcnt (struct item that holds the reference count) should be a ``long``. And while dealing with that, Guido suggested that anything that stores a length should store that number in a ``long``. Chime in Tim Peters. He pointed out that it was agreed upon years ago to move refcnt to ``long`` but no one had bothered to do it. Heck, even Guido thought for a long time that it was a long when it wasn't; it required Tim to "beat that out of [Guido] <wink>" to stop him from saying that it was a ``long``. He then pointed out that Win64 was still only 4 bytes for a ``long``; what was really desired was for it to be ``Py_intptr_t`` which is the Python way for spelling the C99 type that we wanted. Apparently C99 has a way to specify that things be a specific byte length (now if everyone just had a C99 compiler we wouldn't need these macros; oh, to dream...). Tim also pointed out that what we wanted for the type that held a length argument to be size_t since that is what strlen() and malloc() are restricted by. He said that he writes all of his "string-slinging code as using size_t vars now". Tim pointed out that the issue then became "Whether it's worth the pain to change this stuff" which "depends on whether we think 64-bit boxes are just another passing fad like the Internet <wink>". =) Martin V. Lowis agreed with the changing of refcnt to a long but had reservations about using size_t for the length field (ob_size). He pointed out that some objects put negative values into that field. Frederik suggested that the proposed changes be default on 64-bit systems since the chances that they are willing to recompile is higher then people on 32-bit systems. He also suggested making it a compiler option. Guido thought it was a good idea. But then Mats Wichmann discovered that the switch to long killed the performance boost. So Guido re-iterated that he thinks it should be a compiler option only on 64-bit systems; have "compat", "optimal", and "right" compiler options. .. _64-bit process optimization 1: http://mail.python.org/pipermail/python-dev/2002-September/028677.html .. _Include/object.h: http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/python/python/dist/src/Inclu… ========================================== `Weeding out obsolete modules and Demos`_ ========================================== Jack Jansen noticed that there demos for some of the SGI-specific modules that use severely outdated systems and hardware (stuff discontinued 8 to 12 years ago). Guido gave the go-ahead to yank them from CVS. So the demos are now history. .. _Weeding out obsolete modules and Demos: http://mail.python.org/pipermail/python-dev/2002-September/028718.html ============== `utf8 issue`_ ============== (This thread actually started in August) There was a bug in Python 2.2 that raised a UnicodeError when trying to decode a lone surrogate (explanation of surrogates to follow this summary). This caused issues in importing .pyc files that contained a lone surrogate because marshal_ (which is what is used to create .pyc files) encodes Unicode_ literals in UTF-8. This has all been fixed in Python 2.3, but Guido was wondering how to backport this for Python 2.2.2. The option of bumping the magic number for .pyc files was raised and instantly thrown out by Guido; "Bumping MAGIC is a no-no between dot releases". So M.A. Lemburg suggested to either fix the Unicode encoder or change the Unicode decoder to handle the malformed Unicode. MAL wasn't sure, though, if some security issue would be raised by the latter option. Guido said go for the latter and didn't see any possible security issue since "If someone you don't trust can write your .pyc files, they can cause your interpreter to crash by inserting bogus bytecode". Explanation of lone surrogates: In Unicode, a surrogate pair is when you create the representation of a character by using two values. So, for instance, UTF-32 can cover the entire Unicode space (since Unicode is 20 bits, although MvL says it is really more like 21 bits), but UTF-16 can't. To solve the issue for an encoding that cannot cover all possible characters in a single value a character can be represented as a pair of UTF-16 values. The high surrogate cover the high 10 bits while the low surrogate cover the lower 10 bits. High and low surrogates can never be the same since they are defined by a range of possible values and those ranges do not overlap. So with the proper high and low surrogate paired together you can make any possible Unicode character. The problem in Python 2.2.1 is that when there is only a lone surrogate (instead of there being a pair of surrogates), the encoder for UTF-8 messes up and leaves off a UTF-8 value. The following line is an example: >>> u'\ud800'.encode('utf-8') '\xa0\x80' #In Python 2.2.1 '\xed\xa0\x80' #In Python 2.3a0 Notice how in Python 2.3a0 the extra value is inserted so as to make the representation a complete Unicode character instead of only encoding the half of the surrogate pair that the encode was given. You can read http://216.239.37.100/search?q=cache:Dk12BZNt6skC:uk.geocities.com/BabelSto… for more info. Thanks goes to Frederik for the link and Guido for some clarification. .. _utf8 issue: http://mail.python.org/pipermail/python-dev/2002-August/028254.html .. _marshal: http://www.python.org/dev/doc/devel/lib/module-marshal.html .. _Unicode: http://www.unicode.org/ ===================================== `Documentation inconsistency in re`_ ===================================== Christopher Craig noticed that the docs for the re_ module for the \b metacharacter was incorrect; it says that "the end of a word is indicated by whitespace or a non-alphanumeric character". That would indicate that an underscore would be the end of a word, which turns out to be false. Frederik said that "\b is defined in terms of \w and \W" and thus allows underscore to be a alphanumeric character. The documentaiton has been fixed. .. _Documentation inconsistency in re: http://mail.python.org/pipermail/python-dev/2002-September/028644.html .. _re: http://www.python.org/dev/doc/devel/lib/module-re.html ======================= `Codecs lookup order`_ ======================= Francois Pinard discovered that for the codecs_ module "one should be careful about **not** [altered emphasis] naming a module after the encoding name, when closely following the documentation in the Library Reference manual". This is because the codecs module first searches the registry of codecs, then searches for a module with the same name and use that module. The issue comes up when the module does not contain a function named getregentry(); "\`encodings.lookup()\` expects a \`getregentry\` function in that module, does not find it, and raises a CodecRegistryError, not leaving a chance to subsequent codec search functions to be used". M.A. Lemburg said that this has been fixed in Python 2.3 and will be in 2.2.2 by having encodings.lookup() return None if getregentry() is not found and thus allowing the search to continue. .. _Codecs lookup order: http://mail.python.org/pipermail/python-dev/2002-September/028676.html .. _codecs: http://www.python.org/dev/doc/devel/lib/module-codecs.html ================================= `raw headers in rfc822.Message`_ ================================= John Spurling provided a two-line hack to keep the raw headers in an rfc822.Message_ . Barry responded that email.Message.Message_ keeps the raw headers around. But the reason I am summarizing this is what this thread quickly changed to is how to properly generate a patch. Patches should be generated using UNIX diff, either the -c or -u option with preference for -c (using cvs diff -c is even better; puts the version of the file you are diffing with in the output); Mac folk can send MPW diffs, but UNIX diff is the definitely preference. Always put the order of the files `diff -c OLD_FILE NEW_FILE` . And always post the patches_ to SourceForge_! Getting random patches, no matter how small, on the list is annoying (at least to me) because the point of the list is to discuss the design and implementation of Python, not to patch Python. SF is used so that Python-dev does not need to be bothered with mundame problems like applying patches (and to annoy Aahz with SF's UI sucking in Lynx_ =). So please, for my sake and everyone else on Python-dev, use SF! For a funny email from Raymond Hettinger about developing for Python read http://mail.python.org/pipermail/python-dev/2002-September/028725.html . .. _raw headers in rfc822.Message: http://mail.python.org/pipermail/python-dev/2002-September/028682.html .. _rfc822.Message: http://www.python.org/dev/doc/devel/lib/message-objects.html .. _email.Message.Message: http://www.python.org/dev/doc/devel/lib/module-email.Message.html .. _patches: http://sourceforge.net/patch/?group_id=5470 .. _SourceForge: http://www.sourceforge.net/ .. _Lynx: http://lynx.browser.org/ =================== `type categories`_ =================== Yes, the `same thread`_ from the `last summary`_ is back. This thread has become the bane of my summarizing existence. =) Aahz asked "why wouldn't we simply use attributes to hold" interfaces that a class implemented (think of __slots__). David Abrahams then brought up the idea of just adding interfaces to the __class__ attribute. Guido then chimed in on the attributes idea. He pointed out that this is how Zope does it, using the __inherits__ attribute. The limitation is that "it isn't automatically merged properly on multiple inheritance, and adding one new interface to it means you have to copy or reference the base class __inherits__ attribute". And as for David's idea of just adding to __class__, that doesn't work because there is no way to limit the interface; you need "Something like private inheritance" for when an interface is broken by some inherited class. David subsequently added the issue of being able to disinherit when an interface is not valid but is inherited by default as another problem for using inheritence for interfaces. David then brought up the issue of having Python being so dynamic that you could inject an interface if you used __class__ like he suggested through black magic code. If the injected interface didn't work because of the inheritence chain, then you have a problem. Barry Warsaw brought in his objections. He tried playing Devil's Advocate by saying that Guido had said that inheritance would not be the only way to handle interfaces, but that it would be the predominent way. But this duality would complicate any conformsto()-like function since it would have to handle two different ways for a class to get an interface. Barry then brought up the objection that he didn't like the idea of using straight inheritence because he wanted a syntactic way to separate out interfaces. As a side note, Guido pointed out that __slots__ is provisional; nicer syntax will eventually surface when Guido gets over his "fear of adding new keywords". .. _type categories: http://mail.python.org/pipermail/python-dev/2002-September/028738.html .. _same thread: http://www.ocf.berkeley.edu/~bac/python-dev/summaries/2002-08-16--2002-09-0… .. _last summary: http://www.ocf.berkeley.edu/~bac/python-dev/summaries/2002-08-16--2002-09-0… ======================================= `flextype.c -- extended type system`_ ======================================= Christian Tismer has come up with a replacement for the etype which is "a hidden structure that extends types when they are allocated on the heap" (you can find it in `Objects/typeobject.c`_ in the CVS_). There is a limitation with the etype where it could not be extended by metatypes. Well, Chris worked his magic and came up with a new flextype that allows overriding of methods. So with Christian's code you would be able to override methods in a type without having to hack something together to handle the overriding correctly; it would be handled automatically. Through some clarification from Christian and Guido, it was pointed out to me (as of this moment I am the only one to make any noise on this thread, and it was for this summary) that this simplifies an esoteric issue; note the use of the words "metatype" above. This is type/metatype black magic hacking. Spiffy, but something most of us "normal" folk will not have to worry about. .. _flextype.c -- extended type system: http://mail.python.org/pipermail/python-dev/2002-September/028736.html .. _Objects/typeobject.c: http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/python/python/dist/src/Objec… .. _CVS: http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/python/#dirlist

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SystemError: unknown opcode
by Just van Rossum 16 Sep '02

16 Sep '02

After building Python from CVS (it's been a while) I get this error: Python 2.3a0 (#43, Sep 16 2002, 22:47:33) [GCC 2.95.2 19991024 (release)] on darwin Type "help", "copyright", "credits" or "license" for more information. >>> import fontTools XXX lineno: 1, opcode: 127 Traceback (most recent call last): File "<stdin>", line 1, in ? File "/Users/just/code/fonttools/Lib/fontTools/__init__.py", line 1, in ? version = "2.0b2" SystemError: unknown opcode >>> Does this mean the .pyc magic number needs to be changed? Or is it simply the risk of using CVS Python? ;-) Just

2 1

looking for Python programmers
by mcolli＠SyscomCipher.com.ar 16 Sep '02

16 Sep '02

Hi, I would like to know how can I do to get information about Python programmers that could be interested to work in a Zope/Python project in Buenos Aires, Argentina. Is this the right address to contact? Many thanks and regards Mariela

3 2

Please help solving the problem
by Praveen Patil 16 Sep '02

16 Sep '02

Hi , Please help me in solving the problem below. step 1: I have written three dlls : a.dll , b.dll , c.dll. a.dll contains funct_A(); b.dll contains funct_B(); c.dll contains funct_C(); step 2: I am copying a.dll to directory C:\Program Files\Python\DLLs and renaming as a.pyd similarly I am copying b.dll to directory C:\Program Files\Python\DLLs. I am not renaming as b.pyd I am copying c.dll to directory C:\Program Files\Python\DLLs and renaming as c.pyd So my C:\Program Files\Python\DLLs directory contain a.pyd , b.dll , c.pyd step 3: a)Python function func_pyA() calls funct_A() b)funct_A() call funct_B() c)funct_B() call funct_C() d)funct_C() call python fuction func_pyC() step 4: I am importing a.pyd and c.pyd in python program. import a import c step 5: I am having problem in importing 'a' because 'a' need to load b.dll and c.dll. But I copied c.dll as c.pyd. Please suggest me some solution. here is my code : 1)a.c (a.dll) ---------- void func_A(); 2)b.c (b.dll) ----------- void func_B(); 3)c.c( c.dll) ----------- void func_C(); 4) example.py --------- import a import c G_Logfile = None def TestFunction(): G_Logfile = open('Pytestfile.txt', 'w') G_Logfile.write("%s \n"%'I am writing python created text file') G_Logfile.close G_Logfile = None if __name__ == "__main__": a.func_A(); ..... ..... Please help me in solving the problem. Cheers, Praveen. [ The information contained in this e-mail is confidential and is intended for the named recipient only. If you are not the named recipient, please notify us by telephone on +44 (0)1249 442 430 immediately, destroy the message and delete it from your computer. Silver Software has taken every reasonable precaution to ensure that any attachment to this e-mail has been checked for viruses. However, we cannot accept liability for any damage sustained as a result of any such software viruses and advise you to carry out your own virus check before opening any attachment. Furthermore, we do not accept responsibility for any change made to this message after it was sent by the sender.]

2 1

Re: [Python-checkins] python/nondist/sandbox/spambayes GBayes.py,1.7,1.8
by Skip Montanaro 16 Sep '02

16 Sep '02

tim> Straight character n-grams are very appealing because they're the tim> simplest and most language-neutral; I didn't have any luck with tim> them over the weekend, but the size of my training data was tim> trivial. Anybody up for pooling corpi (corpora?)? Skip

21 78

Weekly Python Bug/Patch Summary
by Skip Montanaro 15 Sep '02

15 Sep '02

Bug/Patch Summary ----------------- 281 open / 2853 total bugs (+1) 108 open / 1690 total patches (-7) New Bugs -------- PyString_AsString underdocumented (2002-09-08) http://python.org/sf/606463 defining away __attribute__ is not good (2002-09-08) http://python.org/sf/606493 xml.sax second time file loading problem (2002-09-09) http://python.org/sf/606692 header file problems (2002-09-10) http://python.org/sf/607253 IDE should have "open recent" menu (2002-09-11) http://python.org/sf/607810 IDE look and feel (2002-09-11) http://python.org/sf/607814 IDE Preferences (2002-09-11) http://python.org/sf/607816 IDE output window (2002-09-11) http://python.org/sf/607821 Implied __init__.py not copied (2002-09-11) http://python.org/sf/608033 IDE - Breakpoints don't stick to lines (2002-09-11) http://python.org/sf/608085 gethostbyname("LOCALHOST") fails (2002-09-12) http://python.org/sf/608584 Problems in IDLE Browsers & Viewers (2002-09-12) http://python.org/sf/608595 Unix popen does not return exit status (2002-09-12) http://python.org/sf/608635 test_b1.py, disabling of list test (2002-09-13) http://python.org/sf/609041 cPickle.BadPickleGet is a string (2002-09-13) http://python.org/sf/609164 New Patches ----------- Enhanced file constructor (2002-09-11) http://python.org/sf/608182 configure on Irix (sockets, posix) (2002-09-13) http://python.org/sf/608999 Closed Bugs ----------- 64-bit zip problems (2001-08-19) http://python.org/sf/453208 mmap bus error on linux (2001-09-19) http://python.org/sf/462783 shutil.copy(path, path) deletes contents (2001-12-07) http://python.org/sf/490168 IDLE doesn't save 8bit files (2002-04-18) http://python.org/sf/545600 del __builtins__ breaks out of rexec (2002-07-04) http://python.org/sf/577530 Docs unclear about cleanup. (2002-07-05) http://python.org/sf/577793 Get rid of FutureWarnings in Carbon (2002-08-15) http://python.org/sf/595763 import cycle in distutils (2002-08-19) http://python.org/sf/597604 Python not handling cText (2002-08-22) http://python.org/sf/598981 weird header wrapping in email.Generator (2002-08-28) http://python.org/sf/601392 spurious SyntaxWarning (2002-09-03) http://python.org/sf/604036 pre bug (2002-09-04) http://python.org/sf/604803 Closed Patches -------------- patch for bug 462783 mmap bus error (2002-03-28) http://python.org/sf/536578 OpenBSD updates for build process (2002-05-10) http://python.org/sf/554718 THREAD_STACK_SIZE for 2.1 (2002-05-11) http://python.org/sf/554841 Remove import string in Tools/ directory (2002-06-21) http://python.org/sf/572113 types.BoolType (2002-08-02) http://python.org/sf/590119 improper use of strncpy in getpath (2002-08-29) http://python.org/sf/602108 For Bug [ 490168 ] shutil.copy(path, pat (2002-09-04) http://python.org/sf/604600 Tweaks to calls to AH/Help (2002-09-07) http://python.org/sf/606067 install_IDLE target in Mac/OSX/Makefile (2002-09-07) http://python.org/sf/606134

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type categories
by Andrew Koenig 13 Sep '02

13 Sep '02

While I was driving to work today, I had a thought about the iterator/iterable discussion of a few weeks ago. My impression is that that discussion was inconclusive, but a few general principles emerged from it: 1) Some types are iterators -- that is, they support calls to next() and raise StopIteration when they have no more information to give. 2) Some types are iterables -- that is, they support calls to __iter__() that yield an iterator as the result. 3) Every iterator is also an iterable, because iterators are required to implement __iter__() as well as next(). 4) The way to determine whether an object is an iterator is to call its next() method and see what happens. 5) The way to determine whether an object is an iterable is to call its __iter__() method and see what happens. I'm uneasy about (4) because if an object is an iterator, calling its next() method is destructive. The implication is that you had better not use this method to test if an object is an iterator until you are ready to take irrevocable action based on that test. On the other hand, calling __iter__() is safe, which means that you can test nondestructively whether an object is an iterable, which includes all iterators. Here is what I realized this morning. It may be obvious to you, but it wasn't to me (until after I realized it, of course): ``iterator'' and ``iterable'' are just two of many type categories that exist in Python. Some other categories: callable sequence generator class instance type number integer floating-point number complex number mutable tuple mapping method built-in As far as I know, there is no uniform method of determining into which category or categories a particular object falls. Of course, there are non-uniform ways of doing so, but in general, those ways are, um, nonuniform. Therefore, if you want to check whether an object is in one of these categories, you haven't necessarily learned much about how to check if it is in a different one of these categories. So what I wonder is this: Has there been much thought about making these type categories more explicitly part of the type system?

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Feedback request on popen2.py Unix fix
by Barry Scott 12 Sep '02

12 Sep '02

I have logged a bug against python 2.2.1 with a fix. [ 608635 ] Unix popen does not return exit status Attached to the bug report is a proposed fix for popen2.py. I'd appreciate feedback on the validity of the changes. Barry

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Re: 64-bit process optimization 1
by Mats Wichmann 12 Sep '02

12 Sep '02

>So perhaps the refcnt should have been a long in the first place. A >similar argument may hold for the length of e.g. strings and lists: >one could wish to have a list of more than 2 billion elements, or a >string containing more than 2 gigabytes (that much RAM is easily found >on the larger 64-bit servers, I believe). > >Opinions? If you change to longs it seems the reported performance increase goes away, which would seem to eliminate one of the motivations for accepting the pain of a binary incompatibility. Leaving just "getting it right". Mats

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