Python-Dev May 2007

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103 participants
86 discussions

best practices stdlib: purging xrange
by Anthony Baxter 09 May '07

09 May '07

I'd like to suggest that we remove all (or nearly all) uses of xrange from the stdlib. A quick scan shows that most of the usage of it is unnecessary. With it going away in 3.0, and it being informally deprecated anyway, it seems like a good thing to go away where possible. Any objections? Anthony -- Anthony Baxter <anthony(a)interlink.com.au> It's never too late to have a happy childhood.

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svn logs
by Kristján Valur Jónsson 09 May '07

09 May '07

Hello there. Does anyone know why getting the SVN logs for a project is so excruciatingly slow? Is this an inherent SVN problem or are the python.org servers simply overloaded? It takes something like 10 minutes for me to get the log messages window up for the root of a branch. Cheers, Kristján

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Re: [Python-Dev] Changing string constants to byte arrays ([Python-checkins] r55119 - in python/branches/py3k-struni/Lib: codecs.py test/test_codecs.py)
by M.-A. Lemburg 08 May '07

08 May '07

Hi Walter, if the bytes type does turn out to be a mutable type as suggested in PEP 358, then please make sure that no code (C code in particular), relies on the constantness of these byte objects. This is especially important when it comes to codecs, since the error callback logic would allow the callback to manipulate the byte object contents and length without the codec taking note of this change. I expect there to be other places in the interpreter which would break as well. Otherwise, you end up opening the door for segfaults and easy DOS attacks on Python3. Regards, -- Marc-Andre Lemburg eGenix.com Professional Python Services directly from the Source (#1, May 04 2007) >>> Python/Zope Consulting and Support ... http://www.egenix.com/ >>> mxODBC.Zope.Database.Adapter ... http://zope.egenix.com/ >>> mxODBC, mxDateTime, mxTextTools ... http://python.egenix.com/ ________________________________________________________________________ :::: Try mxODBC.Zope.DA for Windows,Linux,Solaris,MacOSX for free ! :::: eGenix.com Software, Skills and Services GmbH Pastor-Loeh-Str.48 D-40764 Langenfeld, Germany. CEO Dipl.-Math. Marc-Andre Lemburg Registered at Amtsgericht Duesseldorf: HRB 46611 On 2007-05-04 15:05, walter.doerwald wrote: > Author: walter.doerwald > Date: Fri May 4 15:05:09 2007 > New Revision: 55119 > > Modified: > python/branches/py3k-struni/Lib/codecs.py > python/branches/py3k-struni/Lib/test/test_codecs.py > Log: > Make the BOM constants in codecs.py bytes. > > Make the buffered input for decoders a bytes object. >

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PEP 30XZ: Simplified Parsing
by Jim Jewett 08 May '07

08 May '07

PEP: 30xz Title: Simplified Parsing Version: $Revision$ Last-Modified: $Date$ Author: Jim J. Jewett <JimJJewett(a)gmail.com> Status: Draft Type: Standards Track Content-Type: text/plain Created: 29-Apr-2007 Post-History: 29-Apr-2007 Abstract Python initially inherited its parsing from C. While this has been generally useful, there are some remnants which have been less useful for python, and should be eliminated. + Implicit String concatenation + Line continuation with "\" + 034 as an octal number (== decimal 28). Note that this is listed only for completeness; the decision to raise an Exception for leading zeros has already been made in the context of PEP XXX, about adding a binary literal. Rationale for Removing Implicit String Concatenation Implicit String concatentation can lead to confusing, or even silent, errors. [1] def f(arg1, arg2=None): pass f("abc" "def") # forgot the comma, no warning ... # silently becomes f("abcdef", None) or, using the scons build framework, sourceFiles = [ 'foo.c', 'bar.c', #...many lines omitted... 'q1000x.c'] It's a common mistake to leave off a comma, and then scons complains that it can't find 'foo.cbar.c'. This is pretty bewildering behavior even if you *are* a Python programmer, and not everyone here is. Note that in C, the implicit concatenation is more justified; there is no other way to join strings without (at least) a function call. In Python, strings are objects which support the __add__ operator; it is possible to write: "abc" + "def" Because these are literals, this addition can still be optimized away by the compiler. Guido indicated [2] that this change should be handled by PEP, because there were a few edge cases with other string operators, such as the %. The resolution is to treat them the same as today. ("abc %s def" + "ghi" % var) # fails like today. # raises TypeError because of # precedence. (% before +) ("abc" + "def %s ghi" % var) # works like today; precedence makes # the optimization more difficult to # recognize, but does not change the # semantics. ("abc %s def" + "ghi") % var # works like today, because of # precedence: () before % # CPython compiler can already # add the literals at compile-time. Rationale for Removing Explicit Line Continuation A terminal "\" indicates that the logical line is continued on the following physical line (after whitespace). Note that a non-terminal "\" does not have this meaning, even if the only additional characters are invisible whitespace. (Python depends heavily on *visible* whitespace at the beginning of a line; it does not otherwise depend on *invisible* terminal whitespace.) Adding whitespace after a "\" will typically cause a syntax error rather than a silent bug, but it still isn't desirable. The reason to keep "\" is that occasionally code looks better with a "\" than with a () pair. assert True, ( "This Paren is goofy") But realistically, that paren is no worse than a "\". The only advantage of "\" is that it is slightly more familiar to users of C-based languages. These same languages all also support line continuation with (), so reading code will not be a problem, and there will be one less rule to learn for people entirely new to programming. Rationale for Removing Implicit Octal Literals This decision should be covered by PEP ???, on numeric literals. It is mentioned here only for completeness. C treats integers beginning with "0" as octal, rather than decimal. Historically, Python has inherited this usage. This has caused quite a few annoying bugs for people who forgot the rule, and tried to line up their constants. a = 123 b = 024 # really only 20, because octal c = 245 In Python 3.0, the second line will instead raise a SyntaxError, because of the ambiguity. Instead, the line should be written as in one of the following ways: b = 24 # PEP 8 b = 24 # columns line up, for quick scanning b = 0t24 # really did want an Octal! References [1] Implicit String Concatenation, Jewett, Orendorff http://mail.python.org/pipermail/python-ideas/2007-April/000397.html [2] PEP 12, Sample reStructuredText PEP Template, Goodger, Warsaw http://www.python.org/peps/pep-0012 [3] http://www.opencontent.org/openpub/ Copyright This document has been placed in the public domain. Local Variables: mode: indented-text indent-tabs-mode: nil sentence-end-double-space: t fill-column: 70 coding: utf-8 End:

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Re: [Python-Dev] best practices stdlib: purging xrange
by Raymond Hettinger 07 May '07

07 May '07

> I'd like to suggest that we remove all (or nearly all) uses of > xrange from the stdlib. A quick scan shows that most of the usage > of it is unnecessary. With it going away in 3.0, and it being > informally deprecated anyway, it seems like a good thing to go away > where possible. > >Any objections? -1 It isn't "informally deprecated". The xrange() builtin has different performance characteristics and is still needed in Py2.x. Only in Py3k where range() becomes lazy like will the need disappear. Seriously, we should make every effort to make sure that Py3k doesn't unnecessarily backpropagate into an otherwise very stable codebase. An unwarranted s/xrange/range/g would be just one more reason to not upgrade to Py2.6. Raymond

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Commit Keys
by Calvin Spealman 07 May '07

07 May '07

I lost the key I originally gave for commiting my summaries. Who do I talk to about fixing that? -- Read my blog! I depend on your acceptance of my opinion! I am interesting! http://ironfroggy-code.blogspot.com/

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Re: [Python-Dev] Pre-pre PEP for 'super' keyword
by Delaney, Timothy (Tim) 06 May '07

06 May '07

Steve Holden wrote: > Tim Delaney wrote: >> BTW, one of my test cases involves multiple super calls in the same >> method - there is a *very* large performance improvement by >> instantiating it once. >> > And how does speed deteriorate for methods with no uses of super at > all (which will, I suspect, be in the majority)? Zero - in those cases, no super instance is instantiated. There is a small one-time cost when the class is constructed in the reference implementation (due to the need to parse the bytecode to determine if if 'super' is used) but in the final implementation that information will be gathered during compilation. Tim Delaney

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ImportError on no permission
by Georg Brandl 06 May '07

06 May '07

Today, I got a request regarding importing semantics. When a module file cannot be opened because of, say, lacking read permission, the rest of sys.path will be tried, and if nothing else is found, you get "no module named foo". The reporter claimed, and I understand that, that this is a pain to debug and it would be good to at least add a better message to the import error. Now, why don't we change the semantics as follows: if a file with matching name exists (in import.c::find_module), but opening fails, ImportError is raised immediately with the concrete error message, and without trying the rest of sys.path. That shouldn't cause any working and sane setup to break, or did I overlook something obvious here? Georg -- Thus spake the Lord: Thou shalt indent with four spaces. No more, no less. Four shall be the number of spaces thou shalt indent, and the number of thy indenting shall be four. Eight shalt thou not indent, nor either indent thou two, excepting that thou then proceed to four. Tabs are right out.

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Weekly Python Patch/Bug Summary
by Kurt B. Kaiser 05 May '07

05 May '07

Patch / Bug Summary ___________________ Patches : 360 open ( +4) / 3760 closed ( +4) / 4120 total ( +8) Bugs : 971 open ( +3) / 6683 closed (+10) / 7654 total (+13) RFE : 257 open ( +3) / 282 closed ( +0) / 539 total ( +3) New / Reopened Patches ______________________ test_1686475 of test_os & pagefile.sys (2007-04-28) http://python.org/sf/1709112 opened by A.B., Khalid run test_1565150(test_os.py) only on NTFS (2007-04-29) http://python.org/sf/1709599 opened by Hirokazu Yamamoto Update locale.__all__ (2007-04-30) CLOSED http://python.org/sf/1710352 opened by Humberto Diógenes PEP 318 -- add resolution and XRef (2007-05-01) CLOSED http://python.org/sf/1710853 opened by Jim Jewett PEP 3132: extended unpacking (2007-05-02) http://python.org/sf/1711529 opened by Georg Brandl syslog syscall support for SysLogLogger (2007-05-02) http://python.org/sf/1711603 opened by Luke-Jr fix for bug 1712742 (2007-05-04) http://python.org/sf/1713041 opened by Raghuram Devarakonda Fix warnings related to PyLong_FromVoidPtr (2007-05-05) http://python.org/sf/1713234 opened by Hirokazu Yamamoto Patches Closed ______________ Picky floats (2006-04-28) http://python.org/sf/1478364 closed by loewis Update locale.__all__ (2007-05-01) http://python.org/sf/1710352 closed by gbrandl Use MoveFileEx() to implement os.rename() on windows (2007-04-20) http://python.org/sf/1704547 closed by loewis PEP 318 -- add resolution and XRef (2007-05-01) http://python.org/sf/1710853 closed by gbrandl New / Reopened Bugs ___________________ test_1686475 fails when pagefile.sys does not exist (2007-04-28) CLOSED http://python.org/sf/1709282 opened by Calvin Spealman test_1686475 fails because pagefile.sys does not exist (2007-04-28) http://python.org/sf/1709284 opened by Calvin Spealman struct.calcsize() incorrect (2007-04-29) CLOSED http://python.org/sf/1709506 opened by JoelBondurant Tutorial - Section 8.3 - <type 'instance'> (2007-04-30) CLOSED http://python.org/sf/1710295 opened by elrond79 zipfile.ZipFile behavior inconsistent. (2007-05-01) http://python.org/sf/1710703 opened by Mark Flacy Ctrl+Shift block marking by words (2007-05-01) http://python.org/sf/1710718 opened by zorkin subprocess must escape redirection characters under win32 (2007-05-01) CLOSED http://python.org/sf/1710802 opened by Patrick Mézard CGIHttpServer leaves traces of previous requests in env (2007-05-03) http://python.org/sf/1711605 opened by Steve Cassidy CGIHttpServer fails if python exe has spaces (2007-05-03) http://python.org/sf/1711608 opened by Steve Cassidy SequenceMatcher bug with insert/delete block after "replace" (2007-05-03) http://python.org/sf/1711800 opened by Christian Hammond __getslice__ changes integer arguments (2007-05-03) http://python.org/sf/1712236 opened by Imri Goldberg Cannot use dict with unicode keys as keyword arguments (2007-05-04) http://python.org/sf/1712419 opened by Viktor Ferenczi urllib.quote throws exception on Unicode URL (2007-05-04) http://python.org/sf/1712522 opened by John Nagle pprint handles depth argument incorrectly (2007-05-04) http://python.org/sf/1712742 opened by Dmitrii Tisnek character set in Japanese on Ubuntu distribution (2007-05-04) http://python.org/sf/1713252 opened by Christopher Grell Error inside logging module's documentation (2007-05-05) CLOSED http://python.org/sf/1713535 opened by billiejoex Bugs Closed ___________ TimedRotatingFileHandler's doRollover opens file in "w" mode (2007-04-27) http://python.org/sf/1708538 closed by vsajip test_1686475 fails when pagefile.sys does not exist (2007-04-28) http://python.org/sf/1709282 deleted by ironfroggy struct.calcsize() incorrect (2007-04-29) http://python.org/sf/1709506 closed by loewis Tutorial - Section 8.3 - <type 'instance'> (2007-04-30) http://python.org/sf/1710295 closed by gbrandl Portability issue: os.rename behaves differently on win32 (2007-04-03) http://python.org/sf/1693753 closed by loewis subprocess must escape redirection characters under win32 (2007-05-01) http://python.org/sf/1710802 closed by astrand Bypassing __dict__ readonlyness (2005-09-24) http://python.org/sf/1303614 closed by arigo subclassing ModuleType and another built-in type (2005-04-01) http://python.org/sf/1174712 closed by arigo Error inside logging module documentation (2007-05-05) http://python.org/sf/1713535 closed by gbrandl New / Reopened RFE __________________ commands module (2007-05-05) http://python.org/sf/1713624 opened by Joseph Armbruster

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Summary of Tracker Issues
by Tracker 05 May '07

05 May '07

ACTIVITY SUMMARY (04/29/07 - 05/06/07) Tracker at http://bugs.python.org/ To view or respond to any of the issues listed below, click on the issue number. Do NOT respond to this message. 1650 open ( +1) / 8584 closed ( +0) / 10234 total ( +1) Average duration of open issues: 784 days. Median duration of open issues: 736 days. Open Issues Breakdown open 1650 ( +1) pending 0 ( +0) Issues Created Or Reopened (1) ______________________________ yahoo 05/02/07 http://bugs.python.org/issue1030 created step

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Python-Dev May 2007