Mailman 3 September 2000 - Python-Dev

stupid floating point question...
by Fredrik Lundh 27 Sep '00

27 Sep '00

each unicode character has an optional "numeric value", which may be a fractional value. the unicodedata module provides a "numeric" function, which returns a Python float representing this fraction. this is currently implemented by a large switch stmnt, containing entries like: case 0x2159: return (double) 1 / 6; if I replace the numbers here with integer variables (read from the character type table) and return the result to Python, will str(result) be the same thing as before for all reasonable values? </F>

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buffer overlow in PC/getpathp.c
by Jeremy Hylton 27 Sep '00

27 Sep '00

Mark, Would you have some time to review PC/getpathp.c for buffer overflow vulnerabilities? I just fixed several problems in Modules/getpath.c that were caused by assuming that certain environment variables and argv[0] would contain strings less than MAXPATHLEN bytes long. I assume the Windows version of the code could have the same vulnerabilities. Jeremy PS Is there some other Windows expert who could check into this?

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Bogus SAX test case
by Martin v. Loewis 27 Sep '00

27 Sep '00

test_sax.py has the test case test_xmlgen_ns, which reads ns_uri = "http://www.python.org/xml-ns/saxtest/" gen.startDocument() gen.startPrefixMapping("ns1", ns_uri) gen.startElementNS((ns_uri, "doc"), "ns:doc", {}) gen.endElementNS((ns_uri, "doc"), "ns:doc") gen.endPrefixMapping("ns1") gen.endDocument() Translating that to XML, it should look like <?xml version="1.0" encoding="iso-8859-1"?> <ns:doc xmlns:ns1="http://www.python.org/xml-ns/saxtest/"><ns:doc/> (or, alternatively, the element could just be empty). Is that the XML that would produce above sequence of SAX events? It seems to me that this XML is ill-formed, the namespace prefix ns is not defined here. Is that analysis correct? Furthermore, the test checks whether the generator produces <?xml version="1.0" encoding="iso-8859-1"?> <ns1:doc xmlns:ns1="http://www.python.org/xml-ns/saxtest/"></ns1:doc> It appears that the expected output is bogus; I'd rather expect to get the original document back. I noticed this because in PyXML, XMLGenerator *would* produce ns:doc on output, so the test case broke. I have now changed PyXML to follow Python 2.0b2 here. My proposal would be to correct the test case to pass "ns1:doc" as the qname, and to correct the generator to output the qname if that was provided by the reader. Comments? Regards, Martin

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Python 2.0b2 is released!
by Jeremy Hylton 27 Sep '00

27 Sep '00

Python 2.0b2 is released. The BeOpen PythonLabs and our cast of SourceForge volunteers have fixed many bugs since the 2.0b1 release three weeks ago. Please go here to pick up the new release: http://www.pythonlabs.com/tech/python2.0/ There's a tarball, a Windows installer, RedHat RPMs, online documentation, and a long list of fixed bugs. The final release of Python 2.0 is expected in early- to mid-October. We would appreciate feedback on the current beta release in order to fix any remaining bugs before the final release. Confirmation of build and test success on less common platforms is also helpful. Python 2.0 has many new features, including the following: - Augmented assignment, e.g. x += 1 - List comprehensions, e.g. [x**2 for x in range(10)] - Extended import statement, e.g. import Module as Name - Extended print statement, e.g. print >> file, "Hello" - Optional collection of cyclical garbage This release fixes many known bugs. The list of open bugs has dropped to 50, and more than 100 bug reports have been resolved since Python 1.6. To report a new bug, use the SourceForge bug tracker http://sourceforge.net/bugs/?func=addbug&group_id=5470 -- Jeremy Hylton <http://www.python.org/~jeremy/>

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2.0b2 is ... released?
by Tim Peters 27 Sep '00

27 Sep '00

The other guys are sleeping and I'm on vacation. It *appears* that our West Coast webmasters may have finished doing their thing, so pending Jeremy's official announcement perhaps you'd just like to check it out: http://www.pythonlabs.com/products/python2.0/ I can't swear it's a release. *Looks* like one, though!

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RE: [Python-Dev] FW: regarding the Python Developer posting...
by Dan Wolfe 27 Sep '00

27 Sep '00

>>[about the big switch in unicodectype.c] > >[Tim: use the current CVS tree instead... code's been replace...] duh! gotta read them archives before seeing following up on an request... can't trust the hyper-active Python development team with a code freeze.... <wink> I'm happy to report that it now compiles correctly without a -traditional-cpp flag. Unfortuantely, test_re.py now seg faults.... which is caused by test_sre.py... in particular the following: src/Lib/test/test_sre.py if verbose: print 'Test engine limitations' # Try nasty case that overflows the straightforward recursive # implementation of repeated groups. #test(r"""sre.match(r'(x)*', 50000*'x').span()""", # (0, 50000), RuntimeError) #test(r"""sre.match(r'(x)*y', 50000*'x'+'y').span()""", # (0, 50001), RuntimeError) #test(r"""sre.match(r'(x)*?y', 50000*'x'+'y').span()""", # (0, 50001), RuntimeError) test_unicodedata fails... same endian problem as SGI... test_format fails... looks like a problem with the underlying C code. Here's the config instructions for Mac OS X Public Beta: Building Python 2.0b1 + CVS 9/26/2000 Dan Wolfe ./configure -with-threads -with-dyld -with-suffix=.exe change in src/config.h: /* Define if you have POSIX threads */ #define _POSIX_THREADS 1 to /* #define _POSIX_THREADS 1 */ change in src/Makefile # Compiler options passed to subordinate makes OPT= -g -O2 -OPT:Olimit=0 to OPT= -g -O2 comment out the following in src/Lib/test/test_sre.py if verbose: print 'Test engine limitations' # Try nasty case that overflows the straightforward recursive # implementation of repeated groups. #test(r"""sre.match(r'(x)*', 50000*'x').span()""", # (0, 50000), RuntimeError) #test(r"""sre.match(r'(x)*y', 50000*'x'+'y').span()""", # (0, 50001), RuntimeError) #test(r"""sre.match(r'(x)*?y', 50000*'x'+'y').span()""", # (0, 50001), RuntimeError) After install, manually go into /usr/local/bin strip the .exe off the installed files. - Dan

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Re: [Python-Dev] FW: regarding the Python Developer posting...
by Dan Wolfe 27 Sep '00

27 Sep '00

Hi Marc-Andre, Regarding: >You could try to enable the macro at the top of unicodectype.c: > >#if defined(macintosh) || defined(MS_WIN64) >/*XXX This was required to avoid a compiler error for an early Win64 > * cross-compiler that was used for the port to Win64. When the platform is > * released the MS_WIN64 inclusion here should no longer be necessary. > */ >/* This probably needs to be defined for some other compilers too. It >breaks the >** 5000-label switch statement up into switches with around 1000 cases each. >*/ >#define BREAK_SWITCH_UP return 1; } switch (ch) { >#else >#define BREAK_SWITCH_UP /* nothing */ >#endif I've tested it with the BREAK_SWITCH_UP to be true and it fixes the problem - same as using the -traditional-cpp. However, before we commit this change I need to see if they are planning on fixing it... remeber this Mac OS X is Beta software.... :-) >If it does compile with the work-around enabled, please >give us a set of defines which identify the compiler and >platform so we can enable it per default for your setup. Auto-make is making me nuts... it's a long way from a GUI for this poor old mac guy. I'll see what I can do.. stay tuned. ;-) - Dan

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Python syntax checker ?
by Martin von Loewis 27 Sep '00

27 Sep '00

> Would it be possible to write a Python syntax checker that doesn't > stop processing at the first error it finds but instead tries to > continue as far as possible (much like make -k) ? In "Compilerbau", this is referred to as "Fehlerstabilisierung". I suggest to have a look at the dragon book (Aho, Seti, Ullman). The common approch is to insert or remove tokens, using some heuristics. In YACC, it is possible to add error productions to the grammar. Whenever an error occurs, the parser assigns all tokens to the "error" non-terminal until it concludes that it can perform a reduce action. A similar approach might work for the Python Grammar. For each production, you'd define a set of stabilization tokens. If these are encountered, then the rule would be considered complete. Everything is consumed until a stabilization token is found. For example, all expressions could be stabilized with a keyword. I.e. if you encounter a syntax error inside an expression, you ignore all tokens until you see 'print', 'def', 'while', etc. In some cases, it may be better to add input rather than removing it. For example, if you get an "inconsistent dedent" error, you could assume that this really was a consistent dedent, or you could assume it was not meant as a dedent at all. Likewise, if you get a single-quote start-of-string, with no single-quote until end-of-line, you just should assume there was one. Adding error productions to ignore input until stabilization may be feasible on top of the existing parser. Adding tokens in the right place is probably harder - I'd personally go for a pure Python solution, that operates on Grammar/Grammar. Regards, Martin

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Stupid distutils bug
by Greg Ward 27 Sep '00

27 Sep '00

No, I mean *really* stupid. So stupid that I nearly fell out of my chair with embarassment when I saw Thomas Heller's report of it, because I released Distutils 0.9.3 *before* reading my mail. D'oh! Anyways, this is such a colossally stupid bug that I'm *glad* 2.0b2 hasn't gone out yet: it gives me a chance to checkin the (3-line) fix. Here's what I plan to do: * tag distutils-0_9_3 (ie. last bit of bureaucracy for the broken, about-to-be-superseded release) * checkin my fix * release Distutils 0.9.4 (with this 3-line fix and *nothing* more) * tag distutils-0_9_4 * calmly sit back and wait for Jeremy and Tim to flay me alive Egg-on-face, paper-bag-on-head, etc. etc... Greg PS. be sure to cc me: I'm doing this from home, but my python-dev subscription goes to work. -- Greg Ward gward(a)python.net http://starship.python.net/~gward/

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Crisis aversive
by Tim Peters 26 Sep '00

26 Sep '00

I'm going to take a nap now. If there's a Windows crisis for the duration, mail pleas for urgent assistance to bwarsaw(a)beopen.com -- especially if it involves interactions between a Python script running as an NT service and python-mode.el under NT Emacs. Barry *loves* those! Back online in a few hours. sometimes-when-you-hit-the-wall-you-stick-ly y'rs - tim

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