Mailman 3 May 2005 - Python-Dev

Deprecating old bugs, now from 2.2.2
by Facundo Batista 30 May '05

30 May '05

Going on with the old bugs checking, here are the results for 2.2.2 (and one from 2.2.1). When I'll finish this will be put in an informational PEP. When I verified the bug, I filled two fields: - Summary: the same subject as in SF - Group: the bug's group at verifying time. - Bug #: the bug number - Verified: is the date when I checked the bug. - Action: is what I did then. If the bug survived the verification, the next two fields are applicable (if not, I put a dash, the idea is to keep this info easily parseable): - Final: is the action took by someone who eliminated the bug from that category (closed, moved to Py2.4, etc). - By: is the someone who did the final action. So, here's the info... Summary: Python Interpreter shell is crashed Group: 2.2.2 Bug #: 1100673 Verified: 15-Jan-2005 Action: Deprecation alerted. Works ok for me. Final: Closed. Rejected. By: mwh Summary: popen3 under threads reports different stderr results Group: 2.2.2 Bug #: 856706 Verified: 15-Jan-2005 Action: Closed as duplicate of #853411 Final: - By: - Summary: CGIHTTPServer cannot manage cgi in sub directories Group: 2.2.2 Bug #: 778804 Verified: 15-Jan-2005 Action: Closing as Fixed (was fixed already). Final: - By: - Summary: popen does not like filenames with spaces Group: 2.2.2 Bug #: 774546 Verified: 15-Jan-2005 Action: Deprecation alerted. Should be closed with "Won't fix" specially now that we have the subprocess module. Final: Closed. Out of date. By: rhettinger Summary: popen4 doesn't close filedescriptors when in Threads Group: 2.2.2 Bug #: 768649 Verified: 15-Jan-2005 Action: Deprecation alerted. Works ok for me. Final: Closed: Won't fix. By: facundobatista Summary: Sudden death with SIGSEGV in RtlEnterCriticalSection Group: 2.2.2 Bug #: 763190 Verified: 15-Jan-2005 Action: Deprecation alerted. Don't have the context to try it. Final: Closed: Won't fix. By: facundobatista Summary: can't CNTRL-C when running os.system in a thread Group: 2.2.2 Bug #: 756940 Verified: 15-Jan-2005 Action: Deprecation alerted. There's other bug similar to this (#756924) and a patch for it (that has been accepted), but can't try it right now. Final: Closed: Won't fix. By: facundobatista Summary: Calling socket.recv() with a large number breaks Group: 2.2.2 Bug #: 756104 Verified: 15-Jan-2005 Action: Changed to Py2.4. The bug is still there (but in the documentation). Final: - By: - Summary: ftplib.retrbinary fails when called from retrlines callback Group: 2.2.2 Bug #: 751758 Verified: 15-Jan-2005 Action: Changed to Py2.4. The bug is still there. Final: - By: - Summary: CGIHTTPServer does not handle scripts in sub-dirs Group: 2.2.2 Bug #: 737202 Verified: 15-Jan-2005 Action: Deprecation alerted. There's a patch, but actual code has something very similar to it, don't have the context to try if it's fixed. Final: Changed to Py2.4. The bug is still there. By: facundobatista Summary: socketmodule.c: inet_pton() expects 4-byte packed_addr Group: 2.2.2 Bug #: 730222 Verified: 15-Jan-2005 Action: Deprecation alerted. Don't have the context to see if it's already solved (there's a not-applied patch). Final: Closed: Won't fix. By: facundobatista Summary: mmap's resize method resizes the file in win32 but not unix Group: 2.2.2 Bug #: 728515 Verified: 15-Jan-2005 Action: Deprecation alerted. Don't know enough about it to check ir or reproduce it. Final: Closed: Won't fix. By: facundobatista Summary: Core Dumps : Python2.2.2 Group: 2.2.2 Bug #: 727241 Verified: 15-Jan-2005 Action: Deprecation alerted. Not sure if it's a Python or IRIX bug. Final: Closed: Won't fix. By: facundobatista Summary: inspect, class instances and __getattr__ Group: 2.2.2 Bug #: 718532 Verified: 15-Jan-2005 Action: Deprecation alerted. Not sure if there's a bug. Final: Changed to Py2.4. By: facundobatista Summary: "build_ext" "libraries" subcommand not s Group: 2.2.2 Bug #: 716634 Verified: 15-Jan-2005 Action: Deprecation alerted. Not sure if there's a bug. Final: Closed: Won't fix. By: facundobatista Summary: SEEK_{SET,CUR,END} missing in 2.2.2 Group: 2.2.2 Bug #: 711830 Verified: 15-Jan-2005 Action: Deprecation alerted. Not sure if there's a bug. Final: Closed. Fixed. By: loewis Summary: codecs.open and iterators Group: 2.2.2 Bug #: 706595 Verified: 15-Jan-2005 Action: Deprecation alerted. Couldn't reproduce the problem, don't know enough about the subject to be sure if it's a bug or not. Final: Closed. Out of date. By: doerwalter Summary: test_atexit fails in directories with spaces Group: 2.2.2 Bug #: 705792 Verified: 15-Jan-2005 Action: Closing as Fixed (was fixed already). Final: - By: - Summary: --without-cxx flag of configure isn't documented. Group: 2.2.2 Bug #: 702147 Verified: 15-Jan-2005 Action: Deprecation alerted. The offerent never send the proposed patch for docs, really not clear if there's something to be fixed. Final: Closed. Out of date. By: bcannon Summary: Thread running (os.system or popen#) Group: 2.2.2 Bug #: 701836 Verified: 15-Jan-2005 Action: Deprecation alerted. Works ok for me. Final: Closed: Won't fix. By: facundobatista Summary: Canvas origin is off-canvas in create_<item>(). Worka Group: 2.2.2 Bug #: 700650 Verified: 15-Jan-2005 Action: Deprecation alerted. Missing attached file, depend on that to verify the bug. Final: Closed: Won't fix. By: facundobatista Summary: Canvas Widget origin is off-screen Group: 2.2.2 Bug #: 699816 Verified: 15-Jan-2005 Action: Deprecation alerted. Missing attached file, depend on that to verify the bug. Final: Closed: Won't fix. By: facundobatista Summary: imaplib: parsing INTERNALDATE Group: 2.2.2 Bug #: 698706 Verified: 15-Jan-2005 Action: Changed to Py2.4. The bug is still there. Final: - By: - Summary: _iscommand() in webbrowser module Group: 2.2.2 Bug #: 687747 Verified: 15-Jan-2005 Action: Deprecation alerted. Don't have the context to try it. Final: Changed to Py2.3. By: facundobatista Summary: Profilier hooked into SystemExit Group: 2.2.2 Bug #: 687297 Verified: 11-Jan-2005 Action: Deprecation alerted. Don't have the context to try it. Final: Closed: Won't fix. By: facundobatista Summary: Incorrect permissions set in lib-dynload. Group: 2.2.2 Bug #: 680379 Verified: 11-Jan-2005 Action: Deprecation alerted. Don't have the context to try it. Final: Closed: Fixed. By: facundobatista Summary: String formatting operation Unicode problem. Group: 2.2.2 Bug #: 676346 Verified: 11-Jan-2005 Action: Deprecation alerted. Don't know enough about it to be sure if it's really a bug. Final: Closed: Fixed. By: facundobatista Summary: Py_Main() does not perform to spec Group: 2.2.2 Bug #: 672035 Verified: 11-Jan-2005 Action: Closing it, put in "Fixed" previously but still was "Open". Final: - By: - Summary: os.popen+() can take string list and bypass shell. Group: 2.2.2 Bug #: 666700 Verified: 11-Jan-2005 Action: Deprecation alerted. Not sure if there's a bug. Final: Closed: Fixed. By: facundobatista Summary: doctest and exception messages Group: 2.2.2 Bug #: 654783 Verified: 11-Jan-2005 Action: Deprecation alerted. Not sure if there's a bug. Final: Closed: Won't fix. By: facundobatista Summary: for lin in file: file.tell() tells wrong Group: 2.2.2 Bug #: 645594 Verified: 11-Jan-2005 Action: Closed because of #1036626 rationale. Final: - By: - Summary: Misuse of /usr/local/in setup.py Group: 2.2.2 Bug #: 640553 Verified: 08-Jan-2005 Action: Deprecation alerted. Because of the bug discussion is not clear to me if the problem actually existed. Final: Closed: Won't fix. By: facundobatista Summary: crash (SEGV) in Py_EndInterpreter() Group: 2.2.2 Bug #: 639611 Verified: 08-Jan-2005 Action: Deprecation alerted. Don't know enough about the subject to be able to reproduce the issue. Final: Closed: Works for me. By: jlgijsbers Summary: Tkinter: BitmapImage vanishes if not stored in non-local var Group: 2.2.2 Bug #: 632323 Verified: 27-Dec-2004 Action: Deprecation alerted. Don't know what to do with this one. It's marked as Invalid but still Open, and it's not clear to me if was a bug, is still a bug, or any of both. Final: Changed to Py2.3. By: facundobatista Summary: test_signal hangs -- signal broken on OpenBSD? Group: 2.2.1 candidate Bug #: 549081 Verified: 26-Dic-2004 Action: Deprecation alerted. I can not try it, don't have that context. For a comment maybe it's already fixed. Final: Closed: Won't fix. By: facundobatista Regards, . Facundo Blog: http://www.taniquetil.com.ar/plog/ PyAr: http://www.python.org/ar/

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Re: [Python-Dev] [Python-checkins] python/dist/src/Lib/test test_site.py, 1.6, 1.7
by Skip Montanaro 29 May '05

29 May '05

mwh> Fix test_site to not call open('...', 'wU'), as that now raises an mwh> error. mwh> Is anyone running the test suite regularly at the moment? Whoops. I obviously failed to run it after applying that change. My apologies. Skip

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Adding content to exception messages
by Nicolas Fleury 29 May '05

29 May '05

Sorry if this message is not a direct reply to Ka-Ping Yee message on PEP344, I'm in vacation in China and there's a thing I must say that could make sense in PEP344. I do a lot of exception re-raising at work; I use that technique to add content to exception messages while keeping the original stack. I even created a reraise function that I use that way: try: parser.parseFile(file) exeption Exception, exception: reraise(exception, "Error at line %s in file %s" % (x,y)) (x,y) are details, but you get the idea. This very useful in many situations. In the example, it works when an error is happening in parsing a file including other files (like xml files with <xs:include>). That way you get the exact path of inclusion leading to the error. It is also useful when an error happen in very generic code and when traceback is not enough to know which element was causing the error. What I propose is that all exceptions objects have a standard way to add additional informations. Something like: try: foo() except Exception, exception: exception.add_info("some info") raise exception from (whatever the proposition is) You might ask, "why not just reraise a new exception?". It is more useful to reraise the same exception type, making it possible to use selective except clauses and (avoid problems with code using them like hasattr). I think what would be simpler is not affect __str__ representation and prepend to a list the additional infos inside the exception object, adding a function to get these infos. I don't mind how it would be done in fact, as long as the need is fulfilled. I won't be able to read my messages often for the next 10 days, but I hope others will see the point I try to bring;) Regards, Nicolas Discover Yahoo! Have fun online with music videos, cool games, IM and more. Check it out! http://discover.yahoo.com/online.html

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PEP 346: User defined statements (formerly known as PEP 3XX)
by Nick Coghlan 28 May '05

28 May '05

My erstwhile PEP now has a real number (PEP 346), and a home on python.org [1]. At my request, it was withdrawn immediately after submission - the parts I think are important, Guido is taking on board for PEP 343 [2]. Cheers, Nick. [1] http://www.python.org/peps/pep-0346.html [2] http://mail.python.org/pipermail/python-dev/2005-May/053885.html -- Nick Coghlan | ncoghlan(a)gmail.com | Brisbane, Australia --------------------------------------------------------------- http://boredomandlaziness.blogspot.com

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Re: [Python-Dev] AST manipulation and source code generation
by Jeremy Hylton 26 May '05

26 May '05

On 5/26/05, Chad Whitacre <chad(a)zetaweb.com> wrote: > chad: Hmmm ... I don't follow python-dev closely but hasn't there been > resistance to macros in Python? Are we saying macros may be a good idea > after all? > > ?!ng: resistance -> Yes. > ?!ng: good idea -> Not really. AST transformations are useful for > experimenting with the language, but i don't think there is much > enthusiasm for making these transformations a normal part of the way > most programs are written. Right. We fear macros and prefer to suffer getattr hooks, descriptors, and decorators <wink>. Jeremy

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Localized Type Inference of Atomic Types in Python
by Brett C. 25 May '05

25 May '05

My thesis, "Localized Type Inference of Atomic Types in Python", was successfully defended today for my MS in Computer Science at the California Polytechnic State University, San Luis Obispo. With that stamp of approval I am releasing it to the world. You can grab a copy at http://www.drifty.org/thesis.pdf . For those of you who attended my talk at PyCon 2005 this is the thesis that stemmed from the presented data. As of this exact moment I am not planning to release the source code mainly because it's a mess, I am not in the mood to pull the patches together, and the last thing I want happening is people finding mistakes in the code. =) But if enough people request the source I will take the time to generate a tar.bz2 file of patches against the 2.3.4 source release and put them up somewhere. Below is the abstract culled directly from the thesis itself. -Brett C. --------------------------------- ABSTRACT Types serve multiple purposes in programming. One such purpose is in providing information to allow for improved performance. Unfortunately, specifying the types of all variables in a program does not always fit within the design of a programming language. Python is a language where specifying types does not fit within the language design. An open source, dynamic programming language, Python does not support type specifications of variables. This limits the opportunities in Python for performance optimizations based on type information compared to languages that do allow or require the specification of types. Type inference is a way to derive the needed type information for optimizations based on types without requiring type specifications in the source code of a program. By inferring the types of variables based on flow control and other hints in a program, the type information can be derived and used in a constructive manner. This thesis is an exploration of implementing a type inference algorithm for Python without changing the semantics of the language. It also explores the benefit of adding type annotations to method calls in order to garner more type information.

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Weekly Python Patch/Bug Summary
by Kurt B. Kaiser 24 May '05

24 May '05

Patch / Bug Summary ___________________ Patches : 342 open ( +3) / 2839 closed ( +1) / 3181 total ( +4) Bugs : 936 open ( -2) / 4974 closed (+12) / 5910 total (+10) RFE : 189 open ( +2) / 159 closed ( +2) / 348 total ( +4) New / Reopened Patches ______________________ optparse documentation bug fixes (2005-05-18) http://python.org/sf/1204347 opened by Barry A. Warsaw Bugfix for signal-handler on x64 Platform (2005-05-20) http://python.org/sf/1205436 opened by André Fritzsche updates for the compiler package (2005-05-21) http://python.org/sf/1206077 opened by Stelios An URL for UnicodeData File Format 3.2 has changed. (2005-05-24) http://python.org/sf/1207985 opened by Darek Suchojad Patches Closed ______________ workaround deprecated ostat structure in <sys/stat.h> (2005-05-17) http://python.org/sf/1203329 closed by loewis New / Reopened Bugs ___________________ Documentation error? (2005-05-18) http://python.org/sf/1204734 opened by John Eikenberry urllib has spurious print statement (2005-05-20) http://python.org/sf/1205544 opened by Stuart Wray Compile fails on Darwin8 with --with-cxx=g++ (2005-05-20) http://python.org/sf/1205568 opened by Robert M. Zigweid wrong location for math lib with --prefix (2005-05-20) http://python.org/sf/1205736 opened by Thomas Richter IDLE 1.0.5 (Python 2.3.5) crashes under Windows (2005-05-21) http://python.org/sf/1206232 opened by Torsten Bronger weakref cannot handle bound methods (in contrast to docu) (2005-05-22) http://python.org/sf/1206537 opened by Raik Gruenberg class property fset not working (2005-05-24) http://python.org/sf/1207379 opened by Master_Jaf installer ignores changed installation directory (2005-05-24) http://python.org/sf/1207466 opened by Blubb Fallo Issue in grammar (2005-05-24) http://python.org/sf/1207501 opened by venkat manian Issue in grammar (2005-05-24) CLOSED http://python.org/sf/1207509 opened by venkat manian Bugs Closed ___________ Problem with recursion in dict (crash with core dump) (2005-05-13) http://python.org/sf/1201456 closed by vys Windows msi installer fails on virtual drives (2005-05-12) http://python.org/sf/1200287 closed by loewis urllib2 authentication redirection error(?) (2004-11-21) http://python.org/sf/1070735 closed by allanbwilson No documentation for urllib2 exception classes (2004-04-29) http://python.org/sf/944407 closed by fresh file("foo", "wU") is silently accepted (2004-06-05) http://python.org/sf/967182 closed by montanaro UnboundLocalError in cgitb.py (2003-12-16) http://python.org/sf/861340 closed by montanaro Python 2.4.1 Installer ended prematurely (2005-05-11) http://python.org/sf/1199947 closed by loewis xml.dom.minidom.Node.removeChild() doesn't remove (2005-03-06) http://python.org/sf/1157901 closed by mkempka csv writer bug on windows (2004-04-29) http://python.org/sf/944890 closed by montanaro Importing anydbm generates exception if _bsddb unavailable (2003-05-02) http://python.org/sf/731501 closed by montanaro Explicit interp reference during build fails (2003-07-08) http://python.org/sf/768068 closed by montanaro Issue in grammar (2005-05-24) http://python.org/sf/1207509 closed by mwh New / Reopened RFE __________________ Let shift operators take any integer value (2005-05-19) http://python.org/sf/1205239 opened by David Albert Torpey Right Click Context Menu (2005-05-24) http://python.org/sf/1207589 opened by Mike Foord Clipboard Cleared on Close (2005-05-24) http://python.org/sf/1207592 opened by Mike Foord Bottom Scroll Bar (2005-05-24) http://python.org/sf/1207613 opened by Mike Foord RFE Closed __________ enhancing os.chown functionality (2005-05-12) http://python.org/sf/1200804 closed by loewis "replace" function should accept lists. (2005-04-17) http://python.org/sf/1184678 closed by loewis

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Decimal FAQ
by Raymond Hettinger 24 May '05

24 May '05

Some of the private email I've received indicates a need for a decimal FAQ that would shorten the module's learning curve. A discussion draft follows. Raymond ------------------------------------------------------- Q. It is cumbersome to type decimal.Decimal('1234.5'). Is there a way to minimize typing when using the interactive interpreter? A. Some users prefer to abbreviate the constructor to just a single letter: >>> D = decimal.Decimal >>> D('1.23') + D('3.45') Decimal("4.68") Q. I'm writing a fixed-point application to two decimal places. Some inputs have many places and needed to be rounded. Others are not supposed to have excess digits and need to be validated. What methods should I use? A. The quantize() method rounds to a fixed number of decimal places. If the Inexact trap is set, it is also useful for validation: >>> TWOPLACES = Decimal(10) ** -2 >>> # Round to two places >>> Decimal("3.214").quantize(TWOPLACES) Decimal("3.21") >>> # Validate that a number does not exceed two places >>> Decimal("3.21").quantize(TWOPLACES, context=Context(traps=[Inexact])) Decimal("3.21") Q. Once I have valid two place inputs, how do I maintain that invariant throughout an application? A. Some operations like addition and subtraction automatically preserve fixed point. Others, like multiplication and division, change the number of decimal places and need to be followed-up with a quantize() step. Q. There are many ways to write express the same value. The numbers 200, 200.000, 2E2, and .02E+4 all have the same value at various precisions. Is there a way to transform these to a single recognizable canonical value? A. The normalize() method maps all equivalent values to a single representive: >>> values = map(Decimal, '200 200.000 2E2 .02E+4'.split()) >>> [v.normalize() for v in values] [Decimal("2E+2"), Decimal("2E+2"), Decimal("2E+2"), Decimal("2E+2")] Q. Is there a way to convert a regular float to a Decimal? A. Yes, all binary floating point numbers can be exactly expressed as a Decimal. An exact conversion may take more precision than intuition would suggest, so trapping Inexact will signal a need for more precision: def floatToDecimal(f): "Convert a floating point number to a Decimal with no loss of information" # Transform (exactly) a float to a mantissa (0.5 <= abs(m) < 1.0) and an # exponent. Double the mantissa until it is an integer. Use the integer # mantissa and exponent to compute an equivalent Decimal. If this cannot # be done exactly, then retry with more precision. mantissa, exponent = math.frexp(f) while mantissa != int(mantissa): mantissa *= 2 exponent -= 1 mantissa = int(mantissa) oldcontext = getcontext() setcontext(Context(traps=[Inexact])) try: while True: try: return mantissa * Decimal(2) ** exponent except Inexact: getcontext().prec += 1 finally: setcontext(oldcontext) Q. Why isn't the floatToDecimal() routine included in the module? A. There is some question about whether it is advisable to mix binary and decimal floating point. Also, its use requires some care to avoid the representation issues associated with binary floating point: >>> floatToDecimal(1.1) Decimal("1.100000000000000088817841970012523233890533447265625") Q. I have a complex calculation. How can I make sure that I haven't gotten a spurious result because of insufficient precision or rounding anomalies. A. The decimal module makes it easy to test results. A best practice is to re-run calculations using greater precision and with various rounding modes. Widely differing results indicate insufficient precision, rounding mode issues, ill-conditioned inputs, or a numerically unstable algorithm. Q. I noticed that context precision is applied to the results of operations but not to the inputs. Is there anything I should watch out for when mixing values of different precisions? A. Yes. The principle is all values are considered to be exact and so is the arithmetic on those values. Only the results are rounded. The advantage for inputs is that "what you type is what you get". A disadvantage is that the results can look odd if you forget that the inputs haven't been rounded: >>> getcontext().prec = 3 >>> Decimal('3.104') + D('2.104') Decimal("5.21") >>> Decimal('3.104') + D('0.000') + D('2.104') Decimal("5.20") The solution is either to increase precision or to force rounding of inputs using the unary plus operation: >>> getcontext().prec = 3 >>> +Decimal('1.23456789') Decimal("1.23") Alternatively, inputs can be rounded upon creation using the Context.create_decimal() method: >>> Context(prec=5, rounding=ROUND_DOWN).create_decimal('1.2345678') Decimal("1.2345") Q. I'm writing an application that tracks measurement units along with numeric values (for example 1.1 meters and 2.3 grams). Is a Decimal subclass the best approach? A. Like other numeric types, Decimal objects are dimensionless and all of its methods are designed around this concept. To add dimension, a Decimal subclass would likely need to override every method. For example, without an overriding the __add__() method in a Measurement subclass of Decimal, a calculation like "MeasurementA + MeasurementB" would return a dimensionless Decimal object instead of another Measurement object -- the units would be lost. A simple alternative is to construct record tuples such as (Decimal("1.1"), "meters"). This allows direct use of existing decimal methods: if a[1] == b[1]: return (a[0]+b[0], a[1]). A more versatile approach is to create a separate class with Decimal objects as attributes (working in a "has-a" capacity rather than an "is-a" capacity) and then delegating the arithmetic to the Decimal class.

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Re: [Python-Dev] Adventures with Decimal
by Greg Ewing 23 May '05

23 May '05

Raymond Hettinger wrote: > Did you see Mike Cowlishaw's posting where he described why he took our > current position (wysiwig input) in the spec, in Java's BigDecimal, and > in Rexx's numeric model? Yes, it appears that you have channeled him correctly on that point, and Tim hasn't. :-) But I also found it interesting that, while the spec requires the existence of a context for each operation, it apparently *doesn't* mandate that it must be kept in a global variable, which is the part that makes me uncomfortable. Was there any debate about this choice when the Decimal module was being designed? It seems to go against EIBTI, and even against Mr. Cowlishaw's own desire for WYSIWIG, because WYG depends not only on what you can see, but a piece of hidden state as well. Greg

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PEP 344: Explicit vs. Implicit Chaining
by Ka-Ping Yee 23 May '05

23 May '05

Guido van Rossum wrote: > Do we really need both __context__ and __cause__? Well, it depends whose needs we're trying to meet. If we want to satisfy those who have been asking for chaining of unexpected secondary exceptions, then we have to provide that on some attribute. If we also want to provide the facility that Java and C# provide with initCause/InnerException, then we need a separate attribute devoted to explicit chaining. The Java and C# documentation is clear that the cause/inner exception is to be set only on an exception that is "caused" or a "direct result" of the primary exception, which i've taken as a sign that this is an important distinction. I wanted to give a shot at making both camps happy. If the two were unified, we'd still be better off than we are now, but we should be aware that we would not be providing the functionality that Java and C# provide. -- ?!ng

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