Mailman 3 February 2008 - Python-Dev

Re: [Python-Dev] Backporting PEP 3127 to trunk
by Raymond Hettinger Feb. 22, 2008

Feb. 22, 2008

[Eric Smith] > Speaking for myself, these features are generally useful, > and are so even without the new integer literal syntax. I'm curious how these are useful to you in Py2.6 where they are not invertible. In Py3.0, we can count on x == int(bin(x), 2) x == eval(bin(x)) I don't see how these could work in Py2.6 without changing the parser and changing the int() function. Why would you ever want to create a string like '0o144' when there is no way to convert the string back … [View More]

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[ANN] Python 2.5.2 released
by "Martin v. Löwis" Feb. 22, 2008

Feb. 22, 2008

On behalf of the Python development team and the Python community, I'm happy to announce the release of Python 2.5.2 (FINAL). This is the second bugfix release of Python 2.5. Python 2.5 is now in bugfix-only mode; no new features are being added. According to the release notes, over 100 bugs and patches have been addressed since Python 2.5.1, many of them improving the stability of the interpreter, and improving its portability. This is a production release of Python, and should be a painless … [View More]

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ssl - how to switch back to a plain text socket?
by Giampaolo Rodola' Feb. 22, 2008

Feb. 22, 2008

Hi all, I'm trying to extend the base ftplib module to add SSL/TLS support as described in RFC-4217 (see also issue 2054). RFC-4217 defines a certain command ("CCC") which permit to return to a plain text socket state without closing the connection. That is useful since that, being FTP a port-hopping protocol (i.e. data channels may use a random port chosen during the communication), firewalls need to read passing packets to allow the secondary data connections. I've read through ssl.py but I … [View More]

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Re: [Python-Dev] int/float freelists vs pymalloc
by Vladimir Marangozov Feb. 22, 2008

Feb. 22, 2008

May I chime in? :-) Gents, the current implementation of Python's memory management is really fine and most problems it used to have in the past have been fixed in recent years (at least the ones I know of). Probably the only one left, indeed, is the potential unbounded growth of int/float objects' freelists (beyond the shared cache of small ints). Yet, this seems to be a questionable problem because any change in the freelists' management will invariably slow down their allocation. By how … [View More]

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Re: [Python-Dev] trunk-math
by Mark Dickinson Feb. 22, 2008

Feb. 22, 2008

Apologies for the bad formatting. Here's a repost with shorter lines. Dear all, I'd like to draw your attention to some of the work that's been going on in the trunk-math branch. Christian Heimes and I have been working on various aspects of Python mathematics, and we're hoping to get at least some of this work into Python 2.6/3.0. Most of the changes are completed or nearly complete, and 2.6/3.0 isn't very far away, so it seems like a good time to try to get some feedback from python-dev. … [View More] Here's an overview of the changes (overview originally written by Christian, edited and augmented by me. I hope Christian will step in and correct me if I misrepresent him or his work here.) Many of the changes were motivated by Christian's work (already in the trunk) in making infinities and nans more accessible and portable for Python users. (See issue #1640.) * Structural reorganization: there are new files Include/pymath.h and Objects/pymath.c with math-related definitions and replacement functions for platforms without copysign, log1p, hypot and inverse hyperbolic functions. * New math functions: inverse hyperbolic functions (acosh, asinh, atanh). * New float methods: is_finite, is_inf, is_integer and is_nan. * New cmath functions: phase, polar and rect, isinf and isnan. * New complex method: is_finite. * Work on math and cmath functions to make them handle special values (infinities and nans) and floating-point exceptions according to the C99 standard. The general philosophy follows the ideas put forth by Tim Peters and co. many moons ago. and repeated in the issue #1640 thread more recently: where the C99 standard (or IEEE 754) specifies raising 'invalid' or 'divide-by-zero' Python should raise a ValueError. Where the C99 standard specifies raising 'overflow' Python should raise OverflowError. 'underflow' and 'inexact' flags are ignored. From a user's perspective, this means that infinities and nans are never produced by math or cmath operations on finite values (but see below). sqrt(-1) will always raise ValueError, instead of returning a NaN. See issue #711019 and the resulting warning at the bottom of the math module documentation. Although complex_abs doesn't live in cmathmodule.c, it was also fixed up this way. * The cmath module has been rescued: it's no longer numerically unsound (see issue #1381). For the majority of functions (sin, cos, tan, sinh, cosh, tanh, asin, acos, atan, asinh, acosh, atanh, exp, sqrt) the real and imaginary parts of the results are always within a few ulps of the true values. (In extensive but non-exhaustive testing I haven't found errors of more than 5 ulps in either the real or imaginary parts for these functions.) For log and log10 the errors can be larger when the argument has absolute value close to 1; this seems pretty much unavoidable without using multiple-precision arithmetic. pow and two-argument log are less accurate; again, this is essentially unavoidable without adding hundreds of extra lines of code. * Many more tests. In addition to a handful of extra test_* methods in test_math and test_cmath, there are over 1700 testcases (in a badly-named file Lib/test/cmath.ctest) for the cmath and math functions, with a testcase format inspired in no small part by the decimal .decTest file format. Most of the testcase values were produced independently of Python using MPFR and interval arithmetic (C code available on request); some were created by hand. * There's a per-thread state for division operator. In IEEE 754 mode 1./0. and 1.%0. return INF and 0./0. NAN. The contextlib has a new context "ieee754" and the math lib set_ieee754/get_ieee754 (XXX better place for the functions?) Some notes: * We've used the C99 standard (especially Annex F and Annex G) as a reference for deciding what the math and cmath functions should do, wherever possible. It seems to make sense to choose to follow some standard, essentially so that all the hard decisions have been thought through thoroughly by a group of experts. Two obvious choices are the C99 standard and IEEE 754(r); for almost all math issues the two say essentially the same thing. C99 has the advantage that it includes specifications for complex math, while IEEE 754(r) does not. (Actually, I've been using draft version N1124 of the C99 standard, not the standard itself, since I'm too cheap to pay up for a genuine version. Google 'N1124' for a copy.) * I'm offering to act as long-term maintainer for the cmath module, if that's useful. * The most interesting and exciting feature, by far (in my opinion) is the last one. By way of introduction, here's a snippet from Tim Peters, in a comp.lang.python posting (http://mail.python.org/pipermail/python-list/2005-July/330745.html), answering a question from Michael Hudson about 1e300*1e300 and inf/inf. "I believe Python should raise exceptions in these cases by default, because, as above, they correspond to the overflow and invalid-operation signals respectively, and Python should raise exceptions on the overflow, invalid-operation, and divide-by-0 signals by default. But I also believe Python _dare not_ do so unless it also supplies sane machinery for disabling traps on specific signals (along the lines of the relevant standards here). Many serious numeric programmers would be livid, and justifiably so, if they couldn't get non-stop mode back. The most likely x-platfrom accident so far is that they've been getting non-stop mode in Python since its beginning." Christian has found a simple, elegant and practical way to make it possible for Python to raise these exceptions by default, while also allowing serious numeric users access to non-stop mode---i.e., a mode that generates inf from 1/0 instead of raising a Python exception. (I had a much more elaborate plan in mind, involving a thread-local context similar to Decimal's, with control over individual traps and flags. Christian's solution is far more practical.) The idea is that any arithmetic operating under a "with ieee754:" acts like arithmetic on an IEEE 754 platform with no traps enabled: invalid operations like sqrt(-1) produce a nan, division by zero produces an infinity, etc. No Python exceptions related to floating-point are raised. See the thread started by Neal Becker at<http://mail.python.org/pipermail/python-list/2008-February/477064.html> http://mail.python.org/pipermail/python-list/2008-February/477064.html entitled "Turn off ZeroDivisionError?" for a recent discussion of these issues. I fear that the per-thread state change seems like something where a PEP might be necessary; it's also not clear right now that Christian and I have exactly the same goals here (discussion is ongoing). But I hope that the rest of the changes are uncontroversial enough to merit consideration for possible inclusion in 2.6/3.0. Thoughts? Mark [View Less]

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Summary of Tracker Issues
by Tracker Feb. 22, 2008

Feb. 22, 2008

ACTIVITY SUMMARY (02/15/08 - 02/22/08) 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. 1732 open (+27) / 12258 closed (+11) / 13990 total (+38) Open issues with patches: 456 Average duration of open issues: 742 days. Median duration of open issues: 1095 days. Open Issues Breakdown open 1708 (+27) pending 24 ( +0) Issues Created Or Reopened (39) _______________________________ … [View More]

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Tomorrow's bug day and issue #1858
by Tarek Ziadé Feb. 22, 2008

Feb. 22, 2008

Hello, I have prepared a request for enhancement for distutils, together with its patch that also adds more tests for the package. This was discussed in catalog-sig, and explained here : http://wiki.python.org/moin/EnhancedPyPI (see pypirc section). I have followed Brett Cannon's slides to make the patch on the 2.6 trunk (great doc thanks!). I would like to propose this rfe tomorrow at the bug day, amongst other bugs I can try to work on. But I don't know if I should propose it here first … [View More]

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Unit Test Guide
by Virgil Dupras Feb. 22, 2008

Feb. 22, 2008

Hi devs, Being a python dev newbie, I look in http://www.python.org/dev/ for some guide to write unit tests in python and I can't find any. Specifically, I'd like to know about files managements in tests. Is every test expected to clean after itself, or is there an automatic cleanup mechanism in place? Even more specifically, I'd like to create a test for the proposed patch in http://bugs.python.org/issue2127 so I need to create a subdir with non-ascii character in it, then connect to a db in … [View More]

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Re: [Python-Dev] Backporting PEP 3127 to trunk
by Raymond Hettinger Feb. 22, 2008

Feb. 22, 2008

[Eric Smith] > I'm going to work on backporting PEP 3127, specifically >the hex, oct(), and bin() builtins. IMO, these should not be backported. They are strongly associated with 3.0's new literal syntax. They don't don't really fit in with 2.6 and don't make 2.6 any more attractive. Raymond

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Re: [Python-Dev] dir() and __all__
by Raymond Hettinger Feb. 22, 2008

Feb. 22, 2008

[Benjamin] > Are you proposing just a list those modules > or all module objects? The idea is dead. Guido specified that the dir() function returns a list of names for which hasattr() will succeed. I only brought this up because a colleague was using dir() on modules to find-out about the API. He was thrown-off by some of the entries in dir(logging). Raymond

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