Mailman 3 January 2008 - Python-Dev

math and numerical fixes (was: When is min(a, b) != min(b, a)?)
by Christian Heimes Jan. 24, 2008

Jan. 24, 2008

Jason wrote: > Please note that NaN's are very funky and platform dependent. They > depend on their underlying platform's C library for creation and > display. On windows, "float('nan')" will cause an exception, as there > are no valid string representations of NAN that can be converted to > the special floating point value. Also, if you manage to create a nan > under Windows, it displays as "1.#QNAN". > > Infinite values are also problematic. In almost all cases, … [View More]

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rfc822_escape doing the right thing?
by stephen emslie Jan. 23, 2008

Jan. 23, 2008

I've been working on a project that renders PKG-INFO metadata in a number of ways. I have noticed that fields with any indentation were flattened out, which is being done in distutils.util.rfc822_escape. This unfortunately means that you cant use reStructuredText formatting in your long description (suggested in PEP345), or are limited to a set that doesn't require indentation (no block quotes, etc.). It looks like this behavior was intentionally added in rev 20099, but that was about 7 years … [View More]

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Re: [Python-Dev] misbehaving __contains__
by Raymond Hettinger Jan. 23, 2008

Jan. 23, 2008

>> And, would we lose the nice relationship expressed by: >> >> for elem in container: >> assert elem in container [Steven Bethard] >We've already lost this if anyone really wants to break it:: > > >>> class C(object): > ... def __iter__(self): > ... return iter(xrange(3)) > ... def __contains__(self, item): > ... return False I think this is in the same category as writing a __hash__ … [View More]

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PEP: per user site-packages directory
by Christian Heimes Jan. 23, 2008

Jan. 23, 2008

MA Lemburg has suggested a per user site-packages directory in the "pkgutil, pkg_resource and Python 3.0 name space packages" thread. I've written a short PEP about it for Python 2.6 and 3.0. PEP: XXX Title: Per user site-packages directory Version: $Revision$ Last-Modified: $Date$ Author: Christian Heimes <christian(at)cheimes(dot)de> Status: Draft Type: Standards Track Content-Type: text/x-rst Created: 11-Jan-2008 Python-Version: 2.6, 3.0 Post-History: Abstract ======== This PEP … [View More]proposes a new a per user site-packages directory to allow users the local installation of Python packages in their home directory. Rationale ========= Current Python versions don't have an unified way to install packages into the home directory of an user (except for Mac Framework builds). Users are either forced to ask the system administrator to install or update a package for them or to use one of the many workaround like Virtual Python [1]_, Working Env [2]_ or Virtual Env [3]_. It's not the goal of the PEP to replace the tools or to implement isolated installations of Python. It only implements the most common use case of an additional site-packages directory for each user. The feature can't be implemented using the environment variable *PYTHONPATH*. The env var just inserts a new directory to the beginning of *sys.path* but it doesn't parse the pth files in the directory. A full blown site-packages path is required for several applications and Python eggs. Specification ============= site directory (site-packages) A directory in sys.path. In contrast to ordinary directories the pth files in the directory are processed, too. user site directory A site directory inside the users' home directory. An user site directory is specific to a Python version. The path contains the version number (major and minor only). Windows: %APPDATA%/Python/Python26/site-packages Mac: ~/Library/Python/2.6/site-packages Unix: ~/.local/lib/python2.6/site-packages user configuration directory Usually the parent directory of the user site directory. It's meant for Python version specific data like config files. Windows: %APPDATA%/Python/Python26 Mac: ~/Library/Python/2.6 Unix: ~/.local/lib/python2.6 user base directory It's located inside the user's home directory. The user site and use config directory are inside the base directory. On some systems the directory may be shared with 3rd party apps. Windows: %APPDATA%/Python Mac: ~/Library/Python Unix: ~/.local On Windows APPDATA was chosen because it is the most logical place for application data. Microsoft recommands that software doesn't write to USERPROFILE [5]_ and My Documents is not suited for application data, too. [8]_ On Linux ~/.local/ was chosen in favor over ./~python/ because the directory is already used by several other programs in analogy to /usr/local. [7]_ Implementation ============== The site module gets a new method adduserpackage() which adds the appropriate directory to the search path. The directory is not added if it doesn't exist when Python is started. However the location of the user site directory and user base directory is stored in an internal variable for distutils. The user site directory is added before the system site directories but after Python's search paths and PYTHONPATH. This setup allows the user to install a different version of a package than the system administrator but it prevents the user from accidently overwriting a stdlib module. Stdlib modules can still be overwritten with PYTHONPATH. distutils.command.install (setup.py install) gets a new argument --user to install packages in the user site directory. The required directories are created by install. distutils.sysconfig will get methods to access the private variables of site. (not yet implemented) The Windows updater needs to be updated, too. It should create an menu item which opens the user site directory in a new explorer windows. Backwards Compatibility ======================= TBD Open Questions ============== * Are the directories for Windows, Mac and Unix fine? * Mac: Should framework and non-framework builds of Python use the same directories? * The patch also adds a usecustomize hook to site. Is it useful and should it stay? Reference Implementation ======================== A reference implementation is available in the bug tracker. [4]_ Acknowledgments =============== The implementation of this PEP, if accepted, is sponsored by Google through the Google Summer of Code program. Copyright ========= This document has been placed in the public domain. References ========== .. [1] Virtual Python http://peak.telecommunity.com/DevCenter/EasyInstall#creating-a-virtual-pyth… .. [2] Working Env http://pypi.python.org/pypi/workingenv.py http://blog.ianbicking.org/workingenv-revisited.html .. [3] Virtual Env http://pypi.python.org/pypi/virtualenv .. [4] reference implementation http://bugs.python.org/issue1799 .. [5] MSDN: CSIDL http://msdn2.microsoft.com/en-us/library/bb762494.aspx .. [6] Initial suggestion for a per user site-packages directory http://permalink.gmane.org/gmane.comp.python.devel/90902 .. [7] Suggestion of ~/.local/ http://permalink.gmane.org/gmane.comp.python.devel/90925 .. [8] APPDATA discussion http://permalink.gmane.org/gmane.comp.python.devel/90932 .. Local Variables: mode: indented-text indent-tabs-mode: nil sentence-end-double-space: t fill-column: 70 coding: utf-8 End: [View Less]

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Rational approximation methods
by Jeffrey Yasskin Jan. 23, 2008

Jan. 23, 2008

In the Rational class that I've recently checked into Python 2.6 (http://bugs.python.org/issue1682), it might be nice to provide a method that, given a particular rational number, returns a nearby number that's nicer in some way. I know of two reasonable behaviors for this operation. Since I don't know which is likely to be more useful, or even if either is useful enough to include in the first version of the module, I'm coming to you guys for advice. Both were implemented a while ago in http://… [View More]

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Re: [Python-Dev] misbehaving __contains__
by Raymond Hettinger Jan. 23, 2008

Jan. 23, 2008

[Daniel Stutzbach] > There are many places in the C implementation where a slot > returns an int rather than a PyObject. There other replies > in this thread seem to support altering the signature of the > slot to return a PyObject. Is this setting a precedent that > _all_ slots should return a PyObject? I hope not. One cost of these hypergeneralizations is that it makes Python slower. Also, it makes it harder to write code when you can no longer count on simple … [View More]

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misbehaving __contains__
by tomer filiba Jan. 23, 2008

Jan. 23, 2008

i'm using python to create expression objects, for more intuitive usage as predicates, for instance: x = (Arg(0) > 17) & (Arg(1).foo == "bar") instead of x = And(Gt(Arg(0), 17), Eq(GetAttr(Arg(1), "foo"), "bar")) so now i can use x.eval(18, "spam") and get the result of the expression. i'm doing it by overriding all the operators to return expression objects, instead of evaluating the result immediately. it works fine, but i encountered a problem with making __contains__ behave … [View More]

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Bug Day outcome
by A.M. Kuchling Jan. 21, 2008

Jan. 21, 2008

Today's bug day was a great success. Experienced people like Georg, Facundo, and Gregory P. Smith participated, and we also had people who submitted their first patches, some of which got applied today, too. Hopefully we'll see those people again. As of this writing, 37 issues were closed today, leaving 1300 open. (I saved a search in Roundup to list the bugs closed today.) --amk

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Monkeypatching idioms -- elegant or ugly?
by Guido van Rossum Jan. 21, 2008

Jan. 21, 2008

I ran into the need of monkeypatching a large number of classes (for what I think are very good reasons :-) and invented two new recipes. These don't depend on Py3k, and the second one actually works all the way back to Python 2.2. Neither of these allows monkeypatching built-in types like list. If you don't know what monkeypatching is, see see http://en.wikipedia.org/wiki/Monkey_patch. I think it's useful to share these recipes, if only to to establish whether they have been discovered before,… [View More]

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PyCon 2008 Registration Open!
by David Goodger Jan. 21, 2008

Jan. 21, 2008

I am pleased to announce that PyCon 2008 registration is now open! http://us.pycon.org/2008/registration/ Early-bird registration is open until February 20, so there's one month to register at the low rates. Regular on-line registration will be available from February 21 through March 7. PyCon 2008 will be held from March 13 through 20 in Chicago: * Tutorials: Thursday, March 13 * Conference: Friday, March 14, through Sunday, March 16 * Sprints: Monday, March 17 through Thursday, … [View More]

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