Mailman 3 March 2010 - Python-Dev

Matching multiple regexes
by MRAB 03 Mar '10

03 Mar '10

I've thought of a possible additional feature for my regex module and I'm looking for opinions. Occasionally there's a question about matching multiple regexes and someone might suggest combining them into one regex using "|". The feature would be to allow regex.compile, etc, to accept a list or tuple of regex strings. These would be combined into a single regex internally. The match object would get a new attribute .index which would give the index of the regex string which matched. An additional feature could be to allow regex.sub to accept as a replacement any object which has the __getitem__ method and call that method with the match index, if multiple regexes were used. (A replacement string would still behave the same.) This could mean that the following code would become possible: >>> subs = [("foo", "bar"), ("baz", "quux"), ("quuux", "foo")] >>> old_string, new_string = zip(*subs) >>> s = "fooxxxbazyyyquuux" >>> regex.sub(old_string, new_string, s) "barxxxquuxyyyfoo"

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Deprecation warnings in Python 2.7
by Florent Xicluna 03 Mar '10

03 Mar '10

Hello, I would like to open a discussion on the meaning of deprecation warnings in 2.7. I assume, but I may be wrong, that 2.7 will be the last version in the 2.x branch. With this assumption, we should not find many things deprecated in 2.7 final. On the other hand, the list of py3k deprecation warnings is increasing a lot. And more users will probably start to move from 2.7 to the 3.1 release. While working on ticket #7092 and #7849, we started to discuss some proposals to simplify the deprecation warnings for 2.7. We discussed these 2 proposals: 1) in 2.6 there's no distinction between py3k and normal deprecations: they share the same category, DeprecationWarning. The "-3" switch enables the py3k DeprecationWarning and SyntaxWarning. Do we need to introduce a subclass Py3kDeprecationWarning in 2.7? It will make it easier to separate both kinds of deprecations (2.x and 3.x), and to filter them. 2) a different idea is to deprecate the "-3" switch and consider all py3k deprecations as normal deprecations. They will be hidden by default thanks to #7309. Since there's no future for the 2.x branch, it seems normal to consider the migration from 2.7 to 3.1 and show these warnings when the developer uses "-Wd" switch. What do you expect as DeprecationWarning in 2.7? I will post a list of the DeprecationWarnings in the python trunk, in a followup message, for a review, and to help the discussion. Best regards, -- Florent Xicluna

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PEP 3188: Implementation Questions
by Meador Inge 03 Mar '10

03 Mar '10

Hi All, Recently some discussion began in the issue 3132 thread ( http://bugs.python.org/issue3132) regarding implementation of the new struct string syntax for PEP 3118. Mark Dickinson suggested that I bring the discussion on over to Python Dev. Below is a summary of the questions\comments from the thread. Unpacking a long-double =================== 1. Should this return a Decimal object or a ctypes 'long double'? 2. Using ctypes 'long double' is easier to implement, but precision is lost when needing to do arithmetic, since the value for cytpes 'long double' is converted to a Python float. 3. Using Decimal keeps the desired precision, but the implementation would be non-trivial and architecture specific (unless we just picked a fixed number of bytes regardless of the architecture). 4. What representation should be used for standard size and alignment? IEEE 754 extended double precision? Pointers ====== 1. What is a specific pointer? For example, is '&d' is a pointer to a double? 2. How would unpacking a pointer to a Python Object work out? Given an address how would the appropriate object to be unpacked be determined? 3. Can pointers be nested, e.g. '&&d' ? 4. For the 'X{}' format (pointer to a function), is this supposed to mean a Python function or a C function? String Syntax ========== The syntax seems to have transcended verbal description. I think we need to put forth a grammar. There are also some questions regarding nesting levels and mixing specifiers that could perhaps be answered more clearly by having a grammar: 1. What nesting level can structures have? Arbitrary? 2. The new array syntax claims "multi-dimensional array of whatever follows". Truly whatever? Arrays of structures? Arrays of pointers? 3. How do array specifiers and pointer specifiers mix? For example, would '(2, 2)&d' be a two-by-two array of pointers to doubles? What about '&(2, 2)d'? Is this a pointer to an two-by-two array of doubles? An example grammar is contained in a diff against the PEP attached to this mail. NOTE: I am *not* actually submitting a patch against the PEP. This was just the clearest way to present the example grammar. Use Cases ======== 1. What are the real world use cases for these struct string extensions? These should be fleshed out and documented. -- Meador

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ElementTree.tostring() returning str by default in Py3.2
by Stefan Behnel 03 Mar '10

03 Mar '10

Hi, I just noticed that the xml.etree.ElementTree.tostring() function in Py3.2 returns a str object by default, unless an encoding is specified. This is a backwards incompatible change compared to ET 1.2. For one, it breaks tons of tests in lxml's compatibility test suite. Previously, the default encoding was 'ASCII', and tostring() was guaranteed to always return a byte string. According to svn blame, this was changed by GvR in rev. 56841. Is there any reasoning behind this? Stefan

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Python 2.6.5 release candidate 1 now available
by Barry Warsaw 03 Mar '10

03 Mar '10

Hello everyone, The source tarballs and Windows installer for Python 2.6.5 release candidate 1 are now available: http://www.python.org/download/releases/2.6.5/ Please download them, install them, and try to use them with your favorite projects and environments. If no regressions are found, we will do the final release on Monday March 15, 2010. Please test the release candidate as much as possible in the meantime, and help make 2.6.5 a rock solid release! Thanks, -Barry P.S. The Mac installer will hopefully be available soon.

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Packaging JIT-less versions of Python
by Collin Winter 03 Mar '10

03 Mar '10

Hey packaging guys, We recently committed a change to Unladen Swallow [1] that moves all the JIT infrastructure into a Python extension module. The theory [2] behind this patch was that this would make it easier for downstream packagers to ship a JIT-less Python package, with the JIT compiler available via an optional add-on package. Some questions for you, so we're not shooting blind here: - Have you guys thought about how a JIT-enabled Python 3 installation would be packaged by your respective distros? - Would you prefer the default python3.x package to have a JIT, or would you omit the JIT by default? - How would you prefer to build the JIT-less package (current options: via a ./configure flag; or by deleting _llvmjit.so from the JIT-enabled package)? - Would the two packages be able to exist side-by-side, or would they be mutually exclusive? My strong preference would be to have the JIT included by default so that it receives as much testing as possible. Thanks, Collin Winter [1] - http://code.google.com/p/unladen-swallow/source/detail?r=1110 [2] - http://code.google.com/p/unladen-swallow/issues/detail?id=136

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Python and Windows 2000
by "Martin v. Löwis" 02 Mar '10

02 Mar '10

I don't recall whether we have already decided about continued support for Windows 2000. If not, I'd like to propose that we phase out that support: the Windows 2.7 installer should display a warning; 3.2 will stop supporting Windows 2000. Opinions? Regards, Martin

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Status of PEP 381
by Jacob Kaplan-Moss 01 Mar '10

01 Mar '10

Hey folks -- Can someone point me to some information on what's going on with PEP 381 (PyPI mirroring)? There's a bunch of XXX'd material, and it doesn't appear that pypi.python.org implements the statistics or providing parts. I'd be willing -- happy, actually -- to fill in the missing pieces, but only if I'm not stepping on anyone's toes. I'd also need some help adding code to pypi.python.org if that's a necessary part -- I'm not very good at finding my way around that codebase. Thanks, Jacob

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Who needs to be added to python-committers?
by Brett Cannon 01 Mar '10

01 Mar '10

Any people who have commit privileges not subscribed to python-committers? We have gained some new people recently so I just want to make sure everyone is subscribed to the list. Also, anyone have an email address for Hirokazu Yamamoto? His mailbox is full so Mailman unsubscribed him. -Brett

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Draft PEP on RSON configuration file format
by Patrick Maupin 01 Mar '10

01 Mar '10

All: Finding .ini configuration files too limiting, JSON and XML to hard to manually edit, and YAML too complex to parse quickly, I have started work on a new configuration file parser. I call the new format RSON (for "Readable Serial Object Notation"), and it is designed to be a superset of JSON. I would love for it to be considered valuable enough to be a part of the standard library, but even if that does not come to pass, I would be very interested in feedback to help me polish the specification, and then possibly help for implementation and testing. The documentation is in rst PEP form, at: http://rson.googlecode.com/svn/trunk/doc/draftpep.txt Thanks and best regards, Pat

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