python-dev Summary for 2005-05-16 through 2005-05-31
Steven Bethard
steven.bethard at gmail.com
Sun Jun 26 00:36:25 CEST 2005
[The HTML version of this Summary is available at
http://www.python.org/dev/summary/2005-05-16_2005-05-31.html]
=====================
Summary Announcements
=====================
----
QOTF
----
We have our first ever Quote of the Fortnight (QOTF), thanks to
the wave of discussion over `PEP 343`_ and Jack Diederich:
I still haven't gotten used to Guido's heart-attack inducing early
enthusiasm for strange things followed later by a simple
proclamation I like. Some day I'll learn that the sound of
fingernails on the chalkboard is frequently followed by candy for
the whole class.
See, even threads about anonymous block statements can end happily! ;)
.. _PEP 343: http://www.python.org/peps/pep-0343.html
Contributing thread:
- `PEP 343 - Abstract Block Redux
<http://mail.python.org/pipermail/python-dev/2005-May/053828.html>`__
[SJB]
------------------
First PyPy Release
------------------
The first release of `PyPy`_, the Python implementation of Python, is
finally available. The PyPy team has made impressive progress, and
the current release of PyPy now passes around 90% of the Python
language regression tests that do not depend deeply on C-extensions.
The PyPy interpreter still runs on top of a CPython interpreter
though, so it is still quite slow due to the double-interpretation
penalty.
.. _PyPy: http://codespeak.net/pypy
Contributing thread:
- `First PyPy (preview) release
<http://mail.python.org/pipermail/python-dev/2005-May/053964.html>`__
[SJB]
--------------------------------
Thesis: Type Inference in Python
--------------------------------
Brett C. successfully defended his masters thesis `Localized Type
Inference of Atomic Types in Python`_, which investigates some of the
issues of applying type inference to the current Python language, as
well as to the Python language augmented with type annotations.
Congrats Brett!
.. _Localized Type Inference of Atomic Types in Python:
http://www.drifty.org/thesis.pdf
Contributing thread:
- `Localized Type Inference of Atomic Types in Python
<http://mail.python.org/pipermail/python-dev/2005- May/053993.html>`__
[SJB]
=========
Summaries
=========
---------------------------
PEP 343 and With Statements
---------------------------
The discussion on "anonymous block statements" brought itself closer
to a real conclusion this fortnight, with the discussion around
`PEP 343`_ and `PEP 3XX`_ converging not only on the semantics for
"with statements", but also on semantics for using generators as
with-statement templates.
To aid in the adaptation of generators to with-statements, Guido
proposed adding close() and throw() methods to generator objects,
similar to the ones suggested by `PEP 325`_ and `PEP 288`_. The
throw() method would cause an exception to be raised at the point
where the generator is currently suspended, and the close() method
would use throw() to signal the generator to clean itself up by
raising a GeneratorExit exception.
People seemed generally happy with this proposal and -- believe it or
not -- we actually went an entire eight days without an email about
anonymous block statements!! It looked as if an updated `PEP 343`_,
including the new generator functionality, would be coming early the
next month. So stay tuned. ;)
.. _PEP 288: http://www.python.org/peps/pep-0288.html
.. _PEP 325: http://www.python.org/peps/pep-0325.html
.. _PEP 343: http://www.python.org/peps/pep-0343.html
.. _PEP 3XX: http://www.python.org/peps/pep-0346.html
Contributing threads:
- `PEP 343 - Abstract Block Redux
<http://mail.python.org/pipermail/python-dev/2005-May/053731.html>`__
- `Simpler finalization semantics (was Re: PEP 343 - Abstract Block
Redux) <http://mail.python.org/pipermail/python
-dev/2005-May/053812.html>`__
- `Example for PEP 343
<http://mail.python.org/pipermail/python-dev/2005-May/053855.html>`__
- `Combining the best of PEP 288 and PEP 325: generator exceptions and
cleanup <http://mail.python.org/pipermail/python-dev/2005-May/053885.html>`__
- `PEP 343 - New kind of yield statement?
<http://mail.python.org/pipermail/python-dev/2005-May/053905.html>`__
- `PEP 342/343 status?
<http://mail.python.org/pipermail/python-dev/2005-May/054007.html>`__
- `PEP 346: User defined statements (formerly known as PEP 3XX)
<http://mail.python.org/pipermail/python-dev/2005- May/054014.html>`__
[SJB]
-----------
Decimal FAQ
-----------
Raymond Hettinger suggested that a decimal FAQ would shorten the module's
learning curve, and drafted one. There were no objections, but few
adjustments (to the list, at least). Raymond will probably make the FAQ
available at some point.
Contributing thread:
- `Decimal FAQ <http://mail.python.org/pipermail/python-dev/2005-May/053982.html>`__
[TAM]
---------------------
Constructing Decimals
---------------------
A long discussion took place regarding whether the decimal constructor
should or should not respect context settings, and whether matching the
standard (and what the standard says) should be a priority. Raymond
Hettinger took the lead in the status-quo (does not) corner, with Tim
Peters leading the opposition. Tim and Guido eventually called in the
standard's expert, Mike Cowlishaw. He gave a very thorough explanation of
the history behind his decisions in this matter, and eventually weighed in
on Raymond's side. As such, it seems that the status-quo has won (not that
it was a competition, of course <wink>).
For those that need to know, the unary plus operation, as strange as it
looks, forces a rounding using the current context. As such, context-aware
construction can be written::
val = +Decimal(string_repr)
Contributing threads:
- `Adventures with Decimal
<http://mail.python.org/pipermail/python-dev/2005-May/053879.html>`__
- `Decimal construction
<http://mail.python.org/pipermail/python-dev/2005-May/053882.html>`__
- `[Python-checkins] python/nondist/peps pep-0343.txt, 1.8, 1.9
<http://mail.python.org/pipermail/python-dev/2005- May/053766.html>`__
[TAM]
------------------------
Handling old bug reports
------------------------
Facundo Batista continued with his progress checking the open bug reports,
looking for bugs that are specific to 2.2.1 or 2.2.2. The aim is to verify
whether these bugs exist in current CVS, or are old-of-date. There are no
longer any bugs in the 2.1.x or 2.2.x categories, and Facundo wondered
whether removing those categories would be a good idea. The consensus was
that there was no harm in leaving the categories there, but that changing
the text to indicate that those versions are unmaintained would be a good
idea.
Raymond Hettinger reminded us that care needs to be taken in closing old bug
reports. Particularly, a bug report should only be closed if (a) there are
no means of reproducing the error, (b) it is impossible to tell what the
poster meant, and they are no longer contactable, or (c) the bug is no
longer present in current CVS.
Contributing threads:
- `Deprecating old bugs, now from 2.2.2
<http://mail.python.org/pipermail/python-dev/2005-May/054019.html>`__
- `Closing old bugs
<http://mail.python.org/pipermail/python-dev/2005-May/054031.html>`__
- `Old Python version categories in Bug Tracker
<http://mail.python.org/pipermail/python-dev/2005- May/054020.html>`__
[TAM]
------------------
Exception chaining
------------------
Ka-Ping Yee has submitted `PEP 344`_, which is a concrete proposal for
exception chaining. It proposes three standard attributes on trackback
objects: __context__ for implicit chaining, __cause__ for explicit chaining,
and __traceback__ to point to the traceback. Guido likes the motivation
and rationale, but feels that the specification needs more work. A lot of
discussion about the specifics of the PEP took place, and Ka-Ping is
working these into a revised version.
One of the major questions was whether there is no need for both __context__
and __cause__ (to differentiate between explicit and implicit chaining).
Guido didn't feel that there was, but others disagreed.
Discussion branched off into whether which attributes should be
double-underscored, or not. Guido's opinion is that it depends who "owns"
the namespace, and with "magic" behaviour caused (or indicated) by the
presence of the attribute. He felt that the underscores in the proposed
exception attributes should remain.
.. _PEP 344: http://www.python.org/peps/pep-0344.html
Contributing threads:
- `PEP 344: Exception Chaining and Embedded Tracebacks
<http://mail.python.org/pipermail/python-dev/2005- May/053821.html>`__
- `PEP 344: Implicit Chaining Semantics
<http://mail.python.org/pipermail/python-dev/2005-May/053944.html>`__
- `PEP 344: Explicit vs. Implicit Chaining
<http://mail.python.org/pipermail/python-dev/2005-May/053945.html>`__
- `Tidier Exceptions
<http://mail.python.org/pipermail/python-dev/2005-May/053671.html>`__
[TAM]
------------------------------------
Adding content to exception messages
------------------------------------
Nicolas Fleury suggested that there should be a standard method of adding
information to an existing exception (to re-raise it). Nick Coghlan
suggested that this would be reasonably simple to do with PEP 344, if all
exceptions were also new-style classes, but Nicolas indicated that this
wouldn't work in some cases.
Contributing threads:
- `Adding content to exception messages
<http://mail.python.org/pipermail/python-dev/2005-May/053903.html>`__
[TAM]
===============
Skipped Threads
===============
- `Loading compiled modules under MSYS/MingGW?
<http://mail.python.org/pipermail/python-dev/2005-May/053769.html>`__
- `RFC: rewrite fileinput module to use itertools.
<http://mail.python.org/pipermail/python-dev/2005-May/053820.html>`__
- `Multiple interpreters not compatible with current thread module
<http://mail.python.org/pipermail/python-dev/2005-May/053840.html>`__
- `Weekly Python Patch/Bug Summary
<http://mail.python.org/pipermail/python-dev/2005-May/053875.html>`__
- `Request for dev permissions
<http://mail.python.org/pipermail/python-dev/2005-May/053877.html>`__
- `python-dev Summary for 2005-05-01 through 2005-05-15 [draft]
<http://mail.python.org/pipermail/python-dev/2005-May/053916.html>`__
- `AST manipulation and source code generation
<http://mail.python.org/pipermail/python-dev/2005-May/053991.html>`__
- `Weekly Python Patch/Bug Summary
<http://mail.python.org/pipermail/python-dev/2005-May/054000.html>`__
- `AST branch patches (was Re: PEP 342/343 status?)
<http://mail.python.org/pipermail/python-dev/2005-May/054009.html>`__
- `[Python-checkins] python/dist/src/Lib/test test_site.py, 1.6, 1.7
<http://mail.python.org/pipermail/python-dev/2005-May/054011.html>`__
- `Split MIME headers into multiple lines near a space
<http://mail.python.org/pipermail/python-dev/2005-May/054015.html>`__
========
Epilogue
========
------------
Introduction
------------
This is a summary of traffic on the `python-dev mailing list`_ from
May 16, 2005 through May 31, 2005.
It is intended to inform the wider Python community of on-going
developments on the list on a semi-monthly basis. An archive_ of
previous summaries is available online.
An `RSS feed`_ of the titles of the summaries is available. You can
also watch comp.lang.python or comp.lang.python.announce for new
summaries (or through their email gateways of python-list or
python-announce, respectively, as found at http://mail.python.org).
This is the fourth summary written by the python-dev summary cabal of
Steve Bethard, Tim Lesher, and Tony Meyer.
To contact us, please send email:
- Steve Bethard (steven.bethard at gmail.com)
- Tim Lesher (tlesher at gmail.com)
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Do *not* post to comp.lang.python if you wish to reach us.
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--------------------
Commenting on Topics
--------------------
To comment on anything mentioned here, just post to
`comp.lang.python`_ (or email python-list at python.org which is a
gateway to the newsgroup) with a subject line mentioning what you are
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-------------------------
How to Read the Summaries
-------------------------
The in-development version of the documentation for Python can be
found at http://www.python.org/dev/doc/devel/ and should be used when
looking up any documentation for new code; otherwise use the current
documentation as found at http://docs.python.org/ . PEPs (Python
Enhancement Proposals) are located at http://www.python.org/peps/ .
To view files in the Python CVS online, go to
http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/python/ . Reported
bugs and suggested patches can be found at the SourceForge_ project
page.
Please note that this summary is written using reStructuredText_. Any
unfamiliar punctuation is probably markup for reST_ (otherwise it is
probably regular expression syntax or a typo =); you can safely ignore
it. I do suggest learning reST, though; it's simple and is accepted
for `PEP markup`_ and can be turned into many different formats like
HTML and LaTeX. Unfortunately, even though reST is standardized, the
wonders of programs that like to reformat text do not allow me to
guarantee you will be able to run the text version of this summary
through Docutils_ as-is unless it is from the `original text file`_.
.. _python-dev: http://www.python.org/dev/
.. _SourceForge: http://sourceforge.net/tracker/?group_id=5470
.. _python-dev mailing list: http://mail.python.org/mailman/listinfo/python-dev
.. _c.l.py:
.. _comp.lang.python: http://groups.google.com/groups?q=comp.lang.python
.. _PEP Markup: http://www.python.org/peps/pep-0012.html
.. _Docutils: http://docutils.sf.net/
.. _reST:
.. _reStructuredText: http://docutils.sf.net/rst.html
.. _PSF:
.. _Python Software Foundation: http://python.org/psf/
.. _last summary: http://www.python.org/dev/summary/
.. _original text file:
http://www.python.org/dev/summary/2005-05-16_2005-05-31.ht
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