[Python-Dev] python-dev Summary for 2004-02-01 through 2004-02-29 [rough draft] (original) (raw)

Brett C. bac at OCF.Berkeley.EDU
Mon Mar 8 17:10:41 EST 2004

OK, usual deal: read, correct, reply with flattery and expensive gifts. =)

Hope to get this out rather quickly (Wednesday night, perhaps?) so I can start on the next summary in hopes of getting back on to my semi-monthly habit.

I also left out the header since I figure most of you don't bother to read that part every time. If you actually do, just say so and I will make sure to continue to include it when I send out the rough draft.

===================== Summary Announcements

To continue my slight abuse of this space: I am still looking for a summer job or internship programming somewhere (does not have to be Python). If you happen to have something at your company or know of something somewhere that you think might work for me please email me at brett at python.org . Thanks.

OK, on from pimping myself out for the summer to pimping PyCon_ (or at least I think that is how the youngsters these days would phrase that sentence =). You can still register for the conference. The talks have been chosen and scheduled; more info at http://pycon.org/dc2004/talks/ . Talks look really great and cover a huge gamut of areas; bigger variety than last year in my opinion.

There is going to be a Stackless sprint in Berlin March 10-14. See the announcement email at http://mail.python.org/pipermail/python-dev/2004-February/042829.html .

.. _PyCon: http://www.pycon.org/

========= Summaries

Python 2.3 branch open for fixin'

Anthony Baxter, perpetual release manager for the 2.3 branch, announced that CVS commits for 2.3 were open again. He mentioned he thought another release around May or June would probably happen unless a severe bug came up the required immediate patching and release.

Contributing threads:

Early Spring cleaning for what platforms Python supports

Skip Montanaro cleaned up the configure.in script for Python and in the process removed old support for unneeded OSs as stated in PEP 11_. So SunOS 4 support is gone. There was discussion of making Python 2.4 not support libc 5 since Python does not compile with it. The suggestion was made of having configure.in detect libc 5 and if it found it then refuse to continue.

Skip also removed optional universal newline support and antiquated pthread variants from 1997 and before.

.. _PEP 11: http://python.org/peps/pep-0011.html

Contributing threads:

Compiling in profiling support for the interpreter

Jeremy Hylton discovered his old way of turning on gprof_ profiling support when compiling Python no longer worked. Hye-SHik Chang said he got it working by compiling using CC="cc -pg" LDFLAGS="-pg" ./configure. Martin v. Löwis suggested running configure with --without-cxx to get around the problem.

.. _gprof: http://www.cs.utah.edu/dept/old/texinfo/as/gprof_toc.html

Contributing threads:

Python and C89 play nicely together

The question of what version of C Python is required to work with came up. The answer is that C89 is the version of Standard C Python requires. C89 with Amendment 1 (also called C95) nor C99 are required for Python to run (which, in this case, meant wchar.h is not required).

Contributing threads:

Growing lists just got that much faster

Raymond Hettinger (along with the help of various other people on his initial patch) managed to come up with a way to speed up allocating space for list items (either from growth of an exisiting list or creation of a new list). The speed-up is great and at worst has a hit of 4 wasted bytes on platforms that use 8-byte alignment.

While this was being discussed, though, the possibility of 3rd party code messing with the internal values of list items came up. While no specific use-case was found, it was agreed upon that code outside of the Python core should not break the API; there is no guarantee the internals won't change.

Contributing threads:

Do we really need mutability for exceptions groups?

The question was raised as to why except (TypeError, ValueError): is acceptable while except [TypeError, ValueError]: (in other words why use tuples to group exceptions for an 'except' statement and not allow lists). The question was in relation as to whether it had something to do with a tuple's immutability.

Guido said it all had to do with a visual way of grouping tuples and nothing to do with what the underlying container was. If he had it to do over again he would rather change it so that except TypeError, ValueError: did the same thing as above. That change would alleviate the common error of expecting the above behavior using that syntax but instead getting the exception instance bound to ValueError. But the change is not planned for any time in the future since Guido has no proposal on how to change the syntax to handle the assignment to a local variable for the exception instance.

Contributing threads:

No, you can't subclass Bool

François Pinard discovered that you can't subclass the Bool type. This led to the question of "why?" To this he received the answer that since Bool only has two instance, True and False, it shouldn't be allowed to be a subclass of anything since that would suggest more instances of Bool could exist.

Contributing threads:

In case you don't know what the syntax is def fxn() [fun, stuff, here]: pass, which ends up being the same as::

def fxn(): pass fxn = here(stuff(fun(fxn)))

Common use cases are for defining class

The discussion then drifted in discussing how this syntax could even be used with classes and whether it could somehow supplant some metaclass uses. Talking seemed to lead to it not really being that great of a use case.

The order or application also came up. It was suggested that the order be the reversed of that shown above so that it reads the way it would be written by hand instead of in application order.

Using 'as' instead of brackets was brought up again; def fxn() as fun instead of def fxn() [fun]. An argument for this or any other syntax is that using brackets for this overloads the usage of them in Python itself and some feel that is unpythonic. An explicit argument for the brackets, though, is that it is cleaner for multi-line use. There was also the issue with using 'as' in terms of how would one look up its use in the docs? Would someone look up under 'as' or under 'def' naturally?

.. _PEP 318: http://python.org/peps/pep-0318.html .. _PyObjC: http://pyobjc.sourceforge.net/

Contributing threads:

Building Python with the free .NET SDK

Go to the email to see Garth's latest tool and instructions on building Python using Microsoft's free .NET SDK.

Contributing threads:

PEP 326 finished (but still rejected)

PEP 326_ ("A Case for Top and Bottom Values") has its final implementation linked from the PEP. It has been rejected, but the PEP's authors will nice enough to go ahead and finish the code for anyone who might want to use it anyway.

.. _PEP 326: http://python.org/peps/pep-0326.html

Contributing threads:

time.strftime() now checks its argument's bounds

Because of a possible crash from using negative values in the time tuple when passed to time.strftime(), it was decided to bound checks on all values in the time tuple. This will break existing code that naively set all fields to 0 in a passed-in time tuple and thus did not set the values within the proper bounds (year, month, day, and day of year should not be 0).

Contributing threads:

OpenVMS throws a fit over universal newlines

For Python 2.4 the option to compile without universal newline support was removed. Well, it turns out that OpenVMS_ doesn't like this. Apparently the OS is not stream-oriented for its filesystem but is records-based and this leads to there being no newlines in a text file unless it is opened as a plain file.

Bug #903339 has been opened to deal with this.

.. _Bug #903339: http://python.org/sf/903339

.. _OpenVMS: http://www.openvms.org/

Forth-style argument passing for C functions

Raymond Hettinger came up with the idea of adding a new function flag called METH_STACK that would call a C function to be called with a pointer to the execution stack and the number of arguments it is being passed. This would allow the function to pop off its arguments on its own and bypass the expense of putting them into a tuple.

The overall idea did not seem to win out. But it does turn out that Michael Hudson has a patch that implements a similar idea at http://python.org/sf/876193 . A discussion of whether more specific argument passing like METH_O should be considered.

Contributing threads:

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