Mailman 3 January 2009 - Python-Dev

FINAL REMINDER: OSCON 2009: Call For Participation
by Aahz Jan. 31, 2009

Jan. 31, 2009

The O'Reilly Open Source Convention has opened up the Call For Participation -- deadline for proposals is Tuesday Feb 3. OSCON will be held July 20-24 in San Jose, California. For more information, see http://conferences.oreilly.com/oscon http://en.oreilly.com/oscon2009/public/cfp/57 -- Aahz (aahz(a)pythoncraft.com) <*> http://www.pythoncraft.com/ Weinberg's Second Law: If builders built buildings the way programmers wrote programs, then the first woodpecker that … [View More]

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Universal newlines, and the gzip module.
by Christopher Barker Jan. 31, 2009

Jan. 31, 2009

Hi all, Over on the matplotlib mailing list, we ran into a problem with trying to use Universal newlines with gzip. In virtually all of my code that reads text files, I use the 'U' flag to open files, it really helps not having to deal with newline issues. Yes, they are fewer now that the Macintosh uses \n, but they can still be a pain. Anyway, we added such support to some matplotlib methods, and found that gzip file reading broken We were passing the flags though into either file() or … [View More]

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Partial function application 'from the right'
by Ben North Jan. 31, 2009

Jan. 31, 2009

Hi, > [ Potential new "functools.partial_right", e.g., > > split_comma = partial_right(str.split, '.') > ] Thanks for the feedback. Apologies if (as was suggested) this should have gone to python-ideas; I thought as a fairly small extension to existing functionality it would be OK here. I'll try to summarise the responses. There was some very luke-warm support. Terry Reedy suggested it would be worth posting a patch to the tracker, for the record, even if it turns out to … [View More]be rejected. Nick Coghlan made more clear than I did the main reason a 'partial_right' would be useful: > [...] some functions and methods written in C (such as string methods) > *don't* [support keyword args], so partial's keyword support doesn't > help. > > A functools.rpartial would go some way towards addressing that. On the other hand, Collin Winter asked for more evidence that real benefit (beyond mere 'completeness' of the functools module) would result. I don't really have to hand anything more than the three cases mentioned in my original email (str.split, math.log, itertools.islice), but since the change is so small, I thought the feature worth raising. Leif Walsh pointed out that you could achieve the same effect by defining your own function. This is true, but functools.partial exists because it's sometimes useful to create such functions either more concisely, or anonymously. A 'partial_right' would allow more such functions to be so created. Peter Harris was negative on the idea, pointing out that after g = partial_right(f, 7) you don't know which argument of 'f' the '7' is going to end up as, because it depends on how many are supplied in the eventual call to 'g'. This is true, and would require some care in partial_right's use. Peter also wondered > There's probably a reason why Haskell doesn't do this... I have only written about five lines of Haskell in my life, so take this with a hefty pinch of salt, but: Haskell does have a 'flip' function which reverses the order of a function's arguments, so it looks like you can very easily build a 'partial_right' in Haskell, especially since standard functions are in curried form. There was some discussion (started by Antoine Pitrou) of an idea to generalise 'partial' further, potentially using the Ellipsis object, to allow arbitrarily-placed 'holes' in the argument list. E.g., split_comma = partial(str.split, ..., ',') In some ways I quite like the even-more-completeness of this idea, but think that it might be the wrong side of the complexity/benefit trade-off. Scott David Daniels pointed out that using Ellipsis would have the downside of > [...] preventing any use of partial when an argument could be an the > Ellipsis instance. This could be fixed by making the general form be something with the meaning partial_explicit(f, hole_sentinel, *args, **kwargs) where appearances of the exact object 'hole_sentinel' in 'args' would indicate a hole, to be filled in at the time of the future call. A user wanting to have '...' passed in as a true argument could then do g = partial_explicit(f, None, 3, ..., 4, axis = 2) or hole = object() g = partial_explicit(f, hole, 3, ..., hole, 4, axis = 2) if they wanted a true '...' argument and a hole. (I might have the syntax for this wrong, having not played with Python 3.0, but I hope the idea is clear.) There was some concern expressed (by Daniel Stutzbach, Alexander Belopolsky) that the meaning of '...' would be confusing --- 'one hole' or 'arbitrary many holes'? I think the extra complexity vs extra functionality trade-off is worth considering for 'partial_right', but my personal opinion is that a 'partial_explicit' has that trade-off the wrong way. I'll try to find time to create the patch in the tracker in the next few days, by which time perhaps it'll have become clearer whether the idea is a good one or not. Thanks, Ben. [View Less]

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Re: [Python-Dev] Partial function application 'from the right'
by scav＠blueyonder.co.uk Jan. 31, 2009

Jan. 31, 2009

Hi all, > On Thu, Jan 29, 2009 at 6:12 AM, Ben North <ben(a)redfrontdoor.org> wrote: >> Hi, >> >> I find 'functools.partial' useful, but occasionally I'm unable to use it >> because it lacks a 'from the right' version. > -1 For me, the main objection to a partial that places its stored positional arguments from the right is that you don't know which positions those arguments will actually occupy until the partial is called. Who *really* thinks that would … [View More]

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Summary of Python tracker Issues
by Python tracker Jan. 31, 2009

Jan. 31, 2009

ACTIVITY SUMMARY (01/23/09 - 01/30/09) Python 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. 2352 open (+54) / 14582 closed (+20) / 16934 total (+74) Open issues with patches: 788 Average duration of open issues: 697 days. Median duration of open issues: 6 days. Open Issues Breakdown open 2328 (+53) pending 24 ( +1) Issues Created Or Reopened (74) … [View More]

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Re: [Python-Dev] Python 3.0.1
by Nick Efford Jan. 30, 2009

Jan. 30, 2009

> Paul Moore <p.f.moore(a)gmail.com> wrote: > > Serious question: does anybody know how to get better communication > from the user base? My impression is that it's pretty hard to find out > who is actually using 3.0, and get any feedback from them. I suppose a > general query on clp might get some feedback, but otherwise, what? > I've not seen any significant amount of blog activity on 3.0. I teach programming in a CS dept. at a UK university. We've been teaching … [View More]

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python breakpoint opcode
by Dr Andrew Perella Jan. 30, 2009

Jan. 30, 2009

Hi, I was thinking of adding a breakpoint opcode to python to enable less invasive debugging. I came across posts from 1999 by Vladimir Marangozov and Christian Tismer discussing this issue but the links to the code are all out of date. Did anything come of this? Is this a good approach to take? - if so why was this never incorporated? Cheers, Andrew Dr. Andrew Perella Chief Software Architect Eutechnyx Limited. Metro Centre East Business Park, Waterside Drive, Gateshead, Tyne &… [View More]

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Broken Test -- test_distutils
by Raymond Hettinger Jan. 30, 2009

Jan. 30, 2009

In the past couple of days, test_distutils started failing. It looks like a pure python error and may have been introduced by guilherme.polo's checkins: File "c:\py27\lib\distutils\tests\test_sdist.py", line 119, in test_make_distr ibution spawn('tar --help') File "c:\py27\lib\distutils\spawn.py", line 37, in spawn _spawn_nt(cmd, search_path, dry_run=dry_run) File "c:\py27\lib\distutils\spawn.py", line 70, in _spawn_nt cmd = _nt_quote_args(cmd) File "c:\py27\lib\… [View More]

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Include C++ code in the ctypes test suite?
by Thomas Heller Jan. 30, 2009

Jan. 30, 2009

I'm currently working on a patch that adds the __thiscall calling convention to ctypes. This calling convention is used on Windows for calling member functions from C++ classes. The idea is to eventually allow ctypes to wrap C++ classes. To test this functionality it is required to add some C++ source code to the ctypes private test module _ctypes_test.pyd/_ctypes_test.so. Is it appropriate to add C++ source files to the Python repository, or would that create too much trouble on some … [View More]

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Examples in Py2 or Py3
by Facundo Batista Jan. 29, 2009

Jan. 29, 2009

Hi! In the Python Argentina mail list there's already people passing examples and asking help about Python 3. This introduces the problem that some examples are in Py2 and others are in Py3. Sometimes this is not explicit, and gets confusing. I'm trying to avoid this confusion when preparing my own examples. So far, I use (py3) as a prefix for any example block, like: (Py3k) >>> (some example) (some result) Is there any recommended way to avoid confusion in these cases? (I'm … [View More]

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