Mailman 3 March 2009 - Python-Dev

"How to Contribute to Python" doc now online
by Brett Cannon March 23, 2009

March 23, 2009

In preparation for Pycon and the sprints I quickly pulled together a doc explaining how people can help out with Python's development: http://www.python.org/dev/contributing/ . -Brett P.S.: Just so people know, I will be taking a month or two off from Python development (i.e. heavy coding) after PyCon to redo my father's web site and simply to take a slight breather after all the importlib stuff. Plan to keep plugging away at the DVCS PEP, though.

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issue 2170 review
by R. David Murray March 23, 2009

March 23, 2009

Instead of looking at a bunch of issues last week the way I'd originally intended, I wound up doing a review of a particular patch submission, issue 2170. This is a refactoring of the 'normalize' method of xml.dom.minidom. I wound up redoing the patch with a different refactoring after finding out that the submitted patch was slower than the original code. The revised patch is faster than the original code (completes in 1/2 the time of the original code when run on a decent sized document that needed no normalization done). I think the issue stage should be set to 'patch review', as in, it is ready for developer review. The author of the original patch has reviewed my revised patch and concurs. The patch includes additional tests. Now that I've learned more about how the tracker is organized, and read the most-helpful http://www.python.org/dev/workflow/ document, I would be happy to go through and triage issues for which that hasn't yet been done, if I can be given permission to do so. -- R. David Murray http://www.bitdance.com

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Core projects for Summer of Code
by average March 23, 2009

March 23, 2009

> Summer of Code is ramping up. Every year the common complaint is that not > enough Python core projects get proposed by students, and of course a big > reason for that is often the only encouragement we offer prospective > students is a link to the PEP index. > > The challenge is finding project ideas for them that could reasonably occupy > them for the entire Summer and which the results of their work can be > demonstrated. They're being paid for specific projects so "Spend the Summer > fixing bugs on the tracker" is a no-go, and Google has outlined that Summer > of Code is about code, not documentation. Improve doctest by allowing it to be aware of nested test scopes such that a variable defined at "class-level scope" (i.e. the variable b defined at the class-level doctest """>>> b=Bag("abacab")""") can be used in "method-level scopes" without re-defining it every time for each method's doctest (each method would reset the given variable (if used) to its original state rather than live mutated between equal-level scopes). Would be a great improvement for doctest in my opinion--both in ease-of-use, and reduction of redundant, error-prone ("did you define your test variable the same in each method?") code)--as well as other benefits. Appreciate any consideration... marcos

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Re: [Python-Dev] PEP 380 (yield from a subgenerator) comments
by R. David Murray March 22, 2009

March 22, 2009

On Sun Mar 22 09:11:29 CET 2009 Greg Ewing wrote: > As for confusion, we ignore the return values of function > calls all the time, without worrying that someone might be > confused by the fact that their return value doesn't go > anywhere. And that's the right way to think of a yield-from > expression -- as a kind of function call, not a kind of yield. > > If there's anything confusing, it's the presence of the > word 'yield'. Its only virtue is that it gives a clue that > the construct has something to do with generators, but > you'll have to RTM to find out exactly what. Nobody has > thus far suggested any better name, however. The PEP doesn't seem to contain a list of unacceptable names and reasons in the section where the problem with the name is mentioned. So I wonder why the obvious 'delegate to' is not acceptable? (Because adding a keyword would make it less likely to be accepted?) -- R. David Murray http://www.bitdance.com

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PEP 377 - allow __enter__() methods to skip the statement body
by Nick Coghlan March 21, 2009

March 21, 2009

PEP 377 is a proposal to allow context manager __enter__() methods to skip the body of the with statement by raising a specific (new) flow control exception. Since there is a working reference implementation now, I thought it was time to open it up for broader discussion. Full PEP attached, or you can find it in the usual place at http://www.python.org/dev/peps/pep-0377 Cheers, Nick. P.S. I expect a rationale for the StatementSkipped value binding is probably going to be pretty high on the list of questions that aren't currently covered by the PEP. I hope to write more on that some time this week. -- Nick Coghlan | ncoghlan(a)gmail.com | Brisbane, Australia --------------------------------------------------------------- PEP: 377 Title: Allow __enter__() methods to skip the statement body Version: $Revision: 70384 $ Last-Modified: $Date: 2009-03-15 22:48:49 +1000 (Sun, 15 Mar 2009) $ Author: Nick Coghlan <ncoghlan(a)gmail.com> Status: Draft Type: Standards Track Content-Type: text/x-rst Created: 8-Mar-2009 Python-Version: 2.7, 3.1 Post-History: 8-Mar-2009 Abstract ======== This PEP proposes a backwards compatible mechanism that allows ``__enter__()`` methods to skip the body of the associated ``with`` statement. The lack of this ability currently means the ``contextlib.contextmanager`` decorator is unable to fulfil its specification of being able to turn arbitrary code into a context manager by moving it into a generator function with a yield in the appropriate location. One symptom of this is that ``contextlib.nested`` will currently raise ``RuntimeError`` in situations where writing out the corresponding nested ``with`` statements would not [1]. The proposed change is to introduce a new flow control exception ``SkipStatement``, and skip the execution of the ``with`` statement body if ``__enter__()`` raises this exception. Proposed Change =============== The semantics of the ``with`` statement will be changed to include a new ``try``/``except``/``else`` block around the call to ``__enter__()``. If ``SkipStatement`` is raised by the ``__enter__()`` method, then the main section of the ``with`` statement (now located in the ``else`` clause) will not be executed. To avoid leaving the names in any ``as`` clause unbound in this case, a new ``StatementSkipped`` singleton (similar to the existing ``NotImplemented`` singleton) will be assigned to all names that appear in the ``as`` clause. The components of the ``with`` statement remain as described in PEP 343 [2]:: with EXPR as VAR: BLOCK After the modification, the ``with`` statement semantics would be as follows:: mgr = (EXPR) exit = mgr.__exit__ # Not calling it yet try: value = mgr.__enter__() except SkipStatement: VAR = StatementSkipped # Only if "as VAR" is present and # VAR is a single name # If VAR is a tuple of names, then StatementSkipped # will be assigned to each name in the tuple else: exc = True try: try: VAR = value # Only if "as VAR" is present BLOCK except: # The exceptional case is handled here exc = False if not exit(*sys.exc_info()): raise # The exception is swallowed if exit() returns true finally: # The normal and non-local-goto cases are handled here if exc: exit(None, None, None) With the above change in place for the ``with`` statement semantics, ``contextlib.contextmanager()`` will then be modified to raise ``SkipStatement`` instead of ``RuntimeError`` when the underlying generator doesn't yield. Rationale for Change ==================== Currently, some apparently innocuous context managers may raise ``RuntimeError`` when executed. This occurs when the context manager's ``__enter__()`` method encounters a situation where the written out version of the code corresponding to the context manager would skip the code that is now the body of the ``with`` statement. Since the ``__enter__()`` method has no mechanism available to signal this to the interpreter, it is instead forced to raise an exception that not only skips the body of the ``with`` statement, but also jumps over all code until the nearest exception handler. This goes against one of the design goals of the ``with`` statement, which was to be able to factor out arbitrary common exception handling code into a single context manager by putting into a generator function and replacing the variant part of the code with a ``yield`` statement. Specifically, the following examples behave differently if ``cmB().__enter__()`` raises an exception which ``cmA().__exit__()`` then handles and suppresses:: with cmA(): with cmB(): do_stuff() # This will resume here without executing "do_stuff()" @contextlib.contextmanager def combined(): with cmA(): with cmB(): yield with combined(): do_stuff() # This will raise a RuntimeError complaining that the context # manager's underlying generator didn't yield with contextlib.nested(cmA(), cmB()): do_stuff() # This will raise the same RuntimeError as the contextmanager() # example (unsurprising, given that the nested() implementation # uses contextmanager()) # The following class based version shows that the issue isn't # specific to contextlib.contextmanager() (it also shows how # much simpler it is to write context managers as generators # instead of as classes!) class CM(object): def __init__(self): self.cmA = None self.cmB = None def __enter__(self): if self.cmA is not None: raise RuntimeError("Can't re-use this CM") self.cmA = cmA() self.cmA.__enter__() try: self.cmB = cmB() self.cmB.__enter__() except: self.cmA.__exit__(*sys.exc_info()) # Can't suppress in __enter__(), so must raise raise def __exit__(self, *args): suppress = False try: if self.cmB is not None: suppress = self.cmB.__exit__(*args) except: suppress = self.cmA.__exit__(*sys.exc_info()): if not suppress: # Exception has changed, so reraise explicitly raise else: if suppress: # cmB already suppressed the exception, # so don't pass it to cmA suppress = self.cmA.__exit__(None, None, None): else: suppress = self.cmA.__exit__(*args): return suppress With the proposed semantic change in place, the contextlib based examples above would then "just work", but the class based version would need a small adjustment to take advantage of the new semantics:: class CM(object): def __init__(self): self.cmA = None self.cmB = None def __enter__(self): if self.cmA is not None: raise RuntimeError("Can't re-use this CM") self.cmA = cmA() self.cmA.__enter__() try: self.cmB = cmB() self.cmB.__enter__() except: if self.cmA.__exit__(*sys.exc_info()): # Suppress the exception, but don't run # the body of the with statement either raise SkipStatement raise def __exit__(self, *args): suppress = False try: if self.cmB is not None: suppress = self.cmB.__exit__(*args) except: suppress = self.cmA.__exit__(*sys.exc_info()): if not suppress: # Exception has changed, so reraise explicitly raise else: if suppress: # cmB already suppressed the exception, # so don't pass it to cmA suppress = self.cmA.__exit__(None, None, None): else: suppress = self.cmA.__exit__(*args): return suppress There is currently a tentative suggestion [3] to add import-style syntax to the ``with`` statement to allow multiple context managers to be included in a single ``with`` statement without needing to use ``contextlib.nested``. In that case the compiler has the option of simply emitting multiple ``with`` statements at the AST level, thus allowing the semantics of actual nested ``with`` statements to be reproduced accurately. However, such a change would highlight rather than alleviate the problem the current PEP aims to address: it would not be possible to use ``contextlib.contextmanager`` to reliably factor out such ``with`` statements, as they would exhibit exactly the same semantic differences as are seen with the ``combined()`` context manager in the above example. Performance Impact ================== Implementing the new semantics makes it necessary to store the references to the ``__enter__`` and ``__exit__`` methods in temporary variables instead of on the stack. This results in a slight regression in ``with`` statement speed relative to Python 2.6/3.1. However, implementing a custom ``SETUP_WITH`` opcode would negate any differences between the two approaches (as well as dramatically improving speed by eliminating more than a dozen unnecessary trips around the eval loop). Reference Implementation ======================== Patch attached to Issue 5251 [1]. That patch uses only existing opcodes (i.e. no ``SETUP_WITH``). Acknowledgements ================ James William Pye both raised the issue and suggested the basic outline of the solution described in this PEP. References ========== .. [1] Issue 5251: contextlib.nested inconsistent with nested with statements (http://bugs.python.org/issue5251) .. [2] PEP 343: The "with" Statement (http://www.python.org/dev/peps/pep-0343/) .. [3] Import-style syntax to reduce indentation of nested with statements (http://mail.python.org/pipermail/python-ideas/2009-March/003188.html) Copyright ========= This document has been placed in the public domain. .. Local Variables: mode: indented-text indent-tabs-mode: nil sentence-end-double-space: t fill-column: 70 End:

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Re: [Python-Dev] Proposal: new list function: pack
by Hrvoje Niksic March 21, 2009

March 21, 2009

Isaac Morland wrote: >> I propose this because i need a lot of times pack and slide function >> over list and this one >> combine the two in a generator way. I've written functions with a subset of this functionality on more than one occasion. Having it in itertools looks like it would be useful to a lot of people. > See the Python documentation for zip(): > > http://docs.python.org/library/functions.html#zip zip can be used to achieve this purpose, but only with serious itertools-fu. If I want to iterate over a list [1, 2, 3, 4] looking at pairs (1, 2) and (3, 4), it would be much nicer to write: for a, b in itertools.pack(l, 2): ... than for a, b in itertools.izip(*[iter(l)]*2): ... which is what the zip documentation proposes. The former would be clear to anyone looking at the documentation of "pack" (and maybe even without it if we choose a better name), while the latter requires quite some deciphering, followed by carefully looking at izip's documentation that it's actually legal to rely on argument evaluation order and not peeking at iterables, like that code does. izip is not the only contender for this pattern; something similar is possible using groupby, but it's hard to make it fit in an easily understable line either. This is the shortest I came up with: def pack(iterable, n): cycler = (i for i in itertools.count() for j in xrange(n)) return (g for k, g in itertools.groupby(iterable, lambda x: cycler.next())) This has the nice property that it returns iterables rather than tuples, although tuples are probably good enough (they seem to be good enough for izip). The name "pack" is a bit too cryptic, even by itertools standards, so it might be better to choose a name that conveys the intention of returning "groups of n adjacent elements" (group_adjacent?). To fit with the rest of itertools, and to be really useful, the function shouldn't insist on sequences, but should accept any iterable. > http://drj11.wordpress.com/2009/01/28/my-python-dream-about-groups/ That posting ends with: """ It still scares me a bit. This code is obviously ridiculous. I can’t help feeling I’ve missed a more Pythonic way of doing it. """ Looking at izip(*[iter(l)]*n), I tend to agree.

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What level of detail wanted for import and the language reference?
by Brett Cannon March 21, 2009

March 21, 2009

At this point importlib is done for its public API for Python 3.1. That means it's time to turn my attention to making sure the semantics of import are well documented. But where to put all of the details? The language reference for import ( http://docs.python.org/dev/py3k/reference/simple_stmts.html#the-import-stat…) explains the basics, but is lacking all of the details of PEP 302 and other stuff like __path__ that have existed for ages. My question is if I should flesh out the details in the language reference or do it in importlib's intro docs. The main reason I could see not doing it in the langauge reference (or at least duplicating it) is it would be somewhat easier to reference specific objects in importlib but I am not sure if the language reference should try to stay away from stdlib references. -Brett

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Summary of Python tracker Issues
by Python tracker March 20, 2009

March 20, 2009

ACTIVITY SUMMARY (03/13/09 - 03/20/09) 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. 2392 open (+27) / 14957 closed (+14) / 17349 total (+41) Open issues with patches: 836 Average duration of open issues: 661 days. Median duration of open issues: 402 days. Open Issues Breakdown open 2362 (+25) pending 30 ( +2) Issues Created Or Reopened (44) _______________________________ PATCH: Armin's attribute lookup caching for 3.0 03/14/09 http://bugs.python.org/issue1568 reopened pitrou patch merge json library with latest simplejson 2.0.x 03/17/09 http://bugs.python.org/issue4136 reopened pitrou patch profile doesn't support non-UTF8 source code 03/20/09 http://bugs.python.org/issue4282 reopened haypo patch, needs review doc copyedits 03/13/09 CLOSED http://bugs.python.org/issue5486 created dsm001 patch Parts of Tkinter missing (but not when running from IDLE) 03/14/09 CLOSED http://bugs.python.org/issue5487 created oc nb_inplace_divide slot is missing in docs 03/14/09 CLOSED http://bugs.python.org/issue5488 created donlorenzo patch Broken DLL 03/14/09 CLOSED http://bugs.python.org/issue5489 created JCoder Broken DLL 03/14/09 CLOSED http://bugs.python.org/issue5490 created JCoder Clarify contextlib.nested semantics 03/15/09 CLOSED http://bugs.python.org/issue5491 created ncoghlan Error on leaving IDLE with quit() or exit() under Linux 03/15/09 http://bugs.python.org/issue5492 created gerluijten Rephrasing the doc of object.__nonzero__ 03/15/09 CLOSED http://bugs.python.org/issue5493 created ezio.melotti Failure in test_httpservers on Linux 03/15/09 http://bugs.python.org/issue5494 created gerluijten ValueError exception of tuple.index(x) gives imprecise error mes 03/15/09 CLOSED http://bugs.python.org/issue5495 created Retro patch codecs.lookup docstring is misleading 03/15/09 CLOSED http://bugs.python.org/issue5496 created exarkun openssl compileerror with original source 03/17/09 http://bugs.python.org/issue5497 created ocean-city patch Can SGMLParser properly handle <empty/> tags? 03/17/09 http://bugs.python.org/issue5498 created once-off only accept byte for getarg('c') and unicode for getarg('C') 03/17/09 http://bugs.python.org/issue5499 created haypo patch tarfile: path problem in arcname under windows 03/17/09 http://bugs.python.org/issue5500 created ellioh Update multiprocessing docs re: freeze_support 03/17/09 http://bugs.python.org/issue5501 created bcorfman io-c: TextIOWrapper is faster than BufferedReader but not protec 03/18/09 http://bugs.python.org/issue5502 created haypo multiprocessing/connection.py wrong pipe name under win32 03/18/09 http://bugs.python.org/issue5503 created jqcn2003 ctypes should work with systems where mmap can't be PROT_WRITE a 03/18/09 http://bugs.python.org/issue5504 created agoode patch sys.stdin.read() doesn't return after first EOF on Windows 03/18/09 http://bugs.python.org/issue5505 created r_mosaic io.BytesIO doesn't support the buffer protocol 03/18/09 http://bugs.python.org/issue5506 created pitrou ctypes configuration fails on mips-linux (and probably Irix) 03/18/09 http://bugs.python.org/issue5507 created doko maximum recursion depth exceeded in __subclasscheck__ 03/18/09 http://bugs.python.org/issue5508 created gangesmaster cPickle - module object has no attribute 03/18/09 CLOSED http://bugs.python.org/issue5509 created ntroutman patches for Modules/socketmodule.c for NetBSD 03/18/09 http://bugs.python.org/issue5510 created yesmar patch zipfile - add __exit__ attribute to make ZipFile object compatib 03/18/09 http://bugs.python.org/issue5511 created petruchio Streamline integer division 03/18/09 http://bugs.python.org/issue5512 created marketdickinson patch "What's New" should say VERY CLEARLY that the type file is gone 03/18/09 http://bugs.python.org/issue5513 created MLModel Darwin framework libpython3.0.a is not a normal static library 03/18/09 http://bugs.python.org/issue5514 created jhowarth 'n' formatting for int and float handles leading zero padding po 03/19/09 http://bugs.python.org/issue5515 created eric.smith equality not symmetric for subclasses of datetime.date and datet 03/19/09 http://bugs.python.org/issue5516 created jess.austin 2to3 haven't convert buffer object to memoryview 03/19/09 CLOSED http://bugs.python.org/issue5517 created bhy cPickle produces inconsistent output 03/19/09 http://bugs.python.org/issue5518 created rb Deletion of some statements in re documentation 03/19/09 http://bugs.python.org/issue5519 created MLModel refactor test_datetime.py 03/19/09 http://bugs.python.org/issue5520 created jess.austin patch sqlite3.h missing 03/20/09 CLOSED http://bugs.python.org/issue5521 created mendell HTTPRedirectHandler documentation is wrong 03/20/09 http://bugs.python.org/issue5522 created jkugler Python bug tracker won't let you edit your profile 03/20/09 CLOSED http://bugs.python.org/issue5523 created jkugler execfile() removed from Python3 03/20/09 http://bugs.python.org/issue5524 created haypo patch Problem with email.MIME* library, using wrong new line 03/20/09 http://bugs.python.org/issue5525 created lclement Local variables unavailable for operation of list comprehension 03/20/09 CLOSED http://bugs.python.org/issue5526 created evan.greensmith Issues Now Closed (43) ______________________ Test issue 563 days http://bugs.python.org/issue1064 loewis patch locale.format bug if thousand separator is space (french separat 535 days http://bugs.python.org/issue1222 eric.smith patch doctest.testmod gets noisy if called more than once per SystemEx 456 days http://bugs.python.org/issue1611 ncoghlan Implement __format__ for Decimal 270 days http://bugs.python.org/issue2110 marketdickinson patch float compared to decimal is silently incorrect. 352 days http://bugs.python.org/issue2531 jdunck easy Python 3.0b3 doesn't start on German Win XP SP3/SP2 185 days http://bugs.python.org/issue3820 pitrou float(0.0) singleton 168 days http://bugs.python.org/issue4024 rhettinger patch traceback attribute error 166 days http://bugs.python.org/issue4034 haypo patch, needs review open(): use keyword only for arguments other than file and mode 157 days http://bugs.python.org/issue4121 haypo patch, patch, needs review struct.pack('L', -1) 140 days http://bugs.python.org/issue4228 marketdickinson patch Use 30-bit digits instead of 15-bit digits for Python integers. 136 days http://bugs.python.org/issue4258 marketdickinson patch Idle - incorrectly displaying a character (Latin capital letter 126 days http://bugs.python.org/issue4281 vbr PyUnicode_FromWideChar incorrect for characters outside the BMP 108 days http://bugs.python.org/issue4474 marketdickinson patch exception traceback sometimes slow 101 days http://bugs.python.org/issue4503 pitrou Issue with RotatingFileHandler logging handler on Windows 81 days http://bugs.python.org/issue4749 neyro IDLE startup file .Idle.py not documented 28 days http://bugs.python.org/issue5276 georg.brandl patch optparse special usage tokens conflict with formatting character 20 days http://bugs.python.org/issue5374 andybuckley patch json needs object_pairs_hook 20 days http://bugs.python.org/issue5381 rhettinger patch stack overflow after hitting recursion limit twice 13 days http://bugs.python.org/issue5392 pitrou patch os.read not handling O_DIRECT flag 18 days http://bugs.python.org/issue5396 exarkun 2to3 wrong for types.StringTypes 10 days http://bugs.python.org/issue5425 benjamin.peterson patch cmpfunc in Python 3.0.1 windows installer 3 days http://bugs.python.org/issue5431 tjreedy Reference paragraph about the constructs that bind names needs u 5 days http://bugs.python.org/issue5469 georg.brandl round(float, ndigits<0) sometimes rounds to odd 3 days http://bugs.python.org/issue5473 marketdickinson document mistake xml.dom.minidom.Element 4 days http://bugs.python.org/issue5478 georg.brandl Expand Decimal.__format__() support to include "n" 5 days http://bugs.python.org/issue5481 marketdickinson doc copyedits 0 days http://bugs.python.org/issue5486 georg.brandl patch Parts of Tkinter missing (but not when running from IDLE) 0 days http://bugs.python.org/issue5487 loewis nb_inplace_divide slot is missing in docs 1 days http://bugs.python.org/issue5488 georg.brandl patch Broken DLL 0 days http://bugs.python.org/issue5489 ocean-city Broken DLL 0 days http://bugs.python.org/issue5490 loewis Clarify contextlib.nested semantics 1 days http://bugs.python.org/issue5491 georg.brandl Rephrasing the doc of object.__nonzero__ 0 days http://bugs.python.org/issue5493 georg.brandl ValueError exception of tuple.index(x) gives imprecise error mes 0 days http://bugs.python.org/issue5495 benjamin.peterson patch codecs.lookup docstring is misleading 0 days http://bugs.python.org/issue5496 georg.brandl cPickle - module object has no attribute 0 days http://bugs.python.org/issue5509 benjamin.peterson 2to3 haven't convert buffer object to memoryview 0 days http://bugs.python.org/issue5517 benjamin.peterson sqlite3.h missing 0 days http://bugs.python.org/issue5521 benjamin.peterson Python bug tracker won't let you edit your profile 0 days http://bugs.python.org/issue5523 benjamin.peterson Local variables unavailable for operation of list comprehension 0 days http://bugs.python.org/issue5526 benjamin.peterson dir() should only return strings 1603 days http://bugs.python.org/issue1056293 haypo patch Use \r\n, not \n for HTTP headers 849 days http://bugs.python.org/issue1597000 pitrou easy if something as x: 678 days http://bugs.python.org/issue1714448 mrabarnett patch Top Issues Most Discussed (10) ______________________________ 12 Allow auto-numbered replacement fields in str.format() strings 36 days open http://bugs.python.org/issue5237 11 "What's New" should say VERY CLEARLY that the type file is gone 2 days open http://bugs.python.org/issue5513 11 RFC: improve distutils bdist_rpm so it builds pure python modul 7 days open http://bugs.python.org/issue5482 10 Streamline integer division 2 days open http://bugs.python.org/issue5512 10 contextlib.nested inconsistent with, well, nested with statemen 35 days open http://bugs.python.org/issue5251 10 if something as x: 678 days closed http://bugs.python.org/issue1714448 9 rewrite of minidom.Node.normalize 391 days open http://bugs.python.org/issue2170 8 merge json library with latest simplejson 2.0.x 3 days open http://bugs.python.org/issue4136 7 mmap: read_byte/write_byte and object type 20 days open http://bugs.python.org/issue5391 7 locale.format bug if thousand separator is space (french separa 535 days closed http://bugs.python.org/issue1222

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Proposal: new list function: pack
by paul bedaride March 20, 2009

March 20, 2009

I propose a new function for list for pack values of a list and sliding over them: then we can do things like this: for i, j, k in pack(range(10), 3, partialend=False): print i, j, k I propose this because i need a lot of times pack and slide function over list and this one combine the two in a generator way. def pack(l, size=2, slide=2, partialend=True): lenght = len(l) for p in range(0,lenght-size,slide): def packet(): for i in range(size): yield l[p+i] yield packet() p = p + slide if partialend or lenght-p == size: def packet(): for i in range(lenght-p): yield l[p+i] yield packet() a = range(10) print a print 'pack(a, 2, 2, True):', [list(p) for p in pack(a, 2, 2, True)] print 'pack(a, 2, 2, False):', [list(p) for p in pack(a, 2, 2, False)] print 'pack(a, 2, 3, True):', [list(p) for p in pack(a, 2, 3, True)] print 'pack(a, 2, 3, False):', [list(p) for p in pack(a, 2, 3, False)] print 'pack(a, 3, 2, True):', [list(p) for p in pack(a, 3, 2, True)] print 'pack(a, 3, 2, False):', [list(p) for p in pack(a, 3, 2, False)] print 'pack(a, 3, 3, True):', [list(p) for p in pack(a, 3, 3, True)] print 'pack(a, 3, 3, False):', [list(p) for p in pack(a, 3, 3, False)] paul bedaride

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snakebite for GSoC?
by ajaksu March 20, 2009

March 20, 2009

Hi, Does anyone have good ideas for assigning students to snakebite? Is it too early? I think the client-side 'Snakebite daemon' and server-side stuff described at http://tinyurl.com/beyond-buildbot would be great projects. Daniel

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