Mailman 3 March 2009 - Python-Dev

html5lib/BeautifulSoup (was: Integrate lxml into the stdlib? (was: Integrate BeautifulSoup into stdlib?))
by Jim Jewett 06 Mar '09

06 Mar '09

Stefan Behnel wrote: > I would have a hard time feeling happy > if a real-world HTML parser was added to the stdlib that provides a totally > different interface than the best (and fastest) XML library that the stdlib > currently has. I doubt there would be any objection to someone contributing wrappers for upgrades, but I wouldn't count on them being used. lxml may well be the best choice for xml. BeautifulSoup and html5lib wouldn't even exist if that actually mattered for most of *their* use cases. Think of them more as pre-processors, like tidylib. If enough web pages were even valid HTML (let alone valid and well-formed XML), no one would have bothered to write these libraries. BeautifulSoup has the advantage of being long-proven in practice, for ugly html. (You mention an lxml feature with a similar intent, but for lxml, it is one of several addon features; for BeautifulSoup, this is the whole point.) html5lib does not have as long of a history, but it does have the advantage of being almost an endorsed standard. Much of HTML 5 is documenting the workarounds that browser makers already actually employ to handle erroneous input, so that the complexities can at least stop compounding. html5lib is intended as a reference implementation, and the w3c editor has used it to motivate changes in the specification draft. (This may make it unsuitable for inclusion in the stdlib today, because of timing issues.) In other words, it isn't just the heuristics of one particular development team; it is (modulo bugs, and after official publication) the heuristics that the major web browser makers have agreed to treat as "correct" in the future. -jJ

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running the tests...
by Chris Withers 05 Mar '09

05 Mar '09

Hi All, I found the very brief snippet on test-running at: http://python.org/dev/faq/#how-to-test-a-patch ...so thought I'd ask here: - what's the canonical way to run "all the tests"? - what's the canonical way to run the tests for just the package being patched? (I'm assuming it's a standard library package here...) cheers, Chris -- Simplistix - Content Management, Zope & Python Consulting - http://www.simplistix.co.uk

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Re: [Python-Dev] PEP 372 -- Adding an ordered directory to collections ready for pronouncement
by Forest 05 Mar '09

05 Mar '09

On Wed, Wed, 4 Mar 2009 13:52:59 -0800, Guido van Rossum wrote: > On Wed, Mar 4, 2009 at 1:44 PM, Greg Ewing <greg.ewing(a)canterbury.ac.nz> > wrote: >> rdmurray(a)bitdance.com wrote: >> >>> I actually like StableDict best. ?When I hear that I think, "ah, the >>> key order is stable in the face of insertions, unlike a regular dict". >> >> But it still doesn't convey what the ordering actually *is*. > > Please, stick with OrderedDict. That's the name used historically by > most people who independently reinvented this functionality. It's also what I typed into google and PYPI when I went looking for this functionality. +1 for odereddict or odict or OrderedDict.

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How do I get commit access?
by Chris Withers 05 Mar '09

05 Mar '09

Hi All, I want to work on these issues: http://bugs.python.org/issue1823 http://bugs.python.org/issue1874 ...and I'd also like to commit the patch I submitted with this one: http://bugs.python.org/issue1974 How do I go about getting commit access? When I do, I take it I work against the version of python I care about and then foreward port to the trunk and any other maintenence branches necessary? cheers, Chris -- Simplistix - Content Management, Zope & Python Consulting - http://www.simplistix.co.uk

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What type of object mmap.read_byte should return on py3k?
by Hirokazu Yamamoto 05 Mar '09

05 Mar '09

Hello. I noticed mmap.read_byte returns 1-length unicode on py3k. I felt this was strange, so I created issue on bug tracker (http://bugs.python.org/issue5391) and Martin proposed this is suitable for discussion on python-dev. I'll quote messages on bug tracker here. I wrote: > On Python3000, mmap.read_byte returns str not bytes, and mmap.write_byte > accepts str. Is this intended behavior? > >>>> import mmap >>>> m = mmap.mmap(-1, 10) >>>> type(m.read_byte()) > <class 'str'> >>>> m.write_byte("a") >>>> m.write_byte(b"a") > > Maybe another possibility. read_byte() returns int which represents > byte, write_byte accepts int which represents byte. (Like b"abc"[0] > returns int not 1-length bytes) Martin wrote: > Indeed, I think it should use the "b" code, instead of the "c" code. > Please discuss this on python-dev, though. > > It might not be ok to backport this to 3.0, since it may break existing > code. > Furthermore, all other uses of the "c" code might need to be reconsidered.

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PEP 372 -- Adding an ordered directory to collections ready for pronouncement
by Armin Ronacher 05 Mar '09

05 Mar '09

Hi everybody, PEP 372 was modified so that it provides a simpler API (only the dict API to be exact) and it was decided to start with a Python-only implementation and replace it with a C version later if necessary. Annotated changes from earlier versions of the PEP: - the extra API for ordered dict was dropped to keep the interface simple and clean. Future versions can still be expanded but it's impossible to drop features later on. - To keep the implementation simple 3.1 / 2.7 will ship with a Python-only version of the class. It can still be rewritten in C if it turns out to be too slow or thread safety is required. The corresponding issue in the tracker: http://bugs.python.org/issue5397 Link to the PEP: http://www.python.org/dev/peps/pep-0372/ Anything else that should be done? Regards, Armin

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What to do about failing tests
by Tennessee Leeuwenburg 05 Mar '09

05 Mar '09

On my local checkout I notice a number of failing tests (test_fileio test_grp test_io test_urllib2_localnet). Is there anything that I should attempt to do regarding these? -Tennessee

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forgive my patch submission
by Tennessee Leeuwenburg 05 Mar '09

05 Mar '09

I am trying to learn the systems... I'm not trying to force a particular approach to the solution but I want to learn how to correctly follow the process. Please feel free to reject this -- I'm not trying to jump the gun given there isn't even an agreed requirement at this stage. Regards, -Tennessee -- -------------------------------------------------- Tennessee Leeuwenburg http://myownhat.blogspot.com/ "Don't believe everything you think"

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svn (403 Forbidden)
by Luis Saavedra 04 Mar '09

04 Mar '09

Hi, when I run: $ mkdir NewDir $ cd NewDir $ svn checkout http://svn.python.org/projects/python/trunk python svn: Server sent unexpected return value (403 Forbidden) in response to REPORT request for '/projects/!svn/vcc/default' how to fix this problem?, on another machine I don't have this problem..., regards, Luis.

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ABCs and MRO
by Paul Moore 04 Mar '09

04 Mar '09

2009/3/2 Benjamin Peterson <benjamin(a)python.org>: > 2009/3/1 Paul Moore <p.f.moore(a)gmail.com>: >> >> Is it worth getting simplegeneric exposed in 3.1 >> (http://bugs.python.org/issue5135)? If it's going to be in 2.7, I'd >> like to see it hit 3.1. The patch is against trunk (for 2.7) at the >> moment, I'm not sure what the process would be for forward-porting it >> (do I generate a new patch against the py3k branch, or should it be >> applied to trunk and merged in?) > > Patches to the trunk are fine. OK, thanks. > As for the actual feature, I don't think it should hold up releases. Fair enough. The key problem with the patch is that ABCs do not play well with the type of introspection required to implement a generic function - namely enumeration of the superclasses of a class. The MRO of the class is fine for normal inheritance, but for ABCs it is possible to register classes which don't inherit from the ABC, so that you have a situation where issubclass (C, MyABC) can be true without MyABC being in C.__mro__: >>> import abc >>> class MyABC(object): ... __metaclass__ = abc.ABCMeta ... >>> class C(object): ... pass ... >>> MyABC.register(C) >>> issubclass(C, MyABC) True >>> C.__mro__ (<class '__main__.C'>, <type 'object'>) >>> More generally, there is NO WAY to determine the list of classes for which issubclass(C, x) is true. This could be considered a limitation of, or a bug in, ABCs, I don't have a particular opinion on that, but it does mean that no code which relies on being able to traverse the class inheritance graph will see ABCs. One particular case of this is (any implementation I can think of, of) generic functions. In my view, this implies one of the following: 1) It should be a documented limitation of such code that it doesn't work with ABCs (and conversely, this limitation of ABCs should be documented in the ABC documentation) 2) Generic functions, and any other code requiring this type of introspection, is essentially useless unless it can support ABCs, and should not be used in the light of this limitation. 3) This is a bug in ABCs and should be fixed. 4) Something else I didn't think of :-) In my view, (2) is an unreasonable position to take, given the fact that (as I understand it) ABCs are supposed to be largely optional and shouldn't affect code that doesn't care about them... It's not clear to me how (3) should be addressed. Adding a slot to all classes to hold a list of ABCs they are registered against seems to be a large overhead for a relatively rarely used feature. I guess having a global registry of ABC registrations could work, but it seems clumsy. Any other suggestions? The problem with (1) is that it simply acknowledges the issue, but doesn't actually fix it. Nick Coghlan has commented (in the tracker) that he feels that the limitation is significant (enough to push him from +1 to -0 on the feature). I have created an issue in the tracker - http://bugs.python.org/issue5405. In my view, it's fairly critical, but I've refrained from setting a high priority as that may just be my vested interest talking :-) I'd appreciate it if someone could comment (either here or on the tracker item) on what the correct way forward should be. If the answer is "fix the ABC bug", then I'll have a look but I'm not sure if I can do it without help - any assistance would be appreciated. Paul.

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