Mailman 3 February 2015 - Python-Dev

Working on issue 23496: should I use a macro test or an edit to configure.ac?
by Ryan Gonzalez 27 Feb '15

27 Feb '15

So... There was a recent discussion here on porting Python to Android. Well, for those of you who saw too many unread messages and marked the whole thread as read like I usually do, I helped Cyd figure out some patches that make it work. Cyd then opened Issue 23496 <http://bugs.python.org/issue23496>. Now, I'm going to try to redo the patches against HEAD (or tip in Mercurial language). Which leads me to the question. See, of course, the patches should only be enabled if Python is being built targeting Android, but I'm not sure how that should be detected. I know that the Android target triple is arm-linux-androideabi. Should I test for the __ANDROID__ macro in the source file, or should I modify configure.ac to detect Android and define its own macro? Also, if a configure.ac edit is preferred, where should it be? It's slightly painful to scan through all 4000 lines of Python's configure script. ;) -- Ryan If anybody ever asks me why I prefer C++ to C, my answer will be simple: "It's becauseslejfp23(@#Q*(E*EIdc-SEGFAULT. Wait, I don't think that was nul-terminated." Personal reality distortion fields are immune to contradictory evidence. - srean Check out my website: http://kirbyfan64.github.io/

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ubuntu buildbot
by Benjamin Peterson 27 Feb '15

27 Feb '15

Hi David, I noticed you run the "Builder x86 Ubuntu Shared" buildbot. It seems it's running a very old version of Ubuntu. Is there any chance of getting that updated? Regards, Benjamin

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Request for Pronouncement: PEP 486 - Make the Python Launcher aware of virtual environments
by Paul Moore 27 Feb '15

27 Feb '15

The discussion on PEP 486 (started at https://mail.python.org/pipermail/python-dev/2015-February/138171.html, following from the thread at https://mail.python.org/pipermail/python-dev/2015-February/138160.html) seems to have died down. There's an implementation at http://bugs.python.org/issue23465. So, I think this is ready for pronouncement. Thanks, Paul

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Fwd: Request for Pronouncement: PEP 441 - Improving Python ZIP Application Support
by Guido van Rossum 26 Feb '15

26 Feb '15

[Sorry, accidentally dropped the list from this message.] Here's my review. I really like where this is going but I have a few questions and suggestions (I can't help myself :-). [I sneaked a peek at the update you sent to peps(a)python.org.] "Currently, pyyzer [5] and pex [6] are two tools known to exist." -> "... are two such tools." It's not stated whether the archive names include the .pyz[w] extension or not (though I'm guessing it's not -- this should be stated). The naming of the functions feels inconsistent -- maybe pack(directory, target) -> create_archive(directory, archive), and set_interpreter() -> copy_archive(archive, new_archive)? Why no command-line equivalent for the other two methods? I propose the following interface: if there's only one positional argument, we're asking to print its shebang line; if there are two and the input position is an archive instead of a directory, we're copying. (In the future people will want an option to print more stuff, e.g. the main function or even a full listing.) I've not seen the pkg.mod:fn notation before. Where is this taken from? Why can't it be pkg.mod.fn? I'd specify that when the output argument is a file open for writing, it is the caller's responsibility to close the file. Also, can the file be a pipe? (I.e. are we using seek()/tell() or not?) And what about the input archive? Can that be a file open for reading? -- --Guido van Rossum (python.org/~guido)

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how to inspect if something includes a bound first param
by Gregory P. Smith 26 Feb '15

26 Feb '15

inspect.getargspec(method) and inspect.signature(method) both include the 'self' parameter but how are we to figure out from method itself that it is actually bound and that its first parameter is expected to be a bound instance? So far I've come up with: *inspect.ismethod(method) or inspect.ismethoddescriptor(method)* But that is still not quite right as it remains False in 3.4 for the simple case of: >>> class A: ... def x(self): ... pass ... >>> inspect.ismethod(A.x) False >>> inspect.ismethoddescriptor(A.x) False >>> inspect.signature(A.x).parameters mappingproxy(OrderedDict([('self', <Parameter at 0x7fdd8188eae8 'self'>)])) >>> inspect.getargspec(A.x) ArgSpec(args=['self'], varargs=None, keywords=None, defaults=None) The above works if use it on object.__init__, but not on a method of an uninstantiated class. (it also works on the instantiated A().x) Checking if *(inspect.isfunction(method) and method.__qualname__ != method.__name__)* perhaps but that seems questionably hacky. Is there a right way to do this via the inspect module that I've missed? It seems like that'd be nice, but I don't feel like I know enough to write up a feature request for it yet. (granted I hope nobody *wants* to write code that does this...) -gps

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?s re documentation of Python features
by GARRY M CRANE 25 Feb '15

25 Feb '15

I am trying to learn Python for use in computational biology. I am using the interesting book: "Computing for Biologists; Python Programming and Principles" (by Ran Libeskind-Hadas and Eliot Bush). It has an interesting and useful set of programming exercises at www.cs.hmc.edu/CFB. I am actually enjoying solving (doing) the example problems. However, I find some of the instructions non-functional for me. For example the import function does not work, nor f=open("filename.txt"). I have saved files per instructions in the programming exercise inside the Python34 folder (I am using Python 3.4 in Windows 7). But use of the f=open() command produces an error message that the requested file does not exist. I assume I have chosen a wrong location for the saved file within that Python34 folder, but trial and error has not led to a successful use of these functions. import simply leaves a blank line .. no suggestion about the problem. Asking questions in Google and Ask about where to save Python-related files that can be used subsequently have not led to answers - just details about structuring or formatting things to be written/saved/use of the \n at end of each line, etc. Important details, but of no help. I am finding Python to be very handy at many biologic things such as working with DNA strings, etc. but I find the documentation and indexing for finding how to use many Python features exasperating. I am writing to you based on a READ ME file in my Python folder - generated when I installed Python. FYI, I asked a few questions of one of the authors of the interesting book - who politely replied he was too busy to answer right now - the book and problems were meant for a class ... though neither the book nor problems say so. The professor hopes to get around to issues of use by non-students sometime - but not now. Another feature I have come across so far that does not work is importation of matplotlib. I copy computed results (that otherwise would go to your plotting routine) then go to Excel and with manipulation produce a usable chart there - but at a cost of time and energy. Your Python tool has many intriguing features - but some of the most basic functions do not work for me (even though many features do, e.g., import random does work). The failure of these features - so far as I can tell - is because of lack of description (for the general non-expert public) about where/how to install various features. Perhaps I need to reinstall from the ground up??? If so, just what should I do? If there is a less drastic solution, can you tell me about it? Thank you for any help ... and if you could provide me a lead regarding WHERE to ask subsequent questions I would be most grateful. Sometimes, Google or Ask or a U Tube tutorial does a good job - but if one does not know the 'proper' name or term for something, it often is frustrating or impossible to get an answer. I have not heard about any comprehensive handbook for Python34 aimed at one who wants to use Python for creating programs (functions) that work - and is not an expert at back-room structure of files and folders.... have I simply missed it? So far, I have not found a local Python expert to ask for help. I am sure some are in the greater Seattle area where I live- but I don't know how to find even one at this time. Garry Crane gandkcrane(a)msn.com

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Re: [Python-Dev] Request for Pronouncement: PEP 441 - Improving Python ZIP Application Support
by Guido van Rossum 25 Feb '15

25 Feb '15

On Tue, Feb 24, 2015 at 10:50 AM, Paul Moore <p.f.moore(a)gmail.com> wrote: > On 24 February 2015 at 18:24, Guido van Rossum <guido(a)python.org> wrote: > > Here's my review. I really like where this is going but I have a few > > questions and suggestions (I can't help myself :-). > > Thanks. > > > [I sneaked a peek at the update you sent to peps(a)python.org.] > > > > "Currently, pyyzer [5] and pex [6] are two tools known to exist." -> "... > > are two such tools." > > > > It's not stated whether the archive names include the .pyz[w] extension > or > > not (though I'm guessing it's not -- this should be stated). > > No, I assumed that automatically adding extensions is not the norm. A > lot of Windows tools do it, but I don't get the impression Unix tools > do. I'll clarify the wording. > > > The naming of the functions feels inconsistent -- maybe pack(directory, > > target) -> create_archive(directory, archive), and set_interpreter() -> > > copy_archive(archive, new_archive)? > > I'm OK with create_archive. But not so sure about copy_archive - the > purpose of that function is solely to change the shebang line on an > existing archive. It does so by copying, sure, but that's incidental. > I see get_interpreter/set_interpreter as complementary "helper" APIs, > and create_archive as the main API. > To me, the name set_<something>() so strongly evokes the idea of in-place modification that I cannot live with it. (I also assume that your code won't do the right thing if the output is the same as the input, right?) > > Why no command-line equivalent for the other two methods? I propose the > > following interface: if there's only one positional argument, we're > asking > > to print its shebang line; if there are two and the input position is an > > archive instead of a directory, we're copying. (In the future people > will > > want an option to print more stuff, e.g. the main function or even a full > > listing.) > > Mainly because I couldn't think of an API that didn't look muddled, or > make the simple case of "I want to pack up a directory" look messy. > But I'll think about your proposal - it sounds nice, I'll see how it > fares when I try to implement it :-) > > > I've not seen the pkg.mod:fn notation before. Where is this taken from? > > Why can't it be pkg.mod.fn? > > It's common usage in setuptools and things like tat - it's the "entry > point" syntax used in packaging. I don't know of any reason why > all-dotted notation wouldn't work, though. I'll ask around if there's > any reason I'm not aware of. > OK, no need to change this then. > > I'd specify that when the output argument is a file open for writing, it > is > > the caller's responsibility to close the file. Also, can the file be a > > pipe? (I.e. are we using seek()/tell() or not?) And what about the > input > > archive? Can that be a file open for reading? > > I'll clarify all of these points. They are mostly "it can be whatever > the zipfile module accepts", though, which isn't explicitly stated > itself :-( > > The input can't be a file object for pack/create_archive because it's > a directory, not an archive, there. But it could be for > set_interpreter. I just wasn't sure if it was worth adding. It's not > hard to do, though. I'm not sure what use case this is addressing anyway, but assuming there is one, you might as well go all the way (except for directories, obviously). -- --Guido van Rossum (python.org/~guido)

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Emit SyntaxWarning on unrecognized backslash escapes?
by Serhiy Storchaka 25 Feb '15

25 Feb '15

See topic "Unrecognized backslash escapes in string literals" in Python list [1]. I agree that this is a problem, especially for novices (but even experience users can make a typo). May be emit SyntaxWarning on unrecognized backslash escapes? An exception is already raised on invalid octal or hexadecimal escapes. '\x' is syntax error, not two characters '\\' and 'x'. [1] http://comments.gmane.org/gmane.comp.python.general/772455

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easy_install ?
by Laura Creighton 25 Feb '15

25 Feb '15

Hello all, I wonder what the status of easy_install is. I keep finding people who needed to install something 'path.py' is the latest, who needed to use pip, and couldn't get easy_install to work. Should we tell people that easy_install is deprecated, or ask them to file bugs when they could not get it to work, or ... Laura

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getstatusoutput()'s behavior changed in 3.3.4 and 3.4
by Gregory P. Smith 25 Feb '15

25 Feb '15

While porting some code from 2.7 to 3.4 I discovered that command.getstatusoutput() (renamed to subprocess.getstatusoutput() in 3.x) had changed. Surprise! The code was working under an earlier version of 3.3 but broke when I ran it on 3.4. Nowhere was this documented that I could find. Tracking down what changed, I discovered it was unintentional due to the meaning of the returned status int never being tested. http://bugs.python.org/issue23508 filed... Given it has shipped in several stable 3.x releases and as part of some major Linux distros, reverting the behavior change seems wrong. The new behavior is nicer and more consistent with the rest of the subprocess module. I suggest just documenting it and moving on. It seems too late to fix this mistake without causing additional headaches. Anyone disagree? -gps

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