ANN: PyTester v0.6.0
PyTest v0.6.0 - This is a small package that facilitates the unit testing process by aggregating PyUnit tests and making them easier to call from the command line and from within other unit tests. Typical PyUnit tests are written in a 1-1 relationship with the module they test. Module foo.py is typically tested with module test_foo.py. In packages with multiple modules it can become cumbersome to run all of the unit tests from the command line. One could write an aggregator test_all.py module and have it call into each test_*.py module to retrieve a TestCase to assemble a suite. However, that approach requires 2 modifications each time a unit test is added (one modification for the test itself, and one modification in test_all.py). PyTest can run all of the unit tests in a directory via the command line by locating all modules that begin with test_. Reflection is then used to extract the TestCase class, and a suite is constructed reflecting all test cases. Additionally, PyTest can be used programmatically in a test_all.py. Please see my site for more info: http://oss.wxnet.org/pytester -c -- WeatherNet Observations for station: home Temperature: 73.20F Pressure: 29.80in; Dew Point: 70.71F (92%) Wind: 137 at 0 mph Recorded:22:39:52 07/05/05 (http://wsdl.wxnet.org/home/binding.wsdl) -- http://mail.python.org/mailman/listinfo/python-announce-list Support the Python Software Foundation: http://www.python.org/psf/donations.html
Dr. Dobb's Python-URL! - weekly Python news and links (Jul 5)
QOTW: That's what I love in that news group. Someone comes with a stupid and arrogant question, and someone else answers in a calm and reasonable way. - Gustavo Niemeyer After 25 years doing this, I've become something of a Luddite as far as fancy IDEs and non-standard features go... and a huge believer in strict decoupling between my tools, to the point of ignoring things that bundle them together in ways that are, in my opinion, too tight. - Peter Hansen Ralf Grosse-Kunstleve floats a proposal to reduce the amount of code requires to set instance fields from arguments in __init__ methods: http://groups-beta.google.com/group/comp.lang.python/browse_thread/thread/7346ad00a14e821a The Python Software Foundation Summer of Code projects have been selected: http://www.amk.ca/diary/archives/003975.html A discussion about the long-term plan to remove map, filter, reduce and lambda starts out bad-tempered then ... improves little: http://groups-beta.google.com/group/comp.lang.python/browse_thread/thread/ceef909ebd10b65a There's a new wxPython tutorial at Dev Shed: http://www.devshed.com/c/a/Python/A-Look-at-wxPython/ Peter Hansen wants to determine the wall-clock elapsed time taken by a process on a managed host in a reliable, cross-platform way: http://groups-beta.google.com/group/comp.lang.python/browse_thread/thread/cd1222d713730b67 Par Nicolas Lehuen uses Python to compare Microsoft Word documents stored in a Subversion repository (!): http://www.lehuen.com/nicolas/index.php/2005/06/30/60-comparing-microsoft-word-documents-stored-in-a-subversion-repository Terry Hancock explains what ZOPE actually is: http://groups-beta.google.com/group/comp.lang.python/msg/174d4101e0e419e8 Everything Python-related you want is probably one or two clicks away in these pages: Python.org's Python Language Website is the traditional center of Pythonia http://www.python.org Notice especially the master FAQ http://www.python.org/doc/FAQ.html PythonWare complements the digest you're reading with the marvelous daily python url http://www.pythonware.com/daily Mygale is a news-gathering webcrawler that specializes in (new) World-Wide Web articles related to Python. http://www.awaretek.com/nowak/mygale.html While cosmetically similar, Mygale and the Daily Python-URL are utterly different in their technologies and generally in their results. For far, FAR more Python reading than any one mind should absorb, much of it quite interesting, several pages index much of the universe of Pybloggers. http://lowlife.jp/cgi-bin/moin.cgi/PythonProgrammersWeblog http://www.planetpython.org/ http://mechanicalcat.net/pyblagg.html comp.lang.python.announce announces new Python software. Be sure to scan this newsgroup weekly. http://groups.google.com/groups?oi=djqas_ugroup=comp.lang.python.announce Steve Bethard, Tim Lesher, and Tony Meyer continue the marvelous tradition early borne by Andrew Kuchling, Michael Hudson and Brett Cannon of intelligently summarizing action on the python-dev mailing list once every other week. http://www.python.org/dev/summary/ The Python Package Index catalogues packages. http://www.python.org/pypi/ The somewhat older Vaults of Parnassus ambitiously collects references to all sorts of Python resources. http://www.vex.net/~x/parnassus/ Much of Python's real work takes place on Special-Interest Group mailing lists http://www.python.org/sigs/ Python Success Stories--from air-traffic control to on-line match-making--can inspire you or decision-makers to whom you're subject with a vision of what the language makes practical. http://www.pythonology.com/success The Python Software Foundation (PSF) has replaced the Python Consortium as an independent nexus of activity. It has official responsibility for Python's development and maintenance. http://www.python.org/psf/ Among the ways you can support PSF is with a donation. http://www.python.org/psf/donate.html Kurt B. Kaiser publishes a weekly report on faults and patches. http://www.google.com/groups?as_usubject=weekly%20python%20patch Cetus collects Python hyperlinks. http://www.cetus-links.org/oo_python.html Python FAQTS http://python.faqts.com/ The Cookbook is a collaborative effort to capture useful and interesting recipes. http://aspn.activestate.com/ASPN/Cookbook/Python Among several Python-oriented RSS/RDF feeds available are http://www.python.org/channews.rdf
Re: map/filter/reduce/lambda opinions and background unscientific mini-survey
On Tuesday 05 July 2005 06:57 pm, Steven D'Aprano wrote: On Tue, 05 Jul 2005 12:11:47 -0700, mcherm wrote: And besides, def isn't a magic word... it's an abreviation for define... Really? I thought it was an abbreviation for definition. As in, definition of MyFunc is... Does it matter? But no, define is correct, because the def keyword is active. It is *not* a declaration of a function but a command to define one then and there. I hope that any student who didn't understand a word as common as define wouldn't have graduated from our school. How about tuple? It's a generalization rather than a specialization: double (or couple) triple quadruple quintuple sextuple septuple octuple nontuple ... Maybe a wee bit less obvious, but still understandable. Besides, the existence of another poor choice of words wouldn't make the first one any better, would it? If you are arguing that lambda is the right and proper word for this operator that Python should use, I still will have to disagree. OTOH, if you just want the functionality of lambda to remain, I must say I agree. It's a useful construct. But it *is* poorly named. It really stands out as the least intuitive keyword in the language, IMHO. -- Terry Hancock ( hancock at anansispaceworks.com ) Anansi Spaceworks http://www.anansispaceworks.com -- http://mail.python.org/mailman/listinfo/python-list
Re: f*cking re module
On Tuesday 05 July 2005 10:04 am, jwaixs wrote: The python re module is, in my opinion, a non beginner user friendly module. And it's not meant for beginning python programmers. I don't have any experience with perl or related script/programming languages like python. (I prefer to do things in c) So the re module is completely new for me. I think you had an error of expectations here: Python provides a regular expression module which is consistent with regular expression syntax as it has come to be defined. Your frustration was entirely with regular expressions themselves, not the Python implementation. You would've had the same experience in Perl or Ruby or for that matter, sed or awk. In that vein, the Python documentation for the re module is only that -- documentation for the module. It does not (and couldn't reasonably be expected to) cover the subject of regular expressions themselves. You might as well expect the Python manual to explain object oriented programming, data structures, functional programming or other semester-long computer science subjects. There are entire books dedicated to the subject of learning regular expressions and pattern recognition in general. It's a fairly complex subject. After all, it's merely the simplest one-dimensional case of a pattern recognition system, which is essentially an AI discipline. Only the fact that the one-dimensional case of discrete text is an extremely simple case makes the subject tenable at all for ordinary programs. If you're really interested in using this new technique, I would suggest that you be prepared to be patient and tackle the problem of learning it seriously, just as you did when you learned to program in C in the first place. And you might want to read one of those aforementioned books, such as: Mastering Regular Expressions (2nd ed) by Jeffrey E. F. Friedl http://www.oreilly.com/catalog/regex2/ And IMHO, Python actually makes regular expressions a lot easier to handle than they are in some of the other languages you could be attempting this in. I've only tried regexes in Python, Perl, and Javascript, but Python is definitely the one I find easiest to cope with. ;-) -- Terry Hancock ( hancock at anansispaceworks.com ) Anansi Spaceworks http://www.anansispaceworks.com -- http://mail.python.org/mailman/listinfo/python-list
Re: map/filter/reduce/lambda opinions and background unscientific mini-survey
On Tuesday 05 July 2005 03:43 pm, Tom Anderson wrote: I understand that the backslash is popular in some ivory-tower functional languages. Currently, a backslash can be used for explicit line joining, and is illegal elsewhere on a line outside a string literal, so i think it's available for this. It would be utterly unpythonic to use puntuation instead of a keyword, and it would make no sense to novices, but it would scare the crap out of C programmers, which has to be worth something. With list comprehensions and generators becoming so integral, I'm not sure about unpythonic. And a syntax just occured to me -- what about this: [y*x for x,y] ? (that is: [expression for argument list] It's just like the beginning of a list comprehension or generator, but without the iterator. That implies that one must be given, and the result is therefore a callable object. Wouldn't do anything more or less than present day lambda, but gets rid of the weird keyword, and integrates nicely with list comps and generators. It's currently a syntax error, and it requires no special delimiter -- it's really just an extension of list comp syntax. -- Terry Hancock ( hancock at anansispaceworks.com ) Anansi Spaceworks http://www.anansispaceworks.com -- http://mail.python.org/mailman/listinfo/python-list
Re: Lisp development with macros faster than Python development?..
[EMAIL PROTECTED] wrote: The problem is that questions like 'What lang is fastest to develop in?' are hard to answer definitively. FWIW, Google's answer to that question is C++, Java, and Python. For any given problem, any of the three are acceptable. Each programmer or engineering team gets to decide based on his or her language expertise.* Raymond * Source: Greg Stein's keynote address at PyCon 2005. -- http://mail.python.org/mailman/listinfo/python-list
Re: Lisp development with macros faster than Python development?..
So Lisp is for really good programmers, and Python is for mediocre programmers ? Best Regards, Fuzzy http://www.voidspace.org.uk/python -- http://mail.python.org/mailman/listinfo/python-list
Re: f*cking re module
There's really not a single good re tutorial or documentation I could found! With * being a greedy operator, your post's subject line matches, firetrucking which, of course, has nothing to do with regular expressions, or python.org's re how-to guide, or Amazon's 18 books on the subject, or the hundreds of available on-line tutorials. http://www.amk.ca/python/howto/regex/ http://www.amazon.com/exec/obidos/search-handle-form/102-9115182-7050550 http://www.google.com/search?q=regular+expression+tutorial Raymond -- http://mail.python.org/mailman/listinfo/python-list
Re: map/filter/reduce/lambda opinions and background unscientific mini-survey
I said I'd drop the discussion about lambda, but this isn't really the same discussion even if it is part of the same thread. That's my excuse, and I'm sticking to it. Terry Hancock wrote: On Tuesday 05 July 2005 03:43 pm, Tom Anderson wrote: I understand that the backslash is popular in some ivory-tower functional languages. Currently, a backslash can be used for explicit line joining, and is illegal elsewhere on a line outside a string literal, so i think it's available for this. It would be utterly unpythonic to use puntuation instead of a keyword, and it would make no sense to novices, but it would scare the crap out of C programmers, which has to be worth something. With list comprehensions and generators becoming so integral, I'm not sure about unpythonic. And a syntax just occured to me -- what about this: [y*x for x,y] ? (that is: [expression for argument list] It's just like the beginning of a list comprehension or generator, but without the iterator. That implies that one must be given, and the result is therefore a callable object. That is a very long chain of implication: It looks like a list comprehension... but there is no iterator... so we have to supply an iterator... so it takes an argument... so it is a callable object... oh and by the way, it can take any arguments, not just iterators. It is also far too easy to make a mistake, eg to write something like newlist = [y*x for x,y] when you actually wanted the list comp [y*x for x,y in L]. This would create an anonymous function where you expected to create a list. It is hard to think of a usage case where you didn't discover the error reasonably soon, but it would be better for leaving the iterator out of a list comp to remain a syntax error, rather than produce an unexpected, but legal, object. Besides, I think Guido should be very cautious about introducing new features that use punctuation, instead of keywords. We don't want to become perl do we? :-) -- Steven. -- http://mail.python.org/mailman/listinfo/python-list
Re: map/filter/reduce/lambda opinions and background unscientific mini-survey
Op 2005-07-01, Mike Meyer schreef [EMAIL PROTECTED]: iK [EMAIL PROTECTED] writes: Seems like he wants python programmers to solve their problems all in the same way. While that is great for corporate slaves it is terrible for the creative programmer. No, he wants Python to be Pythonic. TMTOWTDI is not Pythonic. If Guido should change his mind on this, then it will be pythonic. I don't think a concept that has so little meaning has any real value. Python is quickly becoming the visual basic of the 21 century. If you want to have fun while getting some work done you need to look elsewhere. It's a shame... If you'd rather spend your time figuring out which of multiple ways to do things is the best for the job at hand than producing code, there's a language that makes TMTOWTDI a way of life. There are always many ways to do things, and depending on circumstances the best way to do something may differ every time. So if python no longer allows multiple ways to do things, it won't help the programmer. The programmer will now face the question if python is still the right language to do the job. -- Antoon Pardon -- http://mail.python.org/mailman/listinfo/python-list
Create datetime instance using a tuple.
Hi, all. I would like to know if it is possible to create a datetime instance using a tuple instead of single values. I mean: from datetime import datetime t = (1, 2, 3) dt = datetime(t) Traceback (most recent call last): File stdin, line 1, in ? TypeError: function takes at least 3 arguments (1 given) (class datetime(year, month, day[, hour[, minute[, second[, microsecond[, tzinfo]) Thanks. -- http://mail.python.org/mailman/listinfo/python-list
Re: TEST
Dear ITtoolbox Groups Subscriber, Your message has NOT been distributed to the ITtoolbox BusinessObjects-L discussion group. Please continue reading for further details and instructions. On Wednesday, May 26, 2004, ITtoolbox launched nine new discussion topics, each focusing on specific Business Objects products. There is no longer one ITtoolbox BusinessObjects-L address. As a current group member, you are automatically subscribed to the new topics and can begin to send and receive messages immediately. Instead of addressing messages to [EMAIL PROTECTED], you must now send messages to one or more of the appropriate ITtoolbox Business Objects discussion topics below. Analytic Applications - [EMAIL PROTECTED] Connectivity - [EMAIL PROTECTED] Data Integration - [EMAIL PROTECTED] Development - [EMAIL PROTECTED] Installations and Upgrades - [EMAIL PROTECTED] Performance Management and Security [EMAIL PROTECTED] Reporting and Analysis - [EMAIL PROTECTED] General Business Objects Issues - [EMAIL PROTECTED] ITtoolbox also hosts the BusinessObjects-Crystal-L discussion group. Unlike the eight discussion topics listed above, you are not automatically subscribed to this group. To begin sending and receiving messages from the ITtoolbox BusinessObjects-Crystal-L discussion group, you can subscribe by visiting http://BI.ITtoolbox.com/groups/groups.asp?v=BUSINESSOBJECTS-CRYSTAL-L. Please read the FAQs below for more information. 1) Why am I receiving messages from different e-mail addresses? There is no longer one BusinessObjects-L e-mail address. Instead, each Business Objects area of discussion has its own e-mail address. You will receive messages from each address corresponding to the new ITtoolbox Business Objects discussion topics. 2) How do I send a message to the new ITtoolbox Business Objects discussion topics? From the list above, choose the most relevant topic based on the subject of your message. For example, if your message is relevant to Reporting, it should be addressed to [EMAIL PROTECTED] 3) What if I want my message to go to more than one topic? Simply address your message to as many ITtoolbox Business Objects discussion topics as are relevant to the subject of your message. ITtoolbox will make sure each user only gets your message one time, even if they are subscribed to multiple groups. 4) What if I do not want to receive messages from all the ITtoolbox Business Objects discussion topics? You may, at any point, choose to unsubscribe from specific ITtoolbox Business Objects discussion topics. To unsubscribe, please sign in to your ITtoolbox User ID with your e-mail address at http://My.ITtoolbox.com/My_Groups.asp. If you have never signed in before, you may request a password by visiting http://My.ITtoolbox.com/ForgotPassword.asp. You must individually unsubscribe from each topic. 5) Why did you add individual Business Objects discussion topics? I thought the ITtoolbox BusinessObjects-L discussion group worked just fine. ITtoolbox received feedback from many group members requesting the opportunity to conduct more specialized discussion about particular Business Objects applications. Since such clear areas exist, we felt they warranted their own discussion topics. The creation of these new topics will improve the overall quality of discussion by enabling you to receive focused, high quality solutions with less turnaround time than ever before. 6) What if I still have questions? If you still have questions, please contact [EMAIL PROTECTED] Thank you for your understanding. Sincerely, List Administrator [EMAIL PROTECTED] -- http://mail.python.org/mailman/listinfo/python-list
RE: threads and sleep?
Is SYS V shared memory a totalyl stupid way of doing distributed locks between processes then? -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Jonathan Ellis Sent: 06 July 2005 05:45 To: python-list@python.org Subject: Re: threads and sleep? Peter Hansen wrote: Jeffrey Maitland wrote: I was hoping that python would allow for the cpu threading such in Java etc.. but I guess not. (from the answers,and other findings) I guess I will have to write this part of the code in something such as java or c or something that allows for it then I can either wrap it in python or avoid python for this part of the app. Or investigate the use of Irmen's Pyro package and how it could let you almost transparently move your code to a *multi-process* architecture Unless you're doing anything that would require distributed locking. Many if not most such projects do, which is why almost everyone prefers to use threads on an SMP machine instead of splitting it across multiple smaller boxes. -Jonathan -- http://mail.python.org/mailman/listinfo/python-list -- http://mail.python.org/mailman/listinfo/python-list
How to disable rangeselect in wxGrid
Hi ! I have a little problem with wxGrid. In Delphi I can set in grids how I want to select cells. I can select only individual cells, or ranges. In my program I don't wanna use ranges. But I don't find any methods or properties what can set this option. The range selection mode is disturb the users. Usually the ranges are used to select more cells, and do any operations with them. But in my program the user can select only one(!) cell, and this cell set the actual day, and actual person. If many cells are selected, the user (and I too) cannot determine, which day/person is the actual. So if possible, I want to protect users from this effect. Is anyone can help me ? Thanx for it: ft - To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] -- http://mail.python.org/mailman/listinfo/python-list
Re: Python exception hook simple example needed
Hi ! I think I found an example: import sys def info(type, value, tb): if hasattr(sys, 'ps1') or not sys.stderr.isatty(): # we are in interactive mode or we don't have a tty-like # device, so we call the default hook print yyy sys.__excepthook__(type, value, tb) else: import traceback, pdb # we are NOT in interactive mode, print the exception... print xxx traceback.print_exception(type, value, tb) # ...then start the debugger in post-mortem mode. pdb.pm() sys.excepthook = info But I don't know it is working or not Thanx: ft Tárgy: Re: Python exception hook simple example needed Feladó: Benji York [EMAIL PROTECTED] Dátum: Tue, 05 Jul 2005 10:34:23 -0400 Címzett: python-list@python.org Címzett: python-list@python.org [EMAIL PROTECTED] wrote: If anyone has an idea, how to I catch exceptions globally, please write me. I believe there is an example of this in the demo that comes with wxPython (don't have an install handy to check). -- Benji York -- http://mail.python.org/mailman/listinfo/python-list
Re: Lisp development with macros faster than Python development?..
Fuzzyman: So Lisp is for really good programmers, and Python is for mediocre programmers ? Python is *also* for mediocre programmers. I see this as a strength, not as a weakness. Michele Simionato -- http://mail.python.org/mailman/listinfo/python-list
Re: Create datetime instance using a tuple.
On 6 Jul 2005 02:01:55 -0700, Negroup [EMAIL PROTECTED] wrote: Hi, all. I would like to know if it is possible to create a datetime instance using a tuple instead of single values. I mean: from datetime import datetime t = (1, 2, 3) dt = datetime(t) Traceback (most recent call last): File stdin, line 1, in ? TypeError: function takes at least 3 arguments (1 given) (class datetime(year, month, day[, hour[, minute[, second[, microsecond[, tzinfo]) Use: dt = datetime(*t) -- Qiangning Hong Get Firefox! http://www.spreadfirefox.com/?q=affiliatesamp;id=67907amp;t=1 -- http://mail.python.org/mailman/listinfo/python-list
Re: precision problems in base conversion of rational numbers
[Terry Hancock] Needless to say, the conventional floating point numbers in Python are actually stored as *binary*, which is why there is a decimal module (which is new). If you're going to be converting between bases anyway, it probably makes little difference whether you are using the decimal module or not, of course. You'll have the same problems the conventional float numbers do. Not really. floats won't do because they may not have sufficient precision to differentiate rational values falling close the split between representable values in a given base. The decimal module offers arbitrarily large precision for making sure the error-term is small enough to not make a difference. [Brian van den Broek] Thanks. mensanator provided the actual formula for my case. I had a magic number in my code by which I multiplied my desired level of number of places in the representation to obtain the value for decimal.getcontext.prec. mensanator wrote: The value you want for x is log(17)/log(10) = 1.2304489213782739285401698943283 where x was my magic number. I've not had a chance to think it through yet, but I feel confident that given the formula, I'll be able to work out *why* that is the formula I need. That formula just gives a starting point estimate. The required decimal precision may be much higher. If the rational falls very close to the half-way point between two representable numbers, the calculation needs to be retried with increased precision until the split-point is definitive (when the error-term becomes less than the distance to the next representable value). For a simple example, convert both 10247448370872321 and 10247448370872319 from base ten to 4 digits of hex. The calculations need to be carried out to 15 places of hex (or 17 places of decimal) just to determine whether the fourth hex digit is a 7 or 8: hex(10247448370872321) '0x246801L' hex(10247448370872319) '0x2467ffL' For an example of using decimal with iteratively increasing precision, see the dsum() recipe at http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/393090 . Raymond -- http://mail.python.org/mailman/listinfo/python-list
Re: map/filter/reduce/lambda opinions and background unscientific mini-survey
Op 2005-07-02, Mike Meyer schreef [EMAIL PROTECTED]: Sean McIlroy [EMAIL PROTECTED] writes: Peter Hansen wrote: snip Sean, what gave you the impression this would change? if that's the case then list comprehensions and/or first class functions are likely to be the next target. The existence of list comprehensions are the reason that these functions are going away, so they aren't likely to be next. It's all part of There should be one-- and preferably only one --obvious way to do it. IMO people concentrate too much on the and preferably only one part of this. If you really want at least one obvious way to do things then, there also will be a lot of things that have more than one obvious way. Trying to eliminate all those mulitiple obvious ways, which seems to be one of the goals here, will result in removing the one obvious way for doing other things. -- Antoon Pardon -- http://mail.python.org/mailman/listinfo/python-list
Using Ghostscript DLL via ctypes in Py2.3/Win
I've written a simple commanline wrapper for calling GhostScript from Python. It uses os.system under Windows and os.popen under unixes. The call looks basically like this: gs -q -dNODISPLAY -dNOPAUSE -dSAFER ps2ai.ps infile.eps outfile.ai I'd prefer to use the GhostScript DLL API* and call it using ctypes under Windows. This way, I could package just the DLL with my application and the user would not necessarily need to install the full GhostScript. However, I don't really know how to handle ctypes very well. Has anyone perhaps written something like that already and cares to share a code snippet? Regards, Adam *) http://www.cs.wisc.edu/~ghost/doc/cvs/API.htm -- http://mail.python.org/mailman/listinfo/python-list
Re: Dr. Dobb's Python-URL! - weekly Python news and links (Jul 5)
Simon Brunning wrote: [snip..] The online Python Journal is posted at pythonjournal.cognizor.com. [EMAIL PROTECTED] and [EMAIL PROTECTED] welcome submission of material that helps people's understanding of Python use, and offer Web presentation of your work. Does the 'pythonjournal' still deserve it's place in these posts ? It doesn't *seem* to have been updated for some years. Regards, Fuzzy http://www.voidspace.org.uk/python -- http://mail.python.org/mailman/listinfo/python-list
Re: Lisp development with macros faster than Python development?..
On 6 Jul 2005 00:30:34 -0700, Raymond Hettinger [EMAIL PROTECTED] wrote: With Lisp or Forth, a master programmer has unlimited power and expressiveness. With Python, even a regular guy can reach for the stars. +1 QOTW -- http://mail.python.org/mailman/listinfo/python-list
frozenset question
Hi,
Are there any benefits in using a frozenset over a set, other than it
being immutable?
Will McGugan
--
http://www.willmcgugan.com
.join({'*':'@','^':'.'}.get(c,0) or chr(97+(ord(c)-84)%26) for c in
jvyy*jvyyzpthtna^pbz)
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Re: frozenset question
On 7/6/05, Will McGugan [EMAIL PROTECTED] wrote:
Hi,
Are there any benefits in using a frozenset over a set, other than it
being immutable?
A frozenset can be used as a key of a dict:
. s1 = set([1])
. s2 = frozenset([2])
. {s1: 1}
Traceback (most recent call last):
File stdin, line 1, in ?
TypeError: set objects are unhashable
. {s2:1}
{frozenset([2]): 1}
--
Qiangning Hong
Get Firefox! http://www.spreadfirefox.com/?q=affiliatesamp;id=67907amp;t=1
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Re: f*cking re module
On 5 Jul 2005 08:04:21 -0700, jwaixs [EMAIL PROTECTED] wrote: ... The python re module is, in my opinion, a non beginner user friendly module. And it's not meant for beginning python programmers. I don't have any experience with perl or related script/programming languages like python. (I prefer to do things in c) So the re module is completely new for me. Actually, REs are a useful tool even in C, for example for validating input before parsing it with custom code, so you can forget about some of the error checking in the parsing code. ... although you have to be on a Unix system to be reasonably sure that they are available, and even then you're looking at a much less powerful RE language than the ones in Python and Perl. That's another problem with REs -- there are many slightly different RE languages, and sometimes you cannot even be sure which one you're working with. /Jorgen -- // Jorgen Grahn jgrahn@ Ph'nglui mglw'nafh Cthulhu \X/algonet.se R'lyeh wgah'nagl fhtagn! -- http://mail.python.org/mailman/listinfo/python-list
Re: frozenset question
Qiangning Hong wrote:
On 7/6/05, Will McGugan [EMAIL PROTECTED] wrote:
Hi,
Are there any benefits in using a frozenset over a set, other than it
being immutable?
A frozenset can be used as a key of a dict:
Thanks, but I meant to imply that.
I was wondering if frozenset was faster or more efficient in some way.
Thinking back to the dark ages of C++, you could optimize things that
you knew to be constant.
Will
--
http://www.willmcgugan.com
.join({'*':'@','^':'.'}.get(c,0) or chr(97+(ord(c)-84)%26) for c in
jvyy*jvyyzpthtna^pbz)
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Tkinter grid layout
Hi there, I've got a tree control in Tkinter (using the ESRF Tree module) but I can't get it to layout how I want it. I'd like to have it so that it streches north/south (anchored to the top and bottom), is of a fixed width and is anchored to the left hand side. Here's my code (its derived from one of the examples from the ESRF web site): class MainWindow(Frame): def __init__(self, master): Frame.__init__(self, master) self.document = # new DOM document self.create_site_list() def create_site_list(self): self.list_model = ListModel(self.document) # ListModel class returns the DOM outline as a simple Python data structure self.site_list = Tree.Tree(master=self,\ root_id=root,\ root_label=Site,\ get_contents_callback=self.get_list_item,\ # get_list_item uses the list_model to build list nodes width=300) self.site_list.grid(row=0, column=0, sticky=N+SW) self.grid_rowconfigure(0, weight=1) vsb = Scrollbar(self, orient=VERTICAL) vsb.grid(row=0, column=1, sticky=NS) self.site_list.configure(yscrollcommand=vsb.set) vsb.configure(command=self.site_list.yview) hsb = Scrollbar(self, orient=HORIZONTAL) hsb.grid(row=1, column=0, sticky=EW+S) self.site_list.configure(xscrollcommand=hsb.set) hsb.configure(command=self.site_list.xview) self.site_list.focus_set() This code makes it centred in the east/west direction and a constant height anchored to the top. I guess its the sticky values I need to play with (?) but I can't find the right combination. I've given the code with the ones that seem logically correct (to me!) I expect this is probably quite trivial for someone who knows what they're doing. Any ideas? Cheers, Richard -- http://mail.python.org/mailman/listinfo/python-list
Re: Outlook COM: how to create a MailItem from a .msg file
Ok, we didn't have the IMAP service running; we do now (no SSL). Connecting to the server is not a problem anymore, but logging in is. It works with the administrator account, but not with my personal account. We have restricted access to all machines in 10.0.0.0/255.255.255.0, which includes my machine. My password is empty (yeah, I know..). Could that be the problem? I'm using this: pw = '' Thanks, g -- http://mail.python.org/mailman/listinfo/python-list
Re: System Independent Wallpaper Changer
On Wednesday 06 July 2005 01:12, Terrance N. Phillip wrote: I've done some searching, and can't seem to find a programatic way of getting *** that to happen. http://www.google.com/search?q=setwallpaper+dcop I hope this helps -- Toby Dickenson -- http://mail.python.org/mailman/listinfo/python-list
Re: map/filter/reduce/lambda opinions and background unscientific mini-survey
Full Acknowledge -- http://mail.python.org/mailman/listinfo/python-list
Re: frozenset question
On Wed, 06 Jul 2005 11:30:14 +0100, Will McGugan wrote: I was wondering if frozenset was faster or more efficient in some way. Thinking back to the dark ages of C++, you could optimize things that you knew to be constant. Why would you want to? py import sets py import time py bigset = sets.Set(range(50)) py bigimmutableset = sets.ImmutableSet(range(50)) py assert len(bigset) == len(bigimmutableset) py py def tester(S, L): ... Test if items from L are in S, and time the process. ... t = time.time() ... for i in range(100): ... for item in L: ... item in S ... return time.time() - t # time returned is for 100 loops ... py Time some successful tests: py tester(bigset, range(100, 500)) 0.11539506912231445 py tester(bigimmutableset, range(100, 500)) 0.12014198303222656 Practically no difference when doing 100*400 checks of whether an integer is in the set. But let's try again, just in case: py tester(bigset, range(100, 500)) 0.10998892784118652 py tester(bigimmutableset, range(100, 500)) 0.4096641540527 The difference is insignificant. How about unsuccessful checks? py tester(bigset, range(-100, -500, -1)) 0.12070298194885254 py tester(bigset, range(-100, -500, -1)) 0.11681413650512695 py tester(bigimmutableset, range(-100, -500, -1)) 0.11313891410827637 py tester(bigimmutableset, range(-100, -500, -1)) 0.11315703392028809 There is no significant speed difference between immutable and mutable sets, at least for queries. Regardless of whether it is successful or unsuccessful, mutable or immutable, it takes about 0.025 second to do each test of item in set. Why would you need to optimize that? If you tell us what you are trying to do, and under what circumstances it is too slow, we'll see if we can suggest some ways to optimize it. But if you are just trying to optimize for the sake of optimization, that's a terrible idea. Get your program working first. Then when it works, measure how fast it runs. If, and ONLY if, it is too slow, identify the parts of the program that make it too slow. That means profiling and timing. Then optimize those parts, and nothing else. Otherwise, you will be like the car designer trying to speed up his sports cars by making the seatbelts aerodynamic. -- Steven. -- http://mail.python.org/mailman/listinfo/python-list
Re: threads and sleep?
Jonathan Ellis wrote: Peter Hansen wrote: Or investigate the use of Irmen's Pyro package and how it could let you almost transparently move your code to a *multi-process* architecture Unless you're doing anything that would require distributed locking. Many if not most such projects do, which is why almost everyone prefers to use threads on an SMP machine instead of splitting it across multiple smaller boxes. I can't address the issue of whether or not most such projects require distributed locking, because I'm not familiar with more than half of such projects, as you appear to be. wink On the other hand, I am (somewhat) familiar with Jeffrey's stated problem area (two postings of his earlier in the thread) and it really doesn't sound like he needs such a thing. Would you normally expect to need distributed locking for a simple system where you had long-running computations and wanted to improve performance by using multiple CPUs? Of course, only he can tell for sure. -Peter -- http://mail.python.org/mailman/listinfo/python-list
Re: adding a character to the last string element of a list
Philippe C. Martin wrote: I guess my slicing was wrong, l[-1] worked Note that that's _not_ a slice, however, but a reference to the last element in the list. You'd have to subclass list to be able to do something with reference-slices. Probably returning a special object from __getslice__ which itself has references back to the original list and implements any changes back in the original instead of in itself. I haven't tried to imagine if this is even feasible. Anything indexing with : in it is a slice, so a copy, while anything with only a single index as you have in l[-1] is just a reference to one element in the list. -Peter -- http://mail.python.org/mailman/listinfo/python-list
Re: Using Ghostscript DLL via ctypes in Py2.3/Win
Adam Twardoch wrote: I'd prefer to use the GhostScript DLL API* and call it using ctypes under Windows. Has anyone perhaps written something like that already and cares to share a code snippet? There is a ctypes mailing list where you might have more success getting a reply (though I suspect most people there read this forum as well). -Peter -- http://mail.python.org/mailman/listinfo/python-list
Re: VBR mp3 length
No One wrote: Hello all, If this isn't the correct newsgroup, please redirect me. I'm trying to extract the song length from variable bit rate mp3's. Does anyone know of a library or bit of code that will do this? I've tried pymad, but it seems to grab the bitrate of the first frame and then apply that to the the file length to come up with a total length. Needless to say, if the bitrate of the first frame isn't close to the overall average, it's wildly off. Thanks, -Steve Take a look at http://pymedia.org. -- -- Lucas Raab lvraab@earthlink.net dotpyFE@gmail.com AIM:Phoenix11890 MSN:dotpyfe @ gmail.com IRC:lvraab ICQ:324767918 Yahoo: Phoenix11890 -- http://mail.python.org/mailman/listinfo/python-list
Re: threads and sleep?
Grant Edwards wrote: On 2005-07-05, Grant Edwards [EMAIL PROTECTED] wrote: Or is the Python interpreter actually doing the context switches itself? Upon further thought, that just can't be the case. There has to be multiple instances of the intepreter because the interpreter can make C system calls that block (thus blocking that instance of the interpreter). Other Python threads within the program continue to run, so there must be multiple Python intepreters. Maybe you should consider and explain what you mean by multiple interpreters? As I understand the concept, and based on my several years' old reading of the virtual machine code, I wouldn't say there are multiple interpreters. There's a reason the GIL is the *global* interpreter lock... -Peter -- http://mail.python.org/mailman/listinfo/python-list
Re: Python exception hook simple example needed
Wax has a brilliant prebuilt dialog/handler. It's a wrapper over wxPython - so you still use wxPython objects, it's jsut all a lot easier. http://zephyrfalcon.org/labs Best Regards, Fuzzy http://www.voidspace.org.uk/python -- http://mail.python.org/mailman/listinfo/python-list
Re: Good starterbook for learning Python?
A book that will stay useful as a referene *after* you've used it to learn is 'Programming Python'. Best Regards, Fuzzy http://www.voidspace.org.uk/python -- http://mail.python.org/mailman/listinfo/python-list
Re: Lisp development with macros faster than Python development?..
Fair enough ;-) I'd like to discover the power of Lisp, but I have a limited amount of time to sink into programming... so maybe I'm better off putting my energies and imagination into Python. *A language is a medium of expression.* - Paul Graham All the best. Fuzzy http://www.voidspace.org.uk/python -- http://mail.python.org/mailman/listinfo/python-list
Dr. Dobb's Python-URL! - weekly Python news and links (Jul 5)
QOTW: That's what I love in that news group. Someone comes with a stupid and arrogant question, and someone else answers in a calm and reasonable way. - Gustavo Niemeyer After 25 years doing this, I've become something of a Luddite as far as fancy IDEs and non-standard features go... and a huge believer in strict decoupling between my tools, to the point of ignoring things that bundle them together in ways that are, in my opinion, too tight. - Peter Hansen Ralf Grosse-Kunstleve floats a proposal to reduce the amount of code requires to set instance fields from arguments in __init__ methods: http://groups-beta.google.com/group/comp.lang.python/browse_thread/thread/7346ad00a14e821a The Python Software Foundation Summer of Code projects have been selected: http://www.amk.ca/diary/archives/003975.html A discussion about the long-term plan to remove map, filter, reduce and lambda starts out bad-tempered then ... improves little: http://groups-beta.google.com/group/comp.lang.python/browse_thread/thread/ceef909ebd10b65a There's a new wxPython tutorial at Dev Shed: http://www.devshed.com/c/a/Python/A-Look-at-wxPython/ Peter Hansen wants to determine the wall-clock elapsed time taken by a process on a managed host in a reliable, cross-platform way: http://groups-beta.google.com/group/comp.lang.python/browse_thread/thread/cd1222d713730b67 Par Nicolas Lehuen uses Python to compare Microsoft Word documents stored in a Subversion repository (!): http://www.lehuen.com/nicolas/index.php/2005/06/30/60-comparing-microsoft-word-documents-stored-in-a-subversion-repository Terry Hancock explains what ZOPE actually is: http://groups-beta.google.com/group/comp.lang.python/msg/174d4101e0e419e8 Everything Python-related you want is probably one or two clicks away in these pages: Python.org's Python Language Website is the traditional center of Pythonia http://www.python.org Notice especially the master FAQ http://www.python.org/doc/FAQ.html PythonWare complements the digest you're reading with the marvelous daily python url http://www.pythonware.com/daily Mygale is a news-gathering webcrawler that specializes in (new) World-Wide Web articles related to Python. http://www.awaretek.com/nowak/mygale.html While cosmetically similar, Mygale and the Daily Python-URL are utterly different in their technologies and generally in their results. For far, FAR more Python reading than any one mind should absorb, much of it quite interesting, several pages index much of the universe of Pybloggers. http://lowlife.jp/cgi-bin/moin.cgi/PythonProgrammersWeblog http://www.planetpython.org/ http://mechanicalcat.net/pyblagg.html comp.lang.python.announce announces new Python software. Be sure to scan this newsgroup weekly. http://groups.google.com/groups?oi=djqas_ugroup=comp.lang.python.announce Steve Bethard, Tim Lesher, and Tony Meyer continue the marvelous tradition early borne by Andrew Kuchling, Michael Hudson and Brett Cannon of intelligently summarizing action on the python-dev mailing list once every other week. http://www.python.org/dev/summary/ The Python Package Index catalogues packages. http://www.python.org/pypi/ The somewhat older Vaults of Parnassus ambitiously collects references to all sorts of Python resources. http://www.vex.net/~x/parnassus/ Much of Python's real work takes place on Special-Interest Group mailing lists http://www.python.org/sigs/ Python Success Stories--from air-traffic control to on-line match-making--can inspire you or decision-makers to whom you're subject with a vision of what the language makes practical. http://www.pythonology.com/success The Python Software Foundation (PSF) has replaced the Python Consortium as an independent nexus of activity. It has official responsibility for Python's development and maintenance. http://www.python.org/psf/ Among the ways you can support PSF is with a donation. http://www.python.org/psf/donate.html Kurt B. Kaiser publishes a weekly report on faults and patches. http://www.google.com/groups?as_usubject=weekly%20python%20patch Cetus collects Python hyperlinks. http://www.cetus-links.org/oo_python.html Python FAQTS http://python.faqts.com/ The Cookbook is a collaborative effort to capture useful and interesting recipes. http://aspn.activestate.com/ASPN/Cookbook/Python Among several Python-oriented RSS/RDF feeds available are http://www.python.org/channews.rdf
Re: Proposal: reducing self.x=x; self.y=y; self.z=z boilerplate code
Ralf, I'd be very interested to hear your opinion on the 'namespace' module, which looks at addressing some of these issues (the Record object, in particular). The URL is http://namespace.python-hosting.com, and any comments should be directed to the [EMAIL PROTECTED] discussion list. Regards, Nick. -- Nick Coghlan | [EMAIL PROTECTED] | Brisbane, Australia --- http://boredomandlaziness.blogspot.com -- http://mail.python.org/mailman/listinfo/python-list
Re: Lisp development with macros faster than Python development?..
Op 2005-07-06, Michele Simionato schreef [EMAIL PROTECTED]: Fuzzyman: So Lisp is for really good programmers, and Python is for mediocre programmers ? Python is *also* for mediocre programmers. I see this as a strength, not as a weakness. But sometimes I get the impression people want it to evolve so it is only for mediocre programmers. -- Antoon Pardon -- http://mail.python.org/mailman/listinfo/python-list
Re: map/filter/reduce/lambda opinions and background unscientificmini-survey
Terry Reedy [EMAIL PROTECTED] wrote: George Sakkis [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] Still it's hard to explain why four specific python keywords - def, del, exec and elif - were chosen to be abbreviated, Precedence in other languages and CS usage? What precedence ? I don't know of another language that uses def or del at least; even C++ which compared to python is much more terse uses delete instead of del. And in any case, curly braces for grouping statements is much more prevalent in other languages and CS usage but (fortunately) python chose indentation. So, who would object the full-word versions for python 3K ? def - define del - delete exec - execute These three I might prefer to keep. elif - else if This one I dislike and would prefer to write out. I never liked it in whatever else language I first encountered it and still don't. In contrast to the first three changes which would be straightforward, changing elif to else if would add (a little?) complexity to the parser by allowing else to be followed either by a colon (the only choice now) or if, though I don't think this would be a decisive factor. George -- http://mail.python.org/mailman/listinfo/python-list
Re: frozenset question
Steven D'Aprano wrote:
There is no significant speed difference between immutable and mutable
sets, at least for queries. Regardless of whether it is successful or
unsuccessful, mutable or immutable, it takes about 0.025 second to do
each test of item in set. Why would you need to optimize that?
If you tell us what you are trying to do, and under what circumstances it
is too slow, we'll see if we can suggest some ways to optimize it.
But if you are just trying to optimize for the sake of optimization,
that's a terrible idea. Get your program working first. Then when it
works, measure how fast it runs. If, and ONLY if, it is too slow,
identify the parts of the program that make it too slow. That means
profiling and timing. Then optimize those parts, and nothing else.
Otherwise, you will be like the car designer trying to speed up his sports
cars by making the seatbelts aerodynamic.
No need for the 'premature optimization is the root of all evil' speech.
I'm not trying to optimize anything - just enquiring about the nature of
frozenset. If typing 'frozenset' over 'set' gave me a saving in time or
memory (even if tiny) I would favour immutable sets, where appropriate.
Thanks for the info.
Will
--
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.join({'*':'@','^':'.'}.get(c,0) or chr(97+(ord(c)-84)%26) for c in
jvyy*jvyyzpthtna^pbz)
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Re: map/filter/reduce/lambda opinions and background unscientific mini-survey
map, filter, reduce and lambda Lisp constructs, bring flexibility to the language and is why I started programming in python to begin with. Removing these constructs will be a shame and one step closer to the death of some of the basic features that make python great. -- http://mail.python.org/mailman/listinfo/python-list
Re: Lisp development with macros faster than Python development?..
You don't say how long it took to develop the macros but you should see what kind of website an experienced Zope/Plone programmer can whip up in a few minutes. Acceleration in programming has always been about the Standard Library (not only Python's standard library but also your standard library). I'm talking about stable, debugged, documented macros, functions and classes that the programmer can use to quickly do very complex tasks. I discovered this well over 30 years ago and taught many young programmers and University students this very important trick. As you write software you will eventually come across common routines that are used in almost every software package (logging, reading from CSV files, date/time manipulation, ...). If you have lots of these to choose from in your library, you will produce code 10-100 times faster than those that start over every time AND the code will be MANY times more reliable because you are utilizing stable code that has been debugged over a long period of time. You will also be producing code that is more maintainable. Discovered a bug in a library routine? Fix it and then it is fixed in 100's (or 1000's) of existing programs that use it. -Larry Bates [EMAIL PROTECTED] wrote: I've been reading the beloved Paul Graham's Hackers and Painters. He claims he developed a web app at light speed using Lisp and lots of macros. It got me curious if Lisp is inherently faster to develop complex apps in. It would seem if you could create your own language in Lisp using macros that that would be quite an advantage I realize that Python has operator overloading and OOP so I'm not sure. Any ideas? Any *evidence* one way or another? thanks! Chris -- http://mail.python.org/mailman/listinfo/python-list
Re: map/filter/reduce/lambda opinions and background unscientific mini-survey
On Wed, 5 Jul 2005, George Sakkis wrote: Steven D'Aprano [EMAIL PROTECTED] wrote: On Tue, 05 Jul 2005 09:46:41 -0500, Terry Hancock wrote: [snip] Def would be short for ... defend? defile? defer? defame? default? deflect? There's always *something* to learn. Why def instead of define? Because easy to write beats instantly obvious to a beginner, if the word is used all the time and is easy to memorize. Still it's hard to explain why four specific python keywords - def, del, exec and elif - were chosen to be abbreviated, while all the rest are full words (http://docs.python.org/ref/keywords.html). Ease of typing is a joke for an excuse; For exec and probably del, yes, but def and elif are two of the most frequently used keywords in the language, so i think it's reasonable to keep them short. So, who would object the full-word versions for python 3K ? def - define I'd keep this short - it's one of the most commonly-used keywords. It's particularly commonly used if you break your programs down into lots of little functions; since this is, IMHO, something we want to encourage people to do, we should strive to minimise boilerplate. del - delete How about just getting rid of del? Removal from collections could be done with a method call, and i'm not convinced that deleting variables is something we really need to be able to do (most other languages manage without it). exec - execute This should be a function somewhere, maybe a builtin, maybe not - it absolutely should not be a keyword. What that function should be called, i don't know! elif - else if I'm not sure about splitting it into two words; there's currently a very simple relationship between flow control keywords, meanings, and blocks of code, which would be broken if we moved to using else if. I don't know that this relationship is actually important, though. tom -- Don't believe his lies. -- http://mail.python.org/mailman/listinfo/python-list
Re: frozenset question
Will McGugan [EMAIL PROTECTED] writes: Qiangning Hong wrote: On 7/6/05, Will McGugan [EMAIL PROTECTED] wrote: Hi, Are there any benefits in using a frozenset over a set, other than it being immutable? A frozenset can be used as a key of a dict: Thanks, but I meant to imply that. I was wondering if frozenset was faster or more efficient in some way. No, the 'usable as a dict key' is the main motivation for frozenset's existence. Cheers, mwh -- The bottom tier is what a certain class of wanker would call business objects ... -- Greg Ward, 9 Dec 1999 -- http://mail.python.org/mailman/listinfo/python-list
Re: Lisp development with macros faster than Python development?..
Larry Bates [EMAIL PROTECTED] writes: You don't say how long it took to develop the macros but you should see what kind of website an experienced Zope/Plone programmer can whip up in a few minutes. Zope/Plone (as frameworks) represent exactly the kinds of DSLs people have been building with Lisp for decades. Shoulders of giants, and all that. Lisp has web app frameworks as well: Uncommon Web and BKNR, to name two. Zac -- http://mail.python.org/mailman/listinfo/python-list
Re: System Independent Wallpaper Changer
Toby Dickenson wrote: On Wednesday 06 July 2005 01:12, Terrance N. Phillip wrote: I've done some searching, and can't seem to find a programatic way of getting *** that to happen. http://www.google.com/search?q=setwallpaper+dcop I hope this helps That helps very much, thank-you! And sorry to previous posters: yes, indeed, I changed naming conventions part way through--you got an intermediate version. Nick. -- http://mail.python.org/mailman/listinfo/python-list
Re: map/filter/reduce/lambda opinions and background unscientific mini-survey
On Wed, 6 Jul 2005, Terry Hancock wrote: On Tuesday 05 July 2005 03:43 pm, Tom Anderson wrote: I understand that the backslash is popular in some ivory-tower functional languages. Currently, a backslash can be used for explicit line joining, and is illegal elsewhere on a line outside a string literal, so i think it's available for this. It would be utterly unpythonic to use puntuation instead of a keyword, and it would make no sense to novices, but it would scare the crap out of C programmers, which has to be worth something. With list comprehensions and generators becoming so integral, I'm not sure about unpythonic. I'm going to resist the temptation to argue that list comps are themselves unpythonic :). Hang on, where's the punctuation in either of those? They *are* done with keywords! A generator is just a function with yield instead of return, list comprehensions are just list literals where the explicit sequence of items is replaced with code producing them, using the keywords for, in and if, and a generator expression is a list comp *without any punctuation!* And a syntax just occured to me -- what about this: [y*x for x,y] ? Terrible. Square brackets mean a list, and a lambda is not anything like a list. I see where you're coming from, though; a lambda is a lot like the first half of a list comp that's broken off and is roaming free. I can't think of a good syntax for it, though. tom -- find porn apricot -- http://mail.python.org/mailman/listinfo/python-list
Re: math.nroot [was Re: A brief question.]
On Tue, Jul 05, 2005 at 09:49:33PM +0100, Tom Anderson wrote: Are there any uses for NaN that aren't met by exceptions? Sure. If you can naturally calculate two things at once, but one might turn out to be a NaN under current rules. x, y = calculate_two_things() if isnan(x): perform_next_step_with_only_y(y) else: perform_next_step_with_both(x, y) Under your scheme, you'd have to write try: x, y = calculate_two_things() except NaNException: y = calculate_one_thing() perform_next_step_with_only_y(y) else: perform_next_step_with_both(x, y) and at the very least duplicate the code for calculating 'y', possibly re-doing a lot of work at runtime too. Jeff pgpVUpJh4xufX.pgp Description: PGP signature -- http://mail.python.org/mailman/listinfo/python-list
Use cases for del
Tom Anderson wrote: How about just getting rid of del? Removal from collections could be done with a method call, and i'm not convinced that deleting variables is something we really need to be able to do (most other languages manage without it). Arguing the case for del: how would I, in doing automated testing, ensure that I've returned everything to a clean starting point in all cases if I can't delete variables? Sometimes a global is the simplest way to do something... how do I delete a global if not with del? -Peter -- http://mail.python.org/mailman/listinfo/python-list
Re: Lisp development with macros faster than Python development?..
Tom Anderson wrote: Perhaps the real question, then, is which language allows you to delete lines of code most quickly. No, then the question becomes which language allows you to quickly write very many lines of code which then have to be deleted. Of course, writing those lines manually would be silly if you could automate the process. After all, the lines of code aren't required, so they don't really have to do anything, do they? So naturally Assembly would be the proper way to get maximum performance out of your automatic code writing program. Therefore Assembly is clearly the fastest development language. -Peter -- http://mail.python.org/mailman/listinfo/python-list
Re: best options for oracle/python?
Mark Harrison [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED]... Any recommendations for Oracle bindings for the DB-API 2.0 specification? This is for Oracle 10g if that makes any difference. Also, any other Oracle related goodies that might be useful? You might want to check out the database topic guide for Python... http://www.python.org/topics/database/modules.html ...as well as the DB-SIG resources and mailing list: http://www.python.org/sigs/db-sig/ http://mail.python.org/pipermail/db-sig/ Paul -- http://mail.python.org/mailman/listinfo/python-list
Re: best options for oracle/python?
Use cx_Oracle: http://starship.python.net/crew/atuining/cx_Oracle/ Grig -- http://mail.python.org/mailman/listinfo/python-list
Re: Use cases for del
On Wed, 06 Jul 2005 09:45:56 -0400, Peter Hansen [EMAIL PROTECTED] wrote: Tom Anderson wrote: How about just getting rid of del? Removal from collections could be done with a method call, and i'm not convinced that deleting variables is something we really need to be able to do (most other languages manage without it). Arguing the case for del: how would I, in doing automated testing, ensure that I've returned everything to a clean starting point in all cases if I can't delete variables? Sometimes a global is the simplest way to do something... how do I delete a global if not with del? Unless you are actually relying on the global name not being defined, someGlobal = None would seem to do just fine. Relying on the global name not being defined seems like an edge case. Jp -- http://mail.python.org/mailman/listinfo/python-list
Re: Tkinter grid layout
On Wed, 06 Jul 2005 11:44:55 +0100, Richard Lewis [EMAIL PROTECTED] said: Hi there, I've got a tree control in Tkinter (using the ESRF Tree module) but I can't get it to layout how I want it. I'd like to have it so that it streches north/south (anchored to the top and bottom), is of a fixed width and is anchored to the left hand side. Here's my code (its derived from one of the examples from the ESRF web site): OK, I've changed it so that the Tree and scroll bars are in a single Frame and added another Frame on the right hand side to put the rest of my stuff in. (Though I believe this is against the principles of grid layout management?) class MainWindow(Frame): def __init__(self, master): Frame.__init__(self, master) self.document = # new DOM document self.create_ui() def create_ui(self): self.master.protocol(WM_DELETE_WINDOW, self.app_quit) self.pack(fill=both) self.master.geometry(%dx%d%+d%+d % (800, 600, 100, 100)) self.master.title(Site Editor) self.create_menu() self.create_site_list() self.rhs_frame = Frame(master=self, background=#FF) self.rhs_frame.grid(row=0, column=1, sticky=E+W+N+S) self.grid_columnconfigure(1, weight=1) self.grid_rowconfigure(0, weight=1) label = Label(master=self.rhs_frame, text=FOO) label.grid(row=0, column=0) def create_site_list(self): self.list_model = ListModel(self.document) self.site_list_frame = Frame(master=self, width=300, background=#00FF00) self.site_list_frame.grid(row=0, column=0, sticky=E+W+N+S) self.site_list = Tree.Tree(master=self.site_list_frame,\ root_id=root,\ root_label=Site,\ get_contents_callback=self.get_list_item,\ width=300,height=600) self.site_list.grid(row=0, column=0, sticky=E+W+N+S) self.site_list_frame.grid_columnconfigure(0, weight=1) self.site_list_frame.grid_rowconfigure(0, weight=1) vsb = Scrollbar(self.site_list_frame, orient=VERTICAL) vsb.grid(row=0, column=1, sticky=NS) self.site_list.configure(yscrollcommand=vsb.set) vsb.configure(command=self.site_list.yview) hsb = Scrollbar(self.site_list_frame, orient=HORIZONTAL) hsb.grid(row=1, column=0, sticky=EW) self.site_list.configure(xscrollcommand=hsb.set) hsb.configure(command=self.site_list.xview) self.site_list.focus_set() I noticed that I had a pack() call in my create_ui() function which I must have pasted in from some example code a while ago. I tried taking this out (having read that you shouldn't mix pack and grid) but, of course, then there was no layout (or something) and I just got a blank window. So I tried using pack(fill=both). It now fills horizontally correctly, but it still doesn't anchor with the bottom. I'm not setting any height for the Tree (if I do then it still doesn't anchor with the bottom) because I don't want it to have a particular height, just to fill the window. Am I heading in the right direction? Cheers, Richard -- http://mail.python.org/mailman/listinfo/python-list
Re: Use cases for del
Peter Hansen wrote: Arguing the case for del: how would I, in doing automated testing, ensure that I've returned everything to a clean starting point in all cases if I can't delete variables? Sometimes a global is the simplest way to do something... how do I delete a global if not with del? globals ().__delitem__ (varname) except that the method would probably be called delete. Daniel -- http://mail.python.org/mailman/listinfo/python-list
Re: frozenset question
Will McGugan wrote: Are there any benefits in using a frozenset over a set, other than it being immutable? No. The underlying implementation is identical with set. The only difference is the addition of a hash method and absence of mutating methods. Everything else is the same. Raymond -- http://mail.python.org/mailman/listinfo/python-list
Re: Lisp development with macros faster than Python development?..
[Raymond Hettinger] [EMAIL PROTECTED] wrote: It got me curious if Lisp is inherently faster to develop complex apps in. With Lisp or Forth, a master programmer has unlimited power and expressiveness. With Python, even a regular guy can reach for the stars. A few years ago, I much hesitated between Scheme and Python as my next day-to-day programming language. My feeling at the time was that Scheme is a very fast language to write into, and in which one can implement new concepts cleanly and compactly. Maybe Python is a bit slower to write, but this is compensated by the fact Python is more legible when it comes to later maintenance, or when many people have to share work on a big set of sources. There is some heaviness and complexity in Python internals, Scheme are purer and simpler by comparison. On its bright side, Python has a nice and comprehensive library, and an interesting community of users. These probably make most of the difference. -- François Pinard http://pinard.progiciels-bpi.ca -- http://mail.python.org/mailman/listinfo/python-list
Re: More On - deepcopy, Tkinter
Thanks, I used some of your methods and believe it is now
working.
I also did a lot of experiments, which I've needed to do,
investigating when references vs values are passed and
returned. Not as obvious as I thought.
Duncan Booth wrote:
phil wrote:
The deepcopy protocol does allow you to specify how complicated
objects should be copied. Try defining __deepcopy__() in your objects
to just copy the reference to the Canvas object instead of the object
itself.
I can't figure out from the docs what __deepcopy__ is or how it
works.
I have about 25 classes of drawn objects. for instance
class linefromslope creates an instance of class line.
One of my ugly solutions involves a class prop: within each class,
put properties like slope and midpoint within the self.prop instance
and making a copy of that.
Would __deepcopy__ facilitate this?
Or am I assuming too much: is __deepcopy__ just a method
I invent to do what I want?
The docs say:
In order for a class to define its own copy implementation, it can
define special methods __copy__() and __deepcopy__(). The former is
called to implement the shallow copy operation; no additional
arguments are passed. The latter is called to implement the deep copy
operation; it is passed one argument, the memo dictionary. If the
__deepcopy__() implementation needs to make a deep copy of a
component, it should call the deepcopy() function with the component
as first argument and the memo dictionary as second argument.
__deepcopy__ is a method which overrides the default way to make a deepcopy
of an object.
So, if you have a class with attributes a, b, and c, and you want to ensure
that deepcopy copies a and b, but doesn't copy c, I guess you could do
something like:
class MyClass:
_dontcopy = ('c',) # Tuple of attributes which must not be copied
def __deepcopy__(self, memo):
clone = copy.copy(self) # Make a shallow copy
for name, value in vars(self).iteritems():
if name not in self._dontcopy:
setattr(clone, name, copy.deepcopy(value, memo))
return clone
class Copyable(object):
def __new__(cls, *args):
print created new copyable
return object.__new__(cls, *args)
m = MyClass()
m.a = Copyable()
created new copyable
m.b = Copyable()
created new copyable
m.c = Copyable()
created new copyable
clone = copy.deepcopy(m)
created new copyable
created new copyable
m.a is clone.a
False
m.c is clone.c
True
As you can see, the deepcopy only creates deep copies of 2 of the 3
attributes, 'c' is simply copied across as a shallow copy.
and if you subclass MyClass you can modify the _dontcopy value to add
additional attributes which must not be copied.
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Re: map/filter/reduce/lambda opinions and background unscientific mini-survey
Tom Anderson wrote: del - delete How about just getting rid of del? Removal from collections could be done with a method call, and i'm not convinced that deleting variables is something we really need to be able to do (most other languages manage without it). Since this is a Python 3k item... What would be the consequence of making None the default value of an undefined name? And then assigning a name to None as a way to delete it? Some benefits = *No more NamesError exceptions! print value None value = 25 print value 25 value = None#same as 'del value' *No initialization needed for a while loop! While not something: if condition: something = True *Test if name exists without using a try-except! if something == None: something = value *And of course one less keyword! Any drawbacks? Cheers, Ron PS... not much sleep last night, so this may not be well thought out. -- http://mail.python.org/mailman/listinfo/python-list
Re: threads and sleep?
On 2005-07-06, Dennis Lee Bieber [EMAIL PROTECTED] wrote:
On Tue, 05 Jul 2005 16:01:23 -, Grant Edwards [EMAIL PROTECTED]
declaimed the following in comp.lang.python:
Or is the Python interpreter actually doing the context
switches itself?
It would seem to be close to doing that, if it has that internal
quantum of releasing the GIL every 100 bytecodes...
Right, but I think that's just _allowing_ a context switch
rather than performing one. The other interpreters are blocked
waiting for the GIL and releasing it lets one of them run.
Though the effect is pretty much the same, it's quite different
than having a single interpreter that does the scheduling and
context switching itself within a single OS process/thread.
At the least, the GIL release/reacquire would be similar to
having a C-language program doing sleep() to let other tasks
run. I'll admit that I don't know if creating a Python thread
also creates a new interpreter from scratch (after all,
Windows doesn't have a fork() operation).
If I were doing it, I don't think I'd use fork() and create a
second address space. I'd use a lightweight thread. All of
the interpreter instances would share a single address space.
I know that Win32 has threads.
It may be that the GIL toggle is part of a thread state
save/restore operation, and could thereby be looked on as a
high-level context switch with the OS-level context switch
basically selecting from the threads blocked on the GIL.
Right -- I think that's what's hapenning. I really ought to go
look at the CPython source code instead of just sputing
conjecture.
{I'm going to louse up the message tracking here by pasting part of your
follow-up into one response}
2 Upon further thought, that just can't be the case. There has
2 to be multiple instances of the intepreter because the
2 interpreter can make C system calls that block (thus blocking
2 that instance of the interpreter). Other Python threads within
2 the program continue to run, so there must be multiple Python
2 intepreters.
From the documentation:
The lock is also released and reacquired around potentially blocking I/O
operations like reading or writing a file, so that other threads can run
while the thread that requests the I/O is waiting for the I/O operation
to complete.
I know. I've worked on modules that release the GIL and call
blocking operations. My point is that when an interpreter
calls a blocking operation, the interpreter itself blocks. It
stops running. It goes to sleep. But, other Python threads
keep running, so there must be other interpreters running those
threads.
Otherwise, I'd say convert the number cruncher to a compiled
module that can be started as a Python thread, drop into the
compiled code, give up the GIL, and crunch away -- only
acquiring the GIL when it has results to give back.
Unfortunately that means you've got to debug a number cruncher
that's written in C.
--
Grant Edwards grante Yow! I'm shaving!! I'M
at SHAVING!!
visi.com
--
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Re: threads and sleep?
On 2005-07-06, Alex Stapleton [EMAIL PROTECTED] wrote: Is SYS V shared memory a totalyl stupid way of doing distributed locks between processes then? Sys V semaphores would seem to be a more logical choice. -- Grant Edwards grante Yow! I'm pretending I'm at pulling in a TROUT! Am I visi.comdoing it correctly?? -- http://mail.python.org/mailman/listinfo/python-list
Re: map/filter/reduce/lambda opinions and background unscientific mini-survey
On Wed, 06 Jul 2005 14:33:47 GMT, Ron Adam [EMAIL PROTECTED] wrote: Since this is a Python 3k item... What would be the consequence of making None the default value of an undefined name? And then assigning a name to None as a way to delete it? [ ... ] Any drawbacks? Lots more hard-to-find errors from code like this: filehandle = open( 'somefile' ) do_something_with_an_open_file( file_handle ) filehandle.close( ) Regards, Dan -- Dan Sommers http://www.tombstonezero.net/dan/ -- http://mail.python.org/mailman/listinfo/python-list
Re: map/filter/reduce/lambda opinions and background unscientific mini-survey
Terry Hancock wrote: And a syntax just occured to me -- what about this: [y*x for x,y] ? (that is: [expression for argument list] If you haven't already, see: http://wiki.python.org/moin/AlternateLambdaSyntax for other similar proposals. STeVe -- http://mail.python.org/mailman/listinfo/python-list
Re: map/filter/reduce/lambda opinions and background unscientificmini-survey
Ron Adam wrote: Yes, I think a different key word would help. My current favorite alternative is to put it in parentheses similar to list comprehensions and use let. (let x,y return x+y) If you haven't already, see: http://wiki.python.org/moin/AlternateLambdaSyntax for other similar proposals. STeVe -- http://mail.python.org/mailman/listinfo/python-list
Re: Lisp development with macros faster than Python development?..
Raymond Hettinger wrote: [EMAIL PROTECTED] wrote: The problem is that questions like 'What lang is fastest to develop in?' are hard to answer definitively. FWIW, Google's answer to that question is C++, Java, and Python. For any given problem, any of the three are acceptable. Each programmer or engineering team gets to decide based on his or her language expertise.* Actually, Google's answer to that question is something called ILOG CPLEX, followed by Visual Basic, English as a second language, PHP, and Holt Software Associates. ;-) http://www.google.com/search?hl=enq=What+language+is+fastest+to+develop+in%3FbtnG=Google+Search Given this finding, I'm not sure I should put much weight into Google search results anymore ... -- http://mail.python.org/mailman/listinfo/python-list
Re: threads and sleep?
On 2005-07-06, Peter Hansen [EMAIL PROTECTED] wrote: Or is the Python interpreter actually doing the context switches itself? Upon further thought, that just can't be the case. There has to be multiple instances of the intepreter because the interpreter can make C system calls that block (thus blocking that instance of the interpreter). Other Python threads within the program continue to run, so there must be multiple Python intepreters. Maybe you should consider and explain what you mean by multiple interpreters? That in a multi-theraded Python program, the code that impliments the Python VM is executing simultaneously in multiple contexts: one for each thread (and possibly one master thread). I was responding to somebody who said that there were two issue with using multiple CPUs: 1) the interpreter (singular) only ran on one CPU. 2) the GIL. My point was that 1) couldn't be true. There must be multiple instances of the interpreter since in a multi-threaded Python program, the interpeter blocks when making libc calls like read() write() recv() send(), and yet other Python threads continue to run. If there _were_ only a single interpeter, and it ran only on a single CPU, then the GIL wouldn't be needed. As I understand the concept, and based on my several years' old reading of the virtual machine code, I wouldn't say there are multiple interpreters. There's a reason the GIL is the *global* interpreter lock... Exactly. -- Grant Edwards grante Yow! I've been WRITING at to SOPHIA LOREN every 45 visi.comMINUTES since JANUARY 1ST!! -- http://mail.python.org/mailman/listinfo/python-list
Re: Use cases for del
Peter Hansen wrote: Tom Anderson wrote: How about just getting rid of del? Removal from collections could be done with a method call, and i'm not convinced that deleting variables is something we really need to be able to do (most other languages manage without it). Arguing the case for del: how would I, in doing automated testing, ensure that I've returned everything to a clean starting point in all cases if I can't delete variables? Sometimes a global is the simplest way to do something... how do I delete a global if not with del? I generally find that unit tests force me to structure the code in a cleaner manner, e.g. to not use globals as much, but if you do need to delete a global you do it in exactly the same way as you delete anything: use the del statement: x = 3 def f(): global x del x x 3 f() x Traceback (most recent call last): File pyshell#7, line 1, in -toplevel- x NameError: name 'x' is not defined Where I have used 'del' in a unit test it has been to delete local variables rather than globals. Specifically I wanted to ensure that some data structures were being torn down properly, so the test went something like this: setup: creates a weakref dictionary. teardown: asserts that the weakref dictionary is empty. then each test does: try: create something add it to the weakref dictionary then test it finally: use del to remove local variables force a garbage collection Without the del, when a test fails you get two failures, because the traceback information keeps the variables alive. -- http://mail.python.org/mailman/listinfo/python-list
Deleting variables [was Re: map/filter/reduce/lambda opinions and background unscientific mini-survey]
On Wed, 06 Jul 2005 14:28:55 +0100, Tom Anderson wrote: del - delete How about just getting rid of del? Removal from collections could be done with a method call, Which would be called object.del() I presume. And that opens a big can of worms. Suppose we have a list L = [4, 3, 2, 1, 0], what should L.del(1) do? It looks like it should result in L becoming [4, 3, 2, 0]. An easy mistake to make, if you forget that the argument is (presumably) an index. You could make it clear by insisting on L.del[1] but that requires a big change in Python's syntax. What should L.del() do, with no arguments? Raise an error? Now, you have something like this: class thing: pass obj = thing() obj.alpha = [4, 3, 2, 1, 0] obj.beta = 5 Python's object model suggests that obj.alpha.del() should call alpha's del method, in the same way that obj.alpha.append() would call alpha's append method. So how do you delete obj.alpha? obj.del(alpha) might work. But what if obj itself is a mapping, with a key alpha as well as an attribute alpha. Which one should obj.del(alpha) delete? Now, if you said that L.del() should raise an exception earlier, what about obj.beta.del()? Presumably every object automatically has a del method, so you don't have to program a del method yourself. obj.del is a method object. So it has a del method. (Yes, sometimes you want to delete methods. Functions are first class objects in Python.) Which has a del method. Which has a del method. What should obj.del.del.del.del.del.del.del.del.del() do? and i'm not convinced that deleting variables is something we really need to be able to do (most other languages manage without it). Most other languages don't have namespaces that can get polluted, or on-the-fly creation of variables. Most other languages don't consider variables to be simply attributes of a module object. And most other languages don't allow you to run interactive sessions where it is easy to mistakenly make variables you don't want. py x = 1 py u = x+2 # oops, typo, meant y not u py del u # prevent confusion in the programmer's mind It is also useful sometimes to delete a module object from the top level namespace before re-importing it, rather than merely reloading it. That requires being able to delete a variable. In summary: del being a keyword works. del() being an object method is unclear, confusing and complicated. -- Steven. -- http://mail.python.org/mailman/listinfo/python-list
Re: Lisp development with macros faster than Python development?..
On Wed, 06 Jul 2005 08:27:55 -0500, Larry Bates [EMAIL PROTECTED] wrote: [ reusable, stable, debugged, and documented libraries are a Good Thing ] Absolutely. Two related stories from my days working as a software engineer for a large telecomm company. Both stories begin with the annual ritual of management telling us that code reuse was the silver bullet of software development. 1. We replied that we needed about 5 calendar years to design, develop, debug, and document sufficient libraries to pay for the effort. Then management would tell us that 5 years is too long, and the project(s) would be scrapped. I worked there for 12 years, and was still watching new hires argue over linked list code and build tools when I left. 2. Right after that (and often in the same speech), management would also tell us that they would be measuring our productivity by (a) LOC written rather than LOC reused, and (b) the number of new ideas and code we submitted for patent. There is no better example of a Mixed Message. (Not to mention that we did all or most of our coding in C and C++, and every department and every project had its own method(s) of determining what a Line Of Code looked like, but that's even farther off-topic) Regards, Dan -- Dan Sommers http://www.tombstonezero.net/dan/ -- http://mail.python.org/mailman/listinfo/python-list
Re: threads and sleep?
Thanks for the info. I was doing some more diggging and I came across a module/class called POSH which should allow me to do what I want. My question now is, has anyone here used this and if so what it as easy to implement as what I am reading it is? (I have to wait for the sys admin to install the module on that server, but I have made a modified implemted the syntax into a copy of the code to test it as soon as the admin installs it.) Once again thanks for the information that you all have shared. Jeff -- http://mail.python.org/mailman/listinfo/python-list
Re: Favorite non-python language trick?
(sorry, my NUA had lost the original article)
I'm curious -- what is everyone's favorite trick from a non-python
language? And -- why isn't it in Python?
Ability to tag some methods 'deprecated' as in Java (from 1.5
onwards?). However, Python interpreter doesn't have to do it: pydoc and
similar tools could detect, say, '@deprecated' in method comment string and
warn user about it.
Currently I just document deprecated methods, and if I feel like it, I also
add
def some_method_which_is_badly_named_or_just_plain_wrong(..)
docstring
This method is now deprecated. Use frob() instead.
sys.stderr.write('warning: method
some_method_which_is_badly_named_or_just_plain_wrong is now deprecated')
--
# Edvard Majakari Software Engineer
# PGP PUBLIC KEY available Soli Deo Gloria!
You shouldn't verb verbs.
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Re: Use cases for del
On Wed, 06 Jul 2005 10:00:02 -0400, Jp Calderone wrote: On Wed, 06 Jul 2005 09:45:56 -0400, Peter Hansen [EMAIL PROTECTED] wrote: Tom Anderson wrote: How about just getting rid of del? Removal from collections could be done with a method call, and i'm not convinced that deleting variables is something we really need to be able to do (most other languages manage without it). Arguing the case for del: how would I, in doing automated testing, ensure that I've returned everything to a clean starting point in all cases if I can't delete variables? Sometimes a global is the simplest way to do something... how do I delete a global if not with del? Unless you are actually relying on the global name not being defined, someGlobal = None would seem to do just fine. Relying on the global name not being defined seems like an edge case. Er, there is a lot of difference between a name not existing and it being set to None. $ cat mymodule1.py # define some temporary names a, b, c, d, e, f = 1, 2, 3, 4, 5, 6 # do some work result = a+b+c+d*e**f # delete the temp variables del a del b del c del d del e del f $ cat mymodule2.py # define some temporary names a, b, c, d, e, f = 1, 2, 3, 4, 5, 6 # do some work result = a+b+c+d*e**f # delete the temp variables a = None b = None c = None d = None e = None f = None Now import them into Python: py import mymodule1, mymodule2 py dir(mymodule1) ['__file__', '__name__', result] py dir(mymodule2) ['__file__', '__name__', result, a, b, c, d, e, f] Or worse, do this: py a = 1 py from mymodule2 import * py a + 1 Traceback (most recent call last): File stdin, line 1, in ? TypeError: unsupported operand type(s) for +: 'NoneType' and 'int' It is bad enough that from module import * can over-write your variables with the modules' variables, but for it to do so with DELETED variables is unforgivable. -- Steven. -- http://mail.python.org/mailman/listinfo/python-list
Re: map/filter/reduce/lambda opinions and background unscientific mini-survey
Dan Sommers wrote: On Wed, 06 Jul 2005 14:33:47 GMT, Ron Adam [EMAIL PROTECTED] wrote: Since this is a Python 3k item... What would be the consequence of making None the default value of an undefined name? And then assigning a name to None as a way to delete it? [ ... ] Any drawbacks? Lots more hard-to-find errors from code like this: filehandle = open( 'somefile' ) do_something_with_an_open_file( file_handle ) filehandle.close( ) Regards, Dan If do_something_with_an_open_file() is not defined. Then you will get: TypeError: 'NoneType' object is not callable If file_handle (vs filehandle) is None. Then you will still get an error as soon as you tried to use the invalid file handle. AttributeError: 'NoneType' object has no attribute 'read' If the error was filehundle.close() you will get: AttributeError: 'NoneType' object has no attribute 'close' I don't think any of those would be hard to find. Cheers, Ron -- http://mail.python.org/mailman/listinfo/python-list
Re: Favorite non-python language trick?
Edvard Majakari [EMAIL PROTECTED] writes: (sorry, my NUA had lost the original article) I'm curious -- what is everyone's favorite trick from a non-python language? And -- why isn't it in Python? Ability to tag some methods 'deprecated' as in Java (from 1.5 onwards?). However, Python interpreter doesn't have to do it: pydoc and similar tools could detect, say, '@deprecated' in method comment string and warn user about it. I don't see what's wrong with this code, and if one wanted, one could also implement a decorator which calls warnings.warn when the function is called: def c_buffer(init, size=None): deprecated, use create_string_buffer instead import warnings warnings.warn(c_buffer is deprecated, use create_string_buffer instead, DeprecationWarning, stacklevel=2) return create_string_buffer(init, size) Thomas -- http://mail.python.org/mailman/listinfo/python-list
Re: Favorite non-python language trick?
Thomas Heller [EMAIL PROTECTED] writes:
I don't see what's wrong with this code, and if one wanted, one could
also implement a decorator which calls warnings.warn when the function
is called:
def c_buffer(init, size=None):
deprecated, use create_string_buffer instead
import warnings
warnings.warn(c_buffer is deprecated, use create_string_buffer instead,
DeprecationWarning, stacklevel=2)
return create_string_buffer(init, size)
Well, nothing's wrong there, and the same could be done with Java
before. However, having a consistent deprecated string everywhere allows
easier eg. automatic finding of such methods from documentation.
Decorators also help here, but that requires version 2.3 or newer (which
usually isn't a problem, but can be)
Hey! I hadn't realized category parameter nor stacklevel in warnings module
(just used a few times, never read the doc because I didn't need to). Neat,
thanks.
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# PGP PUBLIC KEY available Soli Deo Gloria!
$_ = '456476617264204d616a616b6172692c20612043687269737469616e20'; print
join('',map{chr hex}(split/(\w{2})/)),uc substr(crypt(60281449,'es'),2,4),\n;
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Re: Tkinter grid layout
On Wed, 06 Jul 2005 11:44:55 +0100, Richard Lewis [EMAIL PROTECTED] wrote: Hi there, I've got a tree control in Tkinter (using the ESRF Tree module) but I can't get it to layout how I want it. I'd like to have it so that it streches north/south (anchored to the top and bottom), is of a fixed width and is anchored to the left hand side. Here's my code (its derived from one of the examples from the ESRF web site): class MainWindow(Frame): [snip code] First of all, it is not a good idea to make your so-called window inherit from Frame: a Frame is not a window in tk, but a generic container. Creating a Frame without a container window will automatically initialize the tk toolkit, creating a default window which will become the default parent for widgets where you don't specify one. According to the well-known explicit is better than implicit principle, if a MainWindow instance are actually the main window for your application, you'd really better inherit from the Tkinter class for the main window, which is Tk. Doing it this way has a lot of advantages over what you do; for example, if you later have to create a menu bar for your application, you will be able to do it in the MainWindow class. If you inherit from Frame, you won't get any access to the actual window, so you won't be able to create a menu in it. This may seems to be unrelated to your problem, but it's not: by creating a Frame, you introduce one more unneeded container. So, in some code you don't show here, you have to insert the MainWindow instance into its parent window via a call to its pack or grid method. Since the code you show seems to be correct, I guess the problem is in this call to pack or grid, which probably does not tell the Frame how to behave when its parent window is resized, causing it to get the default behaviour, which is do nothing at all. To be sure this actually is the problem, try to replace the line: Frame.__init__(self, master) in MainWindow.__init__ by: Frame.__init__(self, master, bg='blue', bd=2) This way, a blue border will appear around the frame, allowing you to see how it grows. Then run your application, and resize the window. You should see that the frame does not grow when the window grows, explaining why your tree deos not grow (in fact, it would grow if its container did; but its container doesn't...) So you should either make your MainWindow class inherit from Tk, which eliminates the unneeded container and the problems it may cause, or make sure the pack or grid on your MainWindow instance actually tells the container to grow with its container. With pack, it's quite easy: just do myWindow.pack(fill=BOTH, expand=1). With grid, it's a bit more complicated, since you will have to configure the grid on the container. But basically, my advice would be: - Never make your windows inherit from Frame; make them inherit from Tk for the main window or from Toplevel for all other ones - When you have resize problems, always check the whole widget hierarchy from the actual window down to the widget showing the problem. The cause is very often not on the widget itself, but on one of its containers. HTH -- python -c print ''.join([chr(154 - ord(c)) for c in 'U(17zX(%,5.zmz5(17;8(%,5.Z65\'*9--56l7+-']) -- http://mail.python.org/mailman/listinfo/python-list
latex/bibtex python paper?
Hi All,
Does anyone have a good template that I might use for writing a python
paper in latex/bibtex? I've got the paper mostly done, but am having
issues with the references. I am definitely not an expert at
latex/bibtex. Right now, I have references defined like this:
@article{imp,
title = {imp -- Access the import internals},
journal = http://www.python.org/doc/current/lib/module-imp.html;,
author = {Python Software Foundation},
year = {2005}
}
When I cite these, I get something like this (Foundation[2005]). Is
anyone willing to offer up a tarball of a complete paper with sty and
bst that would make for a nice python paper?
Thanks!
-kurt
http://schwehr.org/software/segy-py
--
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Re: Favorite non-python language trick?
On 7/6/05, Edvard Majakari [EMAIL PROTECTED] wrote: Ability to tag some methods 'deprecated' as in Java (from 1.5 onwards?). However, Python interpreter doesn't have to do it: pydoc and similar tools could detect, say, '@deprecated' in method comment string and warn user about it. http://wiki.python.org/moin/PythonDecoratorLibrary?#head-de01988728ccdec415708f10928cc6feb022e7bb -- Cheers, Simon B, [EMAIL PROTECTED], http://www.brunningonline.net/simon/blog/ -- http://mail.python.org/mailman/listinfo/python-list
Re: adding a character to the last string element of a list
Thanks, Philippe Peter Hansen wrote: Philippe C. Martin wrote: I guess my slicing was wrong, l[-1] worked Note that that's _not_ a slice, however, but a reference to the last element in the list. You'd have to subclass list to be able to do something with reference-slices. Probably returning a special object from __getslice__ which itself has references back to the original list and implements any changes back in the original instead of in itself. I haven't tried to imagine if this is even feasible. Anything indexing with : in it is a slice, so a copy, while anything with only a single index as you have in l[-1] is just a reference to one element in the list. -Peter -- http://mail.python.org/mailman/listinfo/python-list
Re: frozenset question
On Wed, 06 Jul 2005 14:25:30 +0100, Will McGugan wrote: But if you are just trying to optimize for the sake of optimization, that's a terrible idea. Get your program working first. Then when it works, measure how fast it runs. If, and ONLY if, it is too slow, identify the parts of the program that make it too slow. That means profiling and timing. Then optimize those parts, and nothing else. Otherwise, you will be like the car designer trying to speed up his sports cars by making the seatbelts aerodynamic. No need for the 'premature optimization is the root of all evil' speech. I'm not trying to optimize anything - just enquiring about the nature of frozenset. If typing 'frozenset' over 'set' gave me a saving in time or memory (even if tiny) I would favour immutable sets, where appropriate. Well, obviously the premature optimization speech just went in one ear and out the other. Saving in time or memory is what optimization is about. What did you think optimization means? set and frozenset have different functionality (one is mutable, the other is not) and use cases (you use one where you need to dynamically add and remove items from a set, and the other where you need to use a set as a key in a dictionary). In most cases, they aren't interchangable. While you're spending time worrying about shaving a thousandth of a millisecond off a program that takes five seconds to run, I'll get on with development using the right object for the functionality needed. -- Steven. -- http://mail.python.org/mailman/listinfo/python-list
Re: Create datetime instance using a tuple.
Qiangning Hong wrote: On 6 Jul 2005 02:01:55 -0700, Negroup [EMAIL PROTECTED] wrote: Hi, all. I would like to know if it is possible to create a datetime instance using a tuple instead of single values. I mean: from datetime import datetime t = (1, 2, 3) dt = datetime(t) Traceback (most recent call last): File stdin, line 1, in ? TypeError: function takes at least 3 arguments (1 given) (class datetime(year, month, day[, hour[, minute[, second[, microsecond[, tzinfo]) Use: dt = datetime(*t) It's better to write: dt = datetime(*t[:6]) This gives you compatibility with the (year, month, day, hour, minute, second, weekday, julian_day, dst) tuples returned by time.gmtime, time.localtime, and time.strptime. -- http://mail.python.org/mailman/listinfo/python-list
Conditionally implementing __iter__ in new style classes
I'm trying to implement __iter__ on an abstract base class while I don't know whether subclasses support that or not. Hope that makes sense, if not, this code should be clearer: class Base: def __getattr__(self, name): if name == __iter__ and hasattr(self, Iterator): return self.Iterator raise AttributeError, name class Concrete(Base): def Iterator(self): yield 1 yield 2 yield 3 The idea is that if a subclass of Base defines an 'Iterator' method, instances are iterable. They are not iterable otherwise. The above gives the expected behaviour: iter(Base()) raises a TypeError: iteration over non-sequence, and iter(Concrete()) returns a generator. If, however, I make Base a newstyle class, this will not work any longer. __getattr__ is never called for __iter__ (neither is __getattribute__, btw). Probably this has to do with data descriptors and non-data descriptors, but I'm too tired at the moment to think further about this. Is there any way I could make the above code work with new style classes? Thanks, Thomas -- http://mail.python.org/mailman/listinfo/python-list
Re: map/filter/reduce/lambda opinions and background unscientific mini-survey
Here's a couple of examples from my own code:
# from a Banzhaf Power Index calculator
# adds things that aren't numbers
return reduce(operator.add,
(VoteDistributionTable({0: 1, v: 1}) for v in electoral_votes))
return sum([VoteDistributionTable({0:1, v:1} for v in
electoral_votes],VoteDistributionTable({}))
Any time you use operator.add, you can probably use
sum(sequence,initialvalue)
# from a custom numeric class
# converts a tuple of digits into a number
mantissa = sign * reduce(lambda a, b: 10 * a + b, mantissa)
I'll admit I can't figure out a way to replace reduce without writing
some ugly code here, but I doubt these sorts of things appear often.
--
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Re: Conditionally implementing __iter__ in new style classes
Thomas Heller [EMAIL PROTECTED] writes: I'm trying to implement __iter__ on an abstract base class while I don't know whether subclasses support that or not. Hope that makes sense, if not, this code should be clearer: class Base: def __getattr__(self, name): if name == __iter__ and hasattr(self, Iterator): return self.Iterator raise AttributeError, name class Concrete(Base): def Iterator(self): yield 1 yield 2 yield 3 The idea is that if a subclass of Base defines an 'Iterator' method, instances are iterable. They are not iterable otherwise. The above gives the expected behaviour: iter(Base()) raises a TypeError: iteration over non-sequence, and iter(Concrete()) returns a generator. If, however, I make Base a newstyle class, this will not work any longer. __getattr__ is never called for __iter__ (neither is __getattribute__, btw). Probably this has to do with data descriptors and non-data descriptors, but I'm too tired at the moment to think further about this. Is there any way I could make the above code work with new style classes? I forgot to mention this: The Base class also implements a __getitem__ method which should be used for iteration if the .Iterator method in the subclass is not available. So it seems impossible to raise an exception in the __iter__ method if .Iterator is not found - __iter__ MUST return an iterator if present. Thomas -- http://mail.python.org/mailman/listinfo/python-list
Re: Conditionally implementing __iter__ in new style classes
I'm trying to implement __iter__ on an abstract base class while I don't know whether subclasses support that or not. Hope that makes sense, if not, this code should be clearer: class Base: def __getattr__(self, name): if name == __iter__ and hasattr(self, Iterator): return self.Iterator raise AttributeError, name class Concrete(Base): def Iterator(self): yield 1 yield 2 yield 3 I don't know how to achieve it, but why don't you simply use class Base: pass class Concrete(Base): def __iter__(self) : yield 1 yield 2 yield 3 What is the advantage to have a baseclass that essentially does some method renaming __iter__ == Iterator? - harold - -- Always remember that you are unique; just like everyone else. -- -- http://mail.python.org/mailman/listinfo/python-list
Re: Use cases for del
Steven D'Aprano wrote: On Wed, 06 Jul 2005 10:00:02 -0400, Jp Calderone wrote: On Wed, 06 Jul 2005 09:45:56 -0400, Peter Hansen [EMAIL PROTECTED] wrote: Tom Anderson wrote: How about just getting rid of del? Removal from collections could be done with a method call, and i'm not convinced that deleting variables is something we really need to be able to do (most other languages manage without it). Arguing the case for del: how would I, in doing automated testing, ensure that I've returned everything to a clean starting point in all cases if I can't delete variables? Sometimes a global is the simplest way to do something... how do I delete a global if not with del? Unless you are actually relying on the global name not being defined, someGlobal = None would seem to do just fine. Relying on the global name not being defined seems like an edge case. Er, there is a lot of difference between a name not existing and it being set to None. Yes, they are not currently the same thing. But what if assigning a name to None actually unbound it's name? And accessing an undefined name returned None instead of a NameError? Using an undefined name in most places will still generate some sort of an None type error. I think the biggest drawback to this second suggestion is that we would have to test for None in places where it would matter, but that's probably a good thing and enables checking if a variable exists without using a try-except. $ cat mymodule2.py # define some temporary names a, b, c, d, e, f = 1, 2, 3, 4, 5, 6 # do some work result = a+b+c+d*e**f # delete the temp variables a = b = c = d = e = f = None# possibly unbind names This would work if None unbound names. It is bad enough that from module import * can over-write your variables with the modules' variables, but for it to do so with DELETED variables is unforgivable. Yes, I agree using None as an alternative to delete currently is unacceptable. Cheers, Ron -- http://mail.python.org/mailman/listinfo/python-list
Re: How do you program in Python?
On 7/6/2005 5:38 AM, Jorgen Grahn wrote: On Sun, 03 Jul 2005 17:35:16 +0100, anthonyberet [EMAIL PROTECTED] wrote: ... What I would really like is something like an old-style BASIC interpreter, in which I could list, modify and test-run sections of You probably want to check out Wing IDE 2.0. There is a free trial. -- http://mail.python.org/mailman/listinfo/python-list
Re: Conditionally implementing __iter__ in new style classes
I'm not sure I understand why you would want to. Just don't define __iter__ on your newstyle class and you'll get the expected behavior. -- http://mail.python.org/mailman/listinfo/python-list
Re: Programmers Contest: Fit pictures on a page
Don wrote: Chung Leong wrote: Isn't that an NP-complete problem or am I crazy? It is NP complete. Its known as the cutting stock problem (aka Knapsack problem). Here's a Wikipedia page that describes it: http://en.wikipedia.org/wiki/Cutting_stock_problem There are commerical applications available that solve the problem in 2D for use in the woodworking industry (among others). This is generally done to minimize waste when cutting down panels (plywood, etc) into smaller pieces for cabinets, etc. -Don For photos, it's a lot simpler, assuming you only want make standard size prints (IE: 8x10, 5x7, 4x6, 2.5x3.5). There are a very limited number of combinations of the standard print sizes which will fit on an 8.5x11 sheet of paper. This could probably be solved pretty easily with just a lookup table. Also, you have to remember that paper cost is only part of the equation when printing photos -- you also have to consider ink costs. In the stock cutting problem, it's assumed that the cutting cost is insignificant. Given the insane cartidge costs for inkjet printers, wasting a little paper -- even expensive paper -- is likely to be a more economical than wasting ink. -- http://mail.python.org/mailman/listinfo/python-list
Re: Conditionally implementing __iter__ in new style classes
Why not define an Iterator method in your Base class that does the iteration using __getitem__, and any subclass that wants to do something else just defines its own Iterator method? For that matter, you could just use the __iter__ methods of Base and Concrete instead of a separate method. -- http://mail.python.org/mailman/listinfo/python-list
Re: Tkinter grid layout
On Wed, 06 Jul 2005 17:36:01 +0200, Eric Brunel [EMAIL PROTECTED] said: On Wed, 06 Jul 2005 11:44:55 +0100, Richard Lewis [EMAIL PROTECTED] wrote: Hi there, I've got a tree control in Tkinter (using the ESRF Tree module) but I can't get it to layout how I want it. I'd like to have it so that it streches north/south (anchored to the top and bottom), is of a fixed width and is anchored to the left hand side. Here's my code (its derived from one of the examples from the ESRF web site): class MainWindow(Frame): [snip code] First of all, it is not a good idea to make your so-called window inherit from Frame: a Frame is not a window in tk, but a generic container. [] But basically, my advice would be: - Never make your windows inherit from Frame; make them inherit from Tk for the main window or from Toplevel for all other ones - When you have resize problems, always check the whole widget hierarchy from the actual window down to the widget showing the problem. The cause is very often not on the widget itself, but on one of its containers. And very sound advice it turns out to be! I've changed my MainWindow class to inherit from Tk and now all the layout works fine. Thanks very much for your help! Cheers, Richard -- http://mail.python.org/mailman/listinfo/python-list
Re: Conditionally implementing __iter__ in new style classes
Something like this: class Base(object): ... def __getitem__(self, key): ... return key ... def __iter__(self): ... yield self[1] ... yield self['foo'] ... yield self[3.0] ... class ConcreteIterable(Base): ... def __iter__(self): ... yield True ... yield 'Blue' ... yield 'Foo' ... class ConcreteNotIterable(Base): ... pass ... [x for x in Base()] [1, 'foo', 3.0] [x for x in ConcreteIterable()] [True, 'Blue', 'Foo'] [x for x in ConcreteNotIterable()] [1, 'foo', 3.0] -- http://mail.python.org/mailman/listinfo/python-list
Re: map/filter/reduce/lambda opinions and background unscientific mini-survey
Devan L wrote: # from a custom numeric class # converts a tuple of digits into a number mantissa = sign * reduce(lambda a, b: 10 * a + b, mantissa) I'll admit I can't figure out a way to replace reduce without writing some ugly code here, but I doubt these sorts of things appear often. It's not ugly or difficult to define a named function. def digits_to_value(seq): v = 0 for d in seq: v = v*10+d return v Then where you need it. mantissa = sign * digits_to_value(mantissa) One of the motivations is the reduce-lambda expressions are a lot harder to read than a properly named function. And a function will often work faster than the reduce-lambda version as well. Cheers, Ron -- http://mail.python.org/mailman/listinfo/python-list
Re: debugger?
Qiangning Hong [EMAIL PROTECTED] writes: (...) However, while I use pdb or inserting print statement to debug my apps, sometimes it is a pain. I think I need a good GUI debugger to help me. The debugger should meet _most_ of the following requirements: 1. can debug wxPython applications (and other GUI lib). 2. an intuitive way to set/clear/enable/disable breakpoints. 3. can set conditional breakpoints (i.e. break when some condition satisfied). 4. variable watch list, namescope watching (local, global) 5. evaluate expression, change variable values, etc within debugging. 6. change the running routine, (i.e. go directly to a statement, skip some statements, etc) 7. clever way to express objects, not just a string returned by repr() 8. perform profiling 9. a clear interface. 10. cross-platform. 11. free, or better, open source. Although we typically use unit tests and 'print' debugging, I settled on Wing IDE as having the best debugger for the times when something more was needed. It's not free (pretty reasonable cost for an IDE though), but otherwise I think would meet your other points, except perhaps for profiling. It's easy enough to grab an evaluation version to try out (http://www.wingide.com). For us, a big point was wxPython debugging, and being able to stop at exceptions within wxPython event handlers. Interestingly enough, that's seems to be a tough requirement for many of the existing debuggers because the exceptions occur in code that has been called out to from within a C++ layer, and thus have to be caught before the C++ layer gets a chance to clear the exception. -- David -- http://mail.python.org/mailman/listinfo/python-list
Re: Tkinter grid layout
Excuse me for intruding, but I followed examples and ended up with a similar architecture: from Tkinter import * class MyMain(Frame): def __init__(self, master): self.root = master self.master=master root = Tk() app = MyMain(root) app.master.title(Object Editor) root.mainloop() Erick, are you saying it should be modified to something like : from Tkinter import * class MyMain(Tk): ... ... app = MyMain() app.title(My App) app.mainloop() Thanks, Bill Eric Brunel wrote: On Wed, 06 Jul 2005 11:44:55 +0100, Richard Lewis [EMAIL PROTECTED] wrote: Hi there, I've got a tree control in Tkinter (using the ESRF Tree module) but I can't get it to layout how I want it. I'd like to have it so that it streches north/south (anchored to the top and bottom), is of a fixed width and is anchored to the left hand side. Here's my code (its derived from one of the examples from the ESRF web site): class MainWindow(Frame): [snip code] First of all, it is not a good idea to make your so-called window inherit from Frame: a Frame is not a window in tk, but a generic container. Creating a Frame without a container window will automatically initialize the tk toolkit, creating a default window which will become the default parent for widgets where you don't specify one. According to the well-known explicit is better than implicit principle, if a MainWindow instance are actually the main window for your application, you'd really better inherit from the Tkinter class for the main window, which is Tk. Doing it this way has a lot of advantages over what you do; for example, if you later have to create a menu bar for your application, you will be able to do it in the MainWindow class. If you inherit from Frame, you won't get any access to the actual window, so you won't be able to create a menu in it. This may seems to be unrelated to your problem, but it's not: by creating a Frame, you introduce one more unneeded container. So, in some code you don't show here, you have to insert the MainWindow instance into its parent window via a call to its pack or grid method. Since the code you show seems to be correct, I guess the problem is in this call to pack or grid, which probably does not tell the Frame how to behave when its parent window is resized, causing it to get the default behaviour, which is do nothing at all. To be sure this actually is the problem, try to replace the line: Frame.__init__(self, master) in MainWindow.__init__ by: Frame.__init__(self, master, bg='blue', bd=2) This way, a blue border will appear around the frame, allowing you to see how it grows. Then run your application, and resize the window. You should see that the frame does not grow when the window grows, explaining why your tree deos not grow (in fact, it would grow if its container did; but its container doesn't...) So you should either make your MainWindow class inherit from Tk, which eliminates the unneeded container and the problems it may cause, or make sure the pack or grid on your MainWindow instance actually tells the container to grow with its container. With pack, it's quite easy: just do myWindow.pack(fill=BOTH, expand=1). With grid, it's a bit more complicated, since you will have to configure the grid on the container. But basically, my advice would be: - Never make your windows inherit from Frame; make them inherit from Tk for the main window or from Toplevel for all other ones - When you have resize problems, always check the whole widget hierarchy from the actual window down to the widget showing the problem. The cause is very often not on the widget itself, but on one of its containers. HTH -- http://mail.python.org/mailman/listinfo/python-list
Re: Conditionally implementing __iter__ in new style classes
Thomas Heller wrote: I forgot to mention this: The Base class also implements a __getitem__ method which should be used for iteration if the .Iterator method in the subclass is not available. So it seems impossible to raise an exception in the __iter__ method if .Iterator is not found - __iter__ MUST return an iterator if present. def Iterator(self): for index in xrange(len(self)): yield self[index] def __iter__(self): return self.Iterator() ...and then override Iterator in subclasses. But this raises the question of why you need to use a specially-named method instead of having subclasses override the __iter__. -- http://mail.python.org/mailman/listinfo/python-list
