ANN: pinocchio 0.1, extensions for nose unit test framework
ANNOUNCING pinocchio v0.1. pinocchio is a collection of plugins for the 'nose' unit testing framework; more about that here: http://somethingaboutorange.com/mrl/projects/nose/ Basic documentation for pinocchio is available at http://darcs.idyll.org/~t/projects/pinocchio/doc/ pinocchio currently contains five plugins: * decorator -- allows you to assign tags to tests from a list file; * figleafsections -- shows you which tests are executing what code; * stopwatch -- lets you pick tests to run based on the last execution time; * outputsave -- saves test stdout into individual files, tagged with success/failure. * spec -- generates specification output from test class/method names. This is the first package release of pinocchio. Note that pinocchio *requires* setuptools to be installed, because that is how nose plugins work! You can install pinocchio with easy_install, or download this release at http://darcs.idyll.org/~t/projects/pinocchio-0.1.tar.gz Documentation is included in the .tar.gz, and you can read the latest docs online at http://darcs.idyll.org/~t/projects/pinocchio/doc/ pinocchio is available under the MIT license. It is Copyright (C) 2006, 2007 C. Titus Brown, except for the spec plugin which is Copyright (C) 2007 Michal Kwiatkowski. --titus -- http://mail.python.org/mailman/listinfo/python-announce-list Support the Python Software Foundation: http://www.python.org/psf/donations.html
Re: unsigned integer?
En Sat, 10 Mar 2007 21:04:00 -0300, Paul Rubin http://phr.cx@NOSPAM.invalid escribió: Gabriel Genellina [EMAIL PROTECTED] writes: If you use %u you get a very large positive value, not +3. Exactly, and that's the right value. (unsigned int)(-3) isn't +3. The OP specified that the expected result was 3. Ouch! Yes, sorry, I overlooked it. And the C code just made things more confusing. -- Gabriel Genellina -- http://mail.python.org/mailman/listinfo/python-list
Re: How to test if a key in a dictionary exists?
On Mar 10, 9:12 pm, Paul Rubin http://[EMAIL PROTECTED] wrote: if hist.has_key(outcome): hist[outcome] += 1 # if key already exists, increment else: hist[outcome] = 1 # else create a new key You could write that: hist[outcome] = 1 + hist.get(outcome, 0) Or with Python 2.5 you could use hist = defaultdict(int) ... hist[outcome] += 1 # automatically initializes to 0 if outcome not found Often when building a histogram, one knows in advance what the keys will be. For instance, when working with data from 0 to 100 and looking for frequencies by decade, you can initialize the histogram- dict with: for i in range(10): histodict[i] = 0 and then just update the appropriate bucket without having to do any testing at all: fibSeqUpTo100 = [1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89] for val in fibSeqUpTo100: key = val/10 histodict[ key ] += 1 This has the added benefit of including entries for the empty buckets as well. -- Paul -- http://mail.python.org/mailman/listinfo/python-list
Re: number generator
On Mar 11, 2:16 am, greg [EMAIL PROTECTED] wrote: MonkeeSage wrote: this ... requires that M be evenly divisible by N, No, it doesn't -- I never said the numbers had to be *equal*. Sorry for not being clear. I was refering to my specific implementation of the algorithm, not the generic design pattern. Regards, Jordan -- http://mail.python.org/mailman/listinfo/python-list
Re: 2 new comment-like characters in Python to aid development?
On Mar 9, 10:30 am, Nick Craig-Wood [EMAIL PROTECTED] wrote: [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: What if 2 new 'special' comment-like characters were added to Python?: 1. The WIP (Work In Progress) comment: I use # FIXME for this purpose or /* FIXME */ in C etc. I have an emacs macro which shows it up in bright red / yellow text so it is easy to see and the company has a system which makes a web page with a list of all the FIXMEs on. FIXME is easy to grep for, language neutral and a lot of people use something similar (eg XXX or TODO). 2. The HALT comment: You can so this with triple quotes. ''' and ''' (if you normally use for docstrings) Python just ignores strings that lie around. -- Nick Craig-Wood [EMAIL PROTECTED] --http://www.craig-wood.com/nick Vim will highlight the following comments too: #FIXME #TODO #XXX - Paddy -- http://mail.python.org/mailman/listinfo/python-list
Help
how to use Python/C API -- http://mail.python.org/mailman/listinfo/python-list
Re: Database module multithreading
En Sat, 10 Mar 2007 22:44:43 -0300, Jon Ribbens [EMAIL PROTECTED] escribió: I don't know, but stock Python 2.5 seems to stick mysterious '.egg' files in the site-packages directory when you install things. Which stock Python? Not the one from www.python.org... If you are talking about some Linux distro, ask the packagers... -- Gabriel Genellina -- http://mail.python.org/mailman/listinfo/python-list
Re: Python in a desktop environment
On Mar 10, 10:52 pm, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: David Cramer wrote: If you had an application that you were about to begin development on which you wanted to be cross platform (at least Mac and Windows), would you suggest using c++ and Python? I'd strongly consider a pure python solution (I'd choose wxpython), but if I needed to code backend stuff in a lower level language I'd use C rather than C++. Well we want it to be very robust, and python isn't exactly the fastest language, or one with the lowest overhead :) -- http://mail.python.org/mailman/listinfo/python-list
Parsing Indented Text (like parsing Python)
Hi, I'm relatively new to Python but have lots of prior programming experience as a developer, instructor, and author (ASP/VBScript/SQL Server and Clipper.) I'm trying to write an app that parses a text file containing an outline useing essentially the same indentation rules as Python source code, i.e. the first level has no indent, the second level has one indent, third level has two indents, and so on. However, I can't know for sure that the indentations are tabs or spaces, or even mixed tabs and spaces. What's more, I can't know for sure what tab spacing the persons editor was using if they saved as spaces, i.e. tab='N' spaces where N= (2,3,4,5,6,7,8,...) Clearly the source code for Python has to figure this out, but I wonder if anyone knows how to do this in Python. Frankly I'm stumped on how to find an elegant algorithm that does require multipass parsing and lots of code. Any help would be appreciated. -- -Mike Schinkel http://www.mikeschinkel.com/blogs/ http://www.welldesignedurls.org http://atlanta-web.org - http://t.oolicio.us -- http://mail.python.org/mailman/listinfo/python-list
Re: Python in a desktop environment
David Cramer schrieb: On Mar 10, 10:52 pm, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: David Cramer wrote: If you had an application that you were about to begin development on which you wanted to be cross platform (at least Mac and Windows), would you suggest using c++ and Python? I'd strongly consider a pure python solution (I'd choose wxpython), but if I needed to code backend stuff in a lower level language I'd use C rather than C++. Well we want it to be very robust, and python isn't exactly the fastest language, or one with the lowest overhead :) Erm, and what has _robustness_ with fast less overhead to do? It's exactly the other way round, a python program is much less likely to crash that C/C++, and if so in manners that are much easier to manage and fix. I've done extensive GUI-development with PyQt, and can say that it's a very productive and powerful combination. And GUI-code usually isn't troublesome performance-wise. Diez -- http://mail.python.org/mailman/listinfo/python-list
Re: Python in a desktop environment
David Cramer [EMAIL PROTECTED] wrote: On Mar 10, 10:52 pm, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: David Cramer wrote: If you had an application that you were about to begin development on which you wanted to be cross platform (at least Mac and Windows), would you suggest using c++ and Python? I'd strongly consider a pure python solution (I'd choose wxpython), but if I needed to code backend stuff in a lower level language I'd use C rather than C++. Well we want it to be very robust, and python isn't exactly the fastest language, or one with the lowest overhead :) So if you want it to be robust it's a no brainer: Python and no C++ or C. I'd advise you to start off doing it in pure Python, then when you get it working see if it is fast enough, and if not profile it and find the bottlenecks. Those bits which really do need speeding up you should then rewrite using Pyrex, which won't take long at all since it is basically the same syntax. Also see whether Psyco helps. Python can be slow, but if you leverage the built in functionality correctly you'll find it isn't much slower than C/C++ for many tasks, and can even be faster than you would get from C/C++ without a spending a very long time optimising it (that's because people have already spent a very long time optimising Python's builtin functionality). Even if you do eventually find you have to rewrite parts of the code in C/C++ you should first have done what you can to optimise it in Python. Usually the best way to speed up something which is too slow is to use a different algorithm. That sort of change is comparatively easy to do in Python but an expensive programming exercise in C/C++. When you come to reimplement it then you'll be converting the already optimised code, which in many cases will be much easier than writing it in C/C++ from scratch. If you look at http://page.mi.fu-berlin.de/~prechelt/Biblio/jccpprtTR.pdf you'll see that, at least for that task, the relative runtimes for C/C++ and Python widely overlap. Yes, the C/C++ implementation included some very fast ones, but they also included slows ones (and only Python of all the languages tested had no unusable implementations). OTOH, time to write the programs does not overlap. Of course, since that paper was written Python has changed a lot. -- http://mail.python.org/mailman/listinfo/python-list
threading and iterator crashing interpreter
I have been having problems with the Python 2.4 and 2.5 interpreters on both Linux and Windows crashing on me. Unfortunately it's rather complex code and difficult to pin down the source. So I've been trying to reduce the code. In the process it's started to crash in different ways. I'm not sure if any of it is related. The following is only crashing Python 2.5 (r25:51908, Sep 19 2006, 09:52:17) [MSC v.1310 32 bit (Intel)] on win32 in two different(?) ways. Using the login1() function will throw a bunch of exceptions the most interesting of which is: Exception in thread Thread-34: Traceback (most recent call last): File C:\Python25\lib\threading.py, line 460, in __bootstrap self.run() File C:\Python25\lib\threading.py, line 440, in run self.__target(*self.__args, **self.__kwargs) File Copy of scratchpad.py, line 20, in login1 random.choice(System.sessions).session_iter.next() RuntimeError: instance.__dict__ not accessible in restricted mode I'm not concerned with the Python exceptions, but about 40% of the time it will launch the Visual Studio JIT Debugger with an Unhandled exception at 0x1e03973e in pythonw.exe: 0xC005: Access violation reading location 0x2024. = Using the login2() function will sometimes (about 30% of the time) cause the following to be printed out: Unhandled exception in thread started by Error in sys.excepthook: Original exception was: === Here's the code. Will it be easier to find the problem if I tried compiling Python myself? from threading import Thread import random def session_iter(f): # second interpreter while 1: yield len(f.__dict__) class Session: def __init__(self): self.session_iter = session_iter(self) class System: sessions = [] def login1(): # first interpreter System.sessions.append(Session()) while 1: random.choice(System.sessions).session_iter.next() def login2(): # first interpreter System.sessions.append(Session()) System.sessions.pop().session_iter.next() # main interpreter threads = [Thread(target=login1) for t in range(2000)] for thread in threads: thread.start() -- http://mail.python.org/mailman/listinfo/python-list
Re: Parsing Indented Text (like parsing Python)
En Sun, 11 Mar 2007 06:34:03 -0300, Mike Schinkel [EMAIL PROTECTED] escribió: I'm trying to write an app that parses a text file containing an outline useing essentially the same indentation rules as Python source code, i.e. the first level has no indent, the second level has one indent, third You can get some ideas from tabnanny.py or reindent.py, but perhaps they are too specific at parsing Python code. I hope this informal description may help: Start with IC = Previous IC = 0, and a stack with a single 0 element For each line in the file: compute the indentation column IC (that is, count the number of leading whitespace characters; perhaps replacing tabs as 8 spaces) compare IC with the Previous IC: same: continue with next line IC previous (indent): push IC onto indent stack IC previous (dedent): discard top of stack look at the new top of stack (but dont discard it); if not the same, indentation error. Previous IC = IC Note: You can rewrite the above without using Previous IC, only the stack... left to the reader :) Note 2: At each stage, the indentation level is the current stack size. -- Gabriel Genellina -- http://mail.python.org/mailman/listinfo/python-list
Re: Database module multithreading
In article [EMAIL PROTECTED], Gabriel Genellina wrote: I don't know, but stock Python 2.5 seems to stick mysterious '.egg' files in the site-packages directory when you install things. Which stock Python? Not the one from www.python.org... Yes, the one from www.python.org. -- http://mail.python.org/mailman/listinfo/python-list
a better solution for GUI in python
Hi, My company is using python currently for our website. We need to develop a GUI front-end for our ERP that would be portable (Windows and Linux). My question is which solution would be better for the GUI (and easier to implement)? I knew there are something like wxidgets, QT and pyGTK? actually we will need some complicated stuff in the GUI and yet I don't know much about GUI programming. Any recommendation guys? -- http://mail.python.org/mailman/listinfo/python-list
Re: Python in a desktop environment
David Cramer [EMAIL PROTECTED] wrote: If you had an application that you were about to begin development on which you wanted to be cross platform (at least Mac and Windows), would you suggest using c++ and Python? I'm asking because we were originally thinking about doing c# but after attending PyCon this year I'm reconsidering. We are already using Python for the website and I figure a c++ backend w/ a Python GUI may work really well, and would be pretty easy to port. Any opinions? Why drag in the C++ ? What do you intend to do in it that you can't do in python? Seems unnecessarily complex to me. And on a desktop, speed issues are kind of irrelevant - Python is snappy enough on modern hardware for most things. My style would be to have the gui connect via pipes to the local backend as a separate process, with a third process if there are any communications needed to off box dbs. But that is just the way I think - YMMV - Hendrik -- http://mail.python.org/mailman/listinfo/python-list
Re: distributed queue?
Paul Rubin http://[EMAIL PROTECTED] wrote: Bjoern Schliessmann [EMAIL PROTECTED] writes: (Why does everyone think that concurrency equals usage of multiple threads?) Well, it doesn't necessarily, but that's easiest a lot of the time. Try Twisted for your networking needs. I should try to understand Twisted better one of these days, but it's much more confusing than threads. Also, the function I want to parallelize does blocking operations (database lookups), so in Twisted I'd have to figure out some way to do them asynchronously. I would think of making 'pullers' in the remote machines in front of whatever it is you are making parallel to get the next thing to do, from a 'queue server' in the originating machine to distribute the stuff. I am not sure if Pyro can help you as I have only read about it and not used it but I think its worth a look. If it were a one on one setup I would not hesitate to recommend it but I can't remember if it is any good for one to many scenarios. - Hendrik -- http://mail.python.org/mailman/listinfo/python-list
Re: Python in a desktop environment
On Mar 11, 12:26 pm, David Cramer [EMAIL PROTECTED] wrote: On Mar 10, 10:52 pm, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: David Cramer wrote: If you had an application that you were about to begin development on which you wanted to be cross platform (at least Mac and Windows), would you suggest using c++ and Python? I'd strongly consider a pure python solution (I'd choose wxpython), but if I needed to code backend stuff in a lower level language I'd use C rather than C++. Well we want it to be very robust, and python isn't exactly the fastest language, or one with the lowest overhead :) only one word caught my attention robust.. do u mean python is not robust??? if this is your feeling, i don't recommend u to reconsider anymore, turn back to ur previous programming language (what did'ya say it was??? c# .. i remember one ad. about it's robustness .. a piece of jelly!) and by the way if u know something about C++, code the GUI with QT (which would make it portable), and enjoy a high speed execution :P -- http://mail.python.org/mailman/listinfo/python-list
Re: distributed queue?
Paul Rubin wrote: Does anyone have an implementation of a distributed queue? I.e. I have a long running computation f(x) and I'd like to be able to evaluate it (for different values of x) on a bunch of different computers simultaneously, the usual worker thread pattern except distributed across a network. I guess this is pretty easy to write with a centralized socket listener that dispatches requests through a Queue to multiple threads on the same machine, each talking synchronously to a server socket. I wonder if something like it already exists. I see a little bit of discussion in the newsgroup archive but no obvious pointers to code. Thanks. Pyro (http://pyro.sf.net) contains 2 examples that do just this. One is a distributed merge sort / md5 cracker, the other is distributed prime factorization of a set of numbers. --Irmen -- http://mail.python.org/mailman/listinfo/python-list
Re: threading and iterator crashing interpreter
En Sun, 11 Mar 2007 07:32:04 -0300, Janto Dreijer [EMAIL PROTECTED] escribió: I have been having problems with the Python 2.4 and 2.5 interpreters on both Linux and Windows crashing on me. Unfortunately it's rather complex code and difficult to pin down the source. So I've been trying to reduce the code. In the process it's started to crash in different ways. I'm not sure if any of it is related. The following is only crashing Python 2.5 (r25:51908, Sep 19 2006, 09:52:17) [MSC v.1310 32 bit (Intel)] on win32 in two different(?) ways. Using the login1() function will throw a bunch of exceptions the most interesting of which is: Exception in thread Thread-34: Traceback (most recent call last): File C:\Python25\lib\threading.py, line 460, in __bootstrap self.run() File C:\Python25\lib\threading.py, line 440, in run self.__target(*self.__args, **self.__kwargs) File Copy of scratchpad.py, line 20, in login1 random.choice(System.sessions).session_iter.next() RuntimeError: instance.__dict__ not accessible in restricted mode From the error message, you appear to be using some form of restricted execution - RExec or similar. I didn't try that way, but using the normal mode, I got this different exception instead (using login1): Exception in thread Thread-85: Traceback (most recent call last): File c:\apps\python\lib\threading.py, line 460, in __bootstrap self.run() File c:\apps\python\lib\threading.py, line 440, in run self.__target(*self.__args, **self.__kwargs) File crash.py, line 20, in login1 random.choice(System.sessions).session_iter.next() ValueError: generator already executing It appears to indicate that you must syncronize the generators. Adding a Lock object to Session appears to work OK: class Session: def __init__(self): self.lock = Lock() self.session_iter = session_iter(self) def login1(): # first interpreter System.sessions.append(Session()) while 1: session = random.choice(System.sessions) session.lock.acquire() session.session_iter.next() session.lock.release() Your login2 version does not generate any error on my PC. -- Gabriel Genellina -- http://mail.python.org/mailman/listinfo/python-list
Re: a better solution for GUI in python
On 11 Mrz., 12:03, ce [EMAIL PROTECTED] wrote: Hi, My company is using python currently for our website. We need to develop a GUI front-end for our ERP that would be portable (Windows and Linux). My question is which solution would be better for the GUI (and easier to implement)? I knew there are something like wxidgets, QT and pyGTK? actually we will need some complicated stuff in the GUI and yet I don't know much about GUI programming. Any recommendation guys? I'd recommend pyGTK. It's easy to use, delivers astonishing results and is perfectly portable as far as I know. I'm working with it myself, having the goal of simplicity as well as portability and I got to say, it works! Hope that was helpful. -- http://mail.python.org/mailman/listinfo/python-list
Re: Database module multithreading
En Sun, 11 Mar 2007 07:55:15 -0300, Jon Ribbens [EMAIL PROTECTED] escribió: In article [EMAIL PROTECTED], Gabriel Genellina wrote: I don't know, but stock Python 2.5 seems to stick mysterious '.egg' files in the site-packages directory when you install things. Which stock Python? Not the one from www.python.org... Yes, the one from www.python.org. Those .egg must come from other installed packages... -- Gabriel Genellina -- http://mail.python.org/mailman/listinfo/python-list
Re: a better solution for GUI in python
ce [EMAIL PROTECTED] writes: My company is using python currently for our website. We need to develop a GUI front-end for our ERP that would be portable (Windows and Linux). Some reason not to use a browser interface instead of a client gui? -- http://mail.python.org/mailman/listinfo/python-list
Re: a better solution for GUI in python
ce wrote: My question is which solution would be better for the GUI (and easier to implement)? I knew there are something like wxidgets, (wxWidgets. It's the C++ lib, its Python bindings are wxPython) QT (same as above, it's called pyQt. Check licensing, it's not as liberal as the others'.) and pyGTK? actually we will need some complicated stuff in the GUI and yet I don't know much about GUI programming. Any recommendation guys? Mostly matter of taste. Without any further details of your needs, no experienced people will be able to help. Why don't you go to the projects' homepages and read, and perhaps check a tutorial. Though biased, this may help: http://www.wxwidgets.org/wiki/index.php/WxWidgets_Compared_To_Other_Toolkits (it's for the C++ original only, but much applies to python bindings) Regards, Björn -- BOFH excuse #137: User was distributing pornography on server; system seized by FBI. -- http://mail.python.org/mailman/listinfo/python-list
Re: a better solution for GUI in python
StD wrote: I'd recommend pyGTK. It's easy to use, delivers astonishing results and is perfectly portable as far as I know. And how does it look on Windows? :) I'm working with it myself, having the goal of simplicity as well as portability and I got to say, it works! Hope that was helpful. Could say the same about wxWidgets, and Qt (the latter only with C++ though). Regards, Björn -- BOFH excuse #52: Smell from unhygienic janitorial staff wrecked the tape heads -- http://mail.python.org/mailman/listinfo/python-list
Re: Database module multithreading
In article [EMAIL PROTECTED], Gabriel Genellina wrote: I don't know, but stock Python 2.5 seems to stick mysterious '.egg' files in the site-packages directory when you install things. Which stock Python? Not the one from www.python.org... Yes, the one from www.python.org. Those .egg must come from other installed packages... My mistake, they are .egg-info. And they certainly do come from stock Python 2.5 from www.python.org and not anything else. They are installed by distutils/command/install_egg_info, which is automatically called by 'python setup.py install'. -- http://mail.python.org/mailman/listinfo/python-list
Re: threading and iterator crashing interpreter
Janto Dreijer wrote: I have been having problems with the Python 2.4 and 2.5 interpreters on both Linux and Windows crashing on me. I don't understand -- does the interpreter crash (segfault) or is just your program terminating due to unhandled exceptions? Regards, Björn -- BOFH excuse #32: techtonic stress -- http://mail.python.org/mailman/listinfo/python-list
Re: a better solution for GUI in python
On Mar 11, 3:05 pm, Paul Rubin http://[EMAIL PROTECTED] wrote: ce [EMAIL PROTECTED] writes: My company is using python currently for our website. We need to develop a GUI front-end for our ERP that would be portable (Windows and Linux). Some reason not to use a browser interface instead of a client gui? it is a matter of input speed only! every record posses some calculations and sometimes fresh data from the database! which i think would be slower in the browser than the local gui client. I know that i can implement the functionality in the browser using javascripts, however, i don't know wither it would be as effective as a local gui or not and which is more convenient. -- http://mail.python.org/mailman/listinfo/python-list
Re: a better solution for GUI in python
Bjoern Schliessmann napisał(a): I'd recommend pyGTK. It's easy to use, delivers astonishing results and is perfectly portable as far as I know. And how does it look on Windows? :) On styled Windows XP it looks like any other styled application (counting those Qt and wx based). On Windows 2000 or unstyled XP since GTK 2.10 it looks far better than Qt3 applications and nearly as good as Win32 native applications (including wx based) or Qt4. -- Jarek Zgoda http://jpa.berlios.de/ -- http://mail.python.org/mailman/listinfo/python-list
Re: threading and iterator crashing interpreter
On Mar 11, 2:20 pm, Bjoern Schliessmann usenet- [EMAIL PROTECTED] wrote: Janto Dreijer wrote: I have been having problems with the Python 2.4 and 2.5 interpreters on both Linux and Windows crashing on me. I don't understand -- does the interpreter crash (segfault) or is just your program terminating due to unhandled exceptions? Segfault. -- http://mail.python.org/mailman/listinfo/python-list
Re: threading and iterator crashing interpreter
On Mar 11, 1:46 pm, Gabriel Genellina [EMAIL PROTECTED] wrote: En Sun, 11 Mar 2007 07:32:04 -0300, Janto Dreijer [EMAIL PROTECTED] escribió: I have been having problems with the Python 2.4 and 2.5 interpreters on both Linux and Windows crashing on me. Unfortunately it's rather complex code and difficult to pin down the source. So I've been trying to reduce the code. In the process it's started to crash in different ways. I'm not sure if any of it is related. The following is only crashing Python 2.5 (r25:51908, Sep 19 2006, 09:52:17) [MSC v.1310 32 bit (Intel)] on win32 in two different(?) ways. Using the login1() function will throw a bunch of exceptions the most interesting of which is: Exception in thread Thread-34: Traceback (most recent call last): File C:\Python25\lib\threading.py, line 460, in __bootstrap self.run() File C:\Python25\lib\threading.py, line 440, in run self.__target(*self.__args, **self.__kwargs) File Copy of scratchpad.py, line 20, in login1 random.choice(System.sessions).session_iter.next() RuntimeError: instance.__dict__ not accessible in restricted mode From the error message, you appear to be using some form of restricted execution - RExec or similar. I didn't try that way, but using the normal mode, I got this different exception instead (using login1): Exception in thread Thread-85: Traceback (most recent call last): File c:\apps\python\lib\threading.py, line 460, in __bootstrap self.run() File c:\apps\python\lib\threading.py, line 440, in run self.__target(*self.__args, **self.__kwargs) File crash.py, line 20, in login1 random.choice(System.sessions).session_iter.next() ValueError: generator already executing It appears to indicate that you must syncronize the generators. Adding a Lock object to Session appears to work OK: class Session: def __init__(self): self.lock = Lock() self.session_iter = session_iter(self) def login1(): # first interpreter System.sessions.append(Session()) while 1: session = random.choice(System.sessions) session.lock.acquire() session.session_iter.next() session.lock.release() Your login2 version does not generate any error on my PC. -- Gabriel Genellina As far as I can tell I'm not running it from restricted mode explicitly. The reason I'm doing the random.choice() is so I don't have a handle (session in this case) that would prevent it from being garbage collected. I am not bothered by the Python-level Exceptions. I am bothered by the interpreter throwing a segfault. What I suspect is happening is the Session object is deallocated, while it still has a reference from within the iterator. It's quite difficult to reproduce these bugs consistently. You might need to run it a few times. -- http://mail.python.org/mailman/listinfo/python-list
Re: Database module multithreading
En Sun, 11 Mar 2007 09:19:51 -0300, Jon Ribbens [EMAIL PROTECTED] escribió: In article [EMAIL PROTECTED], Gabriel Genellina wrote: I don't know, but stock Python 2.5 seems to stick mysterious '.egg' files in the site-packages directory when you install things. Which stock Python? Not the one from www.python.org... Yes, the one from www.python.org. Those .egg must come from other installed packages... My mistake, they are .egg-info. And they certainly do come from stock Python 2.5 from www.python.org and not anything else. They are installed by distutils/command/install_egg_info, which is automatically called by 'python setup.py install'. Ah! Those files contain metadata about the installed packages. See http://docs.python.org/whatsnew/whatsnew25.html , but I think the actual version is http://www.python.org/dev/peps/pep-0345/ . Anyway, nowhere says that the PKG-INFO files are actually copied as packagename.egg-info -- Gabriel Genellina -- http://mail.python.org/mailman/listinfo/python-list
RE: Parsing Indented Text (like parsing Python)
Gabriel Genellina wrote: Start with IC = Previous IC = 0, and a stack with a single 0 element For each line in the file: compute the indentation column IC (that is, count the number of leading whitespace characters; perhaps replacing tabs as 8 spaces) compare IC with the Previous IC: same: continue with next line IC previous (indent): push IC onto indent stack IC previous (dedent): discard top of stack look at the new top of stack (but dont discard it); if not the same, indentation error. Previous IC = IC I went away and reviewed this, but it appears it doesn't tackle the difficult part which was what made me ask the question in the first place. The problem is, how do I figure out how many spaces represent a tab? In one case, someone could have their editor configured to allow tabs to use 3 spaces and the user could intermingle tabs and spaces. In other cases, a user might have their editor configured to have a tab equal 8 spaces yet also intermingle tabs and spaces. When a human looks at the document it is obvious the setting but how can I make it obvious to my program? I could force the user to specify tabwidth at the top of the file, but I'd rather not. And since Python doesn't either, I know it is possible to write a parser to do this. I just don't know how. -- -Mike Schinkel http://www.mikeschinkel.com/blogs/ http://www.welldesignedurls.org http://atlanta-web.org - http://t.oolicio.us -- http://mail.python.org/mailman/listinfo/python-list
Re: Parsing Indented Text (like parsing Python)
The problem is, how do I figure out how many spaces represent a tab? In one case, someone could have their editor configured to allow tabs to use 3 spaces and the user could intermingle tabs and spaces. In other cases, a user might have their editor configured to have a tab equal 8 spaces yet also intermingle tabs and spaces. When a human looks at the document it is obvious the setting but how can I make it obvious to my program? then statistics can do it too. -- cheers, Stef Mientki http://pic.flappie.nl -- http://mail.python.org/mailman/listinfo/python-list
Re: threading and iterator crashing interpreter
En Sun, 11 Mar 2007 09:47:34 -0300, Janto Dreijer [EMAIL PROTECTED] escribió: As far as I can tell I'm not running it from restricted mode explicitly. This error is rather strange then: RuntimeError: instance.__dict__ not accessible in restricted mode restricted mode means that the current builtins are not the standard builtins. The reason I'm doing the random.choice() is so I don't have a handle (session in this case) that would prevent it from being garbage collected. I am not bothered by the Python-level Exceptions. I am bothered by the interpreter throwing a segfault. What I suspect is happening is the Session object is deallocated, while it still has a reference from within the iterator. But on your code Session objects are never deleted; they stay inside System.sessions. Having an extra reference (the session variable) doesnt matter. It's quite difficult to reproduce these bugs consistently. You might need to run it a few times. At least, the problem of using the same generator from different threads still remains, if you don't use my modified code. In general, when using multiple threads you always need some way to syncronize access to shared objects. You are lucky with Sessions because append is an atomic operation on lists; for more information see http://effbot.org/pyfaq/what-kinds-of-global-value-mutation-are-thread-safe.htm -- Gabriel Genellina -- http://mail.python.org/mailman/listinfo/python-list
Re: Parsing Indented Text (like parsing Python)
En Sun, 11 Mar 2007 10:09:57 -0300, Mike Schinkel [EMAIL PROTECTED] escribió: The problem is, how do I figure out how many spaces represent a tab? In You can't, unless you have more context. one case, someone could have their editor configured to allow tabs to use 3 spaces and the user could intermingle tabs and spaces. In other cases, a user might have their editor configured to have a tab equal 8 spaces yet also intermingle tabs and spaces. When a human looks at the document it is obvious the setting but how can I make it obvious to my program? it is obvious the setting? How do you infer that? From other properties of the document, semantics? Just from the content, and the number of tabs and spaces, you can't get anything. I could force the user to specify tabwidth at the top of the file, but I'd rather not. And since Python doesn't either, I know it is possible to write a parser to do this. I just don't know how. Python simply assumes 8 spaces per tab. If your Python source ONLY uses tabs, or ONLY spaces, it doesn't matter. If you mix tabs+spaces, Python simple replaces each tab by 8 spaces. If you edited that using 4 spaces, Python will get it wrong. That's why all people always say never mix tabs and spaces If you know somehow that a certain block -using tabs- has the same indentation that another block -using spaces- you could infer the number of spaces per tab. -- Gabriel Genellina -- http://mail.python.org/mailman/listinfo/python-list
RE: Parsing Indented Text (like parsing Python)
Gabriel Genellina wrote: The problem is, how do I figure out how many spaces represent a tab? You can't, unless you have more context. How does Python do it? one case, someone could have their editor configured to allow tabs to use 3 spaces and the user could intermingle tabs and spaces. In other cases, a user might have their editor configured to have a tab equal 8 spaces yet also intermingle tabs and spaces. When a human looks at the document it is obvious the setting but how can I make it obvious to my program? it is obvious the setting? How do you infer that? From other properties of the document, semantics? Just from the content, and the number of tabs and spaces, you can't get anything. From looking at it. It might require changing tab widths in the editor, but one setting will make it clear. I could force the user to specify tabwidth at the top of the file, but I'd rather not. And since Python doesn't either, I know it is possible to write a parser to do this. I just don't know how. Python simply assumes 8 spaces per tab. If your Python source ONLY uses tabs, or ONLY spaces, it doesn't matter. If you mix tabs+spaces, Python simple replaces each tab by 8 spaces. If you edited that using 4 spaces, Python will get it wrong. That's why all people always say never mix tabs and spaces Ah. I didn't know that. Like I said at first, I am new to Python (but I've been reading a lot about it! 3 books thus far. Nutshell, Cookbook, wxPython) Okay, I'll just use a directive at the top of the file and let the user specify. Not perfect, but such is life. Thanks again. -- -Mike Schinkel http://www.mikeschinkel.com/blogs/ http://www.welldesignedurls.org http://atlanta-web.org - http://t.oolicio.us -- http://mail.python.org/mailman/listinfo/python-list
Re: Python books?
On 9 mar 2007, at 04.06, Tommy Nordgren wrote: Could some kind soul please recommend a few text books on Python 2.5 and it's class library? I've found one interesting text book on Python: Mark Lutz - Programming Python, 3rd Edition. How do you rate it? One of the reasons I find it interesting is because of it's hefty page count - over 1500 pages. -- Home is not where you are born, but where your heart finds peace - Tommy Nordgren, The dying old crone [EMAIL PROTECTED] -- http://mail.python.org/mailman/listinfo/python-list
Re: threading and iterator crashing interpreter
On Mar 11, 3:27 pm, Gabriel Genellina [EMAIL PROTECTED] wrote: En Sun, 11 Mar 2007 09:47:34 -0300, Janto Dreijer [EMAIL PROTECTED] escribió: As far as I can tell I'm not running it from restricted mode explicitly. This error is rather strange then: RuntimeError: instance.__dict__ not accessible in restricted mode restricted mode means that the current builtins are not the standard builtins. Googling says Some googling suggests that this error is a hint that a Python object created in one subinterpreter is being used in a different subinterpreter. The reason I'm doing the random.choice() is so I don't have a handle (session in this case) that would prevent it from being garbage collected. I am not bothered by the Python-level Exceptions. I am bothered by the interpreter throwing a segfault. What I suspect is happening is the Session object is deallocated, while it still has a reference from within the iterator. But on your code Session objects are never deleted; they stay inside System.sessions. Having an extra reference (the session variable) doesnt matter. Hmmm. You're right. It's quite difficult to reproduce these bugs consistently. You might need to run it a few times. At least, the problem of using the same generator from different threads still remains, if you don't use my modified code. In general, when using multiple threads you always need some way to syncronize access to shared objects. You are lucky with Sessions because append is an atomic operation on lists; for more information see http://effbot.org/pyfaq/what-kinds-of-global-value-mutation-are-threa... Again you're right. But even putting a try-except:return around the random.choice still manages to break the interpreter. I'm not looking for any meaningful output really. I just want it not to break. Like I said, this is just watered down code to try and isolate the problem. -- http://mail.python.org/mailman/listinfo/python-list
Re: a better solution for GUI in python
For a browser interface have you thought of Ajax and possibly WPF/E? http://en.wikipedia.org/wiki/AJAX http://en.wikipedia.org/wiki/Windows_Presentation_Foundation -- Regards, Casey -- http://mail.python.org/mailman/listinfo/python-list
Signed zeros: is this a bug?
I get the following behaviour on Python 2.5 (OS X 10.4.8 on PowerPC, in case it's relevant.) x, y = 0.0, -0.0 x, y (0.0, 0.0) x, y = -0.0, 0.0 x, y (-0.0, -0.0) I would have expected y to be -0.0 in the first case, and 0.0 in the second. Should the above be considered a bug, or is Python not expected to honour signs of zeros? I'm working in a situation involving complex arithmetic where branch cuts, and hence signed zeros, are important, and it would be handy if the above code could be relied upon to do the right thing. Mark -- http://mail.python.org/mailman/listinfo/python-list
Re: Signed zeros: is this a bug?
On Mar 11, 9:31 am, Mark Dickinson [EMAIL PROTECTED] wrote: I get the following behaviour on Python 2.5 (OS X 10.4.8 on PowerPC, in case it's relevant.) x, y = 0.0, -0.0 x, y (0.0, 0.0) x, y = -0.0, 0.0 x, y (-0.0, -0.0) I would have expected y to be -0.0 in the first case, and 0.0 in the second. Should the above be considered a bug, or is Python not expected to honour signs of zeros? I'm working in a situation involving complex arithmetic where branch cuts, and hence signed zeros, are important, and it would be handy if the above code could be relied upon to do the right thing. IIRC, float.__repr__ just does whatever libc does. Have you tried using printf(%g, %g, 0.0, -0.0) in a C program? -- http://mail.python.org/mailman/listinfo/python-list
Re: Signed zeros: is this a bug?
On Sunday 11 March 2007 10:31, Mark Dickinson wrote: I get the following behaviour on Python 2.5 (OS X 10.4.8 on PowerPC, in case it's relevant.) x, y = 0.0, -0.0 x, y (0.0, 0.0) x, y = -0.0, 0.0 x, y (-0.0, -0.0) I would have expected y to be -0.0 in the first case, and 0.0 in the second. Should the above be considered a bug, or is Python not expected to honour signs of zeros? I'm working in a situation involving complex arithmetic where branch cuts, and hence signed zeros, are important, and it would be handy if the above code could be relied upon to do the right thing. Mark This works for some reason instead of x,y = -0.0, 0.0 clumpy but the results are right. x = -0.0 y= 0.0 x,y (-0.0, 0.0) jim-on-linux http:\\inqvista.com -- http://mail.python.org/mailman/listinfo/python-list
Re: PIL: reading bytes from Image
Thanks,
I've tried the StringIO option as follows:
=
img = Image.open('/some/path/img.jpg')
img.thumbnail((640,480))
file = StringIO, StringIO()
img.save(file, 'JPEG')
=
But it gives me:
=
exceptions.TypeError Traceback (most
recent call last)
C:\Python24\lib\site-packages\PIL\Image.py in save(self, fp, format,
**params)
1303
1304 try:
- 1305 save_handler(self, fp, filename)
1306 finally:
1307 # do what we can to clean up
C:\Python24\lib\site-packages\PIL\JpegImagePlugin.py in _save(im, fp,
filename)
407 )
408
-- 409 ImageFile._save(im, fp, [(jpeg, (0,0)+im.size, 0,
rawmode)])
410
411 def _save_cjpeg(im, fp, filename):
C:\Python24\lib\site-packages\PIL\ImageFile.py in _save(im, fp, tile)
464 bufsize = max(MAXBLOCK, im.size[0] * 4) # see RawEncode.c
465 try:
-- 466 fh = fp.fileno()
467 fp.flush()
468 except AttributeError:
TypeError: descriptor 'fileno' of 'file' object needs an argument
=
It looks similar to the code in Sparklines except for the fact that
the latter creates an Image from scratch.
2B
Saving the image, in a
format your client understands, to a file like object like
StringIO.StringIO is an easy path to take.
Sparklines shows this in action:
http://bitworking.org/projects/sparklines/
max
--
http://mail.python.org/mailman/listinfo/python-list
Re: Signed zeros: is this a bug?
Dan Bishop [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] | On Mar 11, 9:31 am, Mark Dickinson [EMAIL PROTECTED] wrote: | I get the following behaviour on Python 2.5 (OS X 10.4.8 on PowerPC, | in case it's relevant.) | | x, y = 0.0, -0.0 | x, y | (0.0, 0.0) | x, y = -0.0, 0.0 | x, y | | (-0.0, -0.0) || IIRC, float.__repr__ just does whatever libc does. Have you tried | using printf(%g, %g, 0.0, -0.0) in a C program? Detailed FP behavior like this is system (and yes, libc) dependent. On WinXP IDLE 1.1.3 x,y = 0.0, -0.0 x,y (0.0, 0.0) x,y = -0.0, 0.0 x,y (0.0, 0.0) -0.0 0.0 Terry Jan Reedy -- http://mail.python.org/mailman/listinfo/python-list
Re: Parsing Indented Text (like parsing Python)
On Mar 11, 8:37 am, Gabriel Genellina [EMAIL PROTECTED] wrote: If you mix tabs+spaces, Python simple replaces each tab by 8 spaces. Are you sure about this? This is not the tab problem I am familiar with in the past. In the following sample, the columnar text labeled 'col2' should all be aligned at column 9: xtabcol2 xxxtabcol2 tabcol2 In the first line, the tab is replaced with 7 spaces, the second line by 5, and the third line by 6. So tab replacement is a bit more involved than simply s/\t//g. As I recall, the number of spaces to replace a tab by is something like 8-(col % 8) where col is the column location of the tab with the left most column being 0. -- Paul -- http://mail.python.org/mailman/listinfo/python-list
Re: PIL: reading bytes from Image
cyberco [EMAIL PROTECTED] wrote:
Thanks,
I've tried the StringIO option as follows:
=
img = Image.open('/some/path/img.jpg')
img.thumbnail((640,480))
file = StringIO, StringIO()
Is the above line exactly what you tried? If it is, the comma and
space in the line are likely the problem. Try either:
from StringIO import StringIO
file=StringIO()
or
import StringIO
file=StringIO.StringIO()
(using file as a variable name can cause issues if you later want
access to the built in object 'file')
The following:
import Image
import StringIO
im=Image.new('RGB', (100,100))
fp=StringIO.StringIO()
im.save(fp, 'jpeg')
len(fp.getvalue())
823
Works for me on python 2.5 on windows.
max
--
http://mail.python.org/mailman/listinfo/python-list
Re: Signed zeros: is this a bug?
On Mar 11, 12:13 pm, Terry Reedy [EMAIL PROTECTED] wrote: Dan Bishop [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED] | On Mar 11, 9:31 am, Mark Dickinson [EMAIL PROTECTED] wrote: | I get the following behaviour on Python 2.5 (OS X 10.4.8 on PowerPC, | in case it's relevant.) | | x, y = 0.0, -0.0 | x, y | (0.0, 0.0) | x, y = -0.0, 0.0 | x, y | | (-0.0, -0.0) || IIRC, float.__repr__ just does whatever libc does. Have you tried | using printf(%g, %g, 0.0, -0.0) in a C program? Detailed FP behavior like this is system (and yes, libc) dependent. On WinXP IDLE 1.1.3 x,y = 0.0, -0.0 x,y (0.0, 0.0) x,y = -0.0, 0.0 x,y (0.0, 0.0) -0.0 0.0 Terry Jan Reedy Interesting. So on Windows there's probably no hope of what I want to do working. But on a platform where the C library does the right thing with signed zeros, this behaviour is still a little surprising. I guess what's happening is that there's some optimization that avoids creating two separate float objects for a float literal that appears twice, and that optimization doesn't see the difference between 0. and -0. x, y = 0., -0. id(x) == id(y) True jim-on-linux's solution works in the interpreter, but not in a script, presumably because we've got file-wide optimization rather than line-by-line optimization. #test.py x = -0.0 y = 0.0 print x, y #end test.py import test -0.0 -0.0 Mark -- http://mail.python.org/mailman/listinfo/python-list
Re: Parsing Indented Text (like parsing Python)
Mike Schinkel wrote: Gabriel Genellina wrote: That's why all people always say never mix tabs and spaces That's the one rule in this area Python ought to enforce. If you've got that, you can convert tabs to spaces, or vice versa, safely. John Nagle -- http://mail.python.org/mailman/listinfo/python-list
Re: Best place for a function?
Inyeol Lee a écrit : On Wed, Mar 07, 2007 at 05:27:04PM -0500, Sergio Correia wrote: I'm writing a class, where one of the methods is kinda complex. The method uses a function which I know for certain will not be used anywhere else. This function does not require anything from self, only the args passed by the method. Where should I put the function? Use staticmethod. It's a normal function with class namespace. What do you think the OP will gain from making a simple helper function a staticmethod ? Apart from extra lookup time ? -- http://mail.python.org/mailman/listinfo/python-list
Re: Parsing Indented Text (like parsing Python)
En Sun, 11 Mar 2007 13:12:20 -0300, Paul McGuire [EMAIL PROTECTED] escribió: On Mar 11, 8:37 am, Gabriel Genellina [EMAIL PROTECTED] wrote: If you mix tabs+spaces, Python simple replaces each tab by 8 spaces. As I recall, the number of spaces to replace a tab by is something like 8-(col % 8) where col is the column location of the tab with the left most column being 0. Yes, each tab advances to the next multiple-of-8 column. The problem is that 8 is fixed. -- Gabriel Genellina -- http://mail.python.org/mailman/listinfo/python-list
Re: Python in a desktop environment
David Cramer a écrit : If you had an application that you were about to begin development on which you wanted to be cross platform (at least Mac and Windows), would you suggest using c++ and Python? I'm asking because we were originally thinking about doing c# but after attending PyCon this year I'm reconsidering. We are already using Python for the website and I figure a c++ backend w/ a Python GUI may work really well, and would be pretty easy to port. Any opinions? Yes : forget about the c++ backend. -- http://mail.python.org/mailman/listinfo/python-list
Re: Signed zeros: is this a bug?
Mark Dickinson [EMAIL PROTECTED] wrote: I guess what's happening is that there's some optimization that avoids creating two separate float objects for a float literal that appears twice, and that optimization doesn't see the difference between 0. and -0. Don't guess. Test. def f(): x = 0.0 y = -0.0 return x, y dis.dis(f) 2 0 LOAD_CONST 1 (0.0) 3 STORE_FAST 0 (x) 3 6 LOAD_CONST 1 (0.0) 9 STORE_FAST 1 (y) 4 12 LOAD_FAST0 (x) 15 LOAD_FAST1 (y) 18 BUILD_TUPLE 2 21 RETURN_VALUE Yes. Just the one constant there. Tim Peters wrote in http://blog.gmane.org/gmane.comp.python.devel/day=20050409: All Python behavior in the presence of a NaN, infinity, or signed zero is a platform-dependent accident. This is because C89 has no such concepts, and Python is written to the C89 standard. It's not easy to fix across all platforms (because there is no portable way to do so in standard C), although it may be reasonably easy to fix if all anyone cares about is gcc and MSVC (every platform C compiler has its own set of gimmicks for dealing with these things). -- http://mail.python.org/mailman/listinfo/python-list
Re: Python in a desktop environment
David Cramer a écrit : On Mar 10, 10:52 pm, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: David Cramer wrote: If you had an application that you were about to begin development on which you wanted to be cross platform (at least Mac and Windows), would you suggest using c++ and Python? I'd strongly consider a pure python solution (I'd choose wxpython), but if I needed to code backend stuff in a lower level language I'd use C rather than C++. Well we want it to be very robust, Which is a pretty good reason to favor Python over C or C++. and python isn't exactly the fastest language, or one with the lowest overhead :) It's not exactly one of the slowest languages nor one with the highest overhead neither. Chances are you'll have a fully-functional production level app in Python *way* before you have a first alpha in C++. If by then you *really* have some performance problem, it will be time to port the relevant modules to C extensions. -- http://mail.python.org/mailman/listinfo/python-list
Re: Signed zeros: is this a bug?
Mark Dickinson [EMAIL PROTECTED] wrote:
I get the following behaviour on Python 2.5 (OS X 10.4.8 on PowerPC,
in case it's relevant.)
x, y = 0.0, -0.0
x, y
(0.0, 0.0)
x, y = -0.0, 0.0
x, y
(-0.0, -0.0)
I would have expected y to be -0.0 in the first case, and 0.0 in the
second. Should the above be considered a bug, or is Python not
expected to honour signs of zeros? I'm working in a situation
involving complex arithmetic where branch cuts, and hence signed
zeros, are important, and it would be handy if the above code could be
relied upon to do the right thing.
Looks to me like you've found a bug with the parser/compiler:
c=compile('-0.0,0.0', 'eval', 'eval')
eval(c)
(-0.0, -0.0)
dis.dis(c)
1 0 LOAD_CONST 1 ((-0.0, -0.0))
3 RETURN_VALUE
Similar problems appear in parsing display forms of lists and dicts and
calls to functions with constant arguments (among which a constant 0.0
and a constant -0.0) -- and more generally when both constants -0.0 and
0.0 appear within the same unit of compilation (expression, function,
...) as for example in:
def f():
... a = -0.0
... return a, 0.0
...
f()
(-0.0, -0.0)
Why I think it has specifically to do with parsing/compiling, e.g.:
{23:-0.0, 45:0.0}
{45: -0.0, 23: -0.0}
x=0.0
y=-0.0
{23:x, 45:y}
{45: -0.0, 23: 0.0}
so there appears to be no problem once the 0.0 and -0.0 values come from
variables or the like -- only if they're both from constants within the
same unit of compilation. Indeed, if you put the code above in a
function, rather than in separate entries to the toplevel
interpreter...:
def g():
... x = 0.0
... y = -0.0
... return {23:x, 45:y}
...
g()
{45: 0.0, 23: 0.0}
...the bug surfaces again. Looks a bit like the result of a slightly
errant peephole optimizer pass which tries to roll multiple
occurrences of the same constant within the same codeobject into a
single one, and consider two immutables a multiple occurrence if
they're == to each other (as, indeed, 0.0 and -0.0 must be).
The Python-coded compiler package does NOT give the problem:
compiler.compile('-0.0,0.0','zap','eval')
code object expression at 0x70068, file zap, line 1
dis.dis(_)
1 0 LOAD_CONST 1 (0.0)
3 UNARY_NEGATIVE
4 LOAD_CONST 1 (0.0)
7 BUILD_TUPLE 2
10 RETURN_VALUE
...presumably because it doesn't do peephole optimization (nor any other
kind of optimization).
Unfortunately I've never really looked in depth into these parts of
Python so I can't help much; however, if you open a bug at
http://sourceforge.net/tracker/?group_id=5470 I think you stand a good
chance of eventually seeing it fixed in 2.5.x for some x.
Python/peephole.c does appear to be taking some care in constant
folding:
192 case UNARY_NEGATIVE:
193 /* Preserve the sign of -0.0 */
194 if (PyObject_IsTrue(v) == 1)
195 newconst = PyNumber_Negative(v);
so I suspect the problem is elsewhere, but I can't find it yet.
Alex
In the meantime, I hope that some available workarounds for the bug are
clear from this discussion: avoid using multiple constants in a single
compilation unit where one is 0.0 and another is -0.0, or, if you really
can't avoid that, perhaps use compiler.compile to explicitly build the
bytecode you need.
--
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Re: Need help in using mod_python
[EMAIL PROTECTED] a écrit : Hi, I am trying to setup Apache with Trac which uses mod_python. I get the following error: assert have_pysqlite 0 And I have verify this via command line as well, that seem no problem. (snip) What do you get using tracd (the standalone server) ? -- http://mail.python.org/mailman/listinfo/python-list
Re: Signed zeros: is this a bug?
On Mar 11, 1:21 pm, Duncan Booth [EMAIL PROTECTED] wrote: Tim Peters wrote inhttp://blog.gmane.org/gmane.comp.python.devel/day=20050409: All Python behavior in the presence of a NaN, infinity, or signed zero is a platform-dependent accident. This is because C89 has no such concepts, and Python is written to the C89 standard. It's not easy to fix across all platforms (because there is no portable way to do so in standard C), although it may be reasonably easy to fix if all anyone cares about is gcc and MSVC (every platform C compiler has its own set of gimmicks for dealing with these things). Understood. Platform dependent is fine. But does this really excuse results like the following? from math import atan2 x = -0.; print atan2(0., -1.) -3.14159265359 print atan2(0., -1.) 3.14159265359 Mark -- http://mail.python.org/mailman/listinfo/python-list
Re: Signed zeros: is this a bug?
Duncan Booth [EMAIL PROTECTED] wrote: Mark Dickinson [EMAIL PROTECTED] wrote: I guess what's happening is that there's some optimization that avoids creating two separate float objects for a float literal that appears twice, and that optimization doesn't see the difference between 0. and -0. Don't guess. Test. def f(): x = 0.0 y = -0.0 return x, y dis.dis(f) 2 0 LOAD_CONST 1 (0.0) 3 STORE_FAST 0 (x) 3 6 LOAD_CONST 1 (0.0) 9 STORE_FAST 1 (y) 4 12 LOAD_FAST0 (x) 15 LOAD_FAST1 (y) 18 BUILD_TUPLE 2 21 RETURN_VALUE Yes. Just the one constant there. And yet, as I wrote in a parallel post (the result of quite some exploration), Python/peephole.c takes specific precautions against improperly constant folding for the unary-minus of 0.0 -- the collapsing of 0.0 and -0.0 into the same constant must happen elsewhere (I haven't found out where, yet) and doesn't happen in the Python-coded compiler module. So (on platforms where the underlying C libraries do the right thing) I think this specific overzealous constant folding must be considered a small bug -- and should be easy to fix (by specialcasing -0.0 like Python/peephole.c does) if I could but find out where in the Python sources the folding is happening... Alex -- http://mail.python.org/mailman/listinfo/python-list
Re: threading and iterator crashing interpreter
En Sun, 11 Mar 2007 11:35:58 -0300, Janto Dreijer [EMAIL PROTECTED] escribió: At least, the problem of using the same generator from different threads still remains, if you don't use my modified code. In general, when using multiple threads you always need some way to syncronize access to shared objects. You are lucky with Sessions because append is an atomic operation on lists; for more information see http://effbot.org/pyfaq/what-kinds-of-global-value-mutation-are-threa... Again you're right. But even putting a try-except:return around the random.choice still manages to break the interpreter. I'm not looking for any meaningful output really. I just want it not to break. A try/except won't help a concurrency problem, unfortunately. Like I said, this is just watered down code to try and isolate the problem. So I suggest to start with some small, *correct*, code, and then add more features until you reconstruct your big program in a safe way. -- Gabriel Genellina -- http://mail.python.org/mailman/listinfo/python-list
Re: Signed zeros: is this a bug?
On Mar 11, 1:26 pm, [EMAIL PROTECTED] (Alex Martelli) wrote: [Long analysis of probable cause of the problem] Thank you for this. I was suspecting something along these lines, but I don't yet know my way around the source well enough to figure out where the problem was coming from. In the meantime, I hope that some available workarounds for the bug are clear from this discussion: avoid using multiple constants in a single compilation unit where one is 0.0 and another is -0.0, or, if you really can't avoid that, perhaps use compiler.compile to explicitly build the bytecode you need. Yup: the workaround seems to be as simple as replacing all occurrences of -0.0 with -(0.0). I'm embarrassed that I didn't figure this out sooner. x, y = -(0.0), 0.0 x, y (-0.0, 0.0) Mark -- http://mail.python.org/mailman/listinfo/python-list
Re: Signed zeros: is this a bug?
# Interesting. So on Windows there's probably no hope of what I want to do working. But on a platform where the C library does the right thing with signed zeros, this behaviour is still a little surprising. I guess what's happening is that there's some optimization that avoids creating two separate float objects for a float literal that appears twice, and that optimization doesn't see the difference between 0. and -0. x, y = 0., -0. id(x) == id(y) True jim-on-linux's solution works in the interpreter, but not in a script, presumably because we've got file-wide optimization rather than line-by-line optimization. #test.py x = -0.0 y = 0.0 print x, y #end test.py import test -0.0 -0.0 Mark This is the only way I could make this work in a script. from decimal import Decimal x = Decimal( -0.0) y= Decimal(0.0) print x,y x = Decimal( 0.0) y= Decimal(-0.0) print x,y jim-on-linux http:\\www.inqvista.com -- http://mail.python.org/mailman/listinfo/python-list
Re: Signed zeros: is this a bug?
Mark Dickinson [EMAIL PROTECTED] wrote: On Mar 11, 1:26 pm, [EMAIL PROTECTED] (Alex Martelli) wrote: [Long analysis of probable cause of the problem] Thank you for this. I was suspecting something along these lines, but I don't yet know my way around the source well enough to figure out where the problem was coming from. The parser/compiler/etc are unfortunately some of the hardest parts of the sources -- I'm not all that familiar with that part myself, which is why it took me quite some digging. In the meantime, I hope that some available workarounds for the bug are clear from this discussion: avoid using multiple constants in a single compilation unit where one is 0.0 and another is -0.0, or, if you really can't avoid that, perhaps use compiler.compile to explicitly build the bytecode you need. Yup: the workaround seems to be as simple as replacing all occurrences of -0.0 with -(0.0). I'm embarrassed that I didn't figure this out sooner. x, y = -(0.0), 0.0 x, y (-0.0, 0.0) Glad it works for you, but it's the kind of workaround that could break with any minor tweak/optimization to the compiler... very fragile:-(. I think i found the cause of the bug, BTW. The collection of constants in a code object is built in Python/compile.c and it's built as a dictionary, field u_consts in struct compiler_unit. The visitor for an expression that is a number is (in a case statement) case Num_kind: ADDOP_O(c, LOAD_CONST, e-v.Num.n, consts); break; (line 2947 of compile.c in Python's current sources from svn). ADDOP_O just calls compiler_addop_o, which in turn does compiler_add_o before adding the opcode (LOAD_CONST) compiler_add_o (at lines 903-933) is used for all of the temporary dictionaries in compiler_unit; a Python equivalent, basically, would be: def eqv_cao(somedict, someobj): # make sure types aren't coerced, e.g. int and long t = someobj, type(someobj) if t in somedict: return somedict[t] somedict[t] = index = len(somedict) return index a simple and fast way to provide a distinct numeric index (0 and up) to each of a bunch of (hashable) objects. Alas, here is the problem...: 0.0 and -0.0 are NOT separate as dict keys! They are == to each other. So are 0, 0L, and 0+j0, but the compiler smartly distinguishes these cases by using (obj, type) as the key (the *types* are distinguished, even though the *values*) are; this doesn't help with 0.0 and -0.0 since both have type float. So, the first occurrence of either 0.0 or -0.0 in the compilation unit ends up in the table of constants, and every other occurrence of either value later in the unit is mapped to that one constant value:-( This is not trivial to fix cleanly...:-(. compiler_add_o would have to test is the object I'm storing -0.0 (I don't even know how to do that in portable C...) and then do some kludge -- e.g. use as the key into the dict (-0.0, 0) instead of (-0.0, float) for this one special case. (I think the table of constants would still be emitted OK, since the type part of the key is elided anyway in that table as placed in the bytecode). Or maybe we should give up ever storing -0.0 in the tables of constant and ALWAYS have 0.0, unary-minus wherever it appears (that would presumably require working on the AST-to-bytecode visitors that currently work ever-so-slightly-differently for this specific troublespot in the C-coded version vs the Python-coded one...). If you know the proper way to test for -0.0 in portable C code (or some feature macro to use in a #if to protect nonportable code) I could try proposing the first of these two solutions as a patch (I'm not going to keep delving into that AST and visitors much longer...:-), but I suspect it would be rejected as too tricky [and minisculely slowing down every compilation] for something that's too much of special case [and Python does not undertake to support in general anyway]. Still, we can't be sure unless we try (and maybe somebody can think of a cleaner workaround...). Alex -- http://mail.python.org/mailman/listinfo/python-list
Re: number generator
cesco [EMAIL PROTECTED] ha scritto nel messaggio news:[EMAIL PROTECTED] I have to generate a list of N random numbers (integer) whose sum is equal to M. If, for example, I have to generate 5 random numbers whose sum is 50 a possible solution could be [3, 11, 7, 22, 7]. Is there a simple pattern or function in Python to accomplish that? Thanks and regards Francesco You can initialize a list to [1, 1, 1, 1, 1], and generate 45 random integers between 1 and 5, and every time a number is generated, increase the Nth number in the list by one. Not all distinct lists will have the same chance of occurring, e.g. [46, 1, 1, 1, 1] will be much less likely than [10, 10, 10, 10, 10]. Depending on what you need these numbers for, it can be a good thing or a bad thing. --Army1987 -- http://mail.python.org/mailman/listinfo/python-list
Putting Metaclasses to Work
Forman's book is out of print. Is there a good substitute? Thanks, Alan Isaac -- http://mail.python.org/mailman/listinfo/python-list
Re: Need help in using mod_python
On Mar 11, 1:02 pm, Bruno Desthuilliers [EMAIL PROTECTED] wrote: [EMAIL PROTECTED] a écrit : Hi, I am trying to setup Apache with Trac which uses mod_python. I get the following error: assert have_pysqlite 0 And I have verify this via command line as well, that seem no problem. (snip) What do you get using tracd (the standalone server) ? I am using apache with mod_python. I have done a sanity check with command prompt, it can find 'pysqlite', But when I access Trac using Apache (via mod_python), it somehow can't find 'pysqlite' and gives me an error. So my question is how python command prompt loads library differently from mod_python? # python Python 2.3.4 (#1, Feb 2 2005, 11:44:49) [GCC 3.4.3 20041212 (Red Hat 3.4.3-9.EL4)] on linux2 Type help, copyright, credits or license for more information. import trac.db.sqlite_backend trac.db.sqlite_backend._ver (3, 3, 13) trac.db.sqlite_backend.have_pysqlite 2 trac.db.sqlite_backend.sqlite.version '2.3.3' -- http://mail.python.org/mailman/listinfo/python-list
Re: Python in a Nutshell v2.5 shortcomings
Bjoern Schliessmann [EMAIL PROTECTED] wrote: Alex Martelli wrote: I do know that the 2nd edition of Python in a Nutshell tries to do so, but falls quite a bit short on a number of important new additions to the library Which, if I may ask? For example, all I say about ctypes is that it's scheduled to be added to the standard library in Python 2.5, plus the URL to theller's pages on it; it's surely worth at least the 5 pages I devoted to covering Pyrex (considering that the latter is not in the standard library), not just 5 lines:-(. Similarly, ElementTree is essentially just mentioned, not really covered (while it would deserve the 10-12 pages that I instead used to cover minidom), and SQLite gets less than a page (probably enough for elementary use, since the DBAPI _is_ well covered, but 2-3 pages with advanced issues and a relatively long examples would have been better). You could say, for 2.5 coverage, the book is missing about 20 pages it should have -- not all that much, in comparison to the 700 pages it does have, but not ideal (as for the new compiler stuff -- modules compiler, parser, symbol, etc -- I'm not even sure how long it would take to do them justice... perhaps another 20-30 pages... but perhaps those subjects are a bit too exoteric to keep expanding the book!-). Alex -- http://mail.python.org/mailman/listinfo/python-list
Re: Signed zeros: is this a bug?
Alex Martelli [EMAIL PROTECTED] wrote: ... Yup: the workaround seems to be as simple as replacing all occurrences of -0.0 with -(0.0). I'm embarrassed that I didn't figure this out sooner. x, y = -(0.0), 0.0 x, y (-0.0, 0.0) Glad it works for you, but it's the kind of workaround that could break with any minor tweak/optimization to the compiler... very fragile:-(. OTOH, Python 2.4 works just fine...: Python 2.4.3 (#1, Apr 7 2006, 10:54:33) [GCC 4.0.1 (Apple Computer, Inc. build 5250)] on darwin Type help, copyright, credits or license for more information. 0.0,-0.0 (0.0, -0.0) -0.0,0.0 (-0.0, 0.0) so it seems to be very specifically a 2.5 problem. Alex -- http://mail.python.org/mailman/listinfo/python-list
Re: any better code to initalize a list of lists?
John wrote: For my code of radix sort, I need to initialize 256 buckets. My code looks a little clumsy: radix=[[]] for i in range(255): radix.append([]) any better code to initalize this list? radix = [[[]]*256][0] -- -- http://mail.python.org/mailman/listinfo/python-list
Re: any better code to initalize a list of lists?
Donald Fredkin schrieb: John wrote: For my code of radix sort, I need to initialize 256 buckets. My code looks a little clumsy: radix=[[]] for i in range(255): radix.append([]) any better code to initalize this list? radix = [[[]]*256][0] x = [[[]]*256][0] x [[], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], [], ... x[0].append(1) x [[1], [1], [1], [1], [1], [1], [1], [1], [1], [1], [1], [1], [1], [1], [1], [1], ... Nice one. -- http://mail.python.org/mailman/listinfo/python-list
Re: any better code to initalize a list of lists?
Donald Fredkin wrote:
John wrote:
For my code of radix sort, I need to initialize 256 buckets. My code
looks a little clumsy:
radix=[[]]
for i in range(255):
radix.append([])
any better code to initalize this list?
radix = [[[]]*256][0]
No I fell for that one too - it's the same as 'radix = [[]] * 256. Try
radix[0].append('dead parrot')..
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Re: Signed zeros: is this a bug?
Alex Martelli wrote: Alas, here is the problem...: 0.0 and -0.0 are NOT separate as dict keys! They are == to each other. So are 0, 0L, and 0+j0, but the compiler smartly distinguishes these cases by using (obj, type) as the key (the *types* are distinguished, even though the *values*) are; this doesn't help with 0.0 and -0.0 since both have type float If you know the proper way to test for -0.0 in portable C code (or some feature macro to use in a #if to protect nonportable code) Perhaps you could add a type NegativeFloat -- a subtype of float, and distinguish negative zero from zero that way. Not saying I know how in portable C, but --Scott David Daniels [EMAIL PROTECTED] -- http://mail.python.org/mailman/listinfo/python-list
Re: number generator
Army1987 [EMAIL PROTECTED] wrote: cesco [EMAIL PROTECTED] ha scritto nel messaggio news:[EMAIL PROTECTED] I have to generate a list of N random numbers (integer) whose sum is equal to M. If, for example, I have to generate 5 random numbers whose sum is 50 a possible solution could be [3, 11, 7, 22, 7]. Is there a simple pattern or function in Python to accomplish that? Thanks and regards Francesco You can initialize a list to [1, 1, 1, 1, 1], and generate 45 random integers between 1 and 5, and every time a number is generated, increase the Nth number in the list by one. Not all distinct lists will have the same chance of occurring, e.g. [46, 1, 1, 1, 1] will be much less likely than [10, 10, 10, 10, 10]. Depending on what you need these numbers for, it can be a good thing or a bad thing. And a1-liner way to get the numbers (net of the mandatory +1 for each) is: map([random.randrange(5) for i in xrange(45)].count, xrange(5)) i.e., this gives 5 integers (each between 0 and 45 included) summing to 45 -- add 1 to each of them to get the desired result. Without any specification regarding the distributions required for the 5 random numbers it's really impossible to say whether these are better or worse than other proposed solutions. Alex -- http://mail.python.org/mailman/listinfo/python-list
Watching a file another app is writing
I'm trying to find a way to take a file that another program has opened and writes to periodically, open it simultaneously in Python, and automatically update some of my objects in Python when the file is written to. I can open the file and manually readlines() from it to keep up to date, it's the automatic part I'm having trouble with. This is on Windows. -- http://mail.python.org/mailman/listinfo/python-list
Re: Signed zeros: is this a bug?
En Sun, 11 Mar 2007 15:26:01 -0300, Alex Martelli [EMAIL PROTECTED] escribió: Or maybe we should give up ever storing -0.0 in the tables of constant and ALWAYS have 0.0, unary-minus wherever it appears (that would presumably require working on the AST-to-bytecode visitors that currently work ever-so-slightly-differently for this specific troublespot in the C-coded version vs the Python-coded one...). I think that way is the less intrusive, doesn't rely on a particular FP implementation, and the more likely to be accepted. Looking at ast.c, the culprit is some optimization in ast_for_factor, line 1506 /* If the unary - operator is applied to a constant, don't generate a UNARY_NEGATIVE opcode. Just store the approriate value as a constant. The peephole optimizer already does something like this but it doesn't handle the case where the constant is (sys.maxint - 1). In that case, we want a PyIntObject, not a PyLongObject. */ After the long if, I would use parsenumber(STR(pnum)) and check the type and value of the resulting object; if it's a float and 0.0, skip the optimization and continue below as a normal case. Unfortunately I'm not able to compile and test the code right now, so I can't provide an actual patch. (At least, not until tuesday). But I hope this simple comment is useful anyway... (I cannot find peephole.c on the source distribution for Python 2.5, but you menctioned it on a previous message, and the comment above refers to the peephole optimizer... where is it?) -- Gabriel Genellina -- http://mail.python.org/mailman/listinfo/python-list
Re: Signed zeros: is this a bug?
On Mar 11, 2:59 pm, [EMAIL PROTECTED] (Alex Martelli) wrote: [...] OTOH, Python 2.4 works just fine...: Python 2.4.3 (#1, Apr 7 2006, 10:54:33) [GCC 4.0.1 (Apple Computer, Inc. build 5250)] on darwin Type help, copyright, credits or license for more information. 0.0,-0.0 (0.0, -0.0) -0.0,0.0 (-0.0, 0.0) so it seems to be very specifically a 2.5 problem. I've filed a bug report (bug #1678380) and got an impressively quick response from MvL. It looks like this is a `won't fix'. Oh well. Thanks for all your help. Mark -- http://mail.python.org/mailman/listinfo/python-list
Re: Need help in using mod_python
[EMAIL PROTECTED] a écrit : On Mar 11, 1:02 pm, Bruno Desthuilliers [EMAIL PROTECTED] wrote: [EMAIL PROTECTED] a écrit : Hi, I am trying to setup Apache with Trac which uses mod_python. I get the following error: assert have_pysqlite 0 And I have verify this via command line as well, that seem no problem. (snip) What do you get using tracd (the standalone server) ? I am using apache with mod_python. You're trying to, yes. But what *I*'m asking *you* is what you get using tracd. I have done a sanity check with command prompt, using your account's env it can find 'pysqlite', But when I access Trac using Apache (via mod_python), which uses a somewhat different (and very restricted) env... it somehow can't find 'pysqlite' and gives me an error. So my question is how python command prompt loads library differently from mod_python? I know I'm a little bit dumb, but I had perfectly understood your question (which BTW is not posted at the best place - both Trac and mod_python have dedicated mailing-lists). Can you imagine that I have good reasons to ask you what you get using tracd ? (re-snip already snipped code) -- http://mail.python.org/mailman/listinfo/python-list
cherrypy sub-process
Hi all, I have written a small program in Python which acts as a wrapper around mpd and natd on a FreeBSD system. It gets the status, restarts the processes, etc... Then, I created a tiny cherrypy webapp which provides a webinterface to this program. All works fine, but for the following problem: cherrypy listens on port 1234. whenever I browse to that port and invoke any action that involves (re)starting mpd or natd, which happens with commands.getstatusoutput() (which uses os.popen()), I cannot restart cherrypy without killing the mpd and/or natd processes spawned by it in the previous session, because port 1234 willl still be in use. lsof -i tcp tells me that it's exactly those mpd and/or natd processes which are keeping that port 1234 from freeing up after I (succesfully) kill cherrypy. Is there any explanation to this, or, even better, a solution? Thank you very much in advance. -- regards, BBBart To make a bad day worse, spend it wishing for the impossible. -Calvin -- http://mail.python.org/mailman/listinfo/python-list
Re: Signed zeros: is this a bug?
[attribution lost] ... Yup: the workaround seems to be as simple as replacing all occurrences of -0.0 with -(0.0). I'm embarrassed that I didn't figure this out sooner. x, y = -(0.0), 0.0 x, y (-0.0, 0.0) [Alex Martelli] Glad it works for you, but it's the kind of workaround that could break with any minor tweak/optimization to the compiler... very fragile:-(. [also Alex] OTOH, Python 2.4 works just fine...: Python 2.4.3 (#1, Apr 7 2006, 10:54:33) [GCC 4.0.1 (Apple Computer, Inc. build 5250)] on darwin Type help, copyright, credits or license for more information. 0.0,-0.0 (0.0, -0.0) -0.0,0.0 (-0.0, 0.0) so it seems to be very specifically a 2.5 problem. It's a bug that keeps resurfacing, probably because there's no portable way to test that it stays fixed :-( (it's not an accident that the OP relied on atan2 to distinguish +0.0 from -0.0! they act the same in /almost/ all contexts). Python's grammar doesn't have negative numeric literals. Instead - CONSTANT_LITERAL looks like unary minus applied to the non-negative CONSTANT_LITERAL. All early versions of Python worked that way too. The first time the +/- 0.0 bug occurred is when the front end was changed to act as if - CONSTANT_LITERAL were a literal in its own right, and then that +0.0 == -0.0 caused the first instance of either in a compilation unit to be used as the value for all instances of both throughout the compilation unit. That was fixed by refusing to apply the optimimization if the value of CONSTANT_LITERAL was a float that compared equal to 0.0. 2.5 introduced a new front end and more ambitious constant-folding, and I expect the bug showed up again due to one of those. Note: printing the value of a float 0 may not reveal its sign. IIRC, glibc's float-to-string routines do display the sign of 0, but Microsoft's do not. However, atan2() is sensitive to the sign under both glibm and Microsoft's libm equivalent. -- http://mail.python.org/mailman/listinfo/python-list
Re: Signed zeros: is this a bug?
Tim Peters [EMAIL PROTECTED] writes: 2.5 introduced a new front end and more ambitious constant-folding, and I expect the bug showed up again due to one of those. I hope it does get fixed. Not having referential transparency in a basic math function like atan2 is pretty disturbing in a modern computer language. -- http://mail.python.org/mailman/listinfo/python-list
Re: Signed zeros: is this a bug?
Dennis Lee Bieber [EMAIL PROTECTED] writes: Pardon? What is the right thing with signed zeros... In the last 30 years I've been on machines that normalize floating zero into a true zero (all bits are zero: mantissa, exponent, and sign). This is the first time I've even seen a variable output as a negative 0.0! Most machines these days use IEEE 754 which supports negative zero. http://en.wikipedia.org/wiki/Negative_zero -- http://mail.python.org/mailman/listinfo/python-list
Re: Signed zeros: is this a bug?
On Mar 11, 5:15 pm, Tim Peters [EMAIL PROTECTED] wrote: It's a bug that keeps resurfacing, probably because there's no portable way to test that it stays fixed :-( (it's not an accident that the OP relied on atan2 to distinguish +0.0 from -0.0! they act the same in /almost/ all contexts). Not an accident, but not a contrived example either. I'd rewritten all the cmath routines (in pure Python) to be more numerically aware and use the `correct' (= those recommended by Kahan) branch cuts. It was in writing the unit tests for this that the problems above surfaced. By the way, I don't suppose that anybody would be interested in a rewritten cmath for Python 2.6? It wouldn't be hard for me to rewrite what I already have in C, and add suitable documentation and tests. Mark -- http://mail.python.org/mailman/listinfo/python-list
Bitpacked Data
i need to interface python with a bitpacked data file,
the structure recorded in the file is the following:
struct {
var_1 4bit
var_2 6bit
var_3 2bit
var_3 4bit
}
how can read the struct and convert data into dictionary
Thnx
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Re: a better solution for GUI in python
ce wrote: Hi, My company is using python currently for our website. We need to develop a GUI front-end for our ERP that would be portable (Windows and Linux). My question is which solution would be better for the GUI (and easier to implement)? I knew there are something like wxidgets, QT and pyGTK? actually we will need some complicated stuff in the GUI and yet I don't know much about GUI programming. Any recommendation guys? Take a look at Dabo. It is using wxWidgets and runs on Windows, Mac, Linux. http://www.dabodev.com Uwe -- http://mail.python.org/mailman/listinfo/python-list
Re: Need help with a string plz! (newbie)
On 2007-03-10, Hendrik van Rooyen [EMAIL PROTECTED] wrote: [EMAIL PROTECTED] wrote: Oh, thanks for the advice then. And as for Grant..look forward to seeing more of your posts. YOW! - some recognition at last! :) I see somebody pays attention to sigs -- which, BTW, are old quotes from the Zippy the Pinhead comic strip. www.zippythepinhead.com -- Grant -- http://mail.python.org/mailman/listinfo/python-list
Re: a better solution for GUI in python
On Mar 11, 1:03 pm, ce [EMAIL PROTECTED] wrote: Hi, My company is using python currently for our website. We need to develop a GUI front-end for our ERP that would be portable (Windows and Linux). My question is which solution would be better for the GUI (and easier to implement)? I knew there are something like wxidgets, QT and pyGTK? actually we will need some complicated stuff in the GUI and yet I don't know much about GUI programming. Any recommendation guys? http://pythoncard.sourceforge.net/ - Debugger, visual editor(resource editor) , one place event handlers like on_Object_Command, uses wxPython but easy than VB. -- http://mail.python.org/mailman/listinfo/python-list
Re: Bitpacked Data
none wrote:
i need to interface python with a bitpacked data file,
the structure recorded in the file is the following:
struct {
var_1 4bit
var_2 6bit
var_3 2bit
var_3 4bit
}
Strange data types. What language is this?
how can read the struct and convert data into dictionary
I'd use the module struct, with bit shifting operators to extract
the bits.
Regards,
Björn
--
BOFH excuse #232:
Ionization from the air-conditioning
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Re: Signed zeros: is this a bug?
Mark Dickinson [EMAIL PROTECTED] writes: By the way, I don't suppose that anybody would be interested in a rewritten cmath for Python 2.6? It wouldn't be hard for me to rewrite what I already have in C, and add suitable documentation and tests. I can't speak for the developers but my personal opinion is that this is worthwhile. I'm pretty Common Lisp and Scheme specify the branch cuts and I believe Java does the same. That is to help with the consistency and predicability of program behavior as well as to help various numerical algorithms. C has a different goal, which is to be a semi-portable assembly language, putting priority instead on minimizing intermediation between the programmer and the machine, instead of on predicability. Python should take the approach of the higher level languages and implement this stuff precisely, instead of just going along with whatever loose semantics the underlying C implementation happens to supply. -- http://mail.python.org/mailman/listinfo/python-list
Re: Signed zeros: is this a bug?
On Mar 11, 9:28 pm, Paul Rubin http://[EMAIL PROTECTED] wrote: Dennis Lee Bieber [EMAIL PROTECTED] writes: Pardon? What is the right thing with signed zeros... In the last 30 years I've been on machines that normalize floating zero into a true zero (all bits are zero: mantissa, exponent, and sign). This is the first time I've even seen a variable output as a negative 0.0! Most machines these days use IEEE 754 which supports negative zero. http://en.wikipedia.org/wiki/Negative_zero Isn't negative zero mathematically the same as zero? Isn't -0 just an artefact of the representation of floating point numbers? Shouldn't f(0) == f(-0) for all functions f? I read the wikipedia article about meteorologists using -0 to denote a negative number rounded to zero for the purposes of binning, i.e. if you want to tally days with temperature above and below zero, but it doesn't seem right. You should arrange for any temperature to be in only one range and record temperatures to their determined accuracy. a temperature of zero would only be in one bin and if a temperature is read as -0.2 and th rounding says it should be taken as zero then it should go in the same bin as any positive reading that is rounded to zero. Getting back to Python, shouldn't we strive to remove any distinction? a zero is a zero regardless of sign and a function like atan returning one of two different vaues for an argument of zero is actually mathematically not a bad thing to do? - Paddy. -- http://mail.python.org/mailman/listinfo/python-list
Re: Signed zeros: is this a bug?
Gabriel Genellina wrote: (I cannot find peephole.c on the source distribution for Python 2.5, but you menctioned it on a previous message, and the comment above refers to the peephole optimizer... where is it?) The peephole optimizer is in compile.c - the entry point is optimize_code BTW, I have written a pure-Python compiler which aims to be functionally identical to the Python 2.5 compiler, and is in fact very similar (much closer than stdlib.compiler). It may be helpful in investigating alternative workarounds for the -0.0 issue. http://svn.brownspencer.com/pycompiler/branches/new_ast/ Michael -- http://mail.python.org/mailman/listinfo/python-list
Re: war with china? a different approach?
Are you there, cause I don't want to waste my time writing a response to that if you're not there anymore. Please respond w/ a new post if you do check this. -- http://mail.python.org/mailman/listinfo/python-list
Re: Phase change material ...
Hey, thermate--could you check your post on China from January and respond. Thanks. -- http://mail.python.org/mailman/listinfo/python-list
Re: Signed zeros: is this a bug?
Paddy [EMAIL PROTECTED] writes: Most machines these days use IEEE 754 which supports negative zero. http://en.wikipedia.org/wiki/Negative_zero Isn't negative zero mathematically the same as zero? Isn't -0 just an artefact of the representation of floating point numbers? Shouldn't f(0) == f(-0) for all functions f? Not sure what you mean. Floating point numbers and in particular IEEE 754 floating point numbers are a set of values and operations with particular characteristics, that computers happen to implement. They are not the same thing as the mathematical real numbers. For example, there are infinitely many real numbers, but there are only finitely many 64-bit IEEE floating point numbers (at most 2**64 of them). They don't satisfy the same algebraic laws as real numbers. For example, (1e100 + 1) == 1e100, and as a consequence, (1e100 + 1) - 1e100 == 0, but (1e100 - 1e100) + 1 == 1, so the commutative addition law doesn't hold. These are all part of a mesh of interlocking compromises made in floating point computer arithmetic to approximate real-number arithmetic with finite-precision values. At first (i.e. from the early computer era through the 1970's or so) this stuff was designed somewhat ad hoc by computer architects, but eventually serious numerical mathemticians got into the act, figuring out how to make the best possible choices of these compromises for numerical computation. The result was IEEE 754, which resulted in Prof. Kahan winning the Turing award in 1989. IEEE 754 specifies that -0 and +0 are separate numbers. Yes it is an artifact in the sense of being one of the compromises. But these compromises all interact with each other to make the errors cancel in various numerical algorithms. The existence of -0 in IEEE 754 is part of an intricate framework designed very carefully over a long period by extremely experienced and knowledgeable people who knew what they were doing. It's not really wise to mess with it unless you're planning to undertake a project to redesign computer arithmetic of similar scope to the IEEE 754 effort. Getting back to Python, shouldn't we strive to remove any distinction? a zero is a zero regardless of sign and a function like atan returning one of two different vaues for an argument of zero is actually mathematically not a bad thing to do? No. Floating point numbers are not the same as real numbers and they don't satisfy the same laws. There have been some proposals (rejected) for Python to support exact rational arithmetic in addition to floating point and exact integer arithmetic. Exact rationals in Python (if implemented) should behave like mathematical rationals. But Python floating point arithmetic should follow IEEE 754, at least when the hardware supports it, which these days is almost always. -- http://mail.python.org/mailman/listinfo/python-list
Re: Signed zeros: is this a bug?
On Mar 11, 7:49 pm, Paddy [EMAIL PROTECTED] wrote: Isn't negative zero mathematically the same as zero? Isn't -0 just an artefact of the representation of floating point numbers? Shouldn't f(0) == f(-0) for all functions f? Read the original post again... The relevant part is: I'm working in a situation involving complex arithmetic where branch cuts, and hence signed zeros, are important, and it would be handy if the above code could be relied upon to do the right thing. You may want to read about branch cuts and complex arithmetics. I don't mean this as a putdown - simply as a useful suggestion for you to read. André -- http://mail.python.org/mailman/listinfo/python-list
Re: Bitpacked Data
Bjoern Schliessmann: I'd use the module struct, with bit shifting operators to extract the bits. Maybe Pyrex can be used to create a small module that can manage similar bitfields quickly and with a syntax not too much far from the Erlang bit syntax. Bye, bearophile -- http://mail.python.org/mailman/listinfo/python-list
Weekly Python Patch/Bug Summary
Patch / Bug Summary ___ Patches : 380 open (-36) / 3658 closed (+65) / 4038 total (+29) Bugs: 965 open ( -9) / 6555 closed (+35) / 7520 total (+26) RFE : 272 open ( +4) / 253 closed ( +2) / 525 total ( +6) New / Reopened Patches __ Extension documentation for subclasses (2007-03-01) CLOSED http://python.org/sf/1671450 opened by Pete Shinners MultiCall bug crashing the config dialog (2007-03-02) CLOSED http://python.org/sf/1672481 opened by Tal Einat urllib2 requests history + HEAD support (2007-03-03) http://python.org/sf/1673007 opened by KDanilov aka koder README update: Bash default on ac OS X (2007-03-03) CLOSED http://python.org/sf/1673121 opened by Witten Mac OS X: libtool (2007-03-03) http://python.org/sf/1673122 opened by Witten change repr(...) from 'Ellipsis' to '...' (2007-03-04) CLOSED http://python.org/sf/1673355 opened by John Reese Identify modules to be built and not built (2007-03-04) CLOSED http://python.org/sf/1673619 opened by Skip Montanaro 'G' formatting doesn't catch same errors as 'g' (2007-03-04) http://python.org/sf/1673759 opened by Eric V. Smith Identify modules which couldn't be built (2007-03-04) CLOSED http://python.org/sf/1673619 reopened by loewis sq_ass_slice ignored if sq_slice not defined (2007-03-05) CLOSED http://python.org/sf/1674228 opened by ?iga Seilnacht Epoll wrapper (2007-03-06) http://python.org/sf/1675118 opened by TH Draft implementation for PEP 364 (2007-03-06) http://python.org/sf/1675334 opened by Barry A. Warsaw PEP 3114 -- next() - __next__() (2007-03-07) http://python.org/sf/1675363 opened by Georg Brandl Make PyComplex_AsCComplex use __complex__ (2007-03-07) http://python.org/sf/1675423 opened by Mark Dickinson Zipfile tweaks and test coverage improvement (2007-03-06) http://python.org/sf/1675424 opened by Alan McIntyre Use getaddrinfo() in urllib2.py for IPv6 support (2007-03-07) http://python.org/sf/1675455 opened by David Cantrell Refactor test_pty.py to use unittest. (2007-03-06) CLOSED http://python.org/sf/1675471 opened by Jerry Seutter [gzip] Performance for small reads and fix seek problem (2007-03-07) http://python.org/sf/1675951 opened by Florian Festi Remove dead code in typeobject's type_new() (2007-03-07) CLOSED http://python.org/sf/1675981 opened by ?iga Seilnacht Remove trailing slash from --prefix (2007-03-07) http://python.org/sf/1676135 opened by Björn Lindqvist New File I/O type for Python 3000, plus .h and unit tests (2007-02-28) CLOSED http://python.org/sf/1671314 reopened by collinwinter Add a PeriodicTimer to threading (2007-03-08) http://python.org/sf/1676820 opened by Björn Lindqvist Adding timeout to socket.py and httplib.py (2007-03-08) http://python.org/sf/1676823 opened by Facundo Batista Refactor test_popen2.py to use unittest. (2007-03-08) http://python.org/sf/1676994 opened by Jerry Seutter Support CREATE_SUSPENDED flag in subprocess.py for Win32 (2007-03-09) http://python.org/sf/1677688 opened by Chris Heller site.py small ?bug fix | change? (2007-03-10) http://python.org/sf/1677862 opened by KDanilov aka koder Efficient reverse line iterator (2007-03-10) http://python.org/sf/1677872 opened by Mark Russell Removal of Tuple Parameter Unpacking [PEP3113] (2007-03-10) http://python.org/sf/1678060 opened by Tony Lownds improve telnetlib.Telnet so option negotiation becomes easie (2007-03-10) http://python.org/sf/1678077 opened by Björn Lindqvist Refactor test_operations.py to use unittest. (2007-03-10) http://python.org/sf/1678088 opened by Jerry Seutter Adding a testcase for the bug in find_longest_match (2007-03-11) http://python.org/sf/1678339 opened by Denys Rtveliashvili A fix for the bug #1528074 [warning: quite slow] (2007-03-11) http://python.org/sf/1678345 opened by Denys Rtveliashvili Patches Closed __ Extension documentation for subclasses (2007-03-01) http://python.org/sf/1671450 closed by gbrandl MultiCall bug crashing the config dialog (2007-03-02) http://python.org/sf/1672481 closed by gbrandl README update: Bash default on Mac OS X (2007-03-03) http://python.org/sf/1673121 closed by gbrandl change repr(...) from 'Ellipsis' to '...' (2007-03-04) http://python.org/sf/1673355 closed by gvanrossum Use a set to keep interned strings (2006-06-16) http://python.org/sf/1507011 closed by loewis Add support for the If-Modified-Since header (2006-03-04) http://python.org/sf/1442867 closed by loewis N-d array interface for array object (2006-03-18) http://python.org/sf/1452906 closed by loewis Fix for win32 proxy bypass support (no_proxy) in urllib(2) (2005-03-01)
Object instance reporting to a container class instance
I would like for an object to report to a container object when a
new instance is created or deleted. I could have a container object
that is called when a new instance is created, as below.
class AnyObject:
pass
class Container:
links = []
def add(self,other):
while other not in self.links:
self.links.append(other)
def rem(self,other):
while other in self.links:
self.links.remove(other)
...
container = Container()
a = AnyObject()
container.add(a)
My question is: can (should? :-) this reporting be done inside the
instance's __init__ and __del__ methods (that is, an instance
reports to the container as soon as it is created or deleted)?
Thanks!
Daniel
---
I'm working out a design where Object A is linked to Object B, and
both objects become aware of that relationship. I have implemented an
example successfully; the code is below. My main question is above,
but I would appreciate comments on the code! (For example, I'm
wondering whether my way of defining variables in the class but
assigning them locally to each instance (in the Object.init method)
is really a bad kludge...)
class Object():
def __del__(self):
print buh-bye!, self # Verbose for understanding garbage cleanup
def init(self,name):
self.links = []
self.name = name
def add(self,other):
while other not in self.links:
self.links.append(other)
other.add(self)
def rem(self,other):
while other in self.links:
self.links.remove(other)
other.rem(self)
class Student(Object):
def __init__(self,name):
self.init(name)
class Section(Object):
def __init__(self,name):
self.init(name)
class Task(Object):
def __init__(self,name):
self.init(name)
## Construct test instances!
students = {}
for name in ['Jose','Daniel','Rusty']:
student = Student(name)
students[name] = student
sections = {}
for name in ['English 1']:
section = Section(name)
sections[name] = section
tasks = {}
for name in ['Homework 1','Exam 1','Homework 2','Exam 2']:
task = Task(name)
tasks[name] = task
# Display example connections
def show_connections():
for section in sections:
print sections[section].name
for link in sections[section].links:
print \t, link.name
# Add some connections...
print Now adding connections...
for name in tasks:
sections['English 1'].add(tasks[name])
show_connections()
# Remove some connections...
print Now removing connections...
for name in tasks:
sections['English 1'].rem(tasks[name])
show_connections()
for task in tasks:
print tasks[task].links
for section in sections:
print sections[section].links
## Test garbage cleanup
sections['English 1'].add(tasks['Exam 1'])
print sections['English 1'].links
sections['English 1'].rem(tasks['Exam 1'])
del sections['English 1']
--
http://mail.python.org/mailman/listinfo/python-list
Re: Signed zeros: is this a bug?
Gabriel Genellina [EMAIL PROTECTED] wrote: En Sun, 11 Mar 2007 15:26:01 -0300, Alex Martelli [EMAIL PROTECTED] escribió: Or maybe we should give up ever storing -0.0 in the tables of constant and ALWAYS have 0.0, unary-minus wherever it appears (that would presumably require working on the AST-to-bytecode visitors that currently work ever-so-slightly-differently for this specific troublespot in the C-coded version vs the Python-coded one...). I think that way is the less intrusive, doesn't rely on a particular FP implementation, and the more likely to be accepted. Looking at ast.c, the culprit is some optimization in ast_for_factor, line 1506 /* If the unary - operator is applied to a constant, don't generate a UNARY_NEGATIVE opcode. Just store the approriate value as a constant. The peephole optimizer already does something like this but it doesn't handle the case where the constant is (sys.maxint - 1). In that case, we want a PyIntObject, not a PyLongObject. */ After the long if, I would use parsenumber(STR(pnum)) and check the type and value of the resulting object; if it's a float and 0.0, skip the optimization and continue below as a normal case. Unfortunately I'm not able to compile and test the code right now, so I can't provide an actual patch. (At least, not until tuesday). But I hope this simple comment is useful anyway... Yep, it sure might, if I can make time to act on it:-). (I cannot find peephole.c on the source distribution for Python 2.5, but you menctioned it on a previous message, and the comment above refers to the peephole optimizer... where is it?) http://svn.python.org/view/python/trunk/Python/peephole.c?rev=54086view =auto to browse the current version on the trunk. Right under the Python toplevel subdirectory in the sources, IOW. Alex -- http://mail.python.org/mailman/listinfo/python-list
Re: Signed zeros: is this a bug?
Alex Martelli [EMAIL PROTECTED] wrote: ... Yep, it sure might, if I can make time to act on it:-). ...and I did -- patch 1678668 is right there, brand newm at http://sourceforge.net/tracker/index.php . I hope it also satisfies the timbot's very reasonable lament about the bug resurfacing once in a while, since it included one more unittest to check whether the bug is there (TDD rocks!-). Alex -- http://mail.python.org/mailman/listinfo/python-list
Re: Signed zeros: is this a bug?
Mark Dickinson [EMAIL PROTECTED] wrote: On Mar 11, 2:59 pm, [EMAIL PROTECTED] (Alex Martelli) wrote: [...] OTOH, Python 2.4 works just fine...: Python 2.4.3 (#1, Apr 7 2006, 10:54:33) [GCC 4.0.1 (Apple Computer, Inc. build 5250)] on darwin Type help, copyright, credits or license for more information. 0.0,-0.0 (0.0, -0.0) -0.0,0.0 (-0.0, 0.0) so it seems to be very specifically a 2.5 problem. I've filed a bug report (bug #1678380) and got an impressively quick response from MvL. It looks like this is a `won't fix'. Oh well. That bug isn't formally closed yet, and the discussion's going on, we'll see. Meanwhile can you try my patch 1678668 just to double check it does fix everything? (It's agains the current HEAD of Python's svn). Alex -- http://mail.python.org/mailman/listinfo/python-list
Re: Signed zeros: is this a bug?
Tim Peters [EMAIL PROTECTED] wrote: ... It's a bug that keeps resurfacing, probably because there's no portable way to test that it stays fixed :-( (it's not an accident that the OP relied on atan2 to distinguish +0.0 from -0.0! they act the same in Please take a look at my patch 1678668, brand new at http://sourceforge.net/tracker/index.php and as yet unassigned (hint, hint:-). I hope it satisfies your very reasonable lament about the bug resurfacing once in a while, since it included one more unittest to check whether the bug is there (TDD rocks!-), based exactly on the behavior of atan2 (only on IEEE-format machines, though). 2.5 introduced a new front end and more ambitious constant-folding, and I expect the bug showed up again due to one of those. Yep, in ast.c's ast_for_factor -- it lacks the specialcasing that peephole.c does have (and my patch essentially adds it back). If it's worth specialcasing in peephole.c (and I strongly agree with Raymond's implicit opinion that it is), it should be just as worth specialcasing in ast.c, no?-) Alex -- http://mail.python.org/mailman/listinfo/python-list
