🌐 Mailman 3 August 2004 - Python-list - python.org

__coerce__ vs. new-style classes
by Hallvard B Furuseth Aug. 2, 2004

Aug. 2, 2004

Why do new-style classes disable __coerce__()? It seems cumbersome to have to write a whole set of methods (e.g. __add__, __radd__, etc.) to get the same effect. Is there some way to automatically generate those methods, or are we simply not supposed to do coercion for some reason? -- Hallvard

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MySQLdb select
by John Fabiani Aug. 2, 2004

Aug. 2, 2004

Hi, I'm a newbie and I'm attempting to learn howto create a select statement. When I use >>> string1='18 Tadlock Place' >>> cursor.execute("SELECT * FROM mytest where address = %s",string1) All works as expected. But >>> numb=10 >>> cursor.execute("SELECT * FROM mytest where clientID = %d",numb) Traceback (innermost last): File "<stdin>", line 1, in ? File "/usr/lib64/python2.3/site-packages/MySQLdb/cursors.py", line 95, in execute return self._execute(query, args) File "/usr/lib64/python2.3/site-packages/MySQLdb/cursors.py", line 110, in _execute self.errorhandler(self, TypeError, m) File "/usr/lib64/python2.3/site-packages/MySQLdb/connections.py", line 33, in defaulterrorhandler raise errorclass, errorvalue TypeError: int argument required ClientID was created using "clientID int not null auto_increment primary key" What is the correct way passing the numb var to the string? Thanks John

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Re: module timeit and variable scope
by brianc＠temple.edu Aug. 2, 2004

Aug. 2, 2004

>1. What are the advantages of using timeit compared to using >time.time() or time.clock()? (on Mac OS X) It's more accurate when timing very small bits of code. Though I don't know a thing about Max OS X. >2. How do I introduce a variable into the timeit.Timer? For example I >have a class Foo: Just create an instance in the setup portion of the Timer. t=timeit.Timer('foo.run()','from __main__ import Foo; foo=Foo()') To just test __init__ of your class: t=timeit.Timer('Foo()','from __main__ import Foo') Setup only runs once. -Brian ---- Original message ---- >Date: 2 Aug 2004 10:40:24 -0700 >From: fortepianissimo(a)gmail.com (fortepianissimo) >Subject: module timeit and variable scope >To: python-list(a)python.org > >A couple questions about using timeit to record the CPU time consumed >by an instance method: > > >2. How do I introduce a variable into the timeit.Timer? For example I >have a class Foo: > >class Foo: > def __init__ (self): > # the following line didn't work because the scope is not > # the calling function > # self._timer = timeit.Timer(stmt='self.run(bar)') > pass > > def someMethod (self, bar): > print bar > > def run (self, bar): > # call self.someMethod(bar) and record time using > # self._timer > pass > > >and I want to record the CPU time consumed by someMethod in method >run(), using the timer initialized in __init__(). The reason to set up >the timer in __init__ is to avoid overhead of setting up the same >timer time and time again in run(). > >Thank you. >-- >http://mail.python.org/mailman/listinfo/python-list

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Class optimization at runtime
by brianc＠temple.edu Aug. 2, 2004

Aug. 2, 2004

I would like to optimize my classes at run time. The question is where to put my "if" statement. -Inside __main__? if option: class Foo: def __init__: #do stuff else: class Foo: def __init__: #do other stuff -Inside class definition? class Foo: if option: def __init__: #do stuff else: def __init__: #do other stuff -Inside each method definition? class Foo: def __init__: if option: #do stuff else: #do other stuff Class instances will be created millions of times and the method's on them called even more so whatever brings the most speed will be used. I fear that the more readable way to do it is also the slowest. Thanks in advance, -Brian

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os.walk() maxdepth
by GMTaglia Aug. 2, 2004

Aug. 2, 2004

I've googled a lot but I couldn't figure out how to implement a maxdepth in os.walk(), does anybody had the necessity to do something like that? thanks in advance and.... ...as usual forgive my english -- Liquid http://softwarelibero.kuht.it <-> www.kuht.it

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Q: distutils - name clash protection?
by mb＠muenster.de Aug. 2, 2004

Aug. 2, 2004

Q: How do I make my setup procedure safe? Q: How can I let users specify a different destination dir? By now I think I have some useful modules I'd like to share. In "my world" everything is centered around my name, therefor my stuff typically lives in or beneath a package "mb". To use a module - for example - I do: >>> from mb import mbsql Following this approach a minimalistic setup.py looks like this: # # minimal setup.py # from distutils.core import setup setup(name = "mbsql", version="0.1.0", packages = ["mb","mb.mbsql"],) While this is fine in my little world I hate the idea that somebody else gets unexpectedly and with no warning overwritten what maybe was in his own "mb" package. (1) There should be a check built into the sdist that issues as warning ('mb' already exists - continue?). (2) Or even better: If the user already has an existing "mb" package: let him specify a name he likes, maybe "mbmbmb". For example some tools I found on the web live in a package "SamRushing" on my installation. And I like the according import statement for its clarity: >>> from SamRushing import calldll "distutils" is wonderful but a beast of its own if it comes to customizing. I'd like to know: Q: What's the best way to accomplish (1) and/or (2)? Thank you very much, mb - Martin Bless

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Fine-grained OSError subclasses or cross-platform errnos?
by jjl＠pobox.com Aug. 2, 2004

Aug. 2, 2004

Today, I wanted to do something like this: def nr_files(dirName) try: return len(os.listdir(dirName)) except OSError, e: if e.errno == errno.ENOENT: return 0 else: raise In other words, I wanted to trap only the case of missing directory (and not, for example, insufficient permissions), and I wanted to do it in the EAFP style. The problem is that errno is not cross-platform. Neither is there any subclass of OSError that I can conveniently catch to figure out what went wrong. Is there any better way of doing this? If not, why not? John

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Ann: Revival of the BytecodeHacks
by Christian Tismer Aug. 2, 2004

Aug. 2, 2004

Dear community, I could not resist to do this announcement, although this project belongs to Michael Hudson. Mike, please forgive me. I owe you a beer. In a single day-and-night session, I hacked against bytecodehacks, to upgrade it from Python 1.5.2 to Python 2.3 . This was quite some work, although not so very much, due to the excellent basic layout which Michael created. What are the Bytecodehacks? --------------------------- The bytecodehacks allow you to do certain modifications to compiled Python code objects. There are lots of applications included, like macro expansions and function inlining, things which Python does not provide and also is not supposed to provide. This kind of madness exists for people who ask for it, without worring those who don't care. Again, this great package was written by Michael Hudson in early 2000, and to my knowledge, it was never ported to the more recent Python versions. Michael told me that this is a package he is no longer too fond of, since it was written in his early days. He also told me that he is not keen on supporting it so much, because he would be tempted to give it a whole rewrite. Now, I'm thinking differently. I got the package to work, after about 12 hours of hacking, and it simply works. Since I didn't write the initial version, I have a different relationship to it. In other words: It is easier to maintain a foreign package than your own, since you are not married with it. Why do I dig into foreign areas? -------------------------------- Well, I have enough work with my Stackless package. Stackless is almost ready. (Almost, like your toy railway gets really ready; it really never will.) I just built a minimum Psyco support into it, because I'm basically always after as much speed as I can get. But there are limits with the regular Python interpreter. So my idea is to use these crazy other projects to get more performance, and to support them directly. My first idea to accelerate Psyco using Stackless was to provide Stackless with extra hardware stacks, which can be switched at light-speed. I still have this idea in mind, but the implementation is not so trivial. Comparatively, replacing generators (yield calls) with a couple of save/restores of tuples *is* almost trivial, as I'm probably going to show tomorrow. In Python, these "fake-generators" would be reasonably slower. But, by the fact that these are then Psyco-enabled, makes them really, really fast, and also completely inlineable. I think to name the module "renegate". :-) Why do I want to revive this package ------------------------------------ Well, I am a pragmatic guy, and I have a really good reason why I need the bytecodehacks. I am writing a sophisticated package which involves parsing of PDF files, and I want to do it all in Python. In order to get this PDF processor to almost C speed, I used Armin Rigo's wonderful Psyco package. Unfortunately, Psyco has a few limitations, which act as a show-stopper: - generators are not supported. That means, whenever I use a generator, Psyco will not accelerate it, but will act as a small slow-down. - Psyco is great at optimizing simple structures like lists, tuples, numbers and strings. It is less able to enhance things like object properties. Using self frequently disables almost all of Psyco's capabilities. - Psyco has difficulties with inlining. Simple functions *are* inlined, but when they contain a conditional branch or they exceed some limit, inlining is disabled. This *could* be changed, but with a lot of effort by changing C code. This is not going to happen, because all of this stuff will be enhanced and re-implemented during the PyPy project. Now, by combining the re-animated bytecodehacks project with Psyco, I am almost sure that I can remove certain restrictions from Psyco, by turning problematic Python structures into simple ones, which the current Psyco can handle natively. Poor man's PyPy --------------- Although I am a member of the PyPy project, and I do belong to the people who initiated the PyPy project, I am impatient, and I want to get a few of the expected PyPy results right now. Psyco is phantastic but not perfect, and it needs some help to gather maximum performance. By adding Bytecodehacks in the right manner, I think I can fill this gap. With BCH, I can replace generators by ordinary methods of a class (plus a few bytecode instructions which have no real Python equivalent, like goto). By inspecting the data flow of a self.attribute, I can prove that it is invisible outside and replace it by a simple local variable in many cases. By using Bytecodehacks for proper inlining of functions, I can deliver Psyco from this difficult task. The expected result ------------------- By consequently applying the methods I sketched above, I expect that I can make almost every existing application reasonably faster. I will provide this as a service for customers and charge them for relevant acceleration. The software will stay open-sourced. This is just a few add-ons to Psyco and Bytecodehacks, and I'm not the author of these. I just found out how nicely they can fit together. My guess is an overall acceleration of at least a factor of five for almost any native Python application. There is no proof yet, this is all Vodoo from my stomach. But this stomach tends to be quite reliable Mike, please forgive me this announcement. You should have written it, but I was so very inspired. Getting the bytecodehacks for Python 2.3 ---------------------------------------- The current source code is available at cvs -d:pserver:anonymous@cvs.sourceforge.net:/cvsroot/bytecodehacks login cvs -z3 -d:pserver:anonymous@cvs.sourceforge.net:/cvsroot/bytecodehacks co bytecodehacks cheers -- chris -- Christian Tismer :^) <mailto:tismer@stackless.com> Mission Impossible 5oftware : Have a break! Take a ride on Python's Johannes-Niemeyer-Weg 9a : *Starship* http://starship.python.net/ 14109 Berlin : PGP key -> http://wwwkeys.pgp.net/ work +49 30 89 09 53 34 home +49 30 802 86 56 mobile +49 173 24 18 776 PGP 0x57F3BF04 9064 F4E1 D754 C2FF 1619 305B C09C 5A3B 57F3 BF04 whom do you want to sponsor today? http://www.stackless.com/

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Re: Percentage matching of text
by Mark 'Kamikaze' Hughes Aug. 2, 2004

Aug. 2, 2004

Bruce Eckel <BruceEckel(a)MailBlocks.com> wrote on Fri, 30 Jul 2004 07:52:39 -0600: > Background: for the 4th edition of Thinking in Java, I'm trying to > once again improve the testing scheme for the examples in the book. I > want to verify that the output I show in the book is "reasonably > correct." I say "Reasonably" because a number of examples produce > random numbers or text or the time of day or in general things that do > not repeat themselves from one execution to the next. So, much of the > text will be the same between the "control sample" and the "test > sample," but some of it will be different. > > I will be using Python or Jython for the test framework. > > What I'd like to do is find an algorithm that produces the results of > a text comparison as a percentage-match. Thus I would be able to > assert that my test samples must match the control sample by at least > (for example) 83% for the test to pass. Clearly, this wouldn't be a > perfect test but it would help flag problems, which is primarily what > I need. > > Does anyone know of an algorithm or library that would do this? Thanks > in advance. Here's an outside-the-box solution: set the random number seed and use a fixed date in your tests. Now you can test fixed values, even though the application is "random". -- <a href="http://kuoi.asui.uidaho.edu/~kamikaze/"> Mark Hughes </a> "Virtues foster one another; so too, vices. Bad English kills trees, consumes energy, and befouls the Earth. Good English renews it." -The Underground Grammarian, v1n2

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help with py2exe
by quentin long Aug. 2, 2004

Aug. 2, 2004

i try running it but it gives me an error: AttributeError: DistributionMetadata instance has no attribute 'get__doc__' im a complete noob so help me out _________________________________________________________________ Dont just search. Find. Check out the new MSN Search! http://search.msn.click-url.com/go/onm00200636ave/direct/01/

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