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

Re: Modern dead-tree Python resources
by Brian Gough Aug. 4, 2004

Aug. 4, 2004

Michael Ekstrand <python(a)elehack.net> writes: > Is there a good book that covers Python at least through 2.2 > ..... if someone's publishing print versions of the Python > documentation, that would possibly be of interest.... Hello, I publish printed editions of the Python Documentation (and other free software manuals too). The versions are all fairly recent (2.2 & 2.3). See the following urls for details. http://www.network-theory.co.uk/python/manual/ (Tutorial v2.2.2) http://www.network-theory.co.uk/python/language/ (Language Reference v2.3) The discounted price on Amazon is about $14 for each book. Incidentally, $1 of the price is donated to the Python Software Foundation for each copy sold. -- Brian Gough Network Theory Ltd, Publishing the Python Manuals --- http://www.network-theory.co.uk/

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Re: MySQLdb 'server not initialized'
by Sibylle Koczian Aug. 4, 2004

Aug. 4, 2004

Daniel Baggott schrieb: > Hi, > > I'm seeking assistance in troubleshooting connecting to MySQL (4.0.20) > using Python (2.3.4) and MySQLdb (1.0.0). When I attempt to make a > connection, I get the following exception: > _mysql_exceptions.InternalError: (-1, 'server not initialized') > > The database is definitely running as I can connect to it using the > mysql client. Also, when I attempt to connect to MySQL from within > Python, I don't see any messages in the MySQL logs (ie the .log and .err > files in /usr/local/mysql/data/). > If the server isn't running you'd get another exception anyway: OperationalError: (2003, "Can't connect to MySQL server on 'localhost' (10061)") I tried on Windows, but I can't think there's a difference at this point. What happens if you try the same thing with user "root" and his password - just for diagnostic purposes? > Does anyone have any advice or suggestions as to how to figure out > what's going wrong? Also, if there's a better forum for posting this > question, please point me in the right direction. > There is a help forum for MySQLdb on SourceForge: http://sourceforge.net/forum/forum.php?forum_id=70461 But it doesn't look very active to me, at least at the moment. So I wouldn't call it better, just another possibility. Regards, Koczian

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Re: MySQLdb select
by Sibylle Koczian Aug. 4, 2004

Aug. 4, 2004

Dennis Lee Bieber schrieb: > On Tue, 03 Aug 2004 15:02:21 +0200, Sibylle Koczian > <Sibylle.Koczian(a)Bibliothek.Uni-Augsburg.de> declaimed the following in > comp.lang.python: > > > >>I'm quite surprised that it works the other way - but it does. Could it >>be that previous versions of MySQLdb raised an exception with the other form >> > > > Well, from the MySQLdb code itself, we have these little > comments... > > -=-=-=-=-=-=- > def literal(self, o): > """ > > If o is a single object, returns an SQL literal as a string. > If o is a non-string sequence, the items of the sequence are > converted and returned as a sequence. > > Non-standard. > > """ I don't see where "literal" comes into this? > -=-=-=-=-=-=- > def execute(self, query, args=None): > > """Execute a query. > > query -- string, query to execute on server > args -- optional sequence or mapping, parameters to use with > query. > > Note: If args is a sequence, then %s must be used as the > parameter placeholder in the query. If a mapping is used, > %(key)s must be used as the placeholder. > > Returns long integer rows affected, if any > > """ That would confirm that a single string or number is not a correct args parameter, wouldn't it? There is nothing here like "if args is no sequence, it is treated as a tuple of length one" - but this seems to be what happens. Koczian

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Re: PyQt - clear widget for redraw
by Peter Aug. 4, 2004

Aug. 4, 2004

Phil Thompson wrote: > There are lots of standard graphics techniques for eliminating flicker > when drawing that you can exploit with PyQt. Double buffering for example > - draw to a QPixmap and then blit it to the QWidget. ok - I don't know what QPixmap or blit are, but it gives me some clues to use in google. :) Thanks for your help Peter

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Re: how to do proper subclassing?
by Peter Otten Aug. 4, 2004

Aug. 4, 2004

Jonas Koelker wrote: > Hello there. > > I'm new to this list (/me welcomes himself). > > anyways, I'm having doubts about how to subclass > properly. The big picture is that I want to handle > permutations. As we all know, two popular notation > forms exist: products of disjoint cycles ("(0 1 3)(2 > 4)") and 2*length matrices with the identity > permutation as the first line ([0 1 2 3 4] over [1 3 4 > 0 2]). I find the latter more appropriate, since it's > easy to store as a list (one can skip the first line, > assuming it's _always_ the identity). > > However, I want the permutation to act like a list, in > all those cases where I don't override the operations. > For example, assuming permfooation is the above > permutation [1 3 4 0 2], permfooation[1:3] should > return [3,4]. How is this done? Do I have to actually > implement a slice-mechanism in the permutation class? You already answered your question in the subject - you want a subclass of list: >>> class Perm(list): ... def __init__(self, n): ... list.__init__(self, range(n)) ... def __call__(self, i, k): ... self[i], self[k] = self[k], self[i] ... return self ... >>> p = Perm(5) >>> p [0, 1, 2, 3, 4] >>> p(0,4)(2,4)(0,1)(2,3)(1,2) [1, 3, 4, 0, 2] >>> p[1:2] [3] >>> p[1:3] [3, 4] Just in case you need it later, there is a special method for every operator, e. g. __getitem__() for obj[sliceOrIndex], __mul__() for multiplication etc. Write one for the class in question and it will grow the corresponding operation. In the above example I have made the class "callable" (i. e. its instances can behave like a function) by adding the __call__() method. By returning self I ensure that you can chain these calls. As you may know, this is not the way the list.sort() method behaves, so this is probably bad style for methods mutating the original instance. As to __getitem__(), I think the easiest way to see what happens inside is provided by the following snippet: >>> class C: ... def __getitem__(self, i): ... return i ... >>> C()[1] 1 >>> C()[1:2] slice(1, 2, None) >>> C()[1:2:3] slice(1, 2, 3) I. e. a typical minimal __getitem__() has to test whether it receives a slice or an integer using isinstance(). Peter

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automatic delegation
by Hallvard B Furuseth Aug. 4, 2004

Aug. 4, 2004

Is it possible to write a metaclass or something so that with a class definition not much larger than this: class foo: def __init__(self, val): self.val = val operations on a foo instance f will be applied to f.val? E.g. str(f) -> f.__str__() -> f.val.__str__(). -- Hallvard

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Reading message size
by Edvard Majakari Aug. 4, 2004

Aug. 4, 2004

I'm trying to create an improved front-end for training messages for a spam filter. I discovered an excellent Python module email - now it's so easy to support variety of mailbox formats. However, I need to know exact size of the message (in bytes) and skip the message if it is too large, before passing the message to filter. This is easy with MH or Maildir style directories - because each message is on separate file, it is trivial to get the file size. However, with mbox or any other format containing several messages in a file, I'm unable to find out individual message size. Of course, I could find this out by writing a message to a temp file and afterwards checking the temp file size, but I think that's awkward and inelegant. Is it somehow possible with email module? -- # Edvard Majakari Software Engineer # PGP PUBLIC KEY available Soli Deo Gloria! $_ = '456476617264204d616a616b6172692c20612043687269737469616e20'; print join('',map{chr hex}(split/(\w{2})/)),uc substr(crypt(60281449,'es'),2,4),"\n";

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Re: converting to string
by Josef Dalcolmo Aug. 4, 2004

Aug. 4, 2004

on Wed, 04 Aug 2004 17:03:10 +1000 Ajay Brar <abra9823(a)mail.usyd.edu.au> wrote: > how do i go about converting a Python object or tuple to a string. I guess the simplest is to use the built-in functions: str or repr str(object) if you just need a printable string repr(object) if you need to reconstruct later the original object from the string - Josef

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converting to string
by Ajay Brar Aug. 4, 2004

Aug. 4, 2004

hi! how do i go about converting a Python object or tuple to a string. i am currently doing import cPickle as pickle str = pickle.dumps(obj) is that efficient? is that the best way to do it? thanks cheers -- Ajay Brar CS Honours 2004 Smart Internet Technology Research Group http://www.it.usyd.edu.au/~abrar1

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Quixote demo
by eadorio＠yahoo.com Aug. 4, 2004

Aug. 4, 2004

I am trying out the quixote 1.0 demo in my linux box. I am able to view the main demo page using http://localhost/cgi-bin/demo.cgi with the HelloWorld on top of the page but I was wondering where the demo files for simple, error, publish_error, 12, 12/factorial, etc ... as clicking on these links result in file NOT FOUND error. TIA, Ernie

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