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

ODBC bug
by elbertlev＠hotmail.com Aug. 5, 2004

Aug. 5, 2004

# W2K MSSQL-2000 import dbi, odbc myconn = odbc.odbc('DSN=db; UID=sa; PWD=') mycursor = myconn.cursor() mycursor.execute("SELECT ID, PWD FROM TABLE") rs = mycursor.fetchall() for ID, PWD in rs: upd = "UPDATE TABLE SET PWD = \'%s\' WHERE ID = %u" % \ (encode(PWD), ID) mycursor.execute(upd) myconn.commit() #This script updates (encodes) passwords in the database, #but does this rather slowly if the the recordset contains 2000 records. To speedup I decided to concatenate upd strings and execute it: mycursor.execute("SELECT ID, PWD FROM TABLE") rs = mycursor.fetchall() updlst = [] for ID, PASSWORD in rs: upd = "UPDATE TABLE SET PWD = \'%s\' WHERE ID = %u" % \ (encode(PWD), ID) updlst.append(upd) upd = " ".join(updlst) mycursor.execute(upd) myconn.commit() #This one works much faster, but if the joined upd string is longer then about 40K ONLY THE FIRST 40K are actually executed. The rest is IGNORED. No exceptions and execute() returnes 1.

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Re: RELEASED Python 2.4, alpha 2
by Christopher T King Aug. 5, 2004

Aug. 5, 2004

On Fri, 6 Aug 2004, Anthony Baxter wrote: > On Thu, 5 Aug 2004 12:29:51 -0400, Christopher T King <squirrel(a)wpi.edu> wrote: > > What does one do if a decorator raises an exception? > > def deco(func): > raise TypeError > > @deco > def foo(): > print "hello" Yes yes yes, I /know/ they are /able/ to raise exceptions. My point was about handling them in a clean, concise way. > Silently failing is completely non-pythonic. Then let's say you want to print a warning, "Warning, type checking not installed!" > If you really wanted to handle a missing decorator, something like > missingdec = lambda x:x would do this for you. Ick. That doesn't fix the general case (though I admit it wouldn't come up too often). > > Decorators in general are the right solution for the wrong problem (as I > > detailed in another thread). They are being introduced much too > > prematurely, and have not been given time to be able to have been thought > > through well enough. The @ syntax is the result of trying to shoehorn too > > many solutions into one fix. > > Too prematurely?? staticmethod and classmethod were introduced in 2.2! I'm referring to the syntax, not the decorators themselves. > PyObjC, ctypes, Jython and IronPython can all do with using them, as can > rather a lot of other chunks of code. Anything that applies metadata to > functions can use this - look at all the various places where people are > putting stuff in docstrings as a current hack. Anything that applies metadata to functions can use function attributes much more effictively. They're cleaner, more to the point, and are likely to have much less backlash than @. Example of a previous function attribute proposal: def foo(a,b,c): .accepts = (int,int,int) .returns = str pass > Or, alternately, they're another tool in the toolbox, along with > metaclasses and the like. It just so happens I'm not a big fan of metaclasses, either ;)

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Re: Decorator syntax
by Ames Andreas (MPA/DF) Aug. 5, 2004

Aug. 5, 2004

Hi, Michael Ekstrand wrote: > def(staticmethod) somemethod(self, args): > some code could you or someone else please enlighten me, as someone who wasn't following the decorator syntax discussion, why this syntax was ruled out? It still (after looking up some of the discussed alternatives) seems to be the most appropriate to me, esp. since core changes seem to be acceptable to get a useful decorator syntax. tia, andreas

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DB-API 2.0 question
by Josh Close Aug. 5, 2004

Aug. 5, 2004

I'm using sybase and get this error when running two inserts in a row. Process 88 generated fatal exception c0000005 EXCEPTION_ACCESS_VIOLATION. SQL Server is terminating this process. All I'm doing is conn = connect(host, user, pass, db) cursor = conn.cursor() cursor.execute(update query here) cursor.execute(update query here) Do I need to put a commit() in there or something? I guess I'm not really familiar with how DB-API 2.0 works. I would think upon a second execute, the first would be committed already. -Josh

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Re: Confused about pep 318
by Peter Hansen Aug. 5, 2004

Aug. 5, 2004

Anthony Baxter wrote: > On Thu, 05 Aug 2004 13:29:29 -0400, Peter Hansen <peter(a)engcorp.com> wrote: > >>I'll make another donation to PSF if the final decorator syntax >>does not Perlishly use arbitrary punctuation as the @ syntax does. > > FFS. What exactly is "Perlish" about @? It's an unused symbol. That's all. > It's hardly arbitrary - Java, for instance, already uses @ for the same thing. And Java chose it based on what precedent? Basing a choice on someone else's arbitrary choice makes something only ever so slightly less arbitrary. Python doesn't need to select syntax from other languages. Python leads, it doesn't follow. Until now. :-( -Peter

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Re: MySQLdb select
by Sibylle Koczian Aug. 5, 2004

Aug. 5, 2004

Dennis Lee Bieber schrieb: > > Except that the conversion function, .literal(), /does/ accept > a single item, a sequence (tuple OR list), or a mapping (dictionary). > The arguments are just passed through .execute(), which doesn't really > care one way or the other. > > Tediously, .execute() calls ._execute(), which has: > ... > try: > if args is None: > r = self._query(query) > else: > r = self._query(query % self.connection.literal(args)) > except TypeError, m: > ... > > Since .literal() accepts single objects (well, in truth, I'd > guess one would have to say that it is .escape() that processes the > arguments -- I can't say what that does, as it is likely in the binary > module. However, the actual forming of the final query string /is/ the > standard Python "string" % arg operator, which, in my experience, has > never complained about not being given a 1-tuple. > True. I had hopes that this might explain another riddle I couldn't solve: datefield is a database column of type date, and I execute two queries: a) SELECT * FROM mytable WHERE datefield = %s b) SELECT * FROM mytable WHERE datefield IN (%s, %s) case a): the parameter for %s can be a mx.DateTime object, a datetime.date object or the sort of DateTime object MySQLdb returns from another query; or it can be a string with format 'YYYY-MM-DD'. The results of the query are correct in every case. case b): the parameters must be strings of the form 'YYYY-MM-DD'. With all other sorts of parameters (DateTime objects, strings in other date formats) the query doesn't find anything. I tried this with different versions of MySQL, MySQLdb and Python, under Windows and Linux, always with the same results. Now I've looked at conn.literal(args) for a pair of DateTime objects and for a single one: >>> arg <DateTime object for '2004-06-18 00:00:00.00' at 1199da0> >>> arglist [<DateTime object for '2004-07-29 00:00:00.00' at 117af20>, <DateTime object for '2004-07-07 00:00:00.00' at 1199de0>] >>> conn.literal(arglist) ("'2004-07-29 00:00:00'", "'2004-07-07 00:00:00'") >>> conn.literal(arg) "'2004-06-18 00:00:00'" >>> s1 = 'SELECT * FROM fehllief WHERE fehltag IN (%s, %s)' >>> s1 % conn.literal(arglist) "SELECT * FROM fehllief WHERE fehltag IN ('2004-07-29 00:00:00', '2004-07-07 00:00:00')" >>> s2 = 'SELECT * FROM fehllief WHERE fehltag = %s' >>> s2 % conn.literal(arg) "SELECT * FROM fehllief WHERE fehltag = '2004-06-18 00:00:00'" >>> curs.execute(s1, arglist) 0L >>> curs.execute(s2, arg) 1L Why doesn't the query using IN find anything while the query using = does? The records are there, of course. Koczian

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Re: Confused about pep 318
by Christopher T King Aug. 5, 2004

Aug. 5, 2004

On Fri, 6 Aug 2004, Anthony Baxter wrote: > To summarise: As I've stated already, I'm aware that PEP 318 needs an > update. If no-one else gets it done before next week, I will have time > to work on it again. If one of the people complaining about it wants to > sit down and trawl the (literally) hundreds and hundreds of python-dev > messages, spread over the last 2+ years, and extract the relevant posts, > that would be excellent! If you're only going to sit and bitch about it, > well, I can spend my time better trawling the archives. I'd be willing to do this this weekend (esp. being Python Bug Day), assuming Skip doesn't get to it first. On a related note, I suggest anyone interested read this thread on python-dev, "Call for defense of @decorators": http://mail.python.org/pipermail/python-dev/2004-August/046878.html In it, Guido makes some very interesting remarks, most notably: I also want to find out about superior syntax proposals (from __future__ import decorators might be acceptable). and ... I suggest that the proponents of syntax alternatives will have to agree amongst themselves on a single alternative that they can present to me.

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Re: Re[2]: Need help on how to use Pymedia!
by CptPicard Aug. 5, 2004

Aug. 5, 2004

"Dmitry Borisov" <jbors(a)mail.ru> wrote in message news:mailman.1208.1091724751.5135.python-list@python.org... > > > > > Thank you for your help! > > > > "Lawrence Oluyede" <raims(a)dot.com> wrote in message > > news:3x8w4pqd3emo.15wp1jkrwkqua.dlg@40tude.net... > > > In data Thu, 05 Aug 2004 02:28:48 GMT, CptPicard ha scritto: > > > > > > > Could someone give me a more detailed documentation on pymedia or some > > clues > > > > on how to get the information I need ? > > > > > > AFAIK Pymedia cannot extract ID3 infos from MP3 (altough you can study by > > > yourself the ID3 format a inspect the raw info of the file), anyway the > > web > > > is full of ID3 tools for python such as: > > > http://id3-py.sourceforge.net/ > > Please use this mailing list to get support on pymedia: pymedia-users(a)lists.sourceforge.net > It will make sure you get the quick response. I will do so! > > The documentation is a little scarce at the moment and I'm working on the tutorial to compensate that. Good news! > > Here is the code which will give you what you need( from pycar ). It is modified to match what you need and therefore not tested.: > > f= open( <file_name>, 'rb' ) > dec= acodec.Decoder( <file_extension> ) > s= f.read( 20000 ) > fr= dec.decode( s ) > # Hardcoding for mp3 IDv1 tags > if not dec.hasHeader() and <file_extension>== 'mp3': > f.seek( -128, 2 ) > dec= acodec.Decoder( 'mp3' ) > dec.decode( f.read( 128 ) ) > > print dec.getInfo() I appreciate your support. I understand that this is a piece of code specially written for fixing my problem but where could I find such example in pycar ? I looked for Decoder in the pycar source code (pymedia*-src) and found no match. Do you include support for tag IDv2 too ? > > Hope this helps. > Dmitry/ >

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AVI I/O
by ziaran Aug. 5, 2004

Aug. 5, 2004

Hello, I want to use Python for Image proccessing. I need the following capabilities: 1. To be able to read and WRITE an AVI file frame by frame. 2. To be able to access each fram as a simple matrix. I tried to search for that in google but could not find something intuitive and simple. The matrices part is important since iamge processing is done through matrices manipulation. MATLAB is an example of a tool with scripting capabilities in which you can do that in a simple way. Is Python adequate for that? Thanks, Nir

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Re: RELEASED Python 2.4, alpha 2
by Christopher T King Aug. 5, 2004

Aug. 5, 2004

On Thu, 5 Aug 2004, Heiko Wundram wrote: > Now tell me that using decorators to do synchronization isn't a lot easier to > read than the first (old) example is, and also less error-prone (resp. > acquiring/releasing locks properly and without deadlocks). I'll admit synchronization is a strong use case (since I don't believe it justifies language support, like it has in Java), but I just think there's a better way to go about things that no-one's thought of yet.

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