🌐 Mailman 3 October 2005 - Python-list - python.org

Re: Why the nonsense number appears?
by Steve Horsley Nov. 1, 2005

Nov. 1, 2005

Ben O'Steen wrote: > On Mon, October 31, 2005 10:23, Sybren Stuvel said: >> Ben O'Steen enlightened us with: >>> Using decimal as opposed to float sorts out this error as floats are >>> not built to handle the size of number used here. >> They can handle the size just fine. What they can't handle is 1/1000th >> precision when using numbers in the order of 1e10. >> > > I used the word 'size' here incorrectly, I intended to mean 'length' > rather than numerical value. Sorry for the confusion :) > Sybren is right. The problem is not the length or the size, it's the fact that 0.039 cannot be represented exactly in binary, in just the same way that 1/3 cannot be represented exactly in decimal. They both give recurring numbers. If you truncate those recurring numbers to a finite number of digits, you lose precision. And this shows up when you convert the inaccurate number from binary into decimal representation where an exact representation IS possible. Steve

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Automatically creating a HOME environ variable on Windows?
by jim.eggleston＠gmail.com Nov. 1, 2005

Nov. 1, 2005

Windows doesn't have a HOME environment variable, but it does have HOMEDRIVE and HOMEPATH. Could Windows versions of Python automatically populate os.environ with HOME, where HOME = os.path.join(os.environ['HOMEDRIVE'], os.environ['HOMEPATH'])? If this was done, then modules such as pdb, which load resource files from HOME, would work under Windows. Alternatively, here is a patch to make pdb.py read .pdbrc under Windows. *** pdb_orig.py Mon Jun 16 01:26:30 2003 --- pdb.py Sat Oct 29 11:11:07 2005 *************** *** 65,72 **** --- 65,76 ---- # Read $HOME/.pdbrc and ./.pdbrc self.rcLines = [] + envHome = '' if 'HOME' in os.environ: envHome = os.environ['HOME'] + elif 'HOMEDRIVE' in os.environ and 'HOMEPATH' in os.environ: + envHome = os.path.join(os.environ['HOMEDRIVE'], os.environ['HOMEPATH']) + if envHome: try: rcFile = open(os.path.join(envHome, ".pdbrc")) except IOError:

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cx_Oracle, is anything selected?
by Damjan Nov. 1, 2005

Nov. 1, 2005

Is there a way to see if the SELECT in cx_Oracle didn't return anything? I want to optimize the situation when the number of selected rows is zero. Is select count(*) the only option, seems inefficient? -- damjan

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OpenSSL in Python
by dcrespo Nov. 1, 2005

Nov. 1, 2005

Hi to all, What do I have to install to get the following code work (Win XP, Python 2.4.2) from OpenSSL import SSL import config KEY_FILE = config.SSL_KEY_FILE CERT_FILE = config.SSL_CERT_FILE ---------------------------------- I've been looking for OpenSSL for python. I found pyOpenSSL, but it requires the OpenSSL library, which I only found on http://www.openssl.org/, but don't know how to install. Other thing is the "config" module... I'm lost. Someone knows? :-S My main purpose is to enable xml-rpc server over an SSL connection. Thanks Daniel

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yapsnmp - on windows
by py Nov. 1, 2005

Nov. 1, 2005

I have installed net-snmp and of course python on windows xp. I downloaded yapsnmp (http://yapsnmp.sourceforge.net/) and I can't seem to use it. It has a swig interface...but I get errors when trying to swig it.. C:\yapsnmp-0.7.8\src>"c:\Program Files\swigwin-1.3.25\swig.exe" -python net-snmp.i net-snmp.i(29): Error: Unable to find 'asn1.h' net-snmp.i(30): Error: Unable to find 'snmp_api.h' net-snmp.i(31): Error: Unable to find 'snmp.h' net-snmp.i(32): Error: Unable to find 'snmp_client.h' net-snmp.i(33): Error: Unable to find 'mib.h' net-snmp.i(34): Error: Unable to find 'default_store.h' C:\yapsnmp-0.7.8\src> ...Any ideas? Anyone have this working on windows?

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looking for a good python module for MS SQL server
by Anat Oct. 31, 2005

Oct. 31, 2005

Hi, Does anyone know a good python mudule that works with MS SQL server? Thanks, Anat

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Looking for info on Python's memory allocation
by Steven D'Aprano Oct. 31, 2005

Oct. 31, 2005

Can somebody help me please? I've spent a fruitless hour googling with no luck. I'm discussing memory allocation techniques with somebody, and I'm trying to find a quote from -- I think -- Tim Peters where he discusses the way Python allocates memory when you append to lists. In basic terms, he says that every time you try to append to a list that is already full, Python doubles the size of the list. This wastes no more than 50% of the memory needed for that list, but has various advantages -- and I'm damned if I can remember exactly what those advantages were. Can anyone point me in the right direction? Thanks, -- Steven.

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data hiding/namespace pollution
by Alex Hunsley Oct. 31, 2005

Oct. 31, 2005

There's no really specific questions in this post, but I'm looking for people's thought on the issues within... The two main versions I've encountered for data pseudo-hiding (encapsulation) in python are: method 1: _X - (single underscore) - just cosmetic, a convention to let someone know that this data should be private. method 2: __X - (double underscore) - mangles the name (in a predictable way). Avoids name pollution. How often does either tend to get used? Personally, I'd be a little worried about using method 1, because namespace clashes could happen. Is this overly paranoid? Also, I presume that rather than people writing their own manual getter and setter methods, they tend to use either overloading on __getattr__ and __setattr__, or the Property class (which itself uses aforementioned methods). Overloading __getattr__ etc. seems more attractive to me, as then I can capture access to unknown names, and raise an exception! (I really don't like the idea of random attribute name typos going unnoticed when accessing attributes in a class!) Note: I do know that the use of the above things is quite dependent on what exactly you're coding, the size of the project etc., but what I'm trying to find out about is the python communities' recognised good practices. thanks, alex

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Re: Tkinter problem
by dale cooper Oct. 31, 2005

Oct. 31, 2005

Thanks, but I've got another question: can't find Tcl configuration script "tclConfig.sh" This is what I received trying to install TkBLT. What is tclConfig.sh? I did installed tcl/tk 8.4.9-3 as I mentioned before, I tried to find this file, but I don't have it in my filesystem. How to get it?

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MySQLdb and cgi
by robert Oct. 31, 2005

Oct. 31, 2005

Dear group, I have a problem with importing MySQLdb in a cgi-script. The code fragment at the beginning: 1 #!/usr/bin/env python 2 3 print "Content-Type: text/html\n\n" 4 5 import re 6 import cgi 7 import MySQLdb 8 print "something" but the print statement in line 8 will never be executed. The Apache error log says: "No module named MySQLdb, referer: http://localhost/sqlForm.html" But when executing the import statement outside of an cgi-script, for example at the command line, the import works fine. I assume, it has something to do with the apache. Why does the python interpreter not find the MySQLdb module when executed in apache context? thanks, roebi

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