🌐 Mailman 3 January 2008 - Python-list - python.org

using Tix.FileSelectBox in python
by devnew＠gmail.com Jan. 2, 2008

Jan. 2, 2008

hi i was using Tix.FileSelectBox to select imagefiles from a directory..when i click on image and click my app's okbutton i can get the selected image name by self.selimgname=self.myfileselectbox.selection.cget("value") after this if i just select a folder and not an image and click ok then again the myfileselectbox.selection.cget("value") gives the previously selected image name. i would like to give an error msg asking the user if he doen't select an image..how can i do this? devnew

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Re: os.tmpfile()
by Erik Max Francis Jan. 2, 2008

Jan. 2, 2008

jyoung79(a)kc.rr.com wrote: > Can anyone elaborate on how 'os.tmpfile()' works? I was thinking it would create some sort of temporary file I could quickly add text too and then when I was finished would automatically get rid of it. Here's my questions: ... > Can you actually 'write' to this file? And if so, do you have to 'close()' it when you're done with it? Thanks for your help with this... I'm still learning Python and haven't been able to find out much about this in the documentation or on-line. It's a file. You read strings from it and write strings to it. It isn't a string itself. Given that what you're trying to do doesn't make any sense, it's hard to know where to begin to identify what's confusing you. -- Erik Max Francis && max(a)alcyone.com && http://www.alcyone.com/max/ San Jose, CA, USA && 37 18 N 121 57 W && AIM, Y!M erikmaxfrancis And though the odds say improbable / What do they know -- Stevie Wonder

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Simple server using asyncore/asynchat
by Rick Jan. 2, 2008

Jan. 2, 2008

Hey folks. I'm trying to create a (fairly) simple server that listens for connections and when it receives one sends a message to the client and then waits for a response (and would continue to do that). My problem is, every time my client connects, the server doesn't send the text and then immediately closes the connection with the client, but DOES print that the client was connected. Anyone know why? Here's my code: # conn.py import socket import asyncore import asynchat import string host = 'localhost' #socket.gethostname () port = 8017 buf = 1024 class ConnChannel (asynchat.async_chat): def __init__(self, conn): self.conn = conn def handle_connect(): self.send(self.conn, "Hello, Welcome to BasicMUD.\r\n") # it doesn't do thise self.numberclients = self.numberclients + 1 # or this self.send(self.conn, "There are " + self.numberclients + " players online.") # or this print "Client connected!" # it prints this def handle_read(self): print self.recv(8192) def handle_write(self): print "sending" class ConnTube (asyncore.dispatcher): def __init__(self, hostd, portd): asyncore.dispatcher.__init__(self) self.create_socket(socket.AF_INET, socket.SOCK_STREAM ) self.bind ( ( hostd , portd ) ) self.listen ( 5 ) self.numberclients = 0 def handle_accept(self): channel, addr = self.accept() ConnChannel(channel) connTube = ConnTube(host, port) asyncore.loop() Thanks everyone! Rick

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parse text files in a directory?
by jo3c Jan. 2, 2008

Jan. 2, 2008

hi everybody im a newbie in python, i have a question how do u parse a bunch of text files in a directory? directory: /dir files: H20080101.txt , H20080102.txt,H20080103.txt,H20080104.txt,H20080105.txt etc...... i already got a python script to read and insert a single text files into a postgres db. is there anyway i can do it in a batch, cause i got like 2000 txt files. thanks in advance joe

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Catching external program exceptions
by Marty Jan. 2, 2008

Jan. 2, 2008

I need to catch exceptions thrown by programs started by the os.system function, as indicated by a non-zero return code (e.g. the mount utility). For example, if I get the following results in a bash shell: $mount test mount: can't find /home/marty/test in /etc/fstab or /etc/mtab then I want to catch the same exception from the corresponding os.system() call, i.e. "os.system('mount test')", but it doesn't work as expected: >>> import os, sys >>> try: os.system('mount test') ... except: print 'error' ... mount: can't find /home/marty/test in /etc/fstab or /etc/mtab 256 >>> I get the same results with popon, popen2, popen3, etc. Apparently these also work only when the program does not generate an exception. Is there any way to catch the return code. or if not, a workaround?

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confusion about package/module imports
by Jugdish Jan. 1, 2008

Jan. 1, 2008

Why doesn't the following work? >>> ls $HOME $HOME/pkg/__init__.py $HOME/pkg/subpkg/__init__.py $HOME/pkg/subpkg/a.py $HOME/pkg/subpkg/b.py >>> cat $HOME/pkg/__init__.py # empty >>> cat $HOME/pkg/subpkg/__init__.py import a import b >>> cat $HOME/pkg/subpkg/a.py class A: pass >>> cat $HOME/pkg/subpkg/b.py import pkg.subpkg.a class B(pkg.subpkg.a.A): pass >>> setenv PYTHONPATH $HOME:$PYTHONPATH >>> python $HOME/pkg/subpkg/b.py Traceback (most recent call last): File "pkg/subpkg/b.py", line 1, in ? import pkg.subpkg.a File "$HOME/pkg/subpkg/__init__.py", line 2, in ? import b File "$HOME/pkg/subpkg/b.py", line 2, in ? class B(pkg.subpkg.a.A): AttributeError: 'module' object has no attribute 'subpkg'

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Network Module
by Sunil Ghai Jan. 1, 2008

Jan. 1, 2008

Hello people, I am searching for a python module to interact with the network connections/interfaces. For example the number of active TCP/IP connections via eth0 interface and all that stuff. I have done googling and search at python<dot>org but couldn't find any. Thanks Sunil Kumar Ghai

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Re: TK 8.5
by Leon Jan. 1, 2008

Jan. 1, 2008

> We are planing to use Tcl/Tk 8.5 for Python 2.6 and 3.0. The topic is > currently being discussed but nothing has been decided yet. Great news! I hope you'll decide to use Tcl/Tk 8.5 ! I'm sure I'm not the only one !!! On this page : http://www.python.org/dev/peps/pep-0361/ We can read : "the initial 2.6 target is for April 2008" Great ! But I found nothing about Tk 8.5 ? Leon

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Re: Bizarre behavior with mutable default arguments
by Arnaud Delobelle Jan. 1, 2008

Jan. 1, 2008

On Jan 1, 6:48 pm, "Gabriel Genellina" <gagsl-...(a)yahoo.com.ar> wrote: > En Tue, 01 Jan 2008 15:45:00 -0200, bukzor <workithar...(a)gmail.com> > escribi�: [...] > >> I'm confused by what you mean by 'early binding'. Can you give a quick- > >> n-dirty example? > > Is an 'early bound' variable synonymous with a 'static' variable (in > > C)? > > No. It means, in which moment the name gets its value assigned. Usually > Python does "late binding", that is, names are resolved at the time the > code is executed, not when it's compiled or defined. > Consider this example: > > z = 1 > def foo(a) > print a+z > foo(3) # prints 4 > z = 20 > foo(3) # prints 23 > > The second time it prints 23, not 4, because the value for z is searched > when the code is executed, so the relevant value for z is 20. > Note that if you later assign a non-numeric value to z, foo(3) will fail. > > If you want to achieve the effect of "early binding", that is, you want to > "freeze" z to be always what it was at the time the function was defined, > you can do that using a default argument: > > z = 1 > def foo(a, z=z) > print a+z > z = None > foo(3) # prints 4 > > This way, foo(3) will always print 4, independently of the current value > of z. Moreover, you can `del z` and foo will continue to work. > > This is what I think Chris Mellon was refering to. This specific default > argument semantics allows one to achieve the effect of "early binding" in > a language which is mostly "late binding". If someone changes this, he has > to come with another way of faking early binding semantics at least as > simple as this, else we're solving an [inexistant for me] problem but > creating another one. > > -- > Gabriel Genellina Let me say again that I believe the current behaviour to be the correct one. But I don't think this 'early binding' is critical for this sort of example. There are lots of ways to solve the problem of having persistent state across function calls, for example: * using classes * using modules * or simply nested functions: def getfoo(z): def foo(a): print a + z return foo >>> z = 1 >>> foo = getfoo(z) >>> z = None >>> foo(3) 4 And with nonlocal, we could even modify z inside foo and this change would persist across calls. This will be a much cleaner solution than the current def bar(x, y, _hidden=[startvalue]). Also, note that it's easy to implement default arguments in pure python-without-default-arguments using a decorator: def default(**defaults): defaults = defaults.items() def decorator(f): def decorated(*args, **kwargs): for name, val in defaults: kwargs.setdefault(name, val) return f(*args, **kwargs) return decorated return decorator Here is your example: >>> z=1 >>> @default(z=z) ... def foo(a, z): ... print a + z ... >>> z=None >>> foo(3) 4 Another example, using mutables: >>> @default(history=[]) ... def bar(x, history): ... history.append(x) ... return list(history) ... >>> map(bar, 'spam') [['s'], ['s', 'p'], ['s', 'p', 'a'], ['s', 'p', 'a', 'm']] -- Arnaud

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Some specific exec behavior ?
by Stef Mientki Jan. 1, 2008

Jan. 1, 2008

hello, I find 2 strange behaviors in exec-function, and I can't find anything in the documentation. (Python 2.4.3 Enthought edition) 1. A function definition may not span more than 1 line, e.g. This generates an exception: def _func (x,y): return (1- x/2 + x**5 + y**3)*exp(-x**2-y**2) while this works correct: def _func (x,y): return (1- x/2 + x**5 + y**3)*exp(-x**2-y**2) 2. an emtpy line at the end also generates an exception Is this behavior correct ? where should I find information about it ? thanks, Stef Mientki

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