🌐 Mailman 3 August 2007 - Python-list - python.org

File Handling & TRY/EXCEPT
by Robert Rawlins - Think Blue Aug. 3, 2007

Aug. 3, 2007

Hello Guys, I'm looking for some advice on how best to handle file read/write errors with try/except as i'm a little vague on this, I have a small memory leak in my app and I'm starting to think its generated by my log file write. For an example of the function look below. def addAppLog(self, event): try: logfile = open('/pblue/new/Logs/Application.csv','a') now = datetime.datetime.now() logstring = '%s,%s \n' % (event, str(now)) logfile.write(logstring) except: self.addAppLog(event) else: logfile.close() Now I'm looking for some help to sort this out as I'm sure it's pretty untidy, I want to make it as air tight as possible. The basic concept was that if it tries writing to the log file and it fails, then it needs to reattempt it, right? What's the best way to handle this to ensure that there are not any memory leaks caused when the file is open() but not followed by a close(). I'm running 2.4 and I know some of these newer versions don't need you to explicitly close() the file objects, but I would certainly feel a lot better. Any advice? Thanks guys, Rob

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i am new to python-Please somebody help
by cool.vimalsmail＠gmail.com Aug. 3, 2007

Aug. 3, 2007

i dont know how to convert a txt file into a zip file (i.e.,)i have a file named packages and i want the packages file with a ".gz" extension by implementing a python program

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Re: i am new to python-Please somebody help
by gregarican Aug. 3, 2007

Aug. 3, 2007

On Aug 2, 12:58 pm, "Terry Reedy" <tjre...(a)udel.edu> wrote: > "gregarican" <greg.kuj...(a)gmail.com> wrote in message > > news:1186063842.827016.95030@q3g2000prf.googlegroups.com... > | friendly than Python's. Your points are well-taken in how to properly > | post and how to do your own homework. Message correct. Delivery > | lacking... > > Sorry, I saw nothing rude in Steven's straightforward and indeed polite > suggestion. Your post, however, .... > > tjr Maybe it's just me but the word "grovelling" just doesn't ring of newbie friendliness. To each their own I guess. Kind of like the Smalltalk list where a few respondents are really dry. Someone will post asking something like "Can I use Smalltalk to do X so that it talks to Y?" One guy (without pointing to a link or offering a snippet) just posts "Yes." I guess literally they have contributed. Or someone calls your house and asks, "Is so-and-so there?" You just say "Yes" and hang up on them :-)

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Memory Leak with Tkinter Canvas (Python 2.5 Win32)
by frikk Aug. 3, 2007

Aug. 3, 2007

Hey everyone. I have been working with python for a couple years now, but just recently built my first program with a GUI. I decided to start with Tkinter since it is included with the base package, although wxWindows will likely be my next choice. Tkinter seems to be pretty slow for my needs. Anyway - I am building a genetic algorithm simulator. I have a grid where an Ant moves around. It is infeasible for me to update the grid every simulation step - so I just do it at the end. But what I've realized is that my program performs worse and worse when I update the grid. Turns out there is a memory leak somewhere and I don't think it is in my code. The memory leak occurs only when I write (via create_rectangle) to the canvas widget. I wrote the following small script to demonstrate this problem (see below). Every time the button is pressed, _1040KB_ is added to the RAM of wpython.exe. This adds up FAST. I have not verified this on my OS X box. As you can see- I am doing nothing other than drawing a lot of rectangles on the canvas. I have two questions. 1. Is this a bug in my usage of Tkinter? Am I somehow leaving objects laying around that aren't being deleted? Is create_rectangle not the appropriate function to use?) 2. Is there a better, quicker way to update a "grid"-like object? Thanks, Blaine Current System: Python 2.5 (r25:51908, Sep 19 2006, 09:52:17) [MSC v.1310 32 bit (Intel)] on win32 Windows XP SP2 - all recent patches and updates Script: from Tkinter import * canv = None HEIGHT=600 WIDTH=600 def clear_grid(): for i in range(0,HEIGHT/10): for j in range(0, HEIGHT/10): canv.create_rectangle(i*10,j*10, \ i*10+10, j*10+10, \ fill = "white") def draw_window(master): global canv frame = Frame(master) btn_grid = Button(frame, text="draw grid", command=clear_grid) btn_grid.pack(side=TOP) canv = Canvas(frame, height=HEIGHT, width=WIDTH, bg='white') canv.pack() frame.pack() root = Tk() draw_window(root) mainloop()

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ANN: SonomaSunshine for Django v0.01
by SamFeltus Aug. 2, 2007

Aug. 2, 2007

Presented for your amusement, with source code for the first time!!! LOL The Redneck Riviera's Best Python Powered Folk Art Server... SonomaSunshine v0.01 for Django Django application for creating/editing Shiny/Happy Flash movies. http://samfeltus.com/django/hey_yall.html

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Re: Error with Tkinter and tkMessageBox
by Fabio Z Tessitore Aug. 2, 2007

Aug. 2, 2007

Il Thu, 02 Aug 2007 13:54:46 +1000, John McMonagle ha scritto: > What window manager are you using ? Hi John, I'm using gnome, with gdm. Do you think the problem is this? I'm going to try with another one ... bye

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Re: __call__ considered harmful or indispensable?
by Carl Banks Aug. 2, 2007

Aug. 2, 2007

On Aug 2, 2:30 pm, s...(a)pobox.com wrote: > I'm wondering, are there some general cases where __call__ methods of > a user-defined class are simply indispensable? Indispensable's a strong word, but one thing that entails calling syntax, and can't (reasonably) be done with closures is to override a base class's __call__ method. There is one notable type in Python that defines __call__ and that you might want to subclass, namely type itself. So using __call__ is indispensible for some metaclasses. Here's my little example. I'm sure people could work out ways to do it without __call__ or even a metaclass, but I doubt it'd be so concise and out of the way as this: class CachedResourceMetaclass(type): def __init__(self,name,bases,clsdict): super(CachedResourceMetaclass,self).__init__(name,bases,clsdict) self._cache = {} self._releasefunc = self.release def decref(obj): obj._refcount -= 1 if obj._refcount <= 0: del self._cache[obj._key] obj._releasefunc() self.release = decref def __call__(self,*args): obj = self._cache.get(args) if obj is not None: obj._refcount += 1 else: obj = super(CachedResourceMetaclass,self).__call__(*args) obj._key = args obj._refcount = 1 self._cache[args] = obj return obj Carl Banks

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Job Fair F/OSS project
by emperorcezar＠gmail.com Aug. 2, 2007

Aug. 2, 2007

Hello Pythonistas! I'm looking for some volunteers for a new open source project. At the Institute of Design (http://www.id.iit.edu ), our next project is a system for the management of our job fair (http://www.id.iit.edu/ recruitID/ ) The systems goal is to allow students and employers to enter their availability for interviews and have the system designate times and rooms for each to meet for interviews. The system includes much more than just this of course, but that is the main goal. We decided that this application is generic enough that it should be made into an F/ OSS project. So far the system will be built on Django and uses (hopefully) Prototype.js The project is on the ground floor and some basic wire frames and a few other preliminary designs. I'm personally located in Chicago and West Virginia (about half of my time spent in each place), though you are welcome to help out from anywhere around the world! If you're interested, reply to this message, or contact me at cezar AT id.iit.edu

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Re: Berkely Db. How to iterate over large number of keys "quickly"
by lazy Aug. 2, 2007

Aug. 2, 2007

On Aug 2, 1:42 pm, Ian Clark <icl...(a)mail.ewu.edu> wrote: > lazy wrote: > > I have a berkely db and Im using the bsddb module to access it. The Db > > is quite huge (anywhere from 2-30GB). I want to iterate over the keys > > serially. > > I tried using something basic like > > > for key in db.keys() > > > but this takes lot of time. I guess Python is trying to get the list > > of all keys first and probbaly keep it in memory. Is there a way to > > avoid this, since I just want to access keys serially. I mean is there > > a way I can tell Python to not load all keys, but try to access it as > > the loop progresses(like in a linked list). I could find any accessor > > methonds on bsddb to this with my initial search. > > I am guessing BTree might be a good choice here, but since while the > > Dbs were written it was opened using hashopen, Im not able to use > > btopen when I want to iterate over the db. > > db.iterkeys() > > Looking at the doc for bsddb objects[1] it mentions that "Once > instantiated, hash, btree and record objects support the same methods as > dictionaries." Then looking at the dict documentation[2] you'll find the > dict.iterkeys() method that should do what you're asking. > > Ian > > [1]http://docs.python.org/lib/bsddb-objects.html > [2]http://docs.python.org/lib/typesmapping.html Thanks. I tried using db.first and then db.next for subsequent keys. seems to be faster. Thanks for the pointers

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Re: __call__ considered harmful or indispensable?
by Paul Rubin Aug. 2, 2007

Aug. 2, 2007

skip(a)pobox.com writes: > In this particular case it was clearly unnecessary and just obfuscated the > code. I'm wondering, are there some general cases where __call__ methods of > a user-defined class are simply indispensable? I don't know about "indispensable" but __call__ is convenient sometimes and I do use it. I've wished that modules supported call, so I could say import foo x = foo(3) instead of having to say x=foo.foo(3) or something like that.

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