🌐 Mailman 3 June 2010 - Python-list - python.org

class inheritance
by JLundell Dec. 21, 2010

Dec. 21, 2010

I've got a subclass of fractions.Fraction called Value; it's a mostly trivial class, except that it overrides __eq__ to mean 'nearly equal'. However, since Fraction's operations result in a Fraction, not a Value, I end up with stuff like this: x = Value(1) + Value(2) where x is now a Fraction, not a Value, and x == y uses Fraction.__eq__ rather than Value.__eq__. This appears to be standard Python behavior (int does the same thing). I've worked around it by overriding __add__, etc, with functions that invoke Fraction but coerce the result. But that's tedious; there are a lot of methods to override. So I'm wondering: is there a more efficient way to accomplish what I'm after?

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Re: parse date/time from a log entry with only strftime (and no regexen)
by andrew cooke Nov. 12, 2010

Nov. 12, 2010

> > ValueError: unconverted data remains: this is the remainder of the log > > line > > that I do not care about you could catch the ValueError and split at the ':' in the .args attribute to find the extra data. you could then find the extra data in the original string, use the index to remove it, and re-parse the time. ugly, but should work. andrew

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newbie qns : how do i use xmldiff?
by sWrath swrath Nov. 5, 2010

Nov. 5, 2010

Hi , I am pretty new to python , and reading up on it. Basically I am trying to compare xml files . I know difflib have it but it does not work out as expected. I was looking at xmldiff , unfortunately I am not able to find documentation how to call it from python. Anyone knows a link or doc to it as I have been looking high and low for few days? lastly , is there a py (or algorithm) where it behaves exactly like diff ? Greatly appreciated. Thanks john

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Oct. 25, 2010

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Re: max time threads
by pacopyc Aug. 18, 2010

Aug. 18, 2010

On 19 Giu, 00:27, MRAB <pyt...(a)mrabarnett.plus.com> wrote: > pacopyc wrote: > > [snip] > > Ok, the problem is that I want fix a time max for each thread. For > > example run 10 threads (each can terminate its work in 10 sec. max > > fixed time) and wait them. If they finish its work in < 10 sec. (for > > example 2 sec.) very good ... go on immediately (don't wait > > unnecessary time), but if a thread use more than 10 sec. stop wait (I > > kill it) .... when all threads have finished their work or when they > > have used all their available time (10 sec.) the program must go on > > (don't wait). > > It's not possible to kill a thread. If you want a thread to have a > maximum time, the thread must check occasionally how long it has been > running and terminate if necessary. > > Another programming language (Java) originally had the ability to kill > threads, but that was later deprecated because it caused problems due to > not knowing what the thread was doing when it was killed (it might have > been in the middle of updating something at the time, for example, > leaving the system in an inconsistent state). Ok, I understand. But is possible fix max wait time (for example 60 sec.) in main thread and check queue for task done and at the same time the remaining time. When all task have done or wait time has expired main thread go on. Is it possible? Can you write code? Thank you very much.

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Re: Python as a scripting language. Alternative to bash script?
by John Nagle July 24, 2010

July 24, 2010

On 6/28/2010 7:58 AM, Benjamin Kaplan wrote: > How does a program return anything other than an exit code? Ah, yes, the second biggest design mistake in UNIX. Programs have "argv" and "argc", plus environment variables, going in. So, going in, there are essentially subroutine parameters. But all that comes back is an exit code. They should have had something similar coming back, with arguments to "exit()" returning the results. Then the "many small intercommunicating programs" concept would have worked much better. C was like that once. In the 1970s, all you could return was an "int" or a "float". But that got fixed. John Nagle

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Python Imaging Library available for Python 3.1 ? Fractals
by pdlemper July 16, 2010

July 16, 2010

On the site http://code.activestate.com/recipes/langs/python/ there are several scripts for fractals. See page five. These begin from PIL import Image This fails in my python 3.1.2 Google reveals PIL is Python Imaging Library from pythonware.com According to their website PIL is not available beyond 2.6 : ( Do I need a full GUI like tkinter to image a fractal ( on my python 3.1.2 ) ? Is there any simpler option ? Thanks, Dave WB3DWE

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C interpreter in Lisp/scheme/python
by bolega July 15, 2010

July 15, 2010

I am trying to compare LISP/Scheme/Python for their expressiveness. For this, I propose a vanilla C interpreter. I have seen a book which writes C interpreter in C. The criteria would be the small size and high readability of the code. Are there already answers anywhere ? How would a gury approach such a project ? Bolega

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500 tracker orphans; we need more reviewers
by Terry Reedy July 9, 2010

July 9, 2010

Go to the bottom of http://bugs.python.org/issue?@template=search&status=1 enter 1 in the Message Count box and hit Search. At the moment, this gets 510 hits. Some have had headers updated, nearly half have had a person add himself as 'nosy' (put 1 in the Nosy count box to count those that have not), but none have a written response. In the past two weeks, I have commented on some old orphans and gotten a couple of previously orphaned patches applied and the issue closed. But I am not prepared to spend my whole life on this ;=). We need more issue reviewers. Clearly. If you want to contibute, opportunity is here. With 500 orphans, and 2200 other open issues, there must be something that matches your interests and abilities. Use other search fields to narrow the choices. If you want to contibute to the tracker, this may help: http://wiki.python.org/moin/TrackerDocs/ Then read examples of comments already there. Or consider my first-response comment to http://bugs.python.org/issue8990 To write that, I * verified the reported behavior, though I forgot to explicitly say so; when doing so, include version and system (such as 3.1.2, WinXP), as that is sometimes helpful. * read the relevant doc section and pasted it in to establish a basis for discussion (the OP might have done that, but did not, so I did). Everyone reading this should at least be able to do this much for an issue like this, and this much *is* helpful. * compared behavior and doc and concluded that there is a bug. * read the posted patch as best I could, which is not much in this case, but it at least looked like a real diff file. * noticed that the diff did *not* patch the appropriate unit test file. * discussed two possible fixes and identified which the OP choose. * wrote an 'executive summary' both for the OP and future reviewers. Oh yes, I also adjusted the headers. Although new reviewers cannot do that, you *can* suggest in the message what changes to make. Special offer to readers of this thread, especially new reviewers: if you make such a suggestion, you may email me, subject: Tracker, with one clickable link like the above, cut and pasted from the browser URL box, per line of the message. Perhaps you are shy and uncomfortable saying much. Well so was I. I started about 5 years ago with *safe* comments and have s l o w l y expanded my comfort zone. The shock of discovering this week that there are 500 orphans, some 2 years old, expanded it. After no response for a year or two, even an imperfect response must be better than nothing. While there is occasional negativity on the tracker, I believe it averages less per message than python-list, which itself is pretty decent. Terry Jan Reedy

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A question about the posibility of raise-yield in Python
by Дамјан Георгиевски July 6, 2010

July 6, 2010

I'm writing this as a complete newbie (on the issue), so don't be surprised if it's the stupidest idea ever. I was wondering if there was ever a discusision in the python community on a 'raise-yield' kind-of combined expression. I'd like to know if it was proposed/rejected/discussed/not-decided yet?? A 'raise-yield' expression would break the flow of a program just like an exception, going up the call stack until it would be handled, but also like yield it would be possible to continue the flow of the program from where it was raise-yield-ed. This would be usefull for example in event based frameworks, they could just replace socket.* and similar, normally blocking, modules/functions with it's own 'raise-yield' enabled ones. Then you could just take any normal imperative code that calls normal library networking code (say smtplib, poplib or httplib) nad run it in a event framework. The normal xxxlib calls at some point would get to the now non-blocking, event based socket write/read, break the flow back to the event framework, and when it finishes the event framework would continue the normal flow of the program past the raise-yield. -- дамјан ((( http://damjan.softver.org.mk/ ))) When you do things right, people won't be sure if you did anything at all.

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