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

The untimely dimise of a weak-reference
by Vincent van Beveren July 30, 2010

July 30, 2010

Hi everyone, I was working with weak references in Python, and noticed that it was impossible to create a weak-reference of bound methods. Here is a little python 3.0 program to prove my point: import weakref print("Creating object...") class A(object): def b(self): print("I am still here") a = A() def d(r): print("Aaah! Weakref lost ref") print("Creating weak reference") r = weakref.ref(a.b, d) print("Oh, wait, its already gone!") print("Ref == None, cause of untimely demise: %s" % r()) print("Object is still alive: %s" % a) print("Function is still exists: %s" % a.b) print("See:") a.b() I also tried this in Python 2.5 and 2.6 (with minor modifications to the syntax of course), and it yielded the exact same behavior. Why is this, and is there anything I can do about it? I wish to reference these bound functions, but I do not want to keep them in memory once the object they belong to is no longer referenced. Regards, Vincent van Beveren ___ Ing. V. van Beveren Software Engineer, FOM Rijnhuizen E: V.vanBeveren(a)rijnhuizen.nl

1 0

stdout of external program.
by Paul Lemelle July 30, 2010

July 30, 2010

HELP! :) I am trying to output the following program's output to either a file or variable, how can this be done? # Writing the output to a standard argv argument #1/usr/bin/python import sys for arg in sys.argv: print arg #END Thanks, Paul

2 1

Re: Newbie question regarding SSL and certificate verification
by Gregory Ewing July 30, 2010

July 30, 2010

David Robinow wrote: > Never > use security software version 1.0 or greater. It was written by an > author insufficiently paranoid. Hmmm. So to get people to trust your security software, you should start with version 0.0 and increment by 0.0000001 for each release. :-) -- Greg

1 0

Re: Ascii to Unicode.
by Steven D'Aprano July 30, 2010

July 30, 2010

On Thu, 29 Jul 2010 11:14:24 -0700, Ethan Furman wrote: > Don't think of unicode as a byte stream. It's a bunch of numbers that > map to a bunch of symbols. Not only are Unicode strings a bunch of numbers ("code points", in Unicode terminology), but the numbers are not necessarily all the same width. The full Unicode system allows for 1,114,112 characters, far more than will fit in a two-byte code point. The Basic Multilingual Plane (BMP) includes the first 2**16 (65536) of those characters, or code points U+0000 through U+FFFF; there are a further 16 supplementary planes of 2**16 characters each, or code points U+10000 through U+10FFFF. As I understand it (and I welcome corrections), some implementations of Unicode only support the BMP and use a fixed-width implementation of 16- bit characters for efficiency reasons. Supporting the entire range of code points would require either a fixed-width of 21-bits (which would then probably be padded to four bytes), or a more complex variable-width implementation. It looks to me like Python uses a 16-bit implementation internally, which leads to some rather unintuitive results for code points in the supplementary place... >>> c = chr(2**18) >>> c '\U00040000' >>> len(c) 2 -- Steven

2 1

Re: combined functionality of ipython's %whos and pdb's next (without a resource heavy IDE)
by Cappy2112 July 30, 2010

July 30, 2010

On Jul 29, 12:39 pm, "Benjamin J. Racine" <bjrac...(a)glosten.com> wrote: > I am trying to combine the ability to move line-by-line through the code as is done with pdb's "next" function with ipython's ability to list all variables at once... without the use of a full-fledged IDE. > > I am not seeing how this might be done. Many thanks for your help... > > Ben Racine Ben You can actually use the sys module to do this, with just a few lines of code. This article shows you how http://www.doughellmann.com/PyMOTW/sys/tracing.html

1 0

Enabling/Disabling remote desktop - programmatically
by Cappy2112 July 30, 2010

July 30, 2010

I've already posted this in the Python W32 list, but didn't get what I'm looking for. I want to know how to disable Remote Desktop after logging to into a remote machine, to prevent subsequent logins by other users logging me out. I currently have a Windows XP system configured for coworkers to connect to using VPN & remote desktop, so they can get diagnostic data for test failures. I can disable Remote Desktop manually in Ctrl Panel, but have to navigate through several screens to do this. If I could do this using Python it would be very convenient. Have any of the Windows users on this list done this? Thanks

1 0

Re: Ascii to Unicode.
by Steven D'Aprano July 30, 2010

July 30, 2010

On Wed, 28 Jul 2010 15:58:01 -0700, Joe Goldthwaite wrote: > This still seems odd to me. I would have thought that the unicode > function would return a properly encoded byte stream that could then > simply be written to disk. Instead it seems like you have to re-encode > the byte stream to some kind of escaped Ascii before it can be written > back out. I'm afraid that's not even wrong. The unicode function returns a unicode string object, not a byte-stream, just as the list function returns a sequence of objects, not a byte-stream. Perhaps this will help: http://www.joelonsoftware.com/articles/Unicode.html Summary: ASCII is not a synonym for bytes, no matter what some English-speakers think. ASCII is an encoding from bytes like \x41 to characters like "A". Unicode strings are a sequence of code points. A code point is a number, implemented in some complex fashion that you don't need to care about. Each code point maps conceptually to a letter; for example, the English letter A is represented by the code point U+0041 and the Arabic letter Ain is represented by the code point U+0639. You shouldn't make any assumptions about the size of each code-point, or how they are put together. You shouldn't expect to write code points to a disk and have the result make sense, any more than you could expect to write a sequence of tuples or sets or dicts to disk in any sensible fashion. You have to serialise it to bytes first, and that's what the encode method does. Decode does the opposite, taking bytes and creating unicode strings from them. For historical reasons -- backwards compatibility with files already created, back in the Bad Old Days before unicode -- there are a whole slew of different encodings available. There is no 1:1 mapping between bytes and strings. If all you have are the bytes, there is literally no way of knowing what string they represent (although sometimes you can guess). You need to know what the encoding used was, or take a guess, or make repeated decodings until something doesn't fail and hope that's the right one. As a general rule, Python will try encoding/decoding using the ASCII encoding unless you tell it differently. Any time you are writing to disk, you need to serialise the objects, regardless of whether they are floats, or dicts, or unicode strings. -- Steven

4 3

measuring a function time
by Mahmood Naderan July 29, 2010

July 29, 2010

Hi, I want to measure a function run time. I read http://docs.python.org/library/time.html but I am confused and don't know which one is suitable. I don't know is daylight timing important or not.... or is Y2K issue important for my case or not.... I also don't know how epoch time is related to my work. I just want to do this (pseudocode): start_time = get_current_time; function(); end_time = get_current_time; print (end_time - start_time) the output should be 7600 (s) for example. What is the best and easiest way to do that? Thanks, // Naderan *Mahmood;

6 6

Re: Possible to include \n chars in doctest code samples or output?
by Steven D'Aprano July 29, 2010

July 29, 2010

On Fri, 16 Jul 2010 01:26:40 -0400, python wrote: > Thomas, > >> Recall that doctest doesn't parse the code, it extracts the docstrings. >> And docstrings are just strings, and are parsed like strings. > > I understand what you're saying, but I'm struggling with how to > represent the following strings in doctest code and doctest results. No > matter what combination of backslashes or raw strings I use, I am unable > to find a way to code the following. > >>>> encode( '", \, \t, \n' ) > '\", \\, \\t, \\n' I don't believe that this is a valid example. The interactive interpreter prints the repr() of objects unless you explicitly call print, which you have not done. I don't believe that there is any string whose repr() is what you have given. Consequently, there's no way to get that output in the interpreter (without using print), and the doctest MUST fail. But even if I'm wrong... when you run up against the limitations of doctests, don't use doctests. Is there any reason why you need to show that specific example out of the infinite number of possible examples? Remember that doctests aren't intended for a comprehensive test suite. Use unit tests for that. Or put the tests in a plain text file, not a docstring, and point doctest at that. That will reduce the amount of awkward escaping needed. If you insist on using that example, including it in the docstring should be simple. Call up the interactive interpreter, and run this: >>> from mymodule import encode # whatever your module happens to be >>> encode( '", \, \t, \n' ) something prints here Now copy the last two lines (the encode line, and the output). Paste it into your docstring, adjusting the indentation if needed. Then edit the two lines, doubling EVERY backslash. That should do it. If it doesn't, please show us the code of the encode function, the doctest failure, and the two lines copied from the interactive interpreter. -- Steven

2 1

ANUSHKA HOT PICTURES FOR BOLLYWOOD FANS
by anushkaphotos＠rediffmail.com July 29, 2010

July 29, 2010

ANUSHKA HOT PICTURES FOR BOLLYWOOD FANS ------------------------------------- http://sites.google.com/site/anushkaphotosalert

1 0