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

Third World War is Coming - Who is Webster Tarpley ?
by nanothermite911fbibustards June 29, 2010

June 29, 2010

Third World War is Coming - Who is Webster Tarpley ? http://www.youtube.com/watch?v=jLaaPBV9nqA http://www.youtube.com/watch?v=KV6oKRnM4mY http://www.youtube.com/watch?v=y53R_h-OZAM

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Infinite prime number generator
by Thomas Jollans June 29, 2010

June 29, 2010

I've been toying with Haskell a bit, and after implementing (essentially) the Sieve of Eratosthenes as an infinite list, thus: primes = 1 : foldr elim_mult [] [2..] where elim_mult n l = n : filter ((/=0) . (`mod` n)) l I wondered how easy it would be to do the same thing in Python. Obviously, Python doesn't have Haskell's infinite lists as such, and normally evaluates expressions eagerly instead of lazily, but it's still, with generators, relatively simple do create infinite sequences (which aren't, strictly speaking, sequences) So, here's the same thing as a Python generator, in a simple imperative style: def primes(): yield 1 i = 2 old = set() while True: for p in old: if (i % p) == 0: break else: old.add(i) yield i i += 1 Haskell: *Main> take 10 primes [1,2,3,5,7,11,13,17,19,23] *Main> Python: >>> from itertools import islice >>> list(islice(primes(), 0, 10)) [1, 2, 3, 5, 7, 11, 13, 17, 19, 23] >>> So far, so good. But then I thought, how close to the haskell version can a Python generator get? foldr is like functools.reduce, except that it's right-associative. In Haskell, it works for infinite lists because Haskell is a lazy bastard, but it's not that difficult to express the exactly same thing with recursive generators: if isinstance(filter(None, []), list): # Python 2 from itertools import ifilter as filter def rprimes(): def elim_mult(n): yield n for p in filter((lambda x:x%n != 0), elim_mult(n+1)): yield p yield 1 for p in elim_mult(2): yield p This sort of works: >>> list(islice(rprimes(), 0, 10)) [1, 2, 3, 5, 7, 11, 13, 17, 19, 23] >>> But it has a bit of a problem: >>> sl = islice(rprimes(), None, None, 150) #step=150 >>> next(sl) 1 >>> next(sl) 863 >>> next(sl) [......] File "primes.py", line 21, in elim_mult for p in filter((lambda x:x%n != 0), elim_mult(n+1)): yield p File "primes.py", line 21, in elim_mult for p in filter((lambda x:x%n != 0), elim_mult(n+1)): yield p File "primes.py", line 21, in elim_mult for p in filter((lambda x:x%n != 0), elim_mult(n+1)): yield p RuntimeError: maximum recursion depth exceeded >>> If you happen to have a copy of stackless lying around, I'd expect it to work! -- Thomas

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Re: N00b question: matching stuff with variables.
by sion＠viridian.paintbox June 29, 2010

June 29, 2010

Stephen Hansen <me+list/python(a)ixokai.io> wrote: >On 6/28/10 10:29 AM, Ken D'Ambrosio wrote: >> for line in file: >> match = re.search((seek)",(.*),(.*)", line) # Stuck here > [ ... ] > name, foo, bar = line.split(",") > if seek in name: > # do something with foo and bar > >That'll return True if the word 'seek' appears in the first field of >what appears to be the comma-delimited line. If the file input is comma-delimited, then the OP might very well want a look at the csv module. Something like: for line in reader(file): if line[0] == seek: # first field matches, do something with line[-1] and line[-2] # -- I'm not quite sure what the semantics of a pair of greedy # (.*)s would be -- \S under construction

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python source code -> win/dos executable (on linux)
by superpollo June 29, 2010

June 29, 2010

hi. suppose i work in a linux environment, but i would like to ship a win/dos executable file from time to time, just for test purposes (my "testers" are windows users and don't want to go through the hassle of installing python on their win boxes). what is the best way to do that? (the application should be a simple console app, but my question applies to gui/tkinter apps too) hint: when i do the same in C, i usually do something like: http://www.youtube.com/watch?v=rhe6N7FB1D4 bye

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More MySQL Stuff
by Victor Subervi June 29, 2010

June 29, 2010

Hi; So I'm launching into a major rewrite of my shopping cart because I've finally woken up to the challenge of injection attacks. One of my major problems is that many column names are determined when the shopping cart is built. For example, how many photos are to be uploaded is determined that way, thus there will be a column such as "pic1" and another "pic2" up as many as the client desires. Now, I guess I could cap that at, say, 9, and create as many columns, but then there's the issue of creating columns for all the different "mixins" that I add. For example, when the shop is created, if it's a jewelry store, I automatically add columns appropriate to the same (ring size, etc.). Now, I guess I could just create a table with all those columns added in irrespective of what kind of store it is, then hide those that aren't used when I print to screen such things as product descriptions or the form the client uses to upload his data, but that's inelegant. Any other suggestions? TIA. beno

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validate string representation of a timedelta
by CM June 29, 2010

June 29, 2010

I'm looking for a good way to check whether a certain string is valid. It is a string representation of a Python timedelta object, like this: '0:00:03.695000' (But the first place, the hours, could also be double digits) In trying to figure out how to validate that, I saw this page which creates a parseTimeDelta(s) function, which takes that kind of string and returns a timedelta object: http://kbyanc.blogspot.com/2007/08/python-reconstructing-timedeltas-from.ht… (and I agree that this sort of function should come standard with datetime) I modified the code to accept microseconds, too, and I can use it now by trying to parse my candidate string and if it throws an exception, rejecting that string as invalid. It works fine on strings that are not even close to my format, like '0 min'. But it doesn't throw an exception on something like: '0:00:03.695000extrajunk' I'd like it to be pickier than that with the validation and only accept strings which are truly string representations of timedelta objects. But I have not learned regex yet, so am not sure how to modify parseTimeDetla so it wouldn't work with '0:00:03.695000extrajunk'. My question: is there a simple way to modify the parseTimeDelta so that it will work ONLY with a string that would be the string representation of a timedelta object? Alternately, is there an easier/more Pythonic approach to validate this kind of string? Thanks for any suggestions. Che

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Re: dynamically modify help text
by Ben Finney June 29, 2010

June 29, 2010

Brian Blais <bblais(a)bryant.edu> writes: > On Jun 28, 2010, at 14:25 , Chris Rebert wrote: > > __doc__ is normally defined on classes, e.g. `A`, not instances, > > e.g. `a`. help() looks for __doc__ accordingly. > > so that gets back to my original question: can I change this text at > runtime. Doesn't look like I can, because it is defined for classes > rather than instances. Am I thinking about this correctly? Classes are objects. You can change the ‘__doc__’ attribute of a class object the same as you'd change it for any other object:: A.__doc__ = "new docstring" -- \ “All television is educational television. The question is: | `\ what is it teaching?” —Nicholas Johnson | _o__) | Ben Finney

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Re: Pydev 1.5.8 Released
by ejosvp June 29, 2010

June 29, 2010

I have a problem with pydev 1.5.8 An error has occurred. See error log for more details. com.aptana.editor.common.CommonEditorPlugin.getThemeManager()Lcom/ aptana/editor/common/theme/IThemeManager; I seek the file and that file does not exist

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Re: Python as a scripting language. Alternative to bash script?
by eric dexter June 29, 2010

June 29, 2010

On Jun 28, 5:48 am, Dave Pawson <dave.paw...(a)gmail.com> wrote: > I've a fairly long bash script and I'm wondering > how easy it would be to port to Python. > > Main queries are: > Ease of calling out to bash to use something like imageMagick or Java? > Ease of grabbing return parameters? E.g. convert can return both > height and width of an image. Can this be returned to the Python program? > Can Python access the exit status of a program? > > I'd prefer the advantages of using Python, just wondering if I got > so far with the port then found it wouldn't do something? > > Has anyone made this comparison please? > > TIA > > -- > Dave Pawson > XSLT XSL-FO FAQ. > Docbook FAQ.http://www.dpawson.co.uk You do have a couple of couple of python scriting programs that are like bash. I don't know if they are worth using though (you would have to look them up I don't recall the names right now)

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Re: Python as a scripting language. Alternative to bash script?
by Jorgen Grahn June 29, 2010

June 29, 2010

On Mon, 2010-06-28, Dave Pawson wrote: > I've a fairly long bash script and I'm wondering > how easy it would be to port to Python. > > Main queries are: > Ease of calling out to bash to use something like imageMagick or Java? > Ease of grabbing return parameters? E.g. convert can return both > height and width of an image. Can this be returned to the Python program? > Can Python access the exit status of a program? > > I'd prefer the advantages of using Python, just wondering if I got > so far with the port then found it wouldn't do something? As other remarked, bash has advantages, too. Personally, if my main job is chaining other non-trivial programs into pipelines and sequences, I don't hesitate to use Bourne shell or bash. Perl is for heavier text processing, and Python for problems with more elaborate data types. Note the distinction Bourne shell/bash. If you can get away with it, use bash for medium/large-sized scripts. Many people try to avoid bash-specific syntax, but they miss out on lots of things that make programs maintainable, like local variables. /Jorgen -- // Jorgen Grahn <grahn@ Oo o. . . \X/ snipabacken.se> O o .

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