Re: Is using range() in for loops really Pythonic?

[Ivan Illarionov]

On Mon, 12 May 2008 16:24:23 +1000, Ben Finney wrote:
[...]
> That is also regrettably common in Python code. It still suffers from
> being unnecessarily ambiguous, since there are *also* plenty of loops
> using 'i', 'j', etc. where the loop counter *is* used.
> 
> Differentiating these use cases by appropriate naming is, IMO, worth the
> effort of choosing a meaningful name.

Even if the counter is not used inside the loop's body it's still in 
control of the whole loop and, IMO, any special discriminating and non-
conventional name doesn't worth the added confusion.

-- Ivan
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Re: do you fail at FizzBuzz? simple prog test

[Gabriel Genellina]

En Sat, 10 May 2008 22:12:37 -0300, globalrev <[EMAIL PROTECTED]> escribió:

> http://reddit.com/r/programming/info/18td4/comments
>
> claims people take a lot of time to write a simple program like this:
>
>
> "Write a program that prints the numbers from 1 to 100. But for
> multiples of three print "Fizz" instead of the number and for the
> multiples of five print "Buzz". For numbers which are multiples of
> both three and five print "FizzBuzz".
>
> for i in range(1,101):
> if i%3 == 0 and i%5 != 0:
> print "Fizz"
> elif i%5 == 0 and i%3 != 0:
> print "Buzz"
> elif i%5 == 0 and i%3 == 0:
> print "FizzBuzz"
> else:
> print i
>
>
> is there a better way than my solution? is mine ok?

Is it correct? Did you get at it in less than 15 minutes? If so, then it's OK.
The original test was not "write the most convoluted algorithm you can think 
of", nor "write the best program to solve this". It was a *practical* test: if 
you can't get anything remotely working for such a simple problem in 15 
minutes, we're not interested in your services.

(We used this question last year - some people gave a sensible answer in less 
than 5 minutes, but others did not even know how to start)

-- 
Gabriel Genellina

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Re: Module python-magic on/for Windows?

[Larry Hale]

On May 12, 1:34 am, Larry Hale <[EMAIL PROTECTED]> wrote:

> The file source (previously linked from http://hupp.org/adam/hg/python-magic/)
> has the man pages...


Err...  I meant "http://downloads.sourceforge.net/gnuwin32/file-4.21-
bin.zip?modtime=1180175868&big_mirror=1"!  :)
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Re: Module python-magic on/for Windows?

[Larry Hale]

On May 12, 1:34 am, Larry Hale <[EMAIL PROTECTED]> wrote:

> The file source (previously linked from http://hupp.org/adam/hg/python-magic/)
> has the man pages...


Err...  I meant "http://downloads.sourceforge.net/gnuwin32/file-4.21-
bin.zip?modtime=1180175868&big_mirror=1"!  :)
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Re: Is using range() in for loops really Pythonic?

[Roel Schroeven]

John Salerno schreef:

Ben Finney wrote:


John Salerno <[EMAIL PROTECTED]> writes:


num = 33

for x in xrange(10):
print num += 1

Which is better done by 'num += 10'.

Can you come up with an example that isn't trivially replaced with
clearer code? That might make it clearer what your concern is.


::sigh:: No, unfortunately I don't have a strong enough grasp of Python
to give a really in-depth example. I understand what you're asking
though. Perhaps people don't use this idiom as much as I think they do,
so to give a trivial example to support my point isn't helpful.


Perhaps a function to print some text a number of times:

def print_n(text, n):
  for i in xrange(n):
print text

(Though I guess you can replace that with print '\n'.join(msg * n) )

--
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faster than society gathers wisdom.
  -- Isaac Asimov

Roel Schroeven
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module global variables

[pistacchio]

hi to all!
can i load a module passing to it, automatically and as default, all
the caller's global variables to act as module's global variables?
thanks
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Re: Python and the Bartender

[Aspersieman]

[EMAIL PROTECTED] wrote:

Incidentally, now that everyone knows English, writer would like to
critique his behavior.  I have leaned to the group for approval, at
times by disparaging the efforts of others, but other times not.  I
have expressed negative emotion.  Is anyone in earshot getting work
done that I am interfering with?

Otherwise, I might start telling jokes.

Sincerely,
Two For Bartenders.

P.S.  Please don't write the movies.
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Huh?

Nicol

--

The three things to remember about Llamas:
1) They are harmless
2) They are deadly
3) They are made of lava, and thus nice to cuddle. 



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Re: File Creation Not Working In A Thread Class?

[Duncan Booth]

bc90021 <[EMAIL PROTECTED]> wrote:

> On Sun, 11 May 2008 19:55:31 +, Duncan Booth wrote:
> 
>> 7stud <[EMAIL PROTECTED]> wrote:
>> 
>> 
>>>                             tempfileName =
>>> "\"proctemp\\"                             +
>>> self.matrix[c][0] + "_other.txt\""
>> 
>> It wouldn't exactly result in either of the error messages you
>> posted, but I expect the spurious quote marks round the filename will
>> be giving you problems.
>> 
>> Surely you want the filename to be something like
>> 'proctemp\fred_other.txt' rather than '"proctemp\fred_other.txt"'
>> with the spurious double quotes?
> 
> Yup, that's what it was.  I figured it out two seconds before this
> post.  However, it will be interesting to see how it handles files
> with spaces in the name...
> 
It will handle spaces just fine.

You need to try and understand the difference between passing arguments to 
a program, where the shell will try to parse the command line into separate 
arguments so spaces have to be escaped somehow, and calling a function 
within a program where no such parsing takes place.
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Re: Problem with custom events in wxpython

[Jimmy]

On May 11, 11:27 pm, "Frank Niessink" <[EMAIL PROTECTED]> wrote:
> Hi Jimmy,
>
> 2008/5/11 Jimmy <[EMAIL PROTECTED]>:
>
> > hi, all
>
> > I'm having a problem with creating custom events in wxpython.
>
> > I have a class A handling some data processing work and another class
> > B of GUI matter. I need GUI to display information when data in A is
> > updated.
> > I know cutom events in wxpython may work.
>
> You may want to look at the pubsub module. Available as wx.lib.pubsub
> in wxPython:http://www.wxpython.org/docs/api/wx.lib.pubsub-module.html,
> and also available separately on PyPI:http://pypi.python.org/pypi/PyPubSub/
>
> Cheers, Frank

hi, thanks
it works! however, it seems the message can not be exchanged between
processes :(
actually what I want to do is let a running process send data to GUI
process and display it
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Re: Python doesn't recognize quote types

[Duncan Booth]

Dennis Lee Bieber <[EMAIL PROTECTED]> wrote:
>  The sloppy use of "single quote" for the "apostrophe" is unfortunate
>

True, but that problem is outside of the Python community's control. Given 
that people do often refer to single quote when they mean apostrophe the 
error message should be written so as to minimise confusion. 

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Re: Is using range() in for loops really Pythonic?

[Ben Finney]

Ivan Illarionov <[EMAIL PROTECTED]> writes:

> On Mon, 12 May 2008 16:24:23 +1000, Ben Finney wrote:
> [...]
> > That is also regrettably common in Python code. It still suffers
> > from being unnecessarily ambiguous, since there are *also* plenty
> > of loops using 'i', 'j', etc. where the loop counter *is* used.
> > 
> > Differentiating these use cases by appropriate naming is, IMO,
> > worth the effort of choosing a meaningful name.
> 
> Even if the counter is not used inside the loop's body it's still in
> control of the whole loop

Not in Python it's not. The values that come out of the iterator
aren't "in control of the loop". The state for the loop is in the
*iterator*, not the values that come out.

Having access to the values that come from the iterator is usually
useful, but regardless of whether one uses them or not, they're *not*
controlling the loop, and it's confusing to imply that they are.

So, when not using the values that come from the controlling iterator,
it's good to make that explicit. If Python supported it, we might
prefer to use no name at all for something that isn't used, but the
'for' syntax doesn't allow that.

In the absence of supporting syntax, the next best thing is to choose
a name that *does* make it explicit that the values will not be used.

-- 
 \ “All television is educational television. The question is: |
  `\   what is it teaching?” —Nicholas Johnson |
_o__)  |
Ben Finney
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Re: Is using range() in for loops really Pythonic?

[Ben Finney]

Paddy <[EMAIL PROTECTED]> writes:

> I've used Fortran and C and so would tend to use either i,j,k as the
> unused loop variable above, or, for clarity, call it something
> descriptive like loop_count, if the loop body would be clearer.

The problem with all of these names is that they also have long
precedent as names of values that *will* be used inside the loop.

Because of the precedent of those names, choosing one of those names
doesn't make it clear to the reader that the value is never used; they
have no indication from you of that until they look over the code a
few times. It's implicit rather than explicit.

-- 
 \ "As I bit into the nectarine, it had a crisp juiciness about it |
  `\  that was very pleasurable - until I realized it wasn't a |
_o__)nectarine at all, but A HUMAN HEAD!!"  -- Jack Handey |
Ben Finney
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Re: source beautifier

[Marco Mariani]

Stefan Behnel wrote:


http://www.polystyle.com/features/python-beautifier.jsp

I've never used it, but the example is quite clear.


I tend to believe that running these tools on some average Python code would
not even change whitespace. ;)


I bet it's idempotent against _your_ code, but not in the context of 
python beginners or people who just made up their mind about what coding 
style to use.

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Re: do you fail at FizzBuzz? simple prog test

[bockman]

On 12 Mag, 09:00, "Gabriel Genellina" <[EMAIL PROTECTED]> wrote:
> En Sat, 10 May 2008 22:12:37 -0300, globalrev <[EMAIL PROTECTED]> escribió:
>
>
>
>
>
> >http://reddit.com/r/programming/info/18td4/comments
>
> > claims people take a lot of time to write a simple program like this:
>
> > "Write a program that prints the numbers from 1 to 100. But for
> > multiples of three print "Fizz" instead of the number and for the
> > multiples of five print "Buzz". For numbers which are multiples of
> > both three and five print "FizzBuzz".
>
> > for i in range(1,101):
> >     if i%3 == 0 and i%5 != 0:
> >         print "Fizz"
> >     elif i%5 == 0 and i%3 != 0:
> >         print "Buzz"
> >     elif i%5 == 0 and i%3 == 0:
> >         print "FizzBuzz"
> >     else:
> >         print i
>
> > is there a better way than my solution? is mine ok?
>
> Is it correct? Did you get at it in less than 15 minutes? If so, then it's OK.
> The original test was not "write the most convoluted algorithm you can think 
> of", nor "write the best program to solve this". It was a *practical* test: 
> if you can't get anything remotely working for such a simple problem in 15 
> minutes, we're not interested in your services.
>
> (We used this question last year - some people gave a sensible answer in less 
> than 5 minutes, but others did not even know how to start)
>
> --
> Gabriel Genellina- Nascondi testo tra virgolette -
>
> - Mostra testo tra virgolette -

As a test, I would leave out the last sentence, and see how many
people (and how fast) figure out than a number can be multiple of
three _and_ five and that the requirement is somehow incomplete ...

Ciao
-
FB
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Re: module global variables

[alex23]

On May 12, 5:17 pm, pistacchio <[EMAIL PROTECTED]> wrote:
> hi to all!
> can i load a module passing to it, automatically and as default, all
> the caller's global variables to act as module's global variables?
> thanks

module = __import__('module', globals=globals())

I think that's what you're looking for.

- alex23
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Re: module global variables

[pistacchio]

On 12 Mag, 10:01, alex23 <[EMAIL PROTECTED]> wrote:
> On May 12, 5:17 pm, pistacchio <[EMAIL PROTECTED]> wrote:
>
> > hi to all!
> > can i load a module passing to it, automatically and as default, all
> > the caller's global variables to act as module's global variables?
> > thanks
>
> module = __import__('module', globals=globals())
>
> I think that's what you're looking for.
>
> - alex23


hmm, well, maybe yes.. should i ovveride the standard import function
of the module?
say that the module is called "pycatrix", would adding this to the
module solve the problem?

def __import__('pycatrix', globals=globals()):

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Re: module global variables

[pistacchio]

On 12 Mag, 10:10, pistacchio <[EMAIL PROTECTED]> wrote:
> On 12 Mag, 10:01, alex23 <[EMAIL PROTECTED]> wrote:
>
> > On May 12, 5:17 pm, pistacchio <[EMAIL PROTECTED]> wrote:
>
> > > hi to all!
> > > can i load a module passing to it, automatically and as default, all
> > > the caller's global variables to act as module's global variables?
> > > thanks
>
> > module = __import__('module', globals=globals())
>
> > I think that's what you're looking for.
>
> > - alex23
>
> hmm, well, maybe yes.. should i ovveride the standard import function
> of the module?
> say that the module is called "pycatrix", would adding this to the
> module solve the problem?
>
> def __import__('pycatrix', globals=globals()):

pardon, this:
def __import__('pycatrix', globals=globals()):
pass
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Re: do you fail at FizzBuzz? simple prog test

[Arnaud Delobelle]

On May 11, 4:36 am, Grant Edwards <[EMAIL PROTECTED]> wrote:
> On 2008-05-11, John Machin <[EMAIL PROTECTED]> wrote:
>
>
>
> >> "Write a program that prints the numbers from 1 to 100. But for
> >> multiples of three print "Fizz" instead of the number and for the
> >> multiples of five print "Buzz". For numbers which are multiples of
> >> both three and five print "FizzBuzz".
>
> >> for i in range(1,101):
> >>     if i%3 == 0 and i%5 != 0:
> >>         print "Fizz"
> >>     elif i%5 == 0 and i%3 != 0:
> >>         print "Buzz"
> >>     elif i%5 == 0 and i%3 == 0:
> >>         print "FizzBuzz"
> >>     else:
> >>         print i
>
> >> is there a better way than my solution? is mine ok?
>
> > Try doing it using %3 and %5 only once each.
>
> for i in xrange(101):
>     print (("","Fizz")[i%3==0] + ("","Buzz")[i%5==0]) or str(i)
>
> His is better though, since it's more obvious what's intended.
>
> Here's one that's less opaque
>
> for i in xrange(101):
>     s = ""
>     if i%3 == 0: s += "Fizz"
>     if i%5 == 0: s += "Buzz"
>     if s:
>         print s
>     else:
>         print i
>

Let's not forget to generalise the problem and code it OOP-style :)

class FizzBuzzer(object):
def __init__(self, *fizzles):
self.fizzles = fizzles
def translate(self, n):
return ''.join(val for (p, val) in self.fizzles if not n%p) or
n
def range(self, start, stop=None, step=None):
if stop is None:
start, stop = 0, start
if step is None:
step = 1
for n in xrange(start, stop, step):
yield self.translate(n)
def __getitem__(self, obj):
if isinstance(obj, slice):
return self.range(obj.start, obj.stop, obj.step)
else:
return self.translate(obj)

# FizzBuzzer in action:

>>> fizzbuzz = FizzBuzzer((3, 'Fizz'), (5, 'Buzz'))
>>> for val in fizzbuzz[1:21]:
... print val
...
1 21 1
1
2
Fizz
4
Buzz
Fizz
7
8
Fizz
Buzz
11
Fizz
13
14
FizzBuzz
16
17
Fizz
19
Buzz
>>> abc = FizzBuzzer((2, 'Ah'), (3, 'Bee'), (5, 'Cee'))
>>> list(abc[25:35])
25 35 1
['Cee', 'Ah', 'Bee', 'Ah', 29, 'AhBeeCee', 31, 'Ah', 'Bee', 'Ah']
>>>

--
Arnaud

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Re: threading - race condition?

[Rhamphoryncus]

On May 11, 10:16 am, skunkwerk <[EMAIL PROTECTED]> wrote:
> On May 10, 1:31 pm, Dennis Lee Bieber <[EMAIL PROTECTED]> wrote:
>
>
>
> > On Fri, 9 May 2008 08:40:38 -0700 (PDT),skunkwerk<[EMAIL PROTECTED]>
> > declaimed the following in comp.lang.python:
>
> > Coming in late...
>
> > > On May 9, 12:12 am, John Nagle <[EMAIL PROTECTED]> wrote:
> > > >skunkwerkwrote:
> > > > > i've declared a bunch of workerthreads(100) and a queue into which
> > > > > new requests are inserted, like so:
>
> > 
>
> > > > > queue = Queue.Queue(0)
> > > > >  WORKERS=100
> > > > > for i in range(WORKERS):
> > > > >thread = SDBThread(queue)
> > > > >thread.setDaemon(True)
> > > > >thread.start()
>
> > > > > the thread:
>
> > > > > class SimpleDBThread ( threading.Thread ):
> > > > >def __init__ ( self, queue ):
> > > > >self.__queue = queue
>
> > Note: double-leading __ means "name mangling" -- typically only
> > needed when doing multiple layers of inheritance where different parents
> > have similar named items that need to be kept independent; a single _ is
> > the convention for "don't touch me unless you know what you are doing"
>
> > > > >threading.Thread.__init__ ( self )
> > > > >def run ( self ):
> > > > >while 1:
> > > > >item = self.__queue.get()
> > > > >if item!=None:
> > > > >model = domain.get_item(item[0])
> > > > >logger.debug('sdbthread item:'+item[0])
> > > > >title = model['title']
> > > > >scraped = model['scraped']
> > > > >logger.debug("sdbthread title:"+title)
>
> > > > > any suggestions?
> > > > > thanks
>
> > 
>
> > > thanks John, Gabriel,
> > >   here's the 'put' side of the requests:
>
> > > def prepSDBSearch(results):
> > >modelList = [0]
> > >counter=1
> > >for result in results:
> > >data = [result.item, counter, modelList]
> > >queue.put(data)
> > >counter+=1
> > >while modelList[0] < len(results):
> > >print 'waiting...'#wait for them to come home
> > >modelList.pop(0)#now remove '0'
> > >return modelList
>
> > My suggestion, if you really want diagnostic help -- follow the
> > common recommendation of posting the minimal /runable (if erroneous)/
> > code... If "domain.get_item()" is some sort of RDBM access, you might
> > fake it using a pre-loaded dictionary -- anything that allows it to
> > return something when given the key value.
>
> > > responses to your follow ups:
> > > 1)  'item' in thethreadsis a list that corresponds to the 'data'
> > > list in the above function.  it's not global, and the initial values
> > > seem ok, but i'm not sure if every time i pass in data to the queue it
> > > passes in the same memory address or declares a new 'data' list (which
> > > I guess is what I want)
>
> > Rather confusing usage... In your "put" you have a list whose first
> > element is "result.item", but then in the work thread, you refer to the
> > entire list as "item"
>
> > > 3)  the first item in the modelList is a counter that keeps track of
> > > the number ofthreadsfor this call that have completed - is there any
> > > better way of doing this?
>
> > Where? None of your posted code shows either "counter" or modelList
> > being used by thethreads.
>
> > And yes, if you havethreadstrying to update a shared mutable, you
> > have a race condition.
>
> > You also have a problem if you are using "counter" to define where
> > in modelList a thread is supposed to store its results -- as you can not
> > access an element that doesn't already exist...
>
> > a = [0]
> > a[3] = 1#failure, need to create elements 1, 2, 3 first
>
> > Now, if position is irrelevant, and a thread just appends its
> > results to modelList, then you don't need some counter, all you need is
> > to check the length of modelList against the count expected.
>
> > Overall -- even though you are passing things via the queue, the
> > contents being pass via the queue are being treated as if they were
> > global entities (you could make modelList a global, remove it from the
> > queue entries, and have the same net access)...
>
> > IOWs, you have too much coupling between thethreadsand the feed
> > routine...
>
> > As for me... I'd be using a second queue for return values...
>
> > WORKERTHREADS = 100
> > feed = Queue.Queue()
> > result = Queue.Queue()
>
> > def worker():
> > while True:
> > (ID, item) = feed.get() #I leave the queues 
> > globals
> > 
> > #since they perform locking
> > 
> > #internally
> > mod

Re: module global variables

[Marco Mariani]

pistacchio wrote:

On 12 Mag, 10:01, alex23 <[EMAIL PROTECTED]> wrote:

On May 12, 5:17 pm, pistacchio <[EMAIL PROTECTED]> wrote:


hi to all!
can i load a module passing to it, automatically and as default, all
the caller's global variables to act as module's global variables?


Are you positively sure you need this?

Modifying imported modules is already quite fragile, but this.. it's 
basically a reversed(import *)


It's quite messy. Where quite equals to "very"
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Import/Create module from buffer

[Gruik]

Hi people,

I'm currently working on python embedding with C++. My goal is that
the C++ part handle files writing/reading so that the Python part only
works with buffers.

I succeeded in buffer exchanges. The problem is that some of the files
I read/write are python files so that, before embedding, I imported
them as modules when I needed them.

But now that the Python part only receive buffers, I can't do it
anymore. So I wonder :
- is it possible to import module from a buffer instead of files?
- or is it possible to create a module object from my buffer?

I looked on the Internet but didn't find anything about that. Does
anyone have an idea?

Thanks
Benjamin
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Re: do you fail at FizzBuzz? simple prog test

[Arnaud Delobelle]

On May 12, 9:30 am, Arnaud Delobelle <[EMAIL PROTECTED]> wrote:
[...]
> # FizzBuzzer in action:
>
> >>> fizzbuzz = FizzBuzzer((3, 'Fizz'), (5, 'Buzz'))
> >>> for val in fizzbuzz[1:21]:
>
> ...     print val
> ...
> 1 21 1

Ignore this, it's debugging output

> 1
> 2
> Fizz
> 4
> Buzz
> Fizz
> 7
> 8
> Fizz
> Buzz
> 11
> Fizz
> 13
> 14
> FizzBuzz
> 16
> 17
> Fizz
> 19
> Buzz>>> abc = FizzBuzzer((2, 'Ah'), (3, 'Bee'), (5, 'Cee'))
> >>> list(abc[25:35])
>
> 25 35 1
^
Same

> ['Cee', 'Ah', 'Bee', 'Ah', 29, 'AhBeeCee', 31, 'Ah', 'Bee', 'Ah']

--
Arnaud

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Re: anonymous assignment

[Arnaud Delobelle]

On May 12, 7:31 am, Arnaud Delobelle <[EMAIL PROTECTED]> wrote:
> Yves Dorfsman <[EMAIL PROTECTED]> writes:
> > Is there anyway to tell python I don't care about a value ?
>
> > Say I want today's year and day, I'd like to do something like:
>
> > import time
> > y, None, d, None, None, None, None = time.localtime()
>
> > I know you can't assign anything to None, but I'm sure you get what I
> > mean, a special keyword that means I don't care about this value. In
> > this particular case, there's got to be a better way than:
>
> > d = time.local()
> > y = d[0]
> > d = d[1]
>
> I use Paul Rubin's solution (which is frown upon by many:), but it's
> true it would be nice for tuples to have something like an extract()
> method:
>
> y, d = time.localtime.extract(0, 2)
>
> Where
>
>     mytuple.extract(i1, i2, i3...)
>
> would mean:
>
>     tuple(mytuple[i] for i in (i1, i2, i3...))
>
> Or perhaps allow indexing by tuples:
>
>     mytuple[i1, i2, i3...]
>
> --
> Arnaud

here is a very sophisticated implementation :)

>>> def extract(indices, seq):
... return tuple(seq[i] for i in indices)
...
>>> y, d = extract((0, 2), time.localtime())
>>> y, d
(2008, 12)

--
Arnaud

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Re: module global variables

[pistacchio]

On 12 Mag, 10:47, Marco Mariani <[EMAIL PROTECTED]> wrote:
> pistacchio wrote:
> > On 12 Mag, 10:01, alex23 <[EMAIL PROTECTED]> wrote:
> >> On May 12, 5:17 pm, pistacchio <[EMAIL PROTECTED]> wrote:
>
> >>> hi to all!
> >>> can i load a module passing to it, automatically and as default, all
> >>> the caller's global variables to act as module's global variables?
>
> Are you positively sure you need this?
>
> Modifying imported modules is already quite fragile, but this.. it's
> basically a reversed(import *)
>
> It's quite messy. Where quite equals to "very"

well, i'm writing a module called pycatrix. within the module i have
compile / exec statements in a functions that work on global
variables. ( exec compiledTemplate in globals() ).

now, i don't want to be forced (or force the end user) to import to
call the module's function with a compulsory "globals()" as argument.
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Re: Problem with custom events in wxpython

[Frank Niessink]

Hi Jimmy,

2008/5/12 Jimmy <[EMAIL PROTECTED]>:
> On May 11, 11:27 pm, "Frank Niessink" <[EMAIL PROTECTED]> wrote:
>  > 2008/5/11 Jimmy <[EMAIL PROTECTED]>:
>  > > I have a class A handling some data processing work and another class
>  > > B of GUI matter. I need GUI to display information when data in A is
>  > > updated.
>  > > I know cutom events in wxpython may work.
>  >
> > You may want to look at the pubsub module.
>
>  it works! however, it seems the message can not be exchanged between
>  processes :(
>  actually what I want to do is let a running process send data to GUI
>  process and display it

Well, that is some crucial information you didn't mention in your
original question... I guess for the communication between processes
you can use the regular python batteries available or something like
Pyro. In your GUI process you can use a thread to listen/wait for new
information to display and then send it to the main (GUI) thread. See
http://wiki.wxpython.org/LongRunningTasks

Cheers, Frank
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Re: Problem with help() in python/ipython interpreters

[Gabriel Genellina]

En Fri, 09 May 2008 20:45:09 -0300, Casey <[EMAIL PROTECTED]> escribió:

> I'm running python 2.5.2 on WinXP.  I've always used a GUI for
> interactive development, but I wanted to try out ipython which better
> supports matplotlib in this mode.  Unfortunately, whenever I try to
> use help() I get the following error:
>
> (Sys) The system cannot find the file specified.
>  "C:\documents"
>
> It turns out that the regular (python.exe) interpreter has the same
> problem.  I have the HTML docs installed, my PYTHONDOCS environment
> variable points to the HTML directory, and I actually uninstalled and
> reinstalled every library I use from scratch to make sure it wasn't
> some random config issue.

I don't know exactly how does help() try to find the documentation, but I have 
these differences:

- I don't have a PYTHONDOCS variable (nor PYTHONPATH nor anything similar)
- The Windows registry contains this entry:
[HKEY_LOCAL_MACHINE\SOFTWARE\Python\PythonCore\2.5\Help\Main Python 
Documentation]
@="C:\\Apps\\Python25\\Doc\\Python25.chm"
- I *think* that I installed the HTML docs on that same directory a long time 
ago...

Hope this info could help you.

-- 
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Re: Best technology for agent/web server architecture

[Irmen de Jong]

Gabriel Genellina wrote:

2008/5/8 M.-A. Lemburg <[EMAIL PROTECTED]>:


SOAP would be a good choice if you want to send to data to other
servers as well, e.g. Java-based ones.

XML-RPC and JSON are better for simple data structures.

If you have control over both client and server and don't
need to bother with other backends or frontends, Python
pickle is the best choice.


En Fri, 09 May 2008 05:41:07 -0300, Florencio Cano <[EMAIL PROTECTED]> escribió:


I have control over agent and client but I'm not sure how to use
pickle for this task. Do you suggest to pickle the objects that I want
to send and send it over a usual socket? I have searched a bit in
Google and I have seen that Pickle is insecure by default. What do you
think about this?


"insecure" means that someone could build a specially crafted pickle able to 
run arbitrary code on the unpickling environment. One way to avoid that is to only accept 
pickles from trusted sources: using SSL by example.



While Pyro (http://pyro.sourceforge.net) uses pickle by default, it is well understood 
that you'll have to deal with a potential security issue if your server is open to 
untrusted/uncontrolled clients.

Pyro provides several things that could help you here:
- you can define a connection authenticator that checks client IP and/or 
passphrases
- you can switch to an XML based serialisation protocol (courtesy of gnosis 
tools)
- you can run Pyro over SSL and let SSL deal with authentication/encryption/...

Cheers
Irmen de Jong
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Re: anonymous assignment

[Michele Simionato]

On May 12, 4:28 am, Yves Dorfsman <[EMAIL PROTECTED]> wrote:
>there's got to be a better way than:
>
> d = time.local()
> y = d[0]
> d = d[1]

Uses Python 2.6! ;)

Python 2.6a3 (r26a3:62861, May 12 2008, 11:41:56)
[GCC 4.2.3 (Ubuntu 4.2.3-2ubuntu7)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import time
>>> time.localtime()
time.struct_time(tm_year=2008, tm_mon=5, tm_mday=12, tm_hour=11,
tm_min=43, tm_sec=47, tm_wday=0, tm_yday=133, tm_isdst=1)
>>> t=time.localtime()
>>> t.tm_year, t.tm_mday
(2008, 12)


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Re: Is there no single/uniform RDBMS access API module for Python ?

[Gabriel Genellina]

En Mon, 12 May 2008 03:52:59 -0300, Banibrata Dutta <[EMAIL PROTECTED]> 
escribió:

> Found that SnakeSQL does implement DB2.0 API. However are there such
> implementations for MySQL ?

MySQLdb

-- 
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Re: Is using range() in for loops really Pythonic?

[Ivan Illarionov]

>> On Mon, 12 May 2008 16:24:23 +1000, Ben Finney wrote: [...]
>> > That is also regrettably common in Python code. It still suffers from
>> > being unnecessarily ambiguous, since there are *also* plenty of loops
>> > using 'i', 'j', etc. where the loop counter *is* used.
>> > 
>> > Differentiating these use cases by appropriate naming is, IMO, worth
>> > the effort of choosing a meaningful name.
>> 
>> Even if the counter is not used inside the loop's body it's still in
>> control of the whole loop
> 
> Not in Python it's not. The values that come out of the iterator aren't
> "in control of the loop". The state for the loop is in the *iterator*,
> not the values that come out.
> 
> Having access to the values that come from the iterator is usually
> useful, but regardless of whether one uses them or not, they're *not*
> controlling the loop, and it's confusing to imply that they are.

I agree that "in control" was incorrect phrase.
 
> So, when not using the values that come from the controlling iterator,
> it's good to make that explicit. If Python supported it, we might prefer
> to use no name at all for something that isn't used, but the 'for'
> syntax doesn't allow that.
> 
> In the absence of supporting syntax, the next best thing is to choose a
> name that *does* make it explicit that the values will not be used.

Name 'i' does not imply whether it's used inside the loop or not.
IMO it perfectly covers both cases.

It may have small advantage to "make it explicit that the values will not 
be used", but names like "dummy", "unused", "ignored" or "junk" can be 
confusing for some people and break the established conventions for 
counter variable names (and these conventions are reasonable and are 
taken from mathematics). "i" is still the best choice.

And let's agree to disagree. It's clear that we have different opinions 
and it looks that this discussion is not going to change them.

-- Ivan
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Re: do you fail at FizzBuzz? simple prog test

[Chris]

On May 11, 3:12 am, globalrev <[EMAIL PROTECTED]> wrote:
> http://reddit.com/r/programming/info/18td4/comments
>
> claims people take a lot of time to write a simple program like this:
>
> "Write a program that prints the numbers from 1 to 100. But for
> multiples of three print "Fizz" instead of the number and for the
> multiples of five print "Buzz". For numbers which are multiples of
> both three and five print "FizzBuzz".
>
> for i in range(1,101):
>     if i%3 == 0 and i%5 != 0:
>         print "Fizz"
>     elif i%5 == 0 and i%3 != 0:
>         print "Buzz"
>     elif i%5 == 0 and i%3 == 0:
>         print "FizzBuzz"
>     else:
>         print i
>
> is there a better way than my solution? is mine ok?

personally if you're just checking if a modulus result is 0 or not I
would rather do as it looks neat imho.

for i in xrange(1,101):
if not i % 3 and i % 5:
print 'Fizz'
elif i % 3 and not i % 5:
print 'Buzz'
elif not i % 3 and not i % 5:
print 'FizzBuzz'
else:
print i
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artificiall, agent, movement

[Iman]

hi
i'm working on some simulation project . i'm going to simulate traffic
of a city.
this simulation has cars , passengers , non-movable objects and
Traffic signals  .
i've made cars as intelligent agent . it has thinking method ,
changing states agents ...
the main problem is i have problem to move my agents in world .
it would be possible to add some method to agent which move  agent in
random  destination .
but i'm trying to find some patterns which is designed  for this
problems .
is there any sample source code in python or links, docs to help me ?
 thanks for your attention .
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Re: anonymous assignment

[Gabriel Genellina]

En Mon, 12 May 2008 06:45:40 -0300, Michele Simionato <[EMAIL PROTECTED]> 
escribió:
> On May 12, 4:28 am, Yves Dorfsman <[EMAIL PROTECTED]> wrote:
>> there's got to be a better way than:
>>
>> d = time.local()
>> y = d[0]
>> d = d[1]
>
> Uses Python 2.6! ;)
>
> Python 2.6a3 (r26a3:62861, May 12 2008, 11:41:56)
> [GCC 4.2.3 (Ubuntu 4.2.3-2ubuntu7)] on linux2
> Type "help", "copyright", "credits" or "license" for more information.
 import time
 time.localtime()
> time.struct_time(tm_year=2008, tm_mon=5, tm_mday=12, tm_hour=11,
> tm_min=43, tm_sec=47, tm_wday=0, tm_yday=133, tm_isdst=1)
 t=time.localtime()
 t.tm_year, t.tm_mday
> (2008, 12)

No need of 2.6 - the above code works since Python 2.2 at least:

Python 2.2.3 (#42, May 30 2003, 18:12:08) [MSC 32 bit (Intel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import time
>>> t=time.localtime()
>>> type(t)

>>> t.tm_year
2008

(but struct_time objects were printed as regular tuples)

-- 
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Re: Import/Create module from buffer

[Gabriel Genellina]

En Mon, 12 May 2008 05:49:22 -0300, Gruik <[EMAIL PROTECTED]> escribió:

> I'm currently working on python embedding with C++. My goal is that
> the C++ part handle files writing/reading so that the Python part only
> works with buffers.
>
> I succeeded in buffer exchanges. The problem is that some of the files
> I read/write are python files so that, before embedding, I imported
> them as modules when I needed them.
>
> But now that the Python part only receive buffers, I can't do it
> anymore. So I wonder :
> - is it possible to import module from a buffer instead of files?
> - or is it possible to create a module object from my buffer?

Yes, first compile the buffer to get a code object, then use 
PyImport_ExecCodeModule. See how this function is used in import.c

-- 
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Re: python without while and other "explosive" statements

[ivo talvet]

thanks for the tips, pam limits and http://codepad.org/ are both
interesting tracks.

Ivo

2008/5/12 Matt Nordhoff <[EMAIL PROTECTED]>:
>
> ivo talvet wrote:
>  > Hello,
>  >
>  > Is it possible to have a python which not handle the execution of
>  > "while", "for", and other loop statements ? I would like to allow
>  > remote execution of python on a public irc channel, so i'm looking for
>  > techniques which would do so people won't be able to crash my computer
>  > (while 1: os.fork(1)), or at least won't won't freeze my python in a
>  > infinite loop, make it unresponsive. Is there a compiling option (or
>  > better, something i can get with apt-get cos i think compiling myself
>  > and handle all the metastuff myself is somehow dirty) for have a
>  > "secure python" (you can guess what i mean by "secure" in my case) or
>  > must i touch myself the source disable some code lines ? If last
>  > solution, which modifications in which files should i do ? (sorry for
>  > my bad english)
>  >
>  > Thanks.
>  >
>  > Ivo
>
>   is a pastebin-like website that lets people upload
>  code in a dozen different languages, and it runs it. They have info up
>  about how it's secure at .
>
>  I'm pretty sure there's another similar website that's specific to
>  Python, but I can't remember it. Anyway, it was similar, using virtual
>  machines, a firewall, and killing stuff that ran for longer than 20
>  seconds, IIRC.
>
>  (Thanks for the link to codepad, habnabit.)
>  --
>
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Re: Import/Create module from buffer

[Gruik]

On May 12, 12:31 pm, "Gabriel Genellina" <[EMAIL PROTECTED]>
wrote:
> En Mon, 12 May 2008 05:49:22 -0300, Gruik <[EMAIL PROTECTED]> escribió:
>
> > I'm currently working on python embedding with C++. My goal is that
> > the C++ part handle files writing/reading so that the Python part only
> > works with buffers.
>
> > I succeeded in buffer exchanges. The problem is that some of the files
> > I read/write are python files so that, before embedding, I imported
> > them as modules when I needed them.
>
> > But now that the Python part only receive buffers, I can't do it
> > anymore. So I wonder :
> > - is it possible to import module from a buffer instead of files?
> > - or is it possible to create a module object from my buffer?
>
> Yes, first compile the buffer to get a code object, then use 
> PyImport_ExecCodeModule. See how this function is used in import.c
>
> --
> Gabriel Genellina

Thanks for your quick answer !
I think I'll have no problem with that in C++ and I'm going to try it
right after this message.

But before that 1 question: what if I'm in Python ?
Following your solution, I did that in Python :

def load_buffer(buffer) :
compiled_buffer = compile(buffer, "module_name", "exec")
exec(compiled_buffer)

It works great except that I can't have a module object and that it is
as if I did "from module import *"
But I need the module object and not an "import *" behavior.
Any idea about the way to do that?

Benjamin
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Re: Import/Create module from buffer

[Irmen de Jong]

Gruik wrote:


But before that 1 question: what if I'm in Python ?
Following your solution, I did that in Python :

def load_buffer(buffer) :
compiled_buffer = compile(buffer, "module_name", "exec")
exec(compiled_buffer)

It works great except that I can't have a module object and that it is
as if I did "from module import *"
But I need the module object and not an "import *" behavior.
Any idea about the way to do that?


Something along the lines of:

import new
mymodule = new.module("mymodule")
exec <<>> in mymodule.__dict__



--irmen
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Re: do you fail at FizzBuzz? simple prog test

[Duncan Booth]

Ivan Illarionov <[EMAIL PROTECTED]> wrote:

>>> is there a better way than my solution? is mine ok?
>> 
>> ['%s%s' % (not i%3 and 'Fizz' or '', not i%5 and 'Buzz' or '')
>>  or str(i) for i in xrange(1, 101)]
>> 
>> -- Ivan
> 
> or, more correctly, if you actually need to "print":
> 
> sys.stdout.write('\n'.join('%s%s' % 
> (not i%3 and 'Fizz' or '', not i%5 aBuzz' or '') 
> or str(i) 
> for i in xrange(1, 101)))

I think the variant I came up with is a bit clearer:

for i in range(1,101):
print '%s%s' % ('' if i%3 else 'Fizz', '' if i%5 else 'Buzz') or i
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Re: do you fail at FizzBuzz? simple prog test

[John Machin]

Duncan Booth wrote:

Ivan Illarionov <[EMAIL PROTECTED]> wrote:


is there a better way than my solution? is mine ok?

['%s%s' % (not i%3 and 'Fizz' or '', not i%5 and 'Buzz' or '')
 or str(i) for i in xrange(1, 101)]

-- Ivan

or, more correctly, if you actually need to "print":

sys.stdout.write('\n'.join('%s%s' % 
(not i%3 and 'Fizz' or '', not i%5 aBuzz' or '') 
or str(i) 
for i in xrange(1, 101)))


I think the variant I came up with is a bit clearer:

for i in range(1,101):
print '%s%s' % ('' if i%3 else 'Fizz', '' if i%5 else 'Buzz') or i


More than a bit clearer, IMO. How about
print ('' if i%3 else 'Fizz') + ('' if i%5 else 'Buzz') or i
(or perhaps
print (('' if i%3 else 'Fizz') + ('' if i%5 else 'Buzz')) or i
to save looking up the precedence rules) ?
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Re: Module python-magic on/for Windows?

[Michael Torrie]

Michael Torrie wrote:
> In this case I'd try making a folder in the Python25 folder called
> "share" and put the contents of the gnuwin32 share/file stuff in there.
>  Should look something like this:
> 
> c:/python25/share/file/magic.mime.mgc
> c:/python25/share/file/magic
> c:/python25/share/file/magic.mgc
> c:/python25/share/file/magic.mime

I used linux's strace command to trace the file calls of file.exe via
wine (fun!) and verified that magic1.dll indeed will first in
c:/progra~1/File/share/file/magic and then in ../share/file
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Re: Module python-magic on/for Windows?

[Michael Torrie]

Larry Hale wrote:
> Alternately, if one wishes to leave/place the magic files elsewhere,
> do like:
> 
> >>> test = magic.Magic( magic_file = 'C:\\Program Files\\GnuWin32\
> \share\\file\\magic' ) # <-- spec where/what the file is
> 
> NOTE: Even if the "magic_file" location *is* specified, "mime = True"
> still works fine.  (Haven't checked, but I presume the source simply
> tacks ".mime" to the filename automagically.)  Obviously/also, one
> needn't specify the argument names if one uses proper argument order:
> magic.Magic( mime, magic_file )  :)
> 
> 
> THANKS SO MUCH, Michael, for your answers and helping me alone the
> way...  :)

Glad it's working for you.
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Re: do you fail at FizzBuzz? simple prog test

[Arnaud Delobelle]

On May 12, 1:30 pm, John Machin <[EMAIL PROTECTED]> wrote:
> Duncan Booth wrote:
[...]
> > I think the variant I came up with is a bit clearer:
>
> > for i in range(1,101):
> >    print '%s%s' % ('' if i%3 else 'Fizz', '' if i%5 else 'Buzz') or i
>
> More than a bit clearer, IMO. How about
>      print ('' if i%3 else 'Fizz') + ('' if i%5 else 'Buzz') or i
> (or perhaps
>      print (('' if i%3 else 'Fizz') + ('' if i%5 else 'Buzz')) or i
> to save looking up the precedence rules) ?

Stuff clarity!  How about

for i in xrange(1, 101):
print 'FizzBuzz'[4*(i%3>0):4+4*(i%5<1)] or i

--
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Re: Saving an audio file's waveform into an image

[Robert.Spilleboudt]

I am using Snack to process the audio signal of a rc transmitter.
Look at
http://www.speech.kth.se/snack/
Another audio processing: PortAudio and the Python module PyAudio. Look 
at http://people.csail.mit.edu/hubert/pyaudio/

Robert

Julien wrote:

Hi,

I would like to pull out the waveform of an audio file and save it
into an image file, for example in GIF format. Is that achievable, and
if so, how?

I heard about the Snack module, but the project looks dead and un-
maintained.

Your advice would be greatly appreciated.

Thanks!

Julien

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Re: anonymous assignment

[Richard G Riley]

Yves Dorfsman <[EMAIL PROTECTED]> writes:

> D'Arcy J.M. Cain wrote:
>> On Mon, 12 May 2008 02:28:13 GMT
>> Yves Dorfsman <[EMAIL PROTECTED]> wrote:
>>> particular case, there's got to be a better way than:
>>>
>>> d = time.local()
>>> y = d[0]
>>> d = d[1]
>>
>> Like this?
>>
>> y, d = time.local()[:2]
>
> Sorry this was a typo (again :-), I meant:
>
> d = time.local()
>   y = d[0]
>   d = d[2]
>
> Yves.
> http://www.SollerS.ca

or .localtime()? or is this local() specific to a different python
version?

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Re: Import/Create module from buffer

[Gruik]

On May 12, 1:48 pm, Irmen de Jong <[EMAIL PROTECTED]> wrote:
> Gruik wrote:
> > But before that 1 question: what if I'm in Python ?
> > Following your solution, I did that in Python :
>
> >     def load_buffer(buffer) :
> >         compiled_buffer = compile(buffer, "module_name", "exec")
> >         exec(compiled_buffer)
>
> > It works great except that I can't have a module object and that it is
> > as if I did "from module import *"
> > But I need the module object and not an "import *" behavior.
> > Any idea about the way to do that?
>
> Something along the lines of:
>
> import new
> mymodule = new.module("mymodule")
> exec <<>> in mymodule.__dict__
>
> --irmen

Yeah it works !

exec(compiled_module, globals(), mymodule.__dict__)

Just to add mymodule to sys.modules and it's good!

Thanks again
Benjamin
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Re: Initializing a subclass with a super object?

[frankdmartinez]

On May 11, 3:19 am, Francesco Bochicchio <[EMAIL PROTECTED]> wrote:
> But there is not such a thing, in Python. What you have is that A
> has the same attributes/methods of B plus its own.
> What you could do is  adding in class A a method like this:
>
>   class A(B):
>      ...
>      def set_b_attributes(self, instance_of_b):
>          for k, value in instance_of_b.__dict__:
>                 setattr(self, k, value )
>
> and the use it like this:
>
>    a1.set_b_attributes(b1)

Hi, Francesco.
Thanx!  That's actually exactly what I needed (though I didn't
know it).
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Re: do you fail at FizzBuzz? simple prog test

[Max Erickson]

Arnaud Delobelle <[EMAIL PROTECTED]> wrote:

> On May 12, 1:30 pm, John Machin <[EMAIL PROTECTED]> wrote:
>> Duncan Booth wrote:
> [...]
>> > I think the variant I came up with is a bit clearer:
>>
>> > for i in range(1,101):
>> >    print '%s%s' % ('' if i%3 else 'Fizz', '' if i%5 else
>> > 'Buzz') or 
>  i
>>
>> More than a bit clearer, IMO. How about
>>      print ('' if i%3 else 'Fizz') + ('' if i%5 else 'Buzz') or
>> i (or perhaps
>>      print (('' if i%3 else 'Fizz') + ('' if i%5 else 'Buzz'))
>> or i to save looking up the precedence rules) ?
> 
> Stuff clarity!  How about
> 
> for i in xrange(1, 101):
> print 'FizzBuzz'[4*(i%3>0):4+4*(i%5<1)] or i
> 
> --
> Arnaud
> 
> --
> http://mail.python.org/mailman/listinfo/python-list
> 
> 

With no loop:

i=1
exec"print'FizzBuzz'[4*(i%3>0):4+4*(i%5<1)]or i;i+=1;"*100


max

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Re: Now what!?

[Marco Mariani]

notbob wrote:


frustrated and give up on learning programming, not really caring much for
coding, anyway.  But, dammit, I'm gonna stick with it this time.  I'll learn
python if it kills me!


No, it won't kill you but make you stronger ;)
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Re: artificiall, agent, movement

[Gerry]

Many city travel surveys collect source destination trip-start data;
you might be able to find one of these studies.

I think each car in your simulation should have a destination.  Then
the simulation needs a route-finder, and cars can progress along their
routes as traffic permits -- or even change routes if traffic seems
too slow.

I think if you start with a very small city -- perhaps just a 5 by 5
grid, and generate sources and destinations at intersections randomly
along the perimeter, you'll have enough to prototype all of the
building blocks.

Gerry


On May 12, 6:37 am, Iman <[EMAIL PROTECTED]> wrote:
> hi
> i'm working on some simulation project . i'm going to simulate traffic
> of a city.
> this simulation has cars , passengers , non-movable objects and
> Traffic signals  .
> i've made cars as intelligent agent . it has thinking method ,
> changing states agents ...
> the main problem is i have problem to move my agents in world .
> it would be possible to add some method to agent which move  agent in
> random  destination .
> but i'm trying to find some patterns which is designed  for this
> problems .
> is there any sample source code in python or links, docs to help me ?
>  thanks for your attention .

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execfile python3k

[Odys]

Hi there,

Since execfile() is removed in Python 3.0
I have question about using exec.

I know about
  exec(open('filename').read())
but from documentation the 1st arg of exec can be 'file object'.
However
   exec(open('filename'))
does not work.
Does anybody have idea how to construct 'file object' then?

Thanks,
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Re: artificiall, agent, movement

[Paul McGuire]

On May 12, 5:37 am, Iman <[EMAIL PROTECTED]> wrote:
> is there any sample source code in python or links, docs to help me ?
>  thanks for your attention .

I've used SimPy in the past to implement a factory simulation.  The
SimPy web site claims that it has been used for traffic simulation,
but does not give any links.

http://simpy.sourceforge.net/index.html

I found it to be a very neat discrete event simulator, making good use
of Python language features (especially generators).

HTH,
-- Paul
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Re: Mathematics in Python are not correct

[Mark Dickinson]

On May 12, 2:09 am, "Terry Reedy" <[EMAIL PROTECTED]> wrote:
> Then it seems equally dubious that 0.**y, y>0, should be well-defined.
> It seems to me that lim as x goes to 0. exp(y*log(x)) is equally well
> defined whether y is 0 or not, even though there is a discontinuity in the
> limit.

Well, there's a difference:  the limit of exp(y*log(x)) as (x, y) ->
(0, a) exists for all finite nonzero a.  The limit as (x, y) ->
(0, 0) doesn't.

> 2.5 raises an exception.  In 3.0,>>> (-2)**1.
>
> (3.999722741113-1.2566370355167477e-07j)

Interesting---I hadn't realised that 3.0 had changed this.
I can't quite decide whether I like this behaviour much.  It
seems to be the only case where a computation involving only
floats can produce a complex number.

>
> | Incidentally, the decimal module is slightly schizophrenic about this:
>
> That module follows the IBM-led standard, no matter how crazy.

Yeah---I know. :-).  The current decimal __pow__ code is mostly
my fault, at least in 2.5.2/2.6/3.0 onwards.  For what it's
worth, the author of the Decimal standard has indicated that
the behaviour of 0**0 might change after IEEE 754r finally
sees the light of day.

Mark
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Compiling Python using Microsoft Visual C++ 2008

[Colin J. Williams]

1.I have both 2.5 and 2.6 but both 
appear, under Recent Projects, as 
pcbuild.  It would be helpful if the 
Python Version could be indicated.
2.With 2.6, Python compiles and executes 
OK but various packages are not 
compiled, eg sqlite3.

3.Pythonw compiles OK but not sqlite3.
4.Mike Fletcher suggests an approach 
(http://www.vrplumber.com/programming/mstoolkit/) 
with Visual C for Python 2.4.  Is this 
still the recommended way to compile 
Python 2.6?
5.Python 2.5 source refers to an Older 
Visual C.  Automatic conversion to 
Visual C 2008 gives the message “Some of 
the properties associated with the 
solution could not be read.”  All 
projects except one had a single 
warning, there were no errors reported.
6.After conversion there is no python 
project, it is flagged “unavailable”.
7.Pythoncore builds with no errors and 6 
warnings but there is no executable.
8.Python 2.5 build _tkinter fails – 
tcl.h not found.


I would welcom advice on how to proceed.

Colin W.
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Re: Is using range() in for loops really Pythonic?

[Grant Edwards]

On 2008-05-12, Ben Finney <[EMAIL PROTECTED]> wrote:

>> Maybe my brain works differently, but I find both "dummy" and
>> "unused" are extremely confusing names for loop counters. The loop
>> begins to look like it doesn't iterate at all if its counter is
>> dummy or unused.
>> 
>> If it *counts* it is *used* and it's *not* dummy.
>
> The value is unused by any of the code inside the block. For the
> purposes of that block, it is a dummy value.

The value may be unused, but for me it's the name that matters,
not the value.   The name might be in use by other code, and
the careless choice of a "dummy" name that's _supposed_ to be
unused has broken code precisely becuase the name was being
used (for something else).  Requiring that the user pollute a
namespace with a useless name is a wart.

> That is also regrettably common in Python code. It still
> suffers from being unnecessarily ambiguous, since there are
> *also* plenty of loops using 'i', 'j', etc. where the loop
> counter *is* used.

Perhaps I'm the only one who's ever been stupid enough to
overwrite an index named "i" (that is being used) with another
index named "i" (that isn't being used)...


-- 
Grant Edwards   grante Yow! All of life is a blur
  at   of Republicans and meat!
   visi.com
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Re: frameword vs application server?

[Diez B. Roggisch]

walterbyrd schrieb:

Can somebody help me understand the difference? Not just where Python
is concerned, but in general?

As I understand it, an application server is supposed to be a great
help in developing apps, because most of the business logic is already
there. It seems to me that, usually when applications servers are
discussed, people are talking about Java.


First of all, this is a misconception. An app-server may provide a wide 
range of infrastructure, however this has nothing to do with business 
logic. THat can merely pick parts of that infrastructure to build upon. 
But the distinction to a powerful framework is slim enough.


And it should be (and has been often so) said that especially in the 
java-world, app-servers and the specifications the implement (j2ee) are 
over-engineered and complicated.



I suppose most popular Python frameworks incorporate an application
server, but I get the idea that those app servers are not nearly as
sophisticed as something like JBoss.


The sophistication is a matter of perspective - some of it stems from 
the fact that in java, you need a lot more code to make even pretty 
simple things work. Think of delegation to business objects (session 
beans) that get their respective calls wrapped so that they take place 
inside a transactional context.


Which involves a great deal of design-abstractions, code-generators and 
tons of XML to glue these together.


Or three lines of code in python...



I am not sure if a Python app server, that works like a Java app
server would make sense.


As mentioned above - in some aspects, that is not really needed. But if 
you want more of an app-server, have a look at ZOPE, Kamaelia and maybe 
even twisted.


Diez
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Re: Compiling Python using Microsoft Visual C++ 2008

[Martin v. Löwis]

> 1.I have both 2.5 and 2.6 but both appear, under Recent Projects, as
> pcbuild.  It would be helpful if the Python Version could be indicated.

Hover over the link, and it will display the full path, which you can
then infer to reason about the specific copy of Python you are using.

In any case, compiling Python 2.5 with VS 2008 is not supported.

> 2.With 2.6, Python compiles and executes OK but various packages are not
> compiled, eg sqlite3.

See PCbuild/readme.txt.

> 3.Pythonw compiles OK but not sqlite3.

So what's the error?

> 4.Mike Fletcher suggests an approach
> (http://www.vrplumber.com/programming/mstoolkit/) with Visual C for
> Python 2.4.  Is this still the recommended way to compile Python 2.6?

No. Either use the full product, or the express edition. Neither
requires and additional setup.

> 5.Python 2.5 source refers to an Older Visual C.  Automatic conversion
> to Visual C 2008 gives the message “Some of the properties associated
> with the solution could not be read.”  All projects except one had a
> single warning, there were no errors reported.
> 6.After conversion there is no python project, it is flagged “unavailable”.

See above. This procedure is not supported; you are on your own.
Get a copy of VS 2003 if you want to follow the official
recommendations.

> 7.Pythoncore builds with no errors and 6 warnings but there is no
> executable.
> 8.Python 2.5 build _tkinter fails – tcl.h not found.

See PCbuild/readme.txt.

Regards,
Martin
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Re: Is there no single/uniform RDBMS access API module for Python ?

[Peter Decker]

On Mon, May 12, 2008 at 1:45 AM, Banibrata Dutta
<[EMAIL PROTECTED]> wrote:

> > >  Based on this URL http://wiki.python.org/moin/DatabaseInterfaces , is
> it correct to conclude that there is no RDBMS agnostic, single/uniform DB
> access API for Python ?
> > > Something in the lines of JDBC for Java, DBD for Perl etc. ?
> > >  How is the RDBMS change handled for solutions which need to work with
> different RDBMSs ??
> > >
> >
> > http://www.python.org/dev/peps/pep-0249/
> >
>
> That appears to be only an API specification. Are there any implementations
> of that ?

You might want to take a look at Dabo (http://dabodev.com). They have
a backend-agnostic interface for working with different databases. I
don't do database apps myself, so I can't comment on how well it
works, but based on the comments of others on the Dabo email lists, it
seems as though it works well enough.

-- 

# p.d.
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Removing option from optparse

[GustavoTabares]

Hello,

I'm trying to figure out if the following is a bug or if I'm using the
remove_option in the wrong way.

#!/usr/bin/env python
import optparse
parser = optparse.OptionParser()
parser.add_option("--test", help="This is a test option")
parser.remove_option('--test')
print parser.parse_args()

this will output:
(, [])

If you execute the --help on the file above you will not see --test as
expected. I'm curious as to why parse_args is still returning this as
an option.

Thanks,
Gustavo
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Re: Is using range() in for loops really Pythonic?

[Grant Edwards]

On 2008-05-12, Ben Finney <[EMAIL PROTECTED]> wrote:

I too, agree that requiring a name be bound to the values
coming out of the iterator seems "wrong".

> With "do something N times", there must be *something* to keep track
> of which iteration we're up to (or, equivalently, how many iterations
> remain) at a given moment. A Python iterator seems a fine choice to
> hold that information, and better than many alternatives.

An iterator like xrange() is an excellent choice. But, since
the iterator contains that information, why require that that
value be "exported" by the iterator and bound to an externally
visible name?  In the case in question, the only thing you need
from the iterator is the StopIteration exception.  To me,
exposing the internal state of the iterator and requiring that
the user bind a name to it each time through the loop feels
we're like driving a nail with a screwdriver.

-- 
Grant Edwards   grante Yow! Was my SOY LOAF left
  at   out in th'RAIN?  It tastes
   visi.comREAL GOOD!!
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Re: Is using range() in for loops really Pythonic?

[Grant Edwards]

On 2008-05-12, Ben Finney <[EMAIL PROTECTED]> wrote:
> Paddy <[EMAIL PROTECTED]> writes:
>
>> I've used Fortran and C and so would tend to use either i,j,k as the
>> unused loop variable above, or, for clarity, call it something
>> descriptive like loop_count, if the loop body would be clearer.
>
> The problem with all of these names is that they also have long
> precedent as names of values that *will* be used inside the loop.

I guess people who standardize on loop_count never nest loops. :)

> Because of the precedent of those names, choosing one of those
> names doesn't make it clear to the reader that the value is
> never used; they have no indication from you of that until
> they look over the code a few times. It's implicit rather than
> explicit.

And when somebody adds a nested loop things fall apart.

-- 
Grant Edwards   grante Yow! BARBARA STANWYCK makes
  at   me nervous!!
   visi.com
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Re: Removing option from optparse

[Diez B. Roggisch]

[EMAIL PROTECTED] schrieb:

Hello,

I'm trying to figure out if the following is a bug or if I'm using the
remove_option in the wrong way.

#!/usr/bin/env python
import optparse
parser = optparse.OptionParser()
parser.add_option("--test", help="This is a test option")
parser.remove_option('--test')
print parser.parse_args()

this will output:
(, [])

If you execute the --help on the file above you will not see --test as
expected. I'm curious as to why parse_args is still returning this as
an option.


I'm guessing here - but it is *one* thing to disable an option for the 
user because of whatever condition, and another to remove the options 
default value that code could possibly rely on to work. So I'd say the 
behavior is sane.


Diez
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Wholesale,  LV Sunglasses
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Re: Compiling Python using Microsoft Visual C++ 2008

[Colin J. Williams]

Martin v. Löwis wrote:

1.I have both 2.5 and 2.6 but both appear, under Recent Projects, as
pcbuild.  It would be helpful if the Python Version could be indicated.


Hover over the link, and it will display the full path, which you can
then infer to reason about the specific copy of Python you are using.


Lovely, thanks.  It's at the bottom of 
the screen.




In any case, compiling Python 2.5 with VS 2008 is not supported.


2.With 2.6, Python compiles and executes OK but various packages are not
compiled, eg sqlite3.


See PCbuild/readme.txt.


I presume that this is PCbuild8.txt




3.Pythonw compiles OK but not sqlite3.


So what's the error?


4.Mike Fletcher suggests an approach
(http://www.vrplumber.com/programming/mstoolkit/) with Visual C for
Python 2.4.  Is this still the recommended way to compile Python 2.6?


No. Either use the full product, or the express edition. Neither
requires and additional setup.


5.Python 2.5 source refers to an Older Visual C.  Automatic conversion
to Visual C 2008 gives the message “Some of the properties associated
with the solution could not be read.”  All projects except one had a
single warning, there were no errors reported.
6.After conversion there is no python project, it is flagged “unavailable”.


See above. This procedure is not supported; you are on your own.
Get a copy of VS 2003 if you want to follow the official
recommendations.


7.Pythoncore builds with no errors and 6 warnings but there is no
executable.
8.Python 2.5 build _tkinter fails – tcl.h not found.


See PCbuild/readme.txt.

Regards,
Martin


Thanks.  I'll look at the readme more 
carefully and seek VS 2003.


Now, I would like to remove Python 2.5 
from VS 2008 but see no obvious way of 
getting rid of it.


Colin W.
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buffering choking sys.stdin.readlines() ?

[cshirky]

Newbie question:

I'm trying to turn a large XML file (~7G compressed) into a YAML file,
and my program seems to be buffering the input.

IOtest.py is just

  import sys
  for line in sys.stdin.readlines():
print line

but when I run

$ gzcat bigXMLfile.gz | IOtest.py

but it hangs then dies.

The goal of the program is to build a YAML file with print statements,
rather than building a gigantic nested dictionary, but I am obviously
doing something wrong in passing input through without buffering. Any
advice gratefully fielded.

-clay
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Re: Write a python blog/website?

[Dotan Cohen]

2008/5/9 Sumon Sadhu <[EMAIL PROTECTED]>:
> Hey Dotan,
>
> My apologies if this post caused offense. Your assertion is right, maybe i
> should have emailed everyone individually like i've done with the first 45
> sites, but it was never my intention to spam.

Sumon, I think that you do not understand the perception of spam in
technological circles. Today, there is no way to initiate contact with
a business offer via email. None. All email solicitations are
unwelcome. I tell you this to help you. I do not know if you receive
5000 spam messages a week like I receive, but know that a sizeable
portion of the Python list gets considerably more. These people hate
spam.

> We're programmers like yourself, trying to build something that provides a
> lot of benefit. You can see our intentions are genuine (and our python ad
> server was fun to build)

Actually, I am not a programmer by trade. I learn python for fun while
I study mechanical engineering. I read the python list for the wisdom
that passes, and rarely post.

> So while i appreciate your response, it was never my attention to be
> "spammy"

I recognized that from the beginning, and stated that in my original
post. Which should have been kept private between us, now I realize.

Dotan Cohen

http://what-is-what.com
http://gibberish.co.il
א-ב-ג-ד-ה-ו-ז-ח-ט-י-ך-כ-ל-ם-מ-ן-נ-ס-ע-ף-פ-ץ-צ-ק-ר-ש-ת

A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
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RE: do you fail at FizzBuzz? simple prog test

[Delaney, Timothy (Tim)]

Mensanator wrote:

> Ok, I agree with 101, but I wouldn't necessarily
> say the others were unfortunate. You might be
> surprised at how often such fixations discover
> bugs, something that I have a gift for.

The discovering, the making, or both? ;)

Tim Delaney
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Re: Mathematics in Python are not correct

[Arnaud Delobelle]

On 12 May, 15:21, Mark Dickinson <[EMAIL PROTECTED]> wrote:
> On May 12, 2:09 am, "Terry Reedy" <[EMAIL PROTECTED]> wrote:
>
> > Then it seems equally dubious that 0.**y, y>0, should be well-defined.
> > It seems to me that lim as x goes to 0. exp(y*log(x)) is equally well
> > defined whether y is 0 or not, even though there is a discontinuity in the
> > limit.
>
> Well, there's a difference:  the limit of exp(y*log(x)) as (x, y) ->
> (0, a) exists for all finite nonzero a.  The limit as (x, y) ->
> (0, 0) doesn't.

But exp(y*log(x)) -> 1 as (x, y) -> (0, 0) along any analytic curve
which is not the x=0 axis (I think at least - it seems easy to prove
that given f and g analytic over R, f(x)*ln g(x) -> 0 as x -> 0 if
f(0)=g(0)=0 and g(x)>0 in the neighbourhood of 0).  This should cover
most practical uses?

--
Arnaud
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Re: Is using range() in for loops really Pythonic?

[Paddy]

On May 12, 3:46 pm, Grant Edwards <[EMAIL PROTECTED]> wrote:
> On 2008-05-12, Ben Finney <[EMAIL PROTECTED]> wrote:
>
> > Paddy <[EMAIL PROTECTED]> writes:
>
> >> I've used Fortran and C and so would tend to use either i,j,k as the
> >> unused loop variable above, or, for clarity, call it something
> >> descriptive like loop_count, if the loop body would be clearer.
>
> > The problem with all of these names is that they also have long
> > precedent as names of values that *will* be used inside the loop.
>
> I guess people who standardize on loop_count never nest loops. :)
>
> > Because of the precedent of those names, choosing one of those
> > names doesn't make it clear to the reader that the value is
> > never used; they have no indication from you of that until
> > they look over the code a few times. It's implicit rather than
> > explicit.
>
> And when somebody adds a nested loop things fall apart.
I don't have an example to hand. A lot of casses of repeat_X_times
inside a loop of repeat_Y_times would naturally be written as
repeat_Y*X_times.
Oh, wait a bit,

for i in range(3):
  print "Stay!"
  for j in range(2):
print "Come over."


Which could become:

for outer_stay_repetions in range(3):
  print "Stay!"
  for inner_come_over_repetions in range(2):
print "Come over."

But the second is daft. Nested repeats don't neccessarily pose a
problem to choosing meaningful names for repeat counters that are not
going to be referenced in the loop body, and most times i,j,k are fine
for used and un-used loop indices I find.

- Paddy
(Or were you just having a laugh ;-)
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Re: buffering choking sys.stdin.readlines() ?

[Jean-Paul Calderone]

On Mon, 12 May 2008 08:05:39 -0700 (PDT), cshirky <[EMAIL PROTECTED]> wrote:

Newbie question:

I'm trying to turn a large XML file (~7G compressed) into a YAML file,
and my program seems to be buffering the input.

IOtest.py is just

 import sys
 for line in sys.stdin.readlines():
   print line

but when I run

$ gzcat bigXMLfile.gz | IOtest.py

but it hangs then dies.


file.readlines reads the entire file into a list in memory.  You may not
want to do this.  You could try, instead, iterating over "sys.stdin",
which should not try to load the entire file into memory.

Jean-Paul
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Re: buffering choking sys.stdin.readlines() ?

[Diez B. Roggisch]

cshirky schrieb:

Newbie question:

I'm trying to turn a large XML file (~7G compressed) into a YAML file,
and my program seems to be buffering the input.

IOtest.py is just

  import sys
  for line in sys.stdin.readlines():
print line

but when I run

$ gzcat bigXMLfile.gz | IOtest.py

but it hangs then dies.

The goal of the program is to build a YAML file with print statements,
rather than building a gigantic nested dictionary, but I am obviously
doing something wrong in passing input through without buffering. Any
advice gratefully fielded.


readlines() reads all of the file into the memory. Try using xreadlines, 
the generator-version, instead. And I'm not 100% sure, but I *think* doing


for line in sys.stdin:
   ...

does exactly that.

Diez
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Socket and cycle problem

[petr . poupa]

Hello,
I am beginner but so I need help. I have small script for receive data
from port 3883, but it print only once.

import socket

HOST = 'localhost'
PORT = 3883
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((HOST, PORT))
data = s.recv(2048)
s.close()
print 'receive data from server:', `data`

So I try to write cycle to this script, like this:

import socket

HOST = 'localhost'
PORT = 3883
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
while 1:
s.connect((HOST, PORT))
data = s.recv(2048)
s.close()
print 'receive data from server:', `data`

But Python reporting:

Traceback (most recent call last):
  File "C:\Documents and Settings\poupa\Plocha\TCP3.py", line 7, in

s.connect((HOST, PORT))
  File "", line 1, in connect
  File "C:\Python25\lib\socket.py", line 141, in _dummy
raise error(EBADF, 'Bad file descriptor')
error: (9, 'Bad file descriptor')

Where is the mistake? I dont know.

thaks for help
Petr
--
http://mail.python.org/mailman/listinfo/python-list

Re: do you fail at FizzBuzz? simple prog test

[Paul Hankin]

On May 12, 1:59 pm, Arnaud Delobelle <[EMAIL PROTECTED]> wrote:
> On May 12, 1:30 pm, John Machin <[EMAIL PROTECTED]> wrote:
>
> > Duncan Booth wrote:
> [...]
> > > I think the variant I came up with is a bit clearer:
>
> > > for i in range(1,101):
> > >print '%s%s' % ('' if i%3 else 'Fizz', '' if i%5 else 'Buzz') or i
>
> > More than a bit clearer, IMO. How about
> >  print ('' if i%3 else 'Fizz') + ('' if i%5 else 'Buzz') or i
> > (or perhaps
> >  print (('' if i%3 else 'Fizz') + ('' if i%5 else 'Buzz')) or i
> > to save looking up the precedence rules) ?
>
> Stuff clarity!  How about
>
> for i in xrange(1, 101):
> print 'FizzBuzz'[4*(i%3>0):4+4*(i%5<1)] or i

for i in xrange(1, 101):
print 'Fizz'*(i%3<1)+'Buzz'*(i%5<1) or i

--
Paul Hankin
--
http://mail.python.org/mailman/listinfo/python-list

Re: Mathematics in Python are not correct

[Lou Pecora]

In article 
<[EMAIL PROTECTED]>,
 [EMAIL PROTECTED] wrote:

> I am stunned that this simple misunderstanding of mine ended in a
> mathematical clash of a sort. :)  You guys really blew me away wih
> your mathematical knowledge. And also the 0**0 is a thing I've never
> thought about trying, until now that is. If the mathematical rule is
> that EVERYTHING raised to the power of 0 is 1, then we should accept
> that, even in the case of 0**0. This is just the way it is.

Well, it's really not that simple.  You've seen that 0**0 can lead to 
problems in various areas of mathematics (check the Wikipedia article on 
analysis/calculus application vs. combinatorics and discrete math).  You 
have to be aware of those dangers, what the language (Python here), and 
what your application requires.  Consistency in mathematics is vital.  
If you are using 0**0=1, then your code should be consistent with that 
usage.

-- 
-- Lou Pecora
--
http://mail.python.org/mailman/listinfo/python-list

Pydev 1.3.17 Released

[Fabio Zadrozny]

Hi All,

Pydev and Pydev Extensions 1.3.17 have been released

Details on Pydev Extensions: http://www.fabioz.com/pydev
Details on Pydev: http://pydev.sf.net
Details on its development: http://pydev.blogspot.com

Release Highlights in Pydev Extensions:
-

* Minor bug-fixes

Release Highlights in Pydev:
--

* Pydev Package Explorer: projects that had the project folder in the
pythonpath did not show children items correctly.
* Debugger: Disable all works. Patch from: Oldrich Jedlicka
* Debugger: Problem when making a step return / step over
* Code-completion: Working for attributes found in a superclass
imported with a relative import
  Patches from Felix Schwarz:
  o Allow to configure an interpreter even if the workspace path
name contains spaces
  o Completion server does not work when the eclipse directory
contains spaces
  o Fix deletion of resources in pydev package explorer for Eclipse 3.4



What is PyDev?
---

PyDev is a plugin that enables users to use Eclipse for Python and
Jython development -- making Eclipse a first class Python IDE -- It
comes with many goodies such as code completion, syntax highlighting,
syntax analysis, refactor, debug and many others.


Cheers,

-- 
Fabio Zadrozny
--
Software Developer

ESSS - Engineering Simulation and Scientific Software
http://www.esss.com.br

Pydev Extensions
http://www.fabioz.com/pydev

Pydev - Python Development Enviroment for Eclipse
http://pydev.sf.net
http://pydev.blogspot.com
--
http://mail.python.org/mailman/listinfo/python-list

Re: Mathematics in Python are not correct

[Lou Pecora]

In article <[EMAIL PROTECTED]>,
 "Terry Reedy" <[EMAIL PROTECTED]> wrote:

> "Mark Dickinson" <[EMAIL PROTECTED]> wrote in message 
> news:[EMAIL PROTECTED]
> On May 11, 9:36 pm, "Terry Reedy" <[EMAIL PROTECTED]> wrote:
> |> Do you have in mind any situations in which it is advantageous to have 
> 0**0
> |> undefined?
> 
> | (Playing devil's advocate here.) If you regard x**y as exp(y*log(x))
> 
> Which, of course, I was not, but for the sake of discussion
> 
> | then it's not at all clear that 0.**0. should be considered well-defined.
> 
> Then it seems equally dubious that 0.**y, y>0, should be well-defined.
> It seems to me that lim as x goes to 0. exp(y*log(x)) is equally well 
> defined whether y is 0 or not, even though there is a discontinuity in the 
> limit.

Huh?  That "discontinuity" is the problem.  Actually, the problem is 
that the function f(x,y)=x**y=exp(y*ln(x)) will be double valued at x=0 
and y=0.  It's value will depend on the direction in which the limit 
approaches (x,y)=(0,0).  You cannot have a function that has two values 
at one domain point without adding branch cuts (see complex functions 
like ln(z), z is complex).  That's not well defined -- in your sense.  
You are choosing a branch cut and you must make sure the rest of your 
math and code are consistent with that.  You should also tell any users 
of your code about that decision.

-- 
-- Lou Pecora
--
http://mail.python.org/mailman/listinfo/python-list

Re: Socket and cycle problem

[Jean-Paul Calderone]

On Mon, 12 May 2008 08:34:07 -0700 (PDT), [EMAIL PROTECTED] wrote:

Hello,
I am beginner but so I need help. I have small script for receive data
from port 3883, but it print only once.

import socket

HOST = 'localhost'
PORT = 3883
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((HOST, PORT))
data = s.recv(2048)
s.close()
print 'receive data from server:', `data`

So I try to write cycle to this script, like this:

import socket

HOST = 'localhost'
PORT = 3883
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
while 1:
   s.connect((HOST, PORT))
   data = s.recv(2048)
   s.close()
   print 'receive data from server:', `data`

But Python reporting:

Traceback (most recent call last):
 File "C:\Documents and Settings\poupa\Plocha\TCP3.py", line 7, in

   s.connect((HOST, PORT))
 File "", line 1, in connect
 File "C:\Python25\lib\socket.py", line 141, in _dummy
   raise error(EBADF, 'Bad file descriptor')
error: (9, 'Bad file descriptor')

Where is the mistake? I dont know.


You cannot reconnect a socket.  You need to create a new one for each
connection.  It's also almost certainly the case that the way you are
receiving data is incorrect.  There is no guarantee that you will get
2048 bytes from socket.recv(2048).  It isn't even guaranteed that all
the bytes written to the socket by the peer will be returned by such
a call.  Instead, you need a framing protocol to determine when all
data has been received.  For example, you might length prefix the
data, or you might insert a delimiter (or a terminator) at the end.  Or
if there is exactly one message to receive, then you should just read
until the recv call returns '', indicating EOF.

Jean-Paul
--
http://mail.python.org/mailman/listinfo/python-list

In metaclass, when to use __new__ vs. __init__?

[Matthew Wilson]

I have been experimenting with metaclasses lately.  It seems possible to
define a metaclass by either subclassing type and then either redefining
__init__ or __new__. 

Here's the signature for __init__:

def __init__(cls, name, bases, d):

and here's __new__:

def __new__(meta, classname, bases, d):

Every metaclass I have found monkeys with d, which is available in both
methods.  So when is it better to use one vs the other?

Thanks for the help.

Matt

--
Programming, life in Cleveland, growing vegetables, other stuff.
http://blog.tplus1.com
--
http://mail.python.org/mailman/listinfo/python-list

passing *args "recursively"

[Guillermo]

Hi,

This must be very basic, but how'd you pass the same *args several
levels deep?


def func2(*args)

print args # ((1, 2, 3),)
# i want this to output (1, 2, 3) as func1!
# there must be some better way than args[0]?

def func1(*args):

print args # (1, 2, 3)
func2(args)

func1(1,2,3)

Thanks!

Guillermo
--
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Re: Socket and cycle problem

[petr . poupa]

On 12 Kvě, 17:54, Jean-Paul Calderone <[EMAIL PROTECTED]> wrote:
> On Mon, 12 May 2008 08:34:07 -0700 (PDT), [EMAIL PROTECTED] wrote:
> >Hello,
> >I am beginner but so I need help. I have small script for receive data
> >from port 3883, but it print only once.
>
> >import socket
>
> >HOST = 'localhost'
> >PORT = 3883
> >s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
> >s.connect((HOST, PORT))
> >data = s.recv(2048)
> >s.close()
> >print 'receive data from server:', `data`
>
> >So I try to write cycle to this script, like this:
>
> >import socket
>
> >HOST = 'localhost'
> >PORT = 3883
> >s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
> >while 1:
> >s.connect((HOST, PORT))
> >data = s.recv(2048)
> >s.close()
> >print 'receive data from server:', `data`
>
> >But Python reporting:
>
> >Traceback (most recent call last):
> >  File "C:\Documents and Settings\poupa\Plocha\TCP3.py", line 7, in
> >
> >s.connect((HOST, PORT))
> >  File "", line 1, in connect
> >  File "C:\Python25\lib\socket.py", line 141, in _dummy
> >raise error(EBADF, 'Bad file descriptor')
> >error: (9, 'Bad file descriptor')
>
> >Where is the mistake? I dont know.
>
> You cannot reconnect a socket.  You need to create a new one for each
> connection.  It's also almost certainly the case that the way you are
> receiving data is incorrect.  There is no guarantee that you will get
> 2048 bytes from socket.recv(2048).  It isn't even guaranteed that all
> the bytes written to the socket by the peer will be returned by such
> a call.  Instead, you need a framing protocol to determine when all
> data has been received.  For example, you might length prefix the
> data, or you might insert a delimiter (or a terminator) at the end.  Or
> if there is exactly one message to receive, then you should just read
> until the recv call returns '', indicating EOF.
>
> Jean-Paul

ok thanks, but I am true greenhorn, so you think that the best way is
write new script?
Could you send me code if it isnt long, becase I have no idea and
unfortunately time as well.

Petr
Petr
--
http://mail.python.org/mailman/listinfo/python-list

Re: passing *args "recursively"

[Jerry Hill]

On Mon, May 12, 2008 at 12:19 PM, Guillermo
<[EMAIL PROTECTED]> wrote:
>  def func1(*args):
> print args # (1, 2, 3)
> func2(args)

change this line to:
func2(*args)

-- 
Jerry
--
http://mail.python.org/mailman/listinfo/python-list

Re: passing *args "recursively"

[Matimus]

On May 12, 9:19 am, Guillermo <[EMAIL PROTECTED]> wrote:
> Hi,
>
> This must be very basic, but how'd you pass the same *args several
> levels deep?
>
> def func2(*args)
>
> print args # ((1, 2, 3),)
> # i want this to output (1, 2, 3) as func1!
> # there must be some better way than args[0]?
>
> def func1(*args):
>
> print args # (1, 2, 3)
> func2(args)
>
> func1(1,2,3)
>
> Thanks!
>
> Guillermo

def func1(*args):
print args
func2(*args) # don't forget the '*'

Matt
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Re: Compiling Python using Microsoft Visual C++ 2008

[Christian Heimes]

Colin J. Williams schrieb:
>> See PCbuild/readme.txt.
> 
> I presume that this is PCbuild8.txt

No, it's PCbuild/readme.txt in Python 2.6 and 3.0

By the way you can call Tools\buildbot\external.bat from the root
directory of the 2.6 and 3.0. It checks out and build the dependencies.
The script requires the VS 9.0 tools and the svn command line executables.

Christian

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Re: Mathematics in Python are not correct

[Mark Dickinson]

On May 12, 11:15 am, Arnaud Delobelle <[EMAIL PROTECTED]> wrote:

> But exp(y*log(x)) -> 1 as (x, y) -> (0, 0) along any analytic curve
> which is not the x=0 axis (I think at least - it seems easy to prove
> that given f and g analytic over R, f(x)*ln g(x) -> 0 as x -> 0 if
> f(0)=g(0)=0 and g(x)>0 in the neighbourhood of 0).

Agreed.  And this makes an excellent argument that if you're going to
choose a number for 0.0**0.0 then it's got to be 1.  But I still don't
find it completely convincing as an argument that 0.0**0.0 should be
defined at all.

> This should cover most practical uses?

Maybe.  But if you're evaluating x**y in a situation where x and y
represent physical quantities, or otherwise have some degree of error,
then you probably want to be warned if x and y both turn out to be
zero.


I seem to be digging myself into a hole here.  I'm personally
firmly in the "0**0 should be 1" camp, and always have been---
there are just too many practical benefits to defining 0**0==1
to ignore, and in the case where you're interested in integer
exponents anything else is just plain wrong. The lack of
continuity of the power function at (0,0) seems a small
price to pay.

Mark
--
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Re: Python doesn't recognize quote types

[MRAB]

On May 12, 8:31 am, Duncan Booth <[EMAIL PROTECTED]> wrote:
> Dennis Lee Bieber <[EMAIL PROTECTED]> wrote:
>
> >  The sloppy use of "single quote" for the "apostrophe" is unfortunate
> >
>
> True, but that problem is outside of the Python community's control. Given
> that people do often refer to single quote when they mean apostrophe the
> error message should be written so as to minimise confusion.

FYI, there are actually 2 types of quote character, single and double,
each with 2 forms, left and right. In Unicode the single-quote
characters are U+2018 (‘) and U+2019 (’) and the double-quote
characters are U+201C (“) and U+201D (”). The right-hand single-quote
is also the apostrophe.

In order to reduce the size of the character set needed, computer
manufacturers introduced 'sexless' quote characters, the single-quote/
aphostrophe U+0027 (') and double-quote U+0022 (").
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Re: Mathematics in Python are not correct

[Arnaud Delobelle]

Lou Pecora <[EMAIL PROTECTED]> writes:

> In article <[EMAIL PROTECTED]>,
>  "Terry Reedy" <[EMAIL PROTECTED]> wrote:
>
>> "Mark Dickinson" <[EMAIL PROTECTED]> wrote in message 
>> news:[EMAIL PROTECTED]
>> On May 11, 9:36 pm, "Terry Reedy" <[EMAIL PROTECTED]> wrote:
>> |> Do you have in mind any situations in which it is advantageous to have 
>> 0**0
>> |> undefined?
>> 
>> | (Playing devil's advocate here.) If you regard x**y as exp(y*log(x))
>> 
>> Which, of course, I was not, but for the sake of discussion
>> 
>> | then it's not at all clear that 0.**0. should be considered well-defined.
>> 
>> Then it seems equally dubious that 0.**y, y>0, should be well-defined.
>> It seems to me that lim as x goes to 0. exp(y*log(x)) is equally well 
>> defined whether y is 0 or not, even though there is a discontinuity in the 
>> limit.
>
> Huh?  That "discontinuity" is the problem.  Actually, the problem is 
> that the function f(x,y)=x**y=exp(y*ln(x)) will be double valued at x=0 
> and y=0.  

Actually f(x, y) can take any positive value, depending on how x and y
tend to 0.  Say for example

x = exp(-k/y), k being a positive constant.

Then as y -> 0+, so does x and y*ln(x) = y * (-k/y) = -k

Therefore f(x, y) = exp(-k) and as y -> 0,

x -> 0

f(x, y) -> exp(-k)


> It's value will depend on the direction in which the limit
> approaches (x,y)=(0,0).  You cannot have a function that has two
> values at one domain point without adding branch cuts (see complex
> functions like ln(z), z is complex).  

This is unrelated, z -> ln(z) is a holomorphic function, locally
defined everywhere but at 0, therefore it can be defined on any simply
connected subset of the complex numbers not containing 0.

OTOH, f(x,y) as you defined it above is a real analytic function.
AFAIK, it doesn't have the above property.

-- 
Arnaud
--
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Re: In metaclass, when to use __new__ vs. __init__?

[[EMAIL PROTECTED]]

On 12 mai, 18:10, Matthew Wilson <[EMAIL PROTECTED]> wrote:
> I have been experimenting with metaclasses lately.  It seems possible to
> define a metaclass by either subclassing type and then either redefining
> __init__ or __new__.
>
> Here's the signature for __init__:
>
> def __init__(cls, name, bases, d):
>
> and here's __new__:
>
> def __new__(meta, classname, bases, d):
>
> Every metaclass I have found monkeys with d, which is available in both
> methods.  So when is it better to use one vs the other?

Well... The __new__ method is responsible for creating and returning a
new  instance (so in this case, a new class), which is then passed to
the __init__ method. So which one you want to use depends on what you
want to do. If you only want to add some attributes/methods, register
either the class or some of it's methods somewhere etc, then __init__
is fine. If you have to transform / replace / whatever some of the
(not yet) attributes, fiddle with the inheritance tree, cache the
class object or such things, you'd better do it in __new__.
--
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Python-URL! - weekly Python news and links (May 12)

[Gabriel Genellina]

QOTW:  "With Python, you can program with a smile on your face." - Gary
Herron
"Looking back over the years, after I learned Python I realized that I
never really had enjoyed programming before." - Aahz

http://groups.google.com/group/comp.lang.python/browse_thread/thread/b4aa1d1578c26950/


Python 2.6a3 and 3.0a5 released
http://mail.python.org/pipermail/python-list/2008-May/490243.html

Choosing a license for an open source project, and how it impacts 
users, contributors *and* developers:
http://mail.python.org/pipermail/python-list/2008-May/489663.html
http://mail.python.org/pipermail/python-list/2008-May/489840.html

Are we missing something due to Python not having interfaces?
http://mail.python.org/pipermail/python-list/2008-May/489799.html

Anonymous for-loops (a "repeat N times" loop) and anonymous asignments:
http://mail.python.org/pipermail/python-list/2008-May/490591.html
http://mail.python.org/pipermail/python-list/2008-May/490723.html

Why should a programmer learn Python as a new language?
http://mail.python.org/pipermail/python-list/2008-May/490110.html

Two questions about the Observer pattern:
http://mail.python.org/pipermail/python-list/2008-May/490387.html
http://mail.python.org/pipermail/python-list/2008-May/490168.html

How to use overridable methods when defining a property:
http://mail.python.org/pipermail/python-list/2008-May/490451.html

Tim Golden explains how to recursively walk the Windows registry:
http://mail.python.org/pipermail/python-list/2008-May/489741.html

Find anagrams in a list of words:
http://mail.python.org/pipermail/python-list/2008-May/490061.html



Everything Python-related you want is probably one or two clicks away in
these pages:

Python.org's Python Language Website is the traditional
center of Pythonia
http://www.python.org
Notice especially the master FAQ
http://www.python.org/doc/FAQ.html

PythonWare complements the digest you're reading with the
marvelous daily python url
 http://www.pythonware.com/daily
Mygale is a news-gathering webcrawler that specializes in (new)
World-Wide Web articles related to Python.
 http://www.awaretek.com/nowak/mygale.html
While cosmetically similar, Mygale and the Daily Python-URL
are utterly different in their technologies and generally in
their results.

Just beginning with Python?  This page is a great place to start:
http://wiki.python.org/moin/BeginnersGuide/Programmers

The Python Papers aims to publish "the efforts of Python enthusiats":
http://pythonpapers.org/
The Python Magazine is a technical monthly devoted to Python:
http://pythonmagazine.com

Readers have recommended the "Planet" sites:
http://planetpython.org
http://planet.python.org

comp.lang.python.announce announces new Python software.  Be
sure to scan this newsgroup weekly.

http://groups.google.com/groups?oi=djq&as_ugroup=comp.lang.python.announce

Python411 indexes "podcasts ... to help people learn Python ..."
Updates appear more-than-weekly:
http://www.awaretek.com/python/index.html

The Python Package Index catalogues packages.
http://www.python.org/pypi/

The somewhat older Vaults of Parnassus ambitiously collects references
to all sorts of Python resources.
http://www.vex.net/~x/parnassus/

Much of Python's real work takes place on Special-Interest Group
mailing lists
http://www.python.org/sigs/

Python Success Stories--from air-traffic control to on-line
match-making--can inspire you or decision-makers to whom you're
subject with a vision of what the language makes practical.
http://www.pythonology.com/success

The Python Software Foundation (PSF) has replaced the Python
Consortium as an independent nexus of activity.  It has official
responsibility for Python's development and maintenance.
http://www.python.org/psf/
Among the ways you can support PSF is with a donation.
http://www.python.org/psf/donate.html

Kurt B. Kaiser publishes a weekly report on faults and patches.
http://www.google.com/groups?as_usubject=weekly%20python%20patch

Although unmaintained since 2002, the Cetus collection of Python
hyperlinks retains a few gems.
http://www.cetus-links.org/oo_python.html

Python FAQTS
http://python.faqts.com/

The Cookbook is a collaborative effort to capture useful and
interesting recipes.
http://aspn.activestate.com/ASPN/Cookbook/Python

Many Python conferences around the world are in preparation.
Watch this space for links to them.

Among several Python-oriented RSS/R

Re: Saving an audio file's waveform into an image

[Joshua Kugler]

Julien wrote:

> Hi,
> 
> I would like to pull out the waveform of an audio file and save it
> into an image file, for example in GIF format. Is that achievable, and
> if so, how?

Take a look at http://code.enthought.com/projects/chaco/  One of their
examples does exactly this. Last example on this page:
http://code.enthought.com/projects/chaco/gallery.php

Hope that helps.

j


--
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Re: Socket and cycle problem

[Jean-Paul Calderone]

On Mon, 12 May 2008 09:19:48 -0700 (PDT), [EMAIL PROTECTED] wrote:


[snip]


>Where is the mistake? I dont know.

You cannot reconnect a socket.  You need to create a new one for each
connection.  It's also almost certainly the case that the way you are
receiving data is incorrect.  There is no guarantee that you will get
2048 bytes from socket.recv(2048).  It isn't even guaranteed that all
the bytes written to the socket by the peer will be returned by such
a call.  Instead, you need a framing protocol to determine when all
data has been received.  For example, you might length prefix the
data, or you might insert a delimiter (or a terminator) at the end.  Or
if there is exactly one message to receive, then you should just read
until the recv call returns '', indicating EOF.

Jean-Paul


ok thanks, but I am true greenhorn, so you think that the best way is
write new script?
Could you send me code if it isnt long, becase I have no idea and
unfortunately time as well.



I'm not sure what you want to happen, so I can't write it for you.  I
suggest you start with Twisted instead of the socket module, though,
as Twisted provides a higher-level interface to network programming.

You can find some introductory documentation about writing clients here:

 http://twistedmatrix.com/projects/core/documentation/howto/clients.html

Jean-Paul
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Re: Is there no single/uniform RDBMS access API module for Python ?

[Daniel Fetchinson]

> >>  Again a noob question.
> >>  Based on this URL http://wiki.python.org/moin/DatabaseInterfaces , is it
> >> correct to conclude that there is no RDBMS agnostic, single/uniform DB
> >> access API for Python ?
> >> Something in the lines of JDBC for Java, DBD for Perl etc. ?
> >>  How is the RDBMS change handled for solutions which need to work with
> >> different RDBMSs ??
> >>
> > http://www.python.org/dev/peps/pep-0249/
> >
>
>
> That appears to be only an API specification. Are there any implementations
> of that ?

For sqlite: http://oss.itsystementwicklung.de/trac/pysqlite/ if you
have python < 2.5 for 2.5 and up it is included in the stdlib

For mysql: http://sourceforge.net/projects/mysql-python

There are a tons more, including postgresql, oracle, etc:
http://wiki.python.org/moin/DatabaseInterfaces

Cheers,
Daniel
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question about python statements

[Ohad Frand]

Hi

I am looking for a way to programmically get a list of all python
existing statements that I cannot access by __builtins__ or locals() 

(like ["assert","break","class",...])

 

Thanks,

Ohad

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Learning Python for no reason

[John Salerno]

Just something that crosses my mind every time I delve into "Learning 
Python" each night. Does anyone see any value in learning Python when you 
don't need to for school, work, or any other reason? I mean, sure, there's 
value in learning anything at any time, but for something like a programming 
language, I can't help but feel that I will be mostly unable to use what I 
learn simply because I have no reason to use it.

The *process* of learning is enough fun for me, and every now and then I do 
find a small use for Python that really pays off, but for the most part I'm 
wondering what people's thoughts are as far as simply learning it for the 
sake of learning. Does it seem like a silly endeavor to most people? Did 
anyone here learn a programming language when you didn't need to? If so, how 
much and in what capacity did you use it after you learned it?

Hopefully this question even makes sense! 


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Re: do you fail at FizzBuzz? simple prog test

[Arnaud Delobelle]

Paul Hankin <[EMAIL PROTECTED]> writes:

> On May 12, 1:59 pm, Arnaud Delobelle <[EMAIL PROTECTED]> wrote:
>> On May 12, 1:30 pm, John Machin <[EMAIL PROTECTED]> wrote:
>>
>> > Duncan Booth wrote:
>> [...]
>> > > I think the variant I came up with is a bit clearer:
>>
>> > > for i in range(1,101):
>> > >print '%s%s' % ('' if i%3 else 'Fizz', '' if i%5 else 'Buzz') or i
>>
>> > More than a bit clearer, IMO. How about
>> >  print ('' if i%3 else 'Fizz') + ('' if i%5 else 'Buzz') or i
>> > (or perhaps
>> >  print (('' if i%3 else 'Fizz') + ('' if i%5 else 'Buzz')) or i
>> > to save looking up the precedence rules) ?
>>
>> Stuff clarity!  How about
>>
>> for i in xrange(1, 101):
>> print 'FizzBuzz'[4*(i%3>0):4+4*(i%5<1)] or i
>
> for i in xrange(1, 101):
> print 'Fizz'*(i%3<1)+'Buzz'*(i%5<1) or i

I like this, I can imagine plenty of use cases...

...in codegolf

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Re: Compiling Python using Microsoft Visual C++ 2008

[Martin v. Löwis]

>> See PCbuild/readme.txt.
> 
> I presume that this is PCbuild8.txt

As Christian says: PCbuild/readme.txt are the correct instructions
(and had been since Python 2.0 or so).

> Now, I would like to remove Python 2.5 from VS 2008 but see no obvious
> way of getting rid of it.

You might be able to clear the most-recent-projects list in the registry
somehow, but I personally wouldn't worry - if you open other projects,
this one will scroll off the list eventually.

Regards,
Martin
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Re: Learning Python for no reason

[Martin v. Löwis]

> Hopefully this question even makes sense! 

I completely agree that you don't need to spend time on
learning a language if you don't plan on using it; I'll
leave alone the entire discussion of doing things for fun
only (you don't *need* to eat ice cream, either - right?)

OTOH: do you plan to do any programming at all, in your
life? If yes: consider using Python for every programming
task you'll encounter - unless there are outside constraints
demanding a different language. Python is flexible enough
for *all* you programming needs (I claim); then the acquired
knowledge will be useful.

To be effective in a language, you need to be fluent in it.
This involves both passive reading, as well as active
experimentation.

HTH,
Martin
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Cannot run Python 3.0a5 )-:

[Sven Siegmund]

Hi, I just tried to install Python 3.0a5 an another Windows PC. I did
what I have done yesterday at home:

1. Downloaded the daily snapshot 
http://svn.python.org/snapshots/msi/python-3.0.14011.msi
2. Installed to C:\Python30
3. Added C:\Python30 to the Path environment for all users.

when I run python from the command line, it says: The system cannot
execute the specified program.

I don't understand this.

S.
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Re: Is there no single/uniform RDBMS access API module for Python ?

[Banibrata Dutta]

Thank you all for the pointers and precise information.
Python community support surely rocks!!


On 5/12/08, Daniel Fetchinson <[EMAIL PROTECTED]> wrote:
>
> > >>  Again a noob question.
> > >>  Based on this URL http://wiki.python.org/moin/DatabaseInterfaces ,
> is it
> > >> correct to conclude that there is no RDBMS agnostic, single/uniform
> DB
> > >> access API for Python ?
> > >> Something in the lines of JDBC for Java, DBD for Perl etc. ?
> > >>  How is the RDBMS change handled for solutions which need to work
> with
> > >> different RDBMSs ??
> > >>
> > > http://www.python.org/dev/peps/pep-0249/
> > >
> >
> >
> > That appears to be only an API specification. Are there any
> implementations
> > of that ?
>
> For sqlite: http://oss.itsystementwicklung.de/trac/pysqlite/ if you
> have python < 2.5 for 2.5 and up it is included in the stdlib
>
> For mysql: http://sourceforge.net/projects/mysql-python
>
> There are a tons more, including postgresql, oracle, etc:
> http://wiki.python.org/moin/DatabaseInterfaces
>
> Cheers,
> Daniel
> --
> Psss, psss, put it down! - http://www.cafepress.com/putitdown
> --
> http://mail.python.org/mailman/listinfo/python-list
>



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Banibrata
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http://octapod.wordpress.com
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Re: do you fail at FizzBuzz? simple prog test

[[EMAIL PROTECTED]]

On 12 mai, 09:00, "Gabriel Genellina" <[EMAIL PROTECTED]> wrote:
> En Sat, 10 May 2008 22:12:37 -0300, globalrev <[EMAIL PROTECTED]> escribió:
>
>
>
> >http://reddit.com/r/programming/info/18td4/comments
>
> > claims people take a lot of time to write a simple program like this:
>
> > "Write a program that prints the numbers from 1 to 100. But for
> > multiples of three print "Fizz" instead of the number and for the
> > multiples of five print "Buzz". For numbers which are multiples of
> > both three and five print "FizzBuzz".
>
> > for i in range(1,101):
> > if i%3 == 0 and i%5 != 0:
> > print "Fizz"
> > elif i%5 == 0 and i%3 != 0:
> > print "Buzz"
> > elif i%5 == 0 and i%3 == 0:
> > print "FizzBuzz"
> > else:
> > print i
>
> > is there a better way than my solution? is mine ok?
>
> Is it correct? Did you get at it in less than 15 minutes? If so, then it's OK.
> The original test was not "write the most convoluted algorithm you can think 
> of", nor "write the best program to solve this". It was a *practical* test: 
> if you can't get anything remotely working for such a simple problem in 15 
> minutes, we're not interested in your services.
>
> (We used this question last year - some people gave a sensible answer in less 
> than 5 minutes,  but others did not even know how to start)

I just can't believe someone applying for a programmer position cannot
provide a sensible anwser in 5 or less minutes.

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Re: Learning Python for no reason

[Grant Edwards]

On 2008-05-12, Martin v. L?wis <[EMAIL PROTECTED]> wrote:

> OTOH: do you plan to do any programming at all, in your
> life? If yes: consider using Python for every programming
> task you'll encounter - unless there are outside constraints
> demanding a different language. Python is flexible enough
> for *all* you programming needs (I claim);

Many, but not all.  Python doesn't work well on microprocessors
with a few thousand bytes of ROM and a few hundred bytes of
RAM.  Nor does it work well for writing device drivers for any
popular OS.

For windows/unix hosted user-space applications, Python is
pretty hard to beat.

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Re: do you fail at FizzBuzz? simple prog test

[Grant Edwards]

On 2008-05-12, Paul Hankin <[EMAIL PROTECTED]> wrote:

> for i in xrange(1, 101):
> print 'Fizz'*(i%3<1)+'Buzz'*(i%5<1) or i

Doh!  It never occured to me that 'string' * 0 == ''.

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