Re: subprocess -popen - reading stdout from child - hangs

[Karthik Gurusamy]

On Sep 22, 8:28 pm, "[EMAIL PROTECTED]" <[EMAIL PROTECTED]>
wrote:
> Let's say I have this Python file called loop.py:
>
> import sys
> print 'hi'
> sys.stdout.flush()

Add sys.stdout.close()

> while 1:
> pass
>
> And I want to call it from another Python process and read the value
> 'hi'.  How would I do it?
>
> So far I have tried this:
>
> >>> proc = subprocess.Popen('python 
> >>> /home/chiefinnovator/loop.py',shell=True,stdin=subprocess.PIPE,stdout=subprocess.PIPE)
> >>> proc.stdout.read()
>
> But it just hangs at read()
>
> proc.communicate() also just hangs.  What am I doing wrong?  Please
> advise.

Since your loop.py is still alive and hasn't closed its stdout, the
caller continues to wait for EOF (it doesn't know if loop.py is done
generating all its output)

Karthik

>
> Thanks,
>
> Greg


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Re: newb: glob on windows os.renames creates many nested folders

[Peter Otten]

crybaby wrote:

> when I do this in my python code and run it in windows xp, it creates
> ctemp//.../.../../ so on and creates file t.  Not file starting
> with the name complist and ending with .txt (complist*.txt).  Any idea
> why this may be? glob only works in *nix not on windows?
> 
> os.renames(glob.glob('complist*.txt')
> [0],r'temp/'.join(glob.glob('complist*.txt')[0]))

Python does what you tell it. Let's assume

>>> glob.glob("complist*.txt")
['complist001.txt', 'complist002.txt']

The first argument to os.renames() is then

'complist001.txt'

and the second is 'temp/'.join('complist001.txt'), or

>>> "temp/".join("complist001.txt")
'ctemp/otemp/mtemp/ptemp/ltemp/itemp/stemp/ttemp/0temp/0temp/1temp/.temp/ttemp/xtemp/t'

that is the join() method interprets the string "complist001.txt" as the
character sequence ["c", "o", "m", ...] and stuffs a "temp/" between "c"
and "o", "o" and "m", ...

What you want instead is just "temp/" + "complist001.txt" or, written in
an os-independent way, os.path.join("temp", "complist001.txt") where a
path separator is added automatically. Your code then becomes

fn = glob.glob("complist*.txt")[0] # don't call stuff like that twice
os.renames(fn, os.path.join("temp", fn))

Peter
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Re: Would Anonymous Functions Help in Learning Programming/Python?

[Ron Adam]

Scott David Daniels wrote:
> Ron Adam wrote:
>>
>> Scott David Daniels wrote:
>>> Cristian wrote:
 On Sep 21, 3:44 pm, Ron Adam <[EMAIL PROTECTED]> wrote:

> I think key may be to discuss names and name binding with your friend.
>>> Here's an idea:
>>>
>>> import math
>>>
>>> def sin_integral(start, finish, dx): ...
>>> def cos_integral(start, finish, dx): ...
>>> generalize and separate the integration technique from the
>>> function it integrates.
>> How about this?
>> It's based on the apple basic program example in How to Enjoy Calculus.
>>Ron
>>
>> import math
>> def integrate(fn, x1, x2, n=100):...
>> def fn(x): ...
>> print "Area of fn:", integrate(fn, 0, 2)
>> print "Area of cos fn:", integrate(math.cos, 1, 2)
> 
> The point was a pedagogic suggestion, i.e. 

I understood your point.  I just found it interesting since I've been 
trying to extend my math (for use with python) skills in this area.


>"Try taking your
> friend along this path."   I wasn't trying to do a particularly
> good job integrating, simply trying to show how you could
> motivate first-class functions by showing a "useful" and
> "fun" (at least to an engineer) function that cries out
> for higher order functions.  In my experience engineers
> often want a "reason its useful" before engaging with an
> idea.  I'll bet that after a few such experiences he'll see
> how passing around functions and (later) making functions from
> from functions is a great tool to have in his toolbox.  Once
> he sees that, there will be no problem.

Yes, I agree. Another useful thing I've found is to store functions in a 
dictionary and call them (dispatching) based on some data value.

Ron

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Re: Factory function with keyword arguments

[Ron Adam]

Steven D'Aprano wrote:
> I'm writing a factory function that needs to use keywords in the produced 
> function, not the factory. Here's a toy example:


> I thought of doing this:
> 
> def factory(flag):
> if flag: kw = 'spam'
> else: kw = 'ham'
> def foo(obj, arg):
> kwargs = dict([(kw, arg)])
> return obj.method(**kwargs)
> return foo
> 
> Is this the best way of doing this? Are there any alternative methods 
> that aren't risky, slow or obfuscated?

Looks ok to me.  It can be simplified a bit.

def factory(flag):
kw = 'spam' if flag else 'ham'
def foo(obj, arg):
return obj.method(**{kw:arg})
return foo


Cheers,
Ron
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Re: Factory function with keyword arguments

[David]

On 9/23/07, Ron Adam <[EMAIL PROTECTED]> wrote:
>
>
> Steven D'Aprano wrote:
> > I'm writing a factory function that needs to use keywords in the produced
> > function, not the factory. Here's a toy example:
>

http://docs.python.org/whatsnew/pep-309.html
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directpython question

[veki]

Hello,
I've got IBM Thinkpad 30 laptop with configuration:

IBM Thinkpad R30
P3 Mobile Celeron 900mhz
128mb sdram pc133
15gb hdd
cd-rom Teac cd-224e
56K V.90/92
10/100 Ethernet
lpt port
ps2 port
2 x usb port
vga-out
pcmcia

,then I have been install directx 9.0c,Python 2.5 and directpython for
python 2.5.On my two computers directpython works but on this
laptop it don't want work e.g:

When I want execute this script on laptop:

import d3dx
frame=d3dx.Frame(u'SOME FRAME')
frame.mainloop()

I get this error:

Traceback (most recent call last):
  File "C:\Python25\Lib\site-packages\veki1.py", line 2, in 
fr=d3dx.Frame(u'SOME FRAME')
  File "C:\Python25\lib\site-packages\directpy\d3dx.py", line 639, in
__init__
self._createDevice(area[2:4])
  File "C:\Python25\lib\site-packages\directpy\d3dx.py", line 659, in
_createDevice
raise RuntimeError("No valid mode found")
RuntimeError: No valid mode found

Regards,
Vedran


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Naples is burning

[Hidalgo Vel�zquez]

Please, dear Mr Bush: we don't have weapons of destruction mass, but
bomb my people and save us.
Please, dear old friend Vesuvio: wake up and save us.
Please, dear Jesus Christ: give us the Big One and save us...

http://www.youtube.com/watch?v=eU3fNRcBtQw
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Re: Factory function with keyword arguments

[Steven D'Aprano]

On Sun, 23 Sep 2007 03:55:45 -0500, Ron Adam wrote:

> Steven D'Aprano wrote:
>> I'm writing a factory function that needs to use keywords in the
>> produced function, not the factory. Here's a toy example:

[snip]

Thanks everyone who answered, you've given me a lot of good ideas.

I've run some tests with timeit, and most of the variants given were very 
close in speed. The one exception was (not surprisingly) my version that 
builds a tuple, puts it in a list, then converts it to a dict, *before* 
doing anything useful with it. It was 3-4 times slower than the others.

George's version, with two definitions of foo(), was the fastest. The 
second fastest was the variant using exec, which surprised me a lot. I 
expected exec to be the slowest of the lot. Unfortunately, I doubt that 
these would scale well as the factory becomes more complicated.

Excluding those two, the next fastest was the original code snippet, the 
one I rejected as clearly too slow! It's apparently faster to check a 
flag than it is build and then expand a dict for keyword arguments.

A valuable lesson... always measure before guessing whether code will be 
slow or not.



-- 
Steven.
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Re: Factory function with keyword arguments

[Ben Finney]

Steven D'Aprano <[EMAIL PROTECTED]> writes:

> A valuable lesson... always measure before guessing whether code
> will be slow or not.

And after measuring, don't guess then either :-)

-- 
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  `\  authority." —Richard Dawkins, Big Mistake (The Guardian) |
_o__)  |
Ben Finney
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Re: An Editor that Skips to the End of a Def

[John J. Lee]

Paul Rubin  writes:

> [EMAIL PROTECTED] (John J. Lee) writes:
>> > I think mousing takes more mental work than typing,
>> I'm not sure this is a matter for debate, as much as physical
>> measurement.
>
> I don't know of any way to physically measure mental work.

fMRI is one.  That won't "directly" answer the question of course --
but then physical measurement and scientific progress are never
"direct", theory is always involved.


John
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newb: Question regarding custom exception

[crybaby]

Why you specify type and name of the exception in your custom
exceptions,
but not in built in exceptions

except IOError:
print "no file by the name ccy_rates*.txt"

except MyError, e:
print e.msg

Also, when you do:

try: raise MyError(23)

In "try: MyError(23) ", you are calling MyError class, but actually
get instantiated in except MyError, e: ?

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annoying stdin/stdout + pipes problem

[per9000]

Hi,
I want to create a program that reads input from stdio that can prompt
a user for input while doing so without getting into problems.

A simplified version of what I want:

I have an input file
***>cat input.txt
foo bar baz
fubar barooba xyxxyt
raboof txet
black knight

And a file that replaces certain words
***>cat replace2.py
from sys import stdin, stdout

def censor(foo, bar, input):
return input.replace(foo, bar)

# i = raw_input('Remove what? ').strip()
# o = raw_input('Replace "%s" with what? ' %i).strip()

for line in stdin.xreadlines():
line = censor('foo', 'candy', line)
line = censor('bar', 'donkey', line)
line = censor('baz', 'hare rama', line)
# line = censor(i, o, line)
stdout.write(line)

***>cat input.txt | python replace2.py
candy donkey hare rama
fudonkey donkeyooba xyxxyt
raboof txet
black knight

As you can see I have commented out what I'd like to do but do not
know how to. Can I somehow halt the previous print to stdout (cat
input.txt) - if so can I then start it again, and how?

I want to use this to use it in a small encryption program called txet
in order to do something like this:
tar -blabla ~ | gzip -blabla | txet -e -stdin -stdout > /tmp/
home.tar.gz.txet
Of course I want to use it to get the password from the user.

Thanks,
Per

PS: a prototype can be downloaded from www.txet.org

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Re: newb: Question regarding custom exception

[Steven D'Aprano]

On Sun, 23 Sep 2007 05:32:28 -0700, crybaby wrote:

> Why you specify type and name of the exception in your custom
> exceptions,
> but not in built in exceptions
> except IOError:
> print "no file by the name ccy_rates*.txt"
> 
> except MyError, e:
> print e.msg

You can say:

except IOError, e:
print e.msg


And you can say:

except MyError:
print "whatever I want"


It all depends on what you want to do.


 
> Also, when you do:
> 
> try: raise MyError(23)
> 
> In "try: MyError(23) ", you are calling MyError class, but actually get
> instantiated in except MyError, e: ?

I don't understand what you are actually asking, but I will try my best.


raise MyError(23)

calls the class MyError and creates and instance, and that instance is 
then used as an argument to the raise statement. You can also do this:

instance = MyError(23)
raise instance

You don't need the try block unless you want to catch the exception. The 
exception itself it actually raised by the "raise" statement, not the 
"except" statement. The "except" statement _catches_ the exception.

Try typing these lines in the interactive interpreter:



try:
print "before the exception"
raise Exception("an error occurred")
print "this line is never executed"
print "neither is this"
except Exception, e:
print "the exception is:"
print e
print e.message





Hope this helps.



-- 
Steven.
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Re: newb: Question regarding custom exception

[Lawrence Oluyede]

crybaby <[EMAIL PROTECTED]> wrote:
> Why you specify type and name of the exception in your custom
> exceptions,

It's up to you, if you're interested in the actual exception object you
catch it, otherwise not.

Take a look at this:


-- 
Lawrence, oluyede.org - neropercaso.it
"It is difficult to get a man to understand 
something when his salary depends on not
understanding it" - Upton Sinclair
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building a GUI

[yadin]

if i were up to make a GUI chich are the advantages of choosing python
over matlab or java?

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Re: Getting rid of bitwise operators in Python 3?

[c d saunter]

: arguments and dicts, which are lot more versatile.  Another major use, 
: talking to hardware, is not something oft done in Python either.

Are you sure?  I've been doing lots of exactly that for 4 years, and 
I'm not the only one round here...  Python makes an excellent language for 
talking to hardware.

cds
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Re: building a GUI

[Wildemar Wildenburger]

yadin wrote:
> if i were up to make a GUI chich are the advantages of choosing python
> over matlab or java?
> 
This question is WAY to broad to give sane advice. You might want to 
state your context, objectives and restrictions are.

Since you brought up Matlab, I suspect you're going after a scientific 
problem, involving data entry and display. In that case I'd say you're 
pretty well off using Matlab, since, well, it specific purpose is just 
that (GUI-wise, I mean).

/W
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Re: can I run pythons IDLE from a command line??

[Stargaming]

On Sat, 22 Sep 2007 17:53:09 +0200, Thomas Jollans wrote:

> On Saturday 22 September 2007, [EMAIL PROTECTED] wrote:
>> Hi,
>> Is their a version of pythons IDLE that will run in a dos command line?
>> The reason is that I would like to be able to run python code
>> interactively from my parable by connecting to my desktop using remote
>> command line or a telnet program.
> 
> The Python interpreter should do fine. If your PATH environment variable
> is set up correctly, just run "python", otherwise it's somewhere in your
> Python installation directory.

If you don't want to miss IDLE's advantages, `IPython `_ might be interesting for you.

Stargaming
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Re: building a GUI

[stef mientki]

yadin wrote:
> if i were up to make a GUI chich are the advantages of choosing python
> over matlab or java?
>
>   
As MatLab has a very lousy GUI,
any other language would be an advantage ;-)

The best is Delphi,
second is VB,
then comes SciLab, Python, etc
I don't know where Java fits in.

But as Wildemar said, your question is much to broad.

cheers,
Stef
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Re: annoying stdin/stdout + pipes problem

[Damjan]

> I want to create a program that reads input from stdio that can prompt
> a user for input while doing so without getting into problems.
...
> As you can see I have commented out what I'd like to do but do not
> know how to. Can I somehow halt the previous print to stdout (cat
> input.txt) - if so can I then start it again, and how?

The trick (which works on Linux for sure) is to open /dev/tty and ask
question/get input on/from it.

fp = open('/dev/tty', 'r+')
fp.write('Prompt: ')
answer = fp.readline().strip()


I'm not usre for other *nix-es, and on Windows this will surelly not work
-- 
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Re: building a GUI

[brice . fernandes]

On Sep 23, 4:28 pm, stef mientki <[EMAIL PROTECTED]> wrote:
> yadin wrote:
> > if i were up to make a GUI chich are the advantages of choosing python
> > over matlab or java?
>
> As MatLab has a very lousy GUI,
> any other language would be an advantage ;-)
>
> The best is Delphi,
> second is VB,
> then comes SciLab, Python, etc
> I don't know where Java fits in.
>
> But as Wildemar said, your question is much to broad.
>
> cheers,
> Stef

Form a newbie's point of view, Java's Swing Libraries (gui stuff) are
pretty easy to get to grips with, if a bit big. They are also
incredibly well documented, and are distributed by sun with the core
language.

Compared to most python toolkits, they are approximately as complex,
but far better documented. The other good thing compared to python is
their integration at the language API level rather than as a
supplementary module. A quick look at the 1.6 swing tutorial will tell
you whether this is something you'd like to use:
http://java.sun.com/docs/books/tutorial/uiswing/start/index.html

hope this helps

brice

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Re: Writing Object Data to Disk

[David]

> I would like to know if "Pickling" the class object is the only way of
> writing it to disk for persistent storage. Also, do we have a concept
> similar to "array of objects" in Python? The number of objects is only
> known at "run-time".

Have a look at YAML.

http://freshmeat.net/projects/syck/

Also it is possible to persist python data to and from XML. See
xml.marshal.generic.dumps
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Re: Factory function with keyword arguments

[Ron Adam]

Steven D'Aprano wrote:
> On Sun, 23 Sep 2007 03:55:45 -0500, Ron Adam wrote:
> 
>> Steven D'Aprano wrote:
>>> I'm writing a factory function that needs to use keywords in the
>>> produced function, not the factory. Here's a toy example:
> 
> [snip]
> 
> Thanks everyone who answered, you've given me a lot of good ideas.
> 
> I've run some tests with timeit, and most of the variants given were very 
> close in speed. The one exception was (not surprisingly) my version that 
> builds a tuple, puts it in a list, then converts it to a dict, *before* 
> doing anything useful with it. It was 3-4 times slower than the others.
> 
> George's version, with two definitions of foo(), was the fastest. The 
> second fastest was the variant using exec, which surprised me a lot. I 
> expected exec to be the slowest of the lot. Unfortunately, I doubt that 
> these would scale well as the factory becomes more complicated.

The one with exec (the others less so) will depend on the ratio of how 
often the factory is called vs how often the foo is called.  If the factory 
is called only once, then exec only runs once.  If the factory is called 
every time foo is needed, then it will be much slower.  So  your test needs 
to take into account how the factory function will be used in your program 
also.

Ron

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Re: An Editor that Skips to the End of a Def

[Manuel Graune]

Matthew Woodcraft <[EMAIL PROTECTED]> writes:

> Lawrence D'Oliveiro  <[EMAIL PROTECTED]> wrote:>
>
>> 
>
> An interesting story. They say they picked a test for the express
> purpose of proving that in some circumstances cursor keys can be faster
> than the mouse, but came up with an exercise in which, unusually, the
> keyboard part can be performed with one hand, so eliminating the bit
> where the other hand moves from the keyboard to the mouse and back.
>
> -M-
>

It's quite funny, that what the author proposes as "to make it even
harder" actually speeds up the test for the mouse-users quite a bit.
And "cursor keys"? Please, every self respecting editor has ways for
moving around quite a bit more efficiently. 

And on top of that a use case, which no one in his right mind would
do this way. Accomplishing this task with search-and-replace would
have taken about 10 seconds. With Mouse or Keyboard.

Regards,

Manuel


-- 
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called panic. Neal Stephenson -- System of the world
http://www.graune.org/GnuPG_pubkey.asc
Key fingerprint = 1E44 9CBD DEE4 9E07 5E0A  5828 5476 7E92 2DB4 3C99
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Re: [Bulk] Re: Writing Object Data to Disk

[Amit Kumar Saha]

On Sun, 2007-09-23 at 18:34 +0200, David wrote:
> > I would like to know if "Pickling" the class object is the only way of
> > writing it to disk for persistent storage. Also, do we have a concept
> > similar to "array of objects" in Python? The number of objects is only
> > known at "run-time".
> 
> Have a look at YAML.
> 
> http://freshmeat.net/projects/syck/
> 
> Also it is possible to persist python data to and from XML. See
> xml.marshal.generic.dumps

Thanks David :-)
I appreciate the XML related comment, but as of now I am ready-to-roll
with Python specific pickling. XML will be used in a later version of my
code!

Regards,
Amit
-- 
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me blogs@ http://amitksaha.blogspot.com
URL:http://amitsaha.in.googlepages.com


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Re: I could use some help making this Python code run faster using only Python code.

[Matt McCredie]

> Yes, Digital Mars D is what I was referring to and yes I know D is not
> as efficient as C++.  If I knew of a good C++ compiler that is not
> from Microsoft that works natively with Windows I would be happy to
> consider using it.

I've had good luck with MinGW (gcc compiled for windows).

http://www.mingw.org

Matt
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Re: building a GUI

[Thomas Dybdahl Ahle]

Den Sun, 23 Sep 2007 17:28:38 +0200 skrev stef mientki:
> yadin wrote:
>
>> if i were up to make a GUI chich are the advantages of choosing python
>> over matlab or java?
>>
> The best is Delphi,
> second is VB,

That sounds mostly like a personal preference :)

I would certainly suggest Python very much for any kind of gui.
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Untrusted python code

[Thomas Dybdahl Ahle]

Hi, I have an application for which I want users to be able to make 
themes.
I've planed a rather advanced model (in xml), which gives themes the 
option to redefine various drawing methods.
Now I don't want those themes to be able to take over the current user, 
but I'd still like the scripts to be able to import stuff like math.
Is there a way to ensure no IO and other dangerous stuff is done?
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Re: building a GUI

[stef mientki]

Thomas Dybdahl Ahle wrote:
> Den Sun, 23 Sep 2007 17:28:38 +0200 skrev stef mientki:
>   
>> yadin wrote:
>>
>> 
>>> if i were up to make a GUI chich are the advantages of choosing python
>>> over matlab or java?
>>>
>>>   
>> The best is Delphi,
>> second is VB,
>> 
>
> That sounds mostly like a personal preference :)
>
>   
Well I prefer Python ( because of it's OS-independancy and it's open 
source),
but Python is really (still) much worse for GUI designs.
Just compare some parameters like:
- ease of use
- speed of development
- support of features
- availability of libraries
- documentation
> I would certainly suggest Python very much for any kind of gui.
>   
I agree to that ;-)

cheers,
Stef
>   

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Re: building a GUI

[Diez B. Roggisch]

stef mientki schrieb:
> Thomas Dybdahl Ahle wrote:
>> Den Sun, 23 Sep 2007 17:28:38 +0200 skrev stef mientki:
>>  
>>> yadin wrote:
>>>
>>>
 if i were up to make a GUI chich are the advantages of choosing python
 over matlab or java?

   
>>> The best is Delphi,
>>> second is VB,
>>> 
>>
>> That sounds mostly like a personal preference :)
>>
>>   
> Well I prefer Python ( because of it's OS-independancy and it's open 
> source),
> but Python is really (still) much worse for GUI designs.
> Just compare some parameters like:
> - ease of use
> - speed of development
> - support of features
> - availability of libraries
> - documentation

Sounds like PyQt for me. Best GUI-designer I know, tremendous speed in 
development, giant sized lib that does all kinds of stuff & is 
brilliantly designed + professional grade docus.

Diez
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Re: Preemption in python

[Evan Klitzke]

On Sat, 2007-09-22 at 19:28 -0700, Kurtis Heimerl wrote:
> Hi, I'm developing my first python application, a multi-threaded cell
> phone gadget on ubuntu 7.10. I've just split off my first thread, and
> I've noticed something extremely strange: There doesn't seem to be any
> preemption. There are currently two threads, one that pings a storage
> service to see if there are messages available, and the other that
> runs the gtk windows. If I do not explicitly yield either one, it runs
> forever. I'm assuming this is a setting somewhere, but that's a very
> strange default behavior. 
> 
> How do I get this to go about preempting these threads? Any advice
> would be helpful. Thanks!

I'm far from an expert in threaded Python applications, but threading
ought to work out of the box. By default the Python interpreter will
switch threads every 100 bytecode instructions
(http://docs.python.org/api/threads.html).

Note that if you are synchronizing around a lock, you may need to sleep
before trying to reacquire the the lock to completely exit the critical
section. A good overview of this (and the Python threading model) can be
found at http://linuxgazette.net/107/pai.html

-- 
Evan Klitzke <[EMAIL PROTECTED]>

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Re: Preemption in python

[Kurtis Heimerl]

I ran a brief program to just test the threading properties of my VM, it
seems to be preempting that application.

Are there any interesting locks in the gtk package that I might not be
playing well with?

The reader thread that only runs on a blocking call is at the end of my
response.

I'll explain a bit more. This thread is spawned, I also have the main thread
running a gtk windowed gui. The gui has it's own threads to deal with button
presses and such. The problem is that the gui never seems to let anyone else
run. Only on button presses that cause blocking calls (
ossaudiodev.audio.read for instance) does the reader thread print anything.

Likewise, this thread blocks the GUI thread. There's really just no
preemption at all going on, and it's exceedingly strange.

The GIL locking could be part of my problem. I'm not explicitly releasing
any locks, I have not used the lock interface at all. That shouldn't cause
the behavior I'm seeing though right?

class ReaderThread( threading.Thread ):

def __init__(self, dtn):
self.dtn = dtn
threading.Thread.__init__(self)

def run(self):
print("RUNNING")
while(True):
bundle = api.recv(self.dtn.handle, DTN_PAYLOAD_MEM, 10)
if(bundle):
print("RECEIVED BUNDLE")
else:
print("NO BUNDLE")

Thanks for the help, I really appreciate it. I'm totally blocked on this
without you folk's help.

On 9/23/07, Evan Klitzke <[EMAIL PROTECTED]> wrote:
>
> On Sat, 2007-09-22 at 19:28 -0700, Kurtis Heimerl wrote:
> > Hi, I'm developing my first python application, a multi-threaded cell
> > phone gadget on ubuntu 7.10. I've just split off my first thread, and
> > I've noticed something extremely strange: There doesn't seem to be any
> > preemption. There are currently two threads, one that pings a storage
> > service to see if there are messages available, and the other that
> > runs the gtk windows. If I do not explicitly yield either one, it runs
> > forever. I'm assuming this is a setting somewhere, but that's a very
> > strange default behavior.
> >
> > How do I get this to go about preempting these threads? Any advice
> > would be helpful. Thanks!
>
> I'm far from an expert in threaded Python applications, but threading
> ought to work out of the box. By default the Python interpreter will
> switch threads every 100 bytecode instructions
> (http://docs.python.org/api/threads.html).
>
> Note that if you are synchronizing around a lock, you may need to sleep
> before trying to reacquire the the lock to completely exit the critical
> section. A good overview of this (and the Python threading model) can be
> found at http://linuxgazette.net/107/pai.html
>
> --
> Evan Klitzke <[EMAIL PROTECTED]>
>
> --
> http://mail.python.org/mailman/listinfo/python-list
>
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Re: database persistence with mysql, sqlite

[Bryan Olson]

coldpizza wrote:
> I want to run a database query and then display the first 10 records
> on a web page. Then I want to be able to click the 'Next' link on the
> page to show the next 10 records, and so on.

> My question is how to implement paging, i.e. the 'Next/Prev' NN
> records without reestablishing a database connection every time I
> click Next/Prev? Is it at all possible with cgi/mod_python?

Caching database connections works in mod_python; not so
much with cgi.

> For example, in a NON-web environment, with sqlite3 and most other
> modules, I can establish a database connection once, get a cursor
> object on which I run a single 'SELECT * FROM TABLE' statement and
> then use cursor.fetchmany(NN) as many times as there are still results
> left from the initial query.
> 
> How do I do the same for the web? 

Short answer: you don't. It would mean saving cursors with
partial query results, and arranging for incoming requests to
go to the right process. Web-apps avoid that kind of thing.
Many web toolkits offer session objects, but do not support
saving active objects such as cursors. That said, I've
never tried what you proposing with the tools you name.

Depending on how your database handles transactions, an
open cursor can lock-out writers, and even other readers.
How long do you keep it around if the user doesn't return?

What should happen if the user re-loads a page from a few
sets-of-10 back?


> I am not using any high-level
> framework. I am looking for a solution at the level of cgi or
> mod_python (Python Server Pages under Apache). To call
> cursor.fetchmany(NN) over and over I need to pass a handle to the
> database connection but how do I keep a reference to the cursor object
> across pages? I use mysql and sqlite3 as databases, and I am looking
> for an approach that would work with both database types (one at a
> time). So far I have successfully used the following modules for
> database access: sqlite3, mysqld, and pyodbc.
> 
> So far, with mysql I use 'SELECT * FROM TABLE LIMIT L1, L2' where L1
> and  L2 define the range for the 'Next' and 'Previous' commands. I
> have to run the query every time a click a 'Next/Prev' link. 

You might want to run that query by a MySQL expert.

The basic method is nice in that it needs no server-side
state between requests. (It's a little squirrely in that
it can show a set of records that was never the contents
of the table.)


> But I am
> not sure that this is the best and most efficient way. I suppose using
> CURSOR.FETCHMANY(NN) would probably be faster and nicer but how do I
> pass an object reference across pages? Is it possible without any
> higher-level libraries?

Do you know that you have a performance problem? If so do
you know that it is due to too many cursor.execute() calls?
Keeping partially-executed queries is way down on the list
of optimizations to try.

> What would be the proper way to do it on a non-enterprise scale?

With mod_python, you can cache connections, which may help.
If you use "ORDER BY" with "LIMIT", the right index can make
a big difference.

Have you considered implementing your 'Next/Prev' commands
on the browser side with Javascript? The server could then
get all the records in one query, and the user would see
point-in-time correct results.

Another possibility is to the get all the query results and
save them in a session object, then deal them out a few at
a time. But as a rule of thumb, the less state on the server
the better.


> Would SqlAlchemy or SqlObject make things easier with regard to
> database persistence?

Quite likely, but probably not in the way you propose.
The web frameworks that use those toolkits try to do
things in robust and portable ways.


-- 
--Bryan
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Re: Untrusted python code

[Paul Rubin]

Thomas Dybdahl Ahle <[EMAIL PROTECTED]> writes:
> Hi, I have an application for which I want users to be able to make 
> themes.
> I've planed a rather advanced model (in xml), which gives themes the 
> option to redefine various drawing methods.
> Now I don't want those themes to be able to take over the current user, 
> but I'd still like the scripts to be able to import stuff like math.
> Is there a way to ensure no IO and other dangerous stuff is done?

No.  There used to be something called rexec/bastion but it was
removed because it was insecure.

You might look at http://webpy.org which is a web kit written in
Python, that has its own sandboxed interpreter for a Python-like
user templating language, for doing what you're doing. 

You could also consider using something like client side XSLT.
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Travel around the globe...

[travelingwebs1]

http://world-traveling-destinations.blogspot.com/

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Latest software downloads!!!!!

[freesoftwareweb]

http://freesoftwareupgrades.blogspot.com/

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Re: building a GUI

[Kelvie Wong]

On 9/23/07, Diez B. Roggisch <[EMAIL PROTECTED]> wrote:
>
> stef mientki schrieb:
> > Thomas Dybdahl Ahle wrote:
> >> Den Sun, 23 Sep 2007 17:28:38 +0200 skrev stef mientki:
> >>
> >>> yadin wrote:
> >>>
> >>>
>  if i were up to make a GUI chich are the advantages of choosing
> python
>  over matlab or java?
> 
> 
> >>> The best is Delphi,
> >>> second is VB,
> >>>
> >>
> >> That sounds mostly like a personal preference :)
> >>
> >>
> > Well I prefer Python ( because of it's OS-independancy and it's open
> > source),
> > but Python is really (still) much worse for GUI designs.
> > Just compare some parameters like:
> > - ease of use
> > - speed of development
> > - support of features
> > - availability of libraries
> > - documentation
>
> Sounds like PyQt for me. Best GUI-designer I know, tremendous speed in
> development, giant sized lib that does all kinds of stuff & is
> brilliantly designed + professional grade docus.
>
> Diez
> --
> http://mail.python.org/mailman/listinfo/python-list
>

I'll have to agree completely here, Qt is just so great to work with.  It
makes my day job (I have to do it in C++) much more bearable.  Phil Thompson
(who maintains PyQt) is also very responsive and updates frequently even if
you haven't bought a commercial licence for it.

I also have to agree that the Qt Designer is the best I've ever had to work
with, and I can't think of an instance where Qt Assistant wasn't open on one
desktop or another.

-- 
Kelvie
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Re: building a GUI

[stef mientki]

Diez B. Roggisch wrote:
> stef mientki schrieb:
>   
>> Thomas Dybdahl Ahle wrote:
>> 
>>> Den Sun, 23 Sep 2007 17:28:38 +0200 skrev stef mientki:
>>>  
>>>   
 yadin wrote:


 
> if i were up to make a GUI chich are the advantages of choosing python
> over matlab or java?
>
>   
>   
 The best is Delphi,
 second is VB,
 
 
>>> That sounds mostly like a personal preference :)
>>>
>>>   
>>>   
>> Well I prefer Python ( because of it's OS-independancy and it's open 
>> source),
>> but Python is really (still) much worse for GUI designs.
>> Just compare some parameters like:
>> - ease of use
>> - speed of development
>> - support of features
>> - availability of libraries
>> - documentation
>> 
>
> Sounds like PyQt for me. Best GUI-designer I know, tremendous speed in 
> development, giant sized lib that does all kinds of stuff & is 
> brilliantly designed + professional grade docus.
>   
Could well be,
but I never looked at PyQt seriously,
because of their weird license.

cheers,
Stef

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Re: building a GUI

[Kelvie Wong]

On 9/23/07, Diez B. Roggisch <[EMAIL PROTECTED]> wrote:
>
> stef mientki schrieb:
> > Thomas Dybdahl Ahle wrote:
> >> Den Sun, 23 Sep 2007 17:28:38 +0200 skrev stef mientki:
> >>
> >>> yadin wrote:
> >>>
> >>>
>  if i were up to make a GUI chich are the advantages of choosing
> python
>  over matlab or java?
> 
> 
> >>> The best is Delphi,
> >>> second is VB,
> >>>
> >>
> >> That sounds mostly like a personal preference :)
> >>
> >>
> > Well I prefer Python ( because of it's OS-independancy and it's open
> > source),
> > but Python is really (still) much worse for GUI designs.
> > Just compare some parameters like:
> > - ease of use
> > - speed of development
> > - support of features
> > - availability of libraries
> > - documentation
>
> Sounds like PyQt for me. Best GUI-designer I know, tremendous speed in
> development, giant sized lib that does all kinds of stuff & is
> brilliantly designed + professional grade docus.
>
> Diez
> --
> http://mail.python.org/mailman/listinfo/python-list
>

I'll have to agree completely here, Qt is just so great to work with.  It
makes my day job (I have to do it in C++) much more bearable.  Phil Thompson
(who maintains PyQt) is also very responsive and updates frequently even if
you haven't bought a commercial licence for it.

I also have to agree that the Qt Designer is the best I've ever had to work
with, and I can't think of an instance where Qt Assistant wasn't open on one
desktop or another.

-- 
Kelvie
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Re: os.popen and lengthy operations

[Tommy Nordgren]

On 20 sep 2007, at 08.31, Dmitry Teslenko wrote:

> Hello!
> I'm using os.popen to perform lengthy operation such as building some
> project from source.
> It looks like this:
> def execute_and_save_output( command, out_file, err_file):
>
> import os
>
> def execute_and_save_output( command, out_file, err_file):
>   (i,o,e) = os.popen3( command )
>   try:
>   for line in o:
>   out_file.write( line )
>
>   for line in e:
>   err_file.write( line )
>   finally:
>   i.close()
>   o.close()
>   e.close()
>
> ...
> execute_and_save_output( '', out_file,  
> err_file)
>
> Problem is that script hangs on operations that take long to execute
> and have lots of output such as building scripts.
> -- 
Your problem is that you are not reading the standard output and  
standard error streams in the correct way.
You need to do the reading of standard out and standard err in  
parallell rather than sequentially.
The called process can't proceed when it's output buffers are full.  
Pipes is limited by small buffers (for examples 512 bytes
on Mac OS X)
-
This sig is dedicated to the advancement of Nuclear Power
Tommy Nordgren
[EMAIL PROTECTED]



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Re: Small changes in side library

[Gabriel Genellina]

En Sat, 22 Sep 2007 22:07:27 -0300, [EMAIL PROTECTED]  
<[EMAIL PROTECTED]> escribi�:

> I have the side library which provides wide set of different
> functions, but I'm going to replace some of them with mine and
> provided such 'modified' library thought my project.
>
> The following way works well for my purpose:
>
> --- mylib.py ---
> import sidelib
>
> import os, sys, 
>
> def func():
> .
> sidelib.func = func
> ..
> ?!?!?!?!
> --
>
> But this cause to write mylib.sidelib.func() to function call, is it
> any way to 'map' definitions from sidelib to mylib (possible at point
> marked ?!?!?!?!) such that constructions like mylib.func() will be
> provided and client code don't see difference between changed and
> original library in syntax way?

Your code already works as you like:
import sidelib
sidelib.func()
and you get the modified function.

You don't have to say mylib.sidelib.func - in fact, mylib.sidelib is the  
same module object as sidelib
But you have to ensure that the replacing code (mylib.py) runs *before*  
anyone tries to import something from sidelib.

> One my idea was to do from sidelib import * and then modify globals()
> dictionary, but this isn't good too because mylib imports many other
> modules and they all mapped into it's namespace (like mylib.os,
> mylib.sys).

As you said, a bad idea.

-- 
Gabriel Genellina

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Re: Preemption in python

[Gabriel Genellina]

En Sun, 23 Sep 2007 16:10:03 -0300, Kurtis Heimerl <[EMAIL PROTECTED]>  
escribi�:

> I'll explain a bit more. This thread is spawned, I also have the main  
> thread
> running a gtk windowed gui. The gui has it's own threads to deal with  
> button
> presses and such. The problem is that the gui never seems to let anyone  
> else
> run. Only on button presses that cause blocking calls (
> ossaudiodev.audio.read for instance) does the reader thread print  
> anything.

Google for "python gtk threading tutorial"

-- 
Gabriel Genellina

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Re: Would Anonymous Functions Help in Learning Programming/Python?

[Scott David Daniels]

Ron Adam wrote:
> Scott David Daniels wrote:
>> Ron Adam wrote:
>>>  How about this?
>>> def integrate(fn, x1, x2, n=100):...
>> The point was a pedagogic suggestion, ... 
> I understood your point.  I just found it interesting since I've been 
> trying to extend my math (for use with python) skills in this area.

Ah, sorry.  I had realized I wasn't explicit in my first message.
Yes, a perfectly fine integration.

You can then (and this is a major jump to get used to):
 import functools

 Sine = functools.partial(integrate, math.cos, 0.0, n=100)

Similarly, you can define a derivative that will behave fairly well,
all without examining the definition of the function being operated
upon.

-Scott

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Re: building a GUI

[Phil Thompson]

On Sunday 23 September 2007, stef mientki wrote:
> Diez B. Roggisch wrote:
> > stef mientki schrieb:
> >> Thomas Dybdahl Ahle wrote:
> >>> Den Sun, 23 Sep 2007 17:28:38 +0200 skrev stef mientki:
>  yadin wrote:
> > if i were up to make a GUI chich are the advantages of choosing
> > python over matlab or java?
> 
>  The best is Delphi,
>  second is VB,
> >>>
> >>> That sounds mostly like a personal preference :)
> >>
> >> Well I prefer Python ( because of it's OS-independancy and it's open
> >> source),
> >> but Python is really (still) much worse for GUI designs.
> >> Just compare some parameters like:
> >> - ease of use
> >> - speed of development
> >> - support of features
> >> - availability of libraries
> >> - documentation
> >
> > Sounds like PyQt for me. Best GUI-designer I know, tremendous speed in
> > development, giant sized lib that does all kinds of stuff & is
> > brilliantly designed + professional grade docus.
>
> Could well be,
> but I never looked at PyQt seriously,
> because of their weird license.

It's not weird. It's either GPL or proprietary. Your choice. That's as 
complicated as it gets.

Phil
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strange behavious of the logging module?

[Christian Meesters]

Hi,

having the following code:

import logging
logging.basicConfig(level=logging.ERROR,
format='%(levelname)-8s %(message)s',
filename='mc_rigid.log',
filemode='w')
# define a Handler which writes INFO messages or higher to the sys.stderr
console = logging.StreamHandler()
console.setLevel(logging.INFO)
# set a format which is simpler for console use
formatter = logging.Formatter('%(message)s')
# tell the handler to use this format
console.setFormatter(formatter)
# add the handler to the root logger
logging.getLogger('').addHandler(console)

I observe nothing printed on the console. However if I change the level
(just after the import) from logging.ERROR to logging.DEBUG I do see all
info lines on the console as intended.

Can anybody tell my mistake? I thought changing the level in basicConfig
would have no impact on the following StreamHandler instance.
Also, adding %(funcName)-8s to the formatter in basigConfig does not work
for me: instead of the functions name the level in lower case gets inserted
into the logfile.

My python:
Python 2.5.1 (r251:54863, May  2 2007, 16:56:35) 
[GCC 4.1.2 (Ubuntu 4.1.2-0ubuntu4)] on linux2

TIA
Christian
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Re: building a GUI

[stef mientki]

Phil Thompson wrote:
> On Sunday 23 September 2007, stef mientki wrote:
>   
>> Diez B. Roggisch wrote:
>> 
>>> stef mientki schrieb:
>>>   
 Thomas Dybdahl Ahle wrote:
 
> Den Sun, 23 Sep 2007 17:28:38 +0200 skrev stef mientki:
>   
>> yadin wrote:
>> 
>>> if i were up to make a GUI chich are the advantages of choosing
>>> python over matlab or java?
>>>   
>> The best is Delphi,
>> second is VB,
>> 
> That sounds mostly like a personal preference :)
>   
 Well I prefer Python ( because of it's OS-independancy and it's open
 source),
 but Python is really (still) much worse for GUI designs.
 Just compare some parameters like:
 - ease of use
 - speed of development
 - support of features
 - availability of libraries
 - documentation
 
>>> Sounds like PyQt for me. Best GUI-designer I know, tremendous speed in
>>> development, giant sized lib that does all kinds of stuff & is
>>> brilliantly designed + professional grade docus.
>>>   
>> Could well be,
>> but I never looked at PyQt seriously,
>> because of their weird license.
>> 
>
> It's not weird. It's either GPL or proprietary. Your choice. That's as 
> complicated as it gets.
>   
This is what I find "weird":
== quote ==
Trolltech's commercial license terms do not allow you to start 
developing proprietary software using the Open Source edition.
== end quote ==
Stef

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Re: Properties and Objects...

[Gabriel Genellina]

En Sat, 22 Sep 2007 15:06:38 -0300, George V. Neville-Neil  
<[EMAIL PROTECTED]> escribi�:

> I have been trying to switch this over to using properties, which seem
> at first glance to be cleaner, but which I am having a lot of problems
> with.  In particular I want to add a property to an object, not a
> class.  The field list in a class is actually relatively static but I
> wind up with ugly code like:
>
> class ethernet(pcs.Packet):
> """Ethernet"""
> __layout__ = pcs.Layout()
> _map = ethernet_map.map
>src = pcs.StringField("src", 48)
> dst = pcs.StringField("dst", 48)
> type = pcs.Field("type", 16)
>
> def __init__(self, bytes = None, timestamp = None):
> """initialize an ethernet packet"""
>
> src = pcs.StringField("src", 48)
> dst = pcs.StringField("dst", 48)
> type = pcs.Field("type", 16)
>
> pcs.Packet.__init__(self, [dst, src, type], bytes = bytes)
> self.description = inspect.getdoc(self)

You don't have to repeat the fields:

  pcs.Packet.__init__(self, [self.dst, self.src, self.type], bytes  
= bytes)

does the same thing.
And you can remove self.description=... and use (at the class level):
description = __doc__
or:
description = property(lambda self: self.__doc__)
to automatically enable subclases to share the definition

One could say that the field order is important so I'd finally write it as:

class ethernet(pcs.Packet):
  """Ethernet"""
  __layout__ = pcs.Layout()
  _map = ethernet_map.map
  src = pcs.StringField("src", 48)
  dst = pcs.StringField("dst", 48)
  type = pcs.Field("type", 16)
  _fields = [dst, src, type]
  description = property(lambda self: self.__doc__)

  def __init__(self, bytes = None, timestamp = None):
  """initialize an ethernet packet"""

  pcs.Packet.__init__(self, self._fields, bytes = bytes)

> and assigning the properties at class time means that it's hard to
> have variations, packets with the same name but with slightly varying
> field lists.

This is the part I don't understand. Can't you define a new class, in case  
you want a different field list? Using the above class:

class ethernet_modified(ethernet):
 """Modified ethernet class"""
 added_field = pcs.StringField("whatever", 16)
 _fields = [dst, src, type, added_field]

And it doesn't even requiere an __init__ method

> So, is there a way to assign a property to an object, like this:
>
> def __init__(
>  self.src = property()
>
> or something like that?

I'd use different classes for different kind of objects.

> And, failing that, is there a clean way to modify the class in it's
> __init__() method so I don't have to call the Field objects twice,
> once for the property effect and once to put into the list in the base
> Packet class?

I think my example above does what you want.

-- 
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Re: strange behavious of the logging module?

[Gabriel Genellina]

En Sun, 23 Sep 2007 18:53:53 -0300, Christian Meesters  
<[EMAIL PROTECTED]> escribi�:

> import logging
> logging.basicConfig(level=logging.ERROR,
> format='%(levelname)-8s %(message)s',
> filename='mc_rigid.log',
> filemode='w')
> # define a Handler which writes INFO messages or higher to the sys.stderr
> console = logging.StreamHandler()
> console.setLevel(logging.INFO)
> # set a format which is simpler for console use
> formatter = logging.Formatter('%(message)s')
> # tell the handler to use this format
> console.setFormatter(formatter)
> # add the handler to the root logger
> logging.getLogger('').addHandler(console)
>
> I observe nothing printed on the console. However if I change the level
> (just after the import) from logging.ERROR to logging.DEBUG I do see all
> info lines on the console as intended.

basicConfig sets the root logger level; if it's ERROR, nothing below ERROR  
will pass. Your handler does not have a chance to get the message.

> Can anybody tell my mistake? I thought changing the level in basicConfig
> would have no impact on the following StreamHandler instance.

basicConfig sets the overall verbosity of your application.

> Also, adding %(funcName)-8s to the formatter in basigConfig does not work
> for me: instead of the functions name the level in lower case gets  
> inserted
> into the logfile.

Looks like a bug...

-- 
Gabriel Genellina

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SimPy, audio interview with creators of

[UrsusMaximus]

SimpPy is a powerful simulation package for Python.

I have just posted an interview (podcast) with Dr. Klaus Muller in
Amsterdam and Professor Tony Vignaux in New Zealand about their
creation, SimPY, an object-oriented, process-based discrete-event
simulation language based on standard Python.

Check it out at www.awaretek.com

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Re: Would Anonymous Functions Help in Learning Programming/Python?

[Bruno Desthuilliers]

Cristian a écrit :
(snip)
> To me, the biggest setback for new programmers is the different syntax
> Python has for creating functions. Instead of the common (and easy to
> grasp) syntax of foo = bar

It's actually a mostly *un*common syntax when it comes to functions. The 
only "mainstream" language I know allowing such a syntax is javascript.

Now given python's parsing rules, I wonder how this could be implemented...

> Python has the def foo(): syntax. So, when
> a new programmer is first introduced to functions they are immediately
> confronted with the notion that functions are "different".

Which is the case in most non functional languages.

> After all,
> they have their own special syntax. This seems to only further the
> separation newbies make between "data" and "functions" or "stuff" and
> "actions". Now, the vast majority of us learned this dichotomy when we
> first began to program, so we are ingrained to assume and even expect
> a different syntax for function declaration, but in a program like
> Python there doesn't seem to be any other reason to have it.

Technically, I'd say "patsing rules". From a more conceptual POV, Python 
was meant to be the missing link between shell scripts and C - and some 
design choices clearly (IMHO) came from the desire to look familiar 
enough to C programmers. Even if Python ended up with some (restricted) 
support for functional programming, it's still has it's roots in 
procedural programming.

> Furthermore, I think it actually inhibits the learning of the
> uninitiated. We can, of course, keep the current syntax as sugar.
> 
> To someone who's learning to program wouldn't a syntax like the
> further give them all they need and also reinforces the idea that
> functions are data just like everything else?

Python's functions are *objects* like anything else. And objects are 
more than data. My 2 cents: show your friend that Python's functions are 
objects, and that other objects can be callable too...

> my_function = function(foo, bar): pass
> an_instance_method = function(self, foo): pass
> a_method_declaration = method(self, foo): pass
> 
> The last one is mostly my pet peeve of having Python "magically"
> create methods out of (what is essentially) a function declaration.

There's not much magic in this. What's stored as an attribute of the 
class *is* a function. It's only wrapped in a method object when looked 
up. And FWIW, it's the function object itself that takes care of this, 
thanks to the descriptor protocol (all relevant doc is on python.org).

> When I first learned it, it felt wrong but you had to press through it
> because there was really no other way of declaring methods.

Truth is that you do *not* "declare" methods in Python.
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Re: Would Anonymous Functions Help in Learning Programming/Python?

[Bruno Desthuilliers]

Kay Schluehr a écrit :
(snip)
> 
> I checked out Io once and I disliked it. I expected Io's prototype OO
> being just a more flexible variant of class based OO but Io couples a
> prototype very closely to its offspring. When A produces B and A.f is
> modified after production of B also B.f is modified. A controls the
> state of B during the whole lifetime of B. I think parents shall not
> do this, not in real life and also not in programming language
> semantics.

I may totally miss the point, but how is this different from:

class A(object):
 def dothis(self):
 print "A.dothis(%s)" % self

class B(A):
 pass

b = B()

b.dothis()

def dothat(self):
 print "function dothat(%s)" % self

A.dothis = dothat
b.dothis()

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Re: Would Anonymous Functions Help in Learning Programming/Python?

[Bruno Desthuilliers]

Kay Schluehr a écrit :
> On 22 Sep., 23:17, Erik Max Francis <[EMAIL PROTECTED]> wrote:
> 
> 
>>The attribute and method (not made distinct in Io; they're called
>>"slots") is much the same as with Python; the current instance is
>>checked for the object, then its parents, then _its_ parents, and so on.
> 
> 
> Repeating the same point as Marc doesn't mean that I have to repeat my
> reply as well. Doesn't it?
> 
Then please don't answer my own repeating of the same point !-)
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Re: Would Anonymous Functions Help in Learning Programming/Python?

[Bruno Desthuilliers]

Cristian a écrit :
> On Sep 21, 4:47 pm, "Sean Tierney" <[EMAIL PROTECTED]> wrote:
> 
>>Just tell him that "functions are like all  other variables and can
>>therefore be passed by other functions or returned by other functions.
>>"
>>
> 
> 
> 
> 
> I could """Just tell him that "functions are like all  other variables
> and can
> therefore be passed by other functions or returned by other functions.
> " """ but wouldn't it be great if Python did this for me? It seems to
> me that the ability for Python to explicitly state that functions-are-
> like-other-variables is there so why not expose it?

Ok, then what about classes ? They also are objects-like-any-other, 
after all. So should we have this syntax too ?

MyClass = class(ParentClass):
   __init__ = function (self, name):
 self.name = name

?-)
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Re: building a GUI

[David Boddie]

On Mon Sep 24 00:08:09 CEST 2007, stef mientki wrote:
> Phil Thompson wrote:
> > On Sunday 23 September 2007, stef mientki wrote:
> 
> >> Could well be,
> >> but I never looked at PyQt seriously,
> >> because of their weird license.
> >
> > It's not weird. It's either GPL or proprietary. Your choice. That's as 
> > complicated as it gets.
>
> This is what I find "weird":
> == quote ==
> Trolltech's commercial license terms do not allow you to start 
> developing proprietary software using the Open Source edition.
> == end quote ==

Well, if you know you're going to be developing proprietary software, what
on earth are you doing with the Open Source edition?

OK, perhaps by asking that rhetorical question I'm simplifying people's
reasons and motives for using Open Source (and in this case Free/Libre)
software to develop tools or solutions that they later want to release as
closed, proprietary products. There are lots of ways people can end up in
that position, of course. Some people find their way there by accident;
others know what the situation is going to be well in advance...

In any case, I think it's useful to be clear about what each license does
or does not allow, especially if this leads to people making informed
decisions well before they learn about the consequences. In this case, the
terms of the commercial license place certain demands on the licensee, just
as with many other commercial licenses.

If someone develops a product using a GPL-licensed library, they can always
release that product under the GPL, even if that's not what they had in
mind when they started. ;-)

David
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http://www.agloco.com/r/BBFR2592

[kasim]

http://kgsm.websitesiekle.com/
Thanks

1.  Hi everyone,
For all of you that are asking for caculations for how much pay, just
consider this.
There is truly no way anyone can calculate with all variables. The pay
is dependent upon the advertisers paying agloco, the search engines
paying agloco, the merchants paying agloco the commissions on the
sales to agloco members, and any other sources of income. This money
all goes into a pool, of which agloco management gets 10% and the rest
is divided among the owners/members. There you have it. income is
variable, percentages for management and the owners ia fixed.
membership is variable. These variable parts will change by the
minute. No reasonable mathmatician will attempt to arrive at
meaningful calculations with two massive variables and one fixed
quantity. All the mathmatician can do at this point is offer
statistical possibilities. In the short view, every person you sponsor
now cuts down on the value of the cash pool individually. In the
longer term, more members means agloco can charge more for the ads and
make the cash pool larger. As far as clicking the ads, That will
create cash pool money when the few make purchases and the merchant
pays agloco the commission on the sale. In at least some cases, the
member will immediately benefit from any discounts that are given to
the agloco membership. Regards searches, I do not know what deal
agloco has with google or the other search engines at this time, but I
do know that as the membership goes up, so does the price google and
the others will pay agloco for each search performed. Google currently
pays aol 10 cents per search performed. Best I can tell you is the per
hour pay will fall into a range somewhere between .1 cents and
1,000.00 dollars per hour.( both top and bottom values estimated with
the fact that everyone is so desparate for promises that poor Brian
cannot say anything without it being considered a set in concrete
promise.) I intentionally used extremes. Try to keep your shirt on and
wait and see what materializes.

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Re: Writing Object Data to Disk

[Colin J. Williams]

Amit Kumar Saha wrote:

> Actually, language independence is really not a consideration here. I am
> happy at having it tied to Python :-)
> 
> BTW, do we have something like array of objects here? 
In numpy, one can have a multi-dimensional array of objects.  It would 
be good to have this notion implemented in Python itself.

Colin W.

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Re: __contains__() and overload of in : Bug or Feature ???

[Colin J. Williams]

[EMAIL PROTECTED] wrote:
> Thanks for your quick response.
> 
>>> I need to overload the operator in and let him
>>> return an object ... It seems it is not a
>>> behavior Python expect :
>>>
>> class A:
>>> ...def __contains__(self,a):
>>> ...return 'yop'
>>> ...
>> a=A()
>> print 'toto' in a
>>> True
>> print a.__contains__('toto')
>>> yop
> 
>> Not sure what you're trying to achieve,
> 
> Using Python as an algebraic parser for
> symbolic mathematical equation and I need
> that the 'in' operator returns an object based
> on its two arguments.
> 
>> but the semantics of the "in" operator
>> make it return a boolean value.
> 
> That is why I need to overload it.
> 
>> The string "yop" evaluates to the boolean
>> value True, as it is not empty.
> 
> Does it means that when overloading an operator, python just
> wrap the call to the method and keep control of the returned
> values ??? Is there a way to bypass this wrapping ???
> 
Can you not achieve what you wish to do with a conditional
expression?

"yop" if a in b else "nop"

Colin W.

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Re: Would Anonymous Functions Help in Learning Programming/Python?

[Ron Adam]

Scott David Daniels wrote:
> Ron Adam wrote:
>> Scott David Daniels wrote:
>>> Ron Adam wrote:
  How about this?
 def integrate(fn, x1, x2, n=100):...
>>> The point was a pedagogic suggestion, ... 
>> I understood your point.  I just found it interesting since I've been 
>> trying to extend my math (for use with python) skills in this area.
> 
> Ah, sorry.  I had realized I wasn't explicit in my first message.

Yes, I wasn't trying to correct you.  I'm sorry if it came across that way.


> Yes, a perfectly fine integration.

There's still something about it that bothers me.  I think it may be the 
n=100 rather than delta='.0001', or some other way to specify the minimal 
error.  (Yes, it's a bit off topic.)


> You can then (and this is a major jump to get used to):
>  import functools
> 
>  Sine = functools.partial(integrate, math.cos, 0.0, n=100)

I haven't played around with .partial yet.  I wonder if it could be used in 
dispatching situations where the function signatures differ?


> Similarly, you can define a derivative that will behave fairly well,
> all without examining the definition of the function being operated
> upon.

I'll get around to doing that at some point. ;-)


I also have a class that solves equations that takes a function in a 
similar way.  It uses the same method used by HP calculators to solve TVM 
equations.

Cheers,
Ron


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Re: building a GUI

[Grant Edwards]

On 2007-09-23, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
> On Sep 23, 4:28 pm, stef mientki <[EMAIL PROTECTED]> wrote:
>> yadin wrote:
>> > if i were up to make a GUI chich are the advantages of choosing python
>> > over matlab or java?
>>
>> As MatLab has a very lousy GUI,
>> any other language would be an advantage ;-)
>>
>> The best is Delphi,
>> second is VB,
>> then comes SciLab, Python, etc
>> I don't know where Java fits in.
>>
>> But as Wildemar said, your question is much to broad.
>>
>> cheers,
>> Stef
>
> Form a newbie's point of view, Java's Swing Libraries (gui
> stuff) are pretty easy to get to grips with, if a bit big.
> They are also incredibly well documented, and are distributed
> by sun with the core language.

Since you can use Swing from Python, it seems a false
dichotomoty to choose between Java and Python based on how well
you like Swing.  [I've never used Swing from Python -- I don't
have very heavyweight computers and try to avoid anything
Java-related.]  Though you can probably find more Swing
examples in Java than in Python

-- 
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  at   AGAIN... I might as well
   visi.compay a visit to the LADIES
   ROOM...
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Re: TRying to import files from my folder not pythons lib folder

[Luis M . González]

Steve Holden wrote:
> [EMAIL PROTECTED] wrote:
> > On Sep 21, 12:32 pm, "[EMAIL PROTECTED]" <[EMAIL PROTECTED]>
> > wrote:
> >> Hi,
> >>
> >> I'm trying to create my own lib of functions, but it seems like I can
> >> only import them if they are in pythons lib folder.
> >>
> >> Example
> >> I have a folder called
> >> K:\mypython
> >>
> >> Now in the interactive python shell I type
> >> Import k:\mypython\listall
> >> And get a error on :
> >>
> >> If I store listall.py in pythons lib folder and type
> >> Limport listall
> >>
> >> It works fins.
> >>
> >> Can I create my own library of functions and store them in a separate
> >> dir
> >>
> >> Also I try to creat a folder in pythomns lib folder and that did not
> >> work
> >>
> >> Help
> >> -Ted
> >
> > One workaround is to do to this:
> >
> > 
> >
> > import sys
> > sys.path.append(r'K:\mypython')
> > import listall
> >
> > 
> >
> > You can also add your path to the .pth file, but I've never done that,
> > so I can't tell you how.
> >
> > Hope that helps!
> >
> > Mike
> >
> The easiest way, particularly for testing, is to set the PYTHONPATH
> variable. It should be a colon-separated list of directories on Unices,
> and a semi-colon separated list on Windows. Those directories will be
> added to sys.path.
>
> See http://docs.python.org/tut/node8.html for yet more.
>
> regards
>   Steve
>
> --
> Steve Holden+1 571 484 6266   +1 800 494 3119
> Holden Web LLC/Ltd   http://www.holdenweb.com
> Skype: holdenweb  http://del.icio.us/steve.holden
>
> Sorry, the dog ate my .sigline

This is exactly what I did, but I have a new problem now:
After seting PYTHONPATH I'm no longer able to start IDLE from the
start menu.
It seems the system cannot find the file.
But if I eliminate PYTHONPATH, everything works as it used to.

I set PYTHONPATH because I wanted to import any existing file in my
desktop without having to use sys.path.append...
It works when using the command line but strangely, something get
messed up with IDLE.
Any hint?

Luis

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Re: Would Anonymous Functions Help in Learning Programming/Python?

[Kay Schluehr]

On 22 Sep., 02:14, Bruno Desthuilliers
<[EMAIL PROTECTED]> wrote:
> Kay Schluehr a écrit :
> (snip)
>
>
>
> > I checked out Io once and I disliked it. I expected Io's prototype OO
> > being just a more flexible variant of class based OO but Io couples a
> > prototype very closely to its offspring. When A produces B and A.f is
> > modified after production of B also B.f is modified. A controls the
> > state of B during the whole lifetime of B. I think parents shall not
> > do this, not in real life and also not in programming language
> > semantics.
>
> I may totally miss the point, but how is this different from:
>
> class A(object):
>  def dothis(self):
>  print "A.dothis(%s)" % self
>
> class B(A):
>  pass
>
> b = B()
>
> b.dothis()
>
> def dothat(self):
>  print "function dothat(%s)" % self
>
> A.dothis = dothat
> b.dothis()

It's not a big deal because you do not use a class to propagate
mutable state unless you are using a class attribute intentionally ( i
guess you do not overuse it just to avoid object encapsulation and
make everything global ). When using a prototype as in Io you need to
protect the state of the child object yourself. You can do this by
overwriting the objects slots but then you end up writing your own
object constructors and the templates accordingly, also named
"classes" by some. Not having dedicated object constructors, member
variable initializations and the presumed class definition boilerplate
comes at the price of introducing them on your own.

Prototypes have a purpose of course when you want to transfer state to
a newly created object. Using a prototyping mechanism as a generic
form of a copy constructor is the right kind to thinking about them
IMO.



I have got the impression that the discussion has drifted away from
what Paul Rubin suggested, namely abandone the expression/statement
distinction. Instead we are discussing the advantages and
disadvantages of object models now. Can we stop here, please?

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Re: Getting rid of bitwise operators in Python 3?

[[david]]

[EMAIL PROTECTED] wrote:
> On Sep 22, 7:04 pm, Marc 'BlackJack' Rintsch <[EMAIL PROTECTED]> wrote:
>> On Sat, 22 Sep 2007 21:17:38 +, Bryan Olson wrote:
>>> The operator module offers pow(). Is there any good reason for
>>> pow() as a built-in?
>> The `operator.pow()` is  just the function for ``**``, it lacks the
>> optional third argument of the built in `pow()`.
>>
>> Ciao,
>> Marc 'BlackJack' Rintsch
> 
> But does the three-argument version of pow() really belong in the
> core?  Who uses it?

It was a common cryptographic operation.

The two-argument version is used by the same
person who wrote the semi-colon at the end of
every line of the code I'm working with.

Personally, I'm sorry that 'and' and 'or' weren't
chosen for the bitwise operators: I'd happily give
up 'and' and 'or' for logic operations.

[david]
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Re: Preemption in python

[Kurtis Heimerl]

Thanks a ton!

Just for the eventual webcrawler that logs this, the gtk package requires a
separate thread init function to allow python threads to play nice.

On 9/23/07, Gabriel Genellina <[EMAIL PROTECTED]> wrote:
>
> En Sun, 23 Sep 2007 16:10:03 -0300, Kurtis Heimerl <[EMAIL PROTECTED]>
> escribi�:
>
> > I'll explain a bit more. This thread is spawned, I also have the main
> > thread
> > running a gtk windowed gui. The gui has it's own threads to deal with
> > button
> > presses and such. The problem is that the gui never seems to let anyone
> > else
> > run. Only on button presses that cause blocking calls (
> > ossaudiodev.audio.read for instance) does the reader thread print
> > anything.
>
> Google for "python gtk threading tutorial"
>
> --
> Gabriel Genellina
>
> --
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Re: An Editor that Skips to the End of a Def

[Lawrence D'Oliveiro]

In message <[EMAIL PROTECTED]>, Manuel Graune wrote:

> Matthew Woodcraft <[EMAIL PROTECTED]> writes:
> 
>> Lawrence D'Oliveiro  <[EMAIL PROTECTED]> wrote:>
>>
>>> 
>>
> And "cursor keys"? Please, every self respecting editor has ways for
> moving around quite a bit more efficiently.
> 
> And on top of that a use case, which no one in his right mind would
> do this way. Accomplishing this task with search-and-replace would
> have taken about 10 seconds. With Mouse or Keyboard.

Just to reinforce the point that the above was in no way an artificial or
isolated case:



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Re: subprocess -popen - reading stdout from child - hangs

[Lawrence D'Oliveiro]

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

> Let's say I have this Python file called loop.py:
> 
> import sys
> print 'hi'
> sys.stdout.flush()
> while 1:
> pass
> 
> And I want to call it from another Python process and read the value
> 'hi'.  How would I do it?
> 
> So far I have tried this:
> 
 proc = subprocess.Popen('python
 /home/chiefinnovator/loop.py',shell=True,stdin=subprocess.PIPE,stdout=subprocess.PIPE)
 proc.stdout.read()
> 
> But it just hangs at read()

That's because you didn't tell it how much to read, so by default it tries
to read until EOF . But
since the subprocess is still running and hasn't closed its stdout, the
pipe has not reached EOF.
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Re: [Bulk] Re: Writing Object Data to Disk

[Lawrence D'Oliveiro]

In message <[EMAIL PROTECTED]>, Amit Kumar
Saha wrote:

> I appreciate the XML related comment, but as of now I am ready-to-roll
> with Python specific pickling. XML will be used in a later version of my
> code!

Will you need to maintain backward compatibility with data written by the
current version of your code?
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Re: subprocess -popen - reading stdout from child - hangs

[Lawrence D'Oliveiro]

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

> Well, using this subclass of subprocess.Popen fixes the problem
> (http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/440554)
> 
> I don't understand how it works though.  Would anyone mind
> explaining?  I'm thinking there's something fundamental about Unix
> processes I'm not understanding.

The "select" calls are checking that the subprocess is ready to read before
writing to its stdin, or that it has something to write before reading from
its stdout.

The O_NONBLOCK fcntl simply says not to wait if there is nothing more to be
read, just return what was already read.
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Re: Would Anonymous Functions Help in Learning Programming/Python?

[Cristian]

On Sep 21, 5:21 pm, Bruno Desthuilliers
<[EMAIL PROTECTED]> wrote:

> Ok, then what about classes ? They also are objects-like-any-other,
> after all. So should we have this syntax too ?
>
> MyClass = class(ParentClass):
>__init__ = function (self, name):
>  self.name = name
>
> ?-)

For consistency I would suggest this, but Python already does this!

Foo = type('Foo', (object, ), {'bar': lambda self, bar: bar})

I've created a new class and then binded it to name afterwards. If you
can import modules without special syntax and you can create classes
without special syntax, why should functions be treated any
differently?

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Re: database persistence with mysql, sqlite

[Lawrence D'Oliveiro]

In message <[EMAIL PROTECTED]>, coldpizza
wrote:

> So far, with mysql I use 'SELECT * FROM TABLE LIMIT L1, L2' where L1
> and  L2 define the range for the 'Next' and 'Previous' commands. I
> have to run the query every time a click a 'Next/Prev' link. But I am
> not sure that this is the best and most efficient way.

Try it first, then see what happens. Remember, premature optimization is the
root of all (programming) evil.
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Database Abstraction Layer And/Or ORM

[BJ Dierkes]

Hello all,

I am looking for opinions on preferred methods of Database  
Abstraction Layer or Object Relation Mapper (I'm using Python 2.5).
I have found a number of options such as those listed here:

http://wiki.python.org/moin/HigherLevelDatabaseProgramming


I'm not looking for a holy war based on whether a DAL/ORM *should* be  
used, and/or if it is preferred over direct access to the database  
API layer.  I understand that can be a lengthy discussion.  I would  
just like to see if there is a common 'preferred choice' in the  
area.  I am coding an application around SQLite, but need to keep the  
flexibility to allow the use of MySQL (or other).

Thoughts? 
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Re: Newbie completely confused

[Lawrence D'Oliveiro]

In message <[EMAIL PROTECTED]>, Gabriel
Genellina wrote:

> En Fri, 21 Sep 2007 13:34:40 -0300, Jeroen Hegeman
> <[EMAIL PROTECTED]> escribi�:
> 
>> class ModerateClass:
>>  def __init__(self):
>>  return
>>  def __del__(self):
>>  pass
>>  return
>>
>> class HugeClass:
>>  def __init__(self,line):
>>  self.clear()
>>  self.input(line)
>>  return
>>  def __del__(self):
>>  del self.B4v
>>  return
>>  def clear(self):
>>  self.long_classes = {}
>>  self.B4v={}
>>  return
> 
> (BTW, all those return statements are redundant and useless)

The OP could be trying to use them as some kind of textual indicator of the
end of the function. Myself, I prefer end-comments, e.g.

class HugeClass :

...

def clear(self) :
...
#end clear

#end HugeClass

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Re: building a GUI

[Lawrence D'Oliveiro]

In message <[EMAIL PROTECTED]>, stef
mientki wrote:

> ... I never looked at PyQt seriously, because of their weird license.

What's weird about it? Lots of software products are dual-licensed, e.g.
MySQL, Perl.
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RE: I could use some help making this Python code run faster usingonly Python code.

[Delaney, Timothy (Tim)]

Python Maniac wrote:

> Some benchmarks showing the effectiveness of using Psyco:
> 
> scramble:   4.210
> scramble_listcomp:  2.343
> scramble_gencomp:   2.599
> scramble_map:   1.960
> scramble_imap:  2.231
> scramble_dict:  2.387
> scramble_dict_map:  0.535
> scramble_dict_imap: 0.726
> scramble_translate: 0.010
> 
> Now with Psyco...
> psyco.bind(scramble)...
> scramble:   0.121   4.088   34.670x faster
> scramble_listcomp:  0.215   2.128   10.919x faster
> scramble_gencomp:   2.563   0.036   1.014x faster
> scramble_map:   2.002   -0.043  0.979x slower
> scramble_imap:  2.175   0.056   1.026x faster
> scramble_dict:  0.199   2.188   11.983x faster
> scramble_dict_map:  0.505   0.029   1.058x faster
> scramble_dict_imap: 0.728   -0.001  0.998x slower
> scramble_translate: 0.009   0.001   1.111x faster
> 
> Overall, Psyco helped my little process of converting 20 MB worth of
> ASCII into what may not look like the original at 6x faster than
> without Psyco.

One thing you should notice with the above results:

Psyco made your initial, totally unoptimised algorithm the fastest of
all (except for translate, which is in a different league of course -
but is much more limited in what it can do).

The other algorithms are already heavily working in C code (dicts, etc),
but the initial algorithm provided lots of opportunities for Psyco to
hook in and use the runtime behaviour.

So, before trying to optimise, see if Psyco gives you the performance
you need.

Tim Delaney
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scope, modyfing outside object from inside the method

[Marcin Stępnicki]

Hello.

I thought I understand this, but apparently I don't :(. I'm missing
something very basic and fundamental here, so redirecting me to the
related documentation is welcomed as well as providing working code :).

Trivial example which works as expected:

>>> x = {'a':123, 'b': 456}
>>> y = x 
>>> x['a']=890
>>> y
{'a': 890, 'b': 456}

Now, let's try something more sophisticated (it's not real world example,
I've made up the problem which I think illustrates my issue). Let's say
I've got such a structure:

results = [ {'a': 12, 'b': 30 },
{'a': 13, 'b': 40 } ]

I'd like to have each row and column in separate object of self-made
classes.:

class mycolumn():
  def __init__(self, resultset, row, col):
self.value = resultset[row][col]
  def __str__(self):
return 'Column value: %s' % self.value

class myrow():
  def __init__(self):
self.container = {}
  def __str__ (self):
return self.container

results = [
{'a': 12, 'b' :30 },
{'a': 13, 'b' :40 } 
]

mystruct = []

for row in results:
mystruct.append ( myrow() )
for col in row:
mystruct [len(mystruct)-1].container[col] = \
 mycolumn(results, results.index(row), col)

print mystruct[0].container['b'] # 12
results[0]['b'] = 50 # 
print mystruct[0].container['b'] # also 12 :/

In other words, I'd like to "map" the results to myrow and mycolumn
objects, and have these new objects' values changed when I change "results".

I hope I explained it well enough :). Thank you for your time.

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Re: building a GUI

[Diez B. Roggisch]

stef mientki schrieb:
> Phil Thompson wrote:
>> On Sunday 23 September 2007, stef mientki wrote:
>>  
>>> Diez B. Roggisch wrote:
>>>
 stef mientki schrieb:
  
> Thomas Dybdahl Ahle wrote:
>
>> Den Sun, 23 Sep 2007 17:28:38 +0200 skrev stef mientki:
>>  
>>> yadin wrote:
>>>
 if i were up to make a GUI chich are the advantages of choosing
 python over matlab or java?
   
>>> The best is Delphi,
>>> second is VB,
>>> 
>> That sounds mostly like a personal preference :)
>>   
> Well I prefer Python ( because of it's OS-independancy and it's open
> source),
> but Python is really (still) much worse for GUI designs.
> Just compare some parameters like:
> - ease of use
> - speed of development
> - support of features
> - availability of libraries
> - documentation
> 
 Sounds like PyQt for me. Best GUI-designer I know, tremendous speed in
 development, giant sized lib that does all kinds of stuff & is
 brilliantly designed + professional grade docus.
   
>>> Could well be,
>>> but I never looked at PyQt seriously,
>>> because of their weird license.
>>> 
>>
>> It's not weird. It's either GPL or proprietary. Your choice. That's as 
>> complicated as it gets.
>>   
> This is what I find "weird":
> == quote ==
> Trolltech's commercial license terms do not allow you to start 
> developing proprietary software using the Open Source edition.
> == end quote ==
> Stef

At least you do have the option to develop FOSS-software with it without 
prior buying it. Delpi you _have_ to by. Now what's more weird?

Diez
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