Re: Object Reference question

[Hendrik van Rooyen]

On Friday 21 August 2009 08:07:18 josef wrote:

> My main focus of this post is: "How do I find and use object reference
> memory locations?"

>>> a = [1,2,3,4]
>>> id(a)
8347088
>>>  

- Hendrik
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Re: #elements of seq A in seq B

[Raymond Hettinger]

On Aug 19, 4:19 pm, Neal Becker  wrote:
> What would be a time efficient way to count the number of occurrences of
> elements of sequence A in sequence B?  (in this particular case, these
> sequences are strings, if that matters).

Python 3.1.1 (r311:74483, Aug 17 2009, 17:02:12) [MSC v.1500 32 bit
(Intel)] on win32
Type "copyright", "credits" or "license()" for more information.
>>> import collections
>>> A = 'abc'
>>> B = 'abracadabra'
>>> collections.Counter(filter(set(A).__contains__, B))
Counter({'a': 5, 'b': 2, 'c': 1})

Raymond
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Re: #elements of seq A in seq B

[Raymond Hettinger]

On Aug 19, 4:19 pm, Neal Becker  wrote:
> What would be a time efficient way to count the number of occurrences of
> elements of sequence A in sequence B?  (in this particular case, these
> sequences are strings, if that matters).

Python 3.1.1 (r311:74483, Aug 17 2009, 17:02:12) [MSC v.1500 32 bit
(Intel)] on win32
Type "copyright", "credits" or "license()" for more information.
>>> import collections
>>> A = 'abc'
>>> B = 'abracadabra'
>>> collections.Counter(filter(A.__contains__, B))
Counter({'a': 5, 'b': 2, 'c': 1})


Raymond
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Re: Object Reference question

[Chris Rebert]

On Thu, Aug 20, 2009 at 11:34 PM, Miles Kaufmann wrote:
> On Aug 20, 2009, at 11:07 PM, josef wrote:

>> The following is what I would like to do:
>> I have a list of class instances dk = [ a, b, c, d ], where a, b, c, d
>> is an object reference. Entering dk gives me the object: [MyClass0
>> instance at 0x, MyClass1 instance at 0x0008, MyClass2 instance at
>> 0x0010 ... ]
>>
>> I need the object reference name (a,b,c,d) from dk to use as input for
>> a file.
>
> It sounds like you should either be storing that name as an attribute of the
> object, or using a dictionary ({'a': a, 'b': b, ...}).

Shorter way to produce the same dictionary:
dict(a=a, b=b, ...)

Cheers,
Chris
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Re: Object Reference question

[Miles Kaufmann]

On Aug 20, 2009, at 11:07 PM, josef wrote:


To begin, I'm new with python. I've read a few discussions about
object references and I think I understand them.

To be clear, Python uses a "Pass By Object Reference" model.
x = 1
x becomes the object reference, while an object is created with the
type 'int', value 1, and identifier (id(x)). Doing this with a class,
x = myclass(), does the same thing, but with more or less object
attributes. Every object has a type and an identifier (id()),
according to the Python Language Reference for 2.6.2 section 3.1.

x in both cases is the object reference. I would like to use the
object to refer to the object reference.


Stop right there.  'x' is not *the* object reference.  It is *an*  
object reference (or in my preferred terminology, a label).  Suppose  
you do:


x = myclass()
y = x

The labels 'x' and 'y' both refer to the same object with equal  
precedence.  There is no mapping from object back to label; it is a  
one-way pointer.  Also importantly, labels themselves are not objects,  
and cannot be accessed or referred to.


(This is a slight oversimplification; thanks to Python's reflection  
and introspection capabilities, it is possible to access labels to  
some extent, and in some limited situations it is possible to use  
stack inspection to obtain a label for an object.  But this is hackish  
and error-prone, and should never be used when a more Pythonic method  
is available.)



The following is what I would like to do:
I have a list of class instances dk = [ a, b, c, d ], where a, b, c, d
is an object reference. Entering dk gives me the object: [MyClass0
instance at 0x, MyClass1 instance at 0x0008, MyClass2 instance at
0x0010 ... ]

I need the object reference name (a,b,c,d) from dk to use as input for
a file.


It sounds like you should either be storing that name as an attribute  
of the object, or using a dictionary ({'a': a, 'b': b, ...}).


-Miles

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Re: Waiting for a subprocess to exit

[Miles Kaufmann]

On Aug 20, 2009, at 10:13 PM, Ben Finney wrote:

The module documentation has a section on replacing ‘os.system’
, which
says to use::

   process = subprocess.Popen("mycmd" + " myarg", shell=True)
   status = os.waitpid(process.pid, 0)

But a ‘Popen’ instance has its own ‘wait’ method, which waits for exit
http://docs.python.org/library/subprocess#subprocess.Popen.wait>.
Why would I use ‘os.waitpid’ instead of::

   process = subprocess.Popen("mycmd" + " myarg", shell=True)
   process.wait()
   status = process.returncode


Really, you can just use:

  process = subprocess.Popen("mycmd" + " myarg", shell=True)
  status = process.wait()

I'm not sure why the documentation suggests using os.waitpid.

I would recommend avoiding shell=True whenever possible.  It's used in  
the examples, I suspect, to ease the transition from the functions  
being replaced, but all it takes is for a filename or some other input  
to unexpectedly contain whitespace or a metacharacter and your script  
will stop working--or worse, do damage (cf. the iTunes 2 installer  
debacle[1]).  Leaving shell=False makes scripts more secure and  
robust; besides, when I'm putting together a command and its  
arguments, it's as convenient to build a list (['mycmd', 'myarg']) as  
it is a string (if not more so).


-Miles

[1]: http://apple.slashdot.org/article.pl?sid=01/11/04/0412209#comment_2518563
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Object Reference question

[josef]

To begin, I'm new with python. I've read a few discussions about
object references and I think I understand them.

To be clear, Python uses a "Pass By Object Reference" model.
x = 1
x becomes the object reference, while an object is created with the
type 'int', value 1, and identifier (id(x)). Doing this with a class,
x = myclass(), does the same thing, but with more or less object
attributes. Every object has a type and an identifier (id()),
according to the Python Language Reference for 2.6.2 section 3.1.

x in both cases is the object reference. I would like to use the
object to refer to the object reference. If I have a gross
misunderstanding, please correct me.

The following is what I would like to do:
I have a list of class instances dk = [ a, b, c, d ], where a, b, c, d
is an object reference. Entering dk gives me the object: [MyClass0
instance at 0x, MyClass1 instance at 0x0008, MyClass2 instance at
0x0010 ... ]

I need the object reference name (a,b,c,d) from dk to use as input for
a file. Where do I find the memory location of the object reference
and the object reference name memory location? I am unconcerned with
the fact that the memory location will change the next time I run a
python session. I will be using the object reference name for
processing right away.

My main focus of this post is: "How do I find and use object reference
memory locations?"

Thoughts?
Thanks,

Josef
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Re: install package in a particular python version

[Ben Finney]

Steve1234  writes:

> I installed the boto module in my Ubuntu system using "python setup.py
> install" and it installs in my python2.6 version and works great.

That's because your ‘python’ command is doing the same thing as if you'd
typed::

$ python2.6 setup.py install

The Python 2.6 interpreter knows where its ‘site-packages’ path is, and
so ‘setup.py’ in turn knows where to put files.

> Now I want to install boto into my python2.5 version

Invoke the specific Python interpreter you want::

$ python2.5 setup.py install

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_o__)—Howard Aiken |
Ben Finney
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Re: 2.6 windows install

[alex23]

"Tim Arnold"  wrote:
> Any ideas on what I'm missing here?

Most likely the required configuration of the local environments.

Did you install Python to the network device from your XP box? That
would explain why you can run it: the required registry settings &
environment variables are added by the installer, none of which is
occurring on any computer other than the one from which you installed.

To be honest, I've never seen a single-point-of-access network
installation of Python for a Windows environment. If it was possible,
I'd expect ActiveState's ActivePython to support it but there's no
mention of it in the list of acceptable installer switches[1].

[1]: http://docs.activestate.com/activepython/2.6/installnotes.html#msi

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Waiting for a subprocess to exit

[Ben Finney]

Howdy all,

I'm looking to replace some usages of ‘os.system’ with the more secure
‘subprocess.Popen’ methods.

The module documentation has a section on replacing ‘os.system’
, which
says to use::

process = subprocess.Popen("mycmd" + " myarg", shell=True)
status = os.waitpid(process.pid, 0)

But a ‘Popen’ instance has its own ‘wait’ method, which waits for exit
http://docs.python.org/library/subprocess#subprocess.Popen.wait>.
Why would I use ‘os.waitpid’ instead of::

process = subprocess.Popen("mycmd" + " myarg", shell=True)
process.wait()
status = process.returncode

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  `\Philosophique_ |
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2.6 windows install

[Tim Arnold]

Hi,
I installed python2.6 to a netapp device. I can use it from my local windows 
machine (XP). But others cannot use it from their pcs.

They get this response
"The system cannot execute the specified program.".

If they double click on python.exe, they get a window

with: This application has failed to start because the application

configuration is incorrect.  Reinstalling the application may fix this

problem.

When I installed it I didn't see any mention of an 'administrators' install, 
it just installed. The permissions on the directories where it installed are 
set wide-open for everyone.

Any ideas on what I'm missing here?

thanks,
--Tim Arnold


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Re: install package in a particular python version

[Steve1234]

Benjamin suggested:
sudo python2.5 setup.py install
and it works.  This makes sense, thanks.

I downloaded pythonpkgmgr from source and installed it.  I got the
error that reguired wx package was missing.  I couldn't find this
package for Linux or source.
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Re: IDLE is not as interactive as Maple

[laser]

Thanks very much for your information. Reinteract looks like exactly
what I want. It give me the similary feeling of using Maple. I like
this kind of programming style. People who did not have this
experience really should take a try.

On 8月20日, 下午9时11分, André  wrote:
> On Aug 20, 12:22 am, laser  wrote:
>
> > In the future, will Python provide programe enviroment like Maple
> > does?
>
> A quick, flip answer: perhaps if you design one?  Tools for Python are
> designed by people scratching an itch.
>
> That being said, have a look at 
> reinteract:http://www.reinteract.org/trac/wiki/Tutorial/Introduction
>
> > In Maple, you can remove anything unneeded in the editor. And
> > the code execution order are not necessary in one direction. You can
> > run any command line on the screen by
> > push Enter key. These functions gave a lot of flaxibility for users to
> > start with programming something.
>
> André

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Re: How to create functors?

[Charles Yeomans]

On Aug 20, 2009, at 5:25 AM, Steven D'Aprano wrote:


On Thu, 20 Aug 2009 01:36:14 -0700, Paul Rubin wrote:


Steven D'Aprano  writes:

As near as I can tell, a functor is just an object which is callable
like a function without actually being implemented as a function,  
e.g.:


No it's not anything like that either, at least as I'm used to the  
term

in programming or in mathematics.  Maybe it's used other ways though.


According to Wikipedia, functor can be used as a synonym for "function
object":

http://en.wikipedia.org/wiki/Function_object

which is what I was thinking of. So it seems there are at least two
meanings for the word, neither of which seems to apply to this  
thread :)




As I'm used to it, it's a feature of certain static type systems.   
The

notion isn't that useful in Python


I find the Haskell page entirely opaque and unintelligible. Well,  
perhaps

not *entirely* opaque, but pretty close: it assumes a mathematical
sophistication that I don't think I even had when I was getting my  
maths

degree, let alone can remember two decades later. (Pity the poor VB
coders wondering what Haskell is good for...) The Wikipedia page is a
little better, but it's section on Examples is laughable -- the  
examples

are as unintelligible to this reader as the description before them.



To this reader -- an Rb coder -- the examples were pretty clear.



But let me try an example to see if I've got it right:


class Int2StrFunctor:
   def map1(self, n):
   if type(n) is not int:
   raise TypeError('argument must be an int')
   return "-"*n
   def map2(self, f):
   if type(f) is not type(lambda: None):
   raise TypeError('argument must be a function')
   # assume f takes an int, and returns another int
   def inner(n):
   return self.map1(f(n))
   return inner


The functor can take an int and return a string:


F = Int2StrFunctor()  # F is a functor
F.map1(3)

'---'

It can also take a function (of int -> int) and return a new function
(int -> str):


def myfunc(n):

... return n+2
...

f = F.map2(myfunc)
f(3)

'-'

f(4)

'--'


There's nothing special about the methods map1() and map2(), I could  
call

them anything I like, or even do this:



def __call__(self, arg):

... if type(arg) is int:
... return self.map1(arg)
... else:
... return self.map2(arg)
...

Int2StrFunctor.__call__ = __call__

F(2)

'--'

F(myfunc)(0)

'--'


There are some technical restrictions on functors, relating to the  
sorts

of functions and types (strictly "categories") they can accept,
presumably to make them mathematically well-behaved.


Have I got it correct?



I don't think so.  Paul Rubin's square example was, I thought,  
particularly instructive.


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Re: #elements of seq A in seq B

[Jan Kaliszewski]

 a = set(a)
 n = sum(item in a for item in b)



Why set?  Does it matter if I say that items in A are already unique?


Sets are hash-based, so it's (most probably) far more efficient for
sets than for sequences (especially if we say about big/long ones).

Regards,
*j

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Re: install package in a particular python version

[David Lyon]

On Thu, 20 Aug 2009 17:57:53 -0700 (PDT), Steve1234 
wrote:
> I installed the boto module in my Ubuntu system using "python setup.py
> install" and it installs in my python2.6 version and works great.  Now
> I want to install boto into my python2.5 version because my hosting
> services supports 2.5 but not 2.6. and I want to test my code locally,
> "sting".format() is not in 2.5.
> 
> How do I install a package in a particular version of python?
> 
> I tried several different install switches without any luck.

If you wish to do it in a gui rather than at the commandline then
you could try the python package manager at :

  http://sourceforge.net/projects/pythonpkgmgr/

You will need to download it from source.

In the Options Dialog, there is a dropdown list that allow you to 
easily change from one version of python to another.

Regards

David
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Re: install package in a particular python version

[Benjamin Kaplan]

whoops, sent it to you instead of the list

On Thu, Aug 20, 2009 at 9:05 PM, Benjamin
Kaplan wrote:
> On Thu, Aug 20, 2009 at 8:57 PM, Steve1234 wrote:
>>
>> I installed the boto module in my Ubuntu system using "python setup.py
>> install" and it installs in my python2.6 version and works great.  Now
>> I want to install boto into my python2.5 version because my hosting
>> services supports 2.5 but not 2.6. and I want to test my code locally,
>> "sting".format() is not in 2.5.
>>
>> How do I install a package in a particular version of python?
>>
>> I tried several different install switches without any luck.
>> --
>> http://mail.python.org/mailman/listinfo/python-list
>>
> It's not an install switch- it's the version of python you use to
> install it. If you want to install it to Python 2.5, run python2.5
> setup.py install
>
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Re: platform-specific overrides of functions and class methods (expanding on imputils demo code)

[Aahz]

In article <77715735-2668-43e7-95da-c91d175b3...@z31g2000yqd.googlegroups.com>,
lkcl   wrote:
>
>if somebody would like to add this to the python bugtracker, as a
>contribution, that would be great.  alternatively, you might like to
>have a word with the python developers to get them to remove the
>censorship on my contributions.

Excuse me?  What censorship?
-- 
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"Given that C++ has pointers and typecasts, it's really hard to have a
serious conversation about type safety with a C++ programmer and keep a
straight face.  It's kind of like having a guy who juggles chainsaws
wearing body armor arguing with a guy who juggles rubber chickens wearing
a T-shirt about who's in more danger."  --Roy Smith
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install package in a particular python version

[Steve1234]

I installed the boto module in my Ubuntu system using "python setup.py
install" and it installs in my python2.6 version and works great.  Now
I want to install boto into my python2.5 version because my hosting
services supports 2.5 but not 2.6. and I want to test my code locally,
"sting".format() is not in 2.5.

How do I install a package in a particular version of python?

I tried several different install switches without any luck.
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Re: Silly question

[John Machin]

On Aug 21, 5:33 am, David C Ullrich  wrote:

> So I'm slow, fine. (There were several times when I was using 1.5.3
> and wished they were there - transposing matrices, etc.)

1.5.THREE ??
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Python on Crays

[Carrie Farberow]

I am trying to build a statically-linked Python based on directions at:

http://yt.enzotools.org/wiki/CrayXT5Installation

I have tried this on multiple systems.  The first time I attempt to build 
python, 'make' runs fine but 'make install' fails with the following error:

Sorry: UnicodeError: ("\\N escapes not supported (can't load unicodedata 
module)",)

Any help regarding the source of this error and possible fixes would be 
appreciated.

Carrie



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Re: Annoying octal notation

[James Harris]

On 20 Aug, 20:06, David <71da...@libero.it> wrote:

> Hi all,
>
> Is there some magic to make the 2.x CPython interpreter to ignore the
> annoying octal notation?
> I'd really like 012 to be "12" and not "10".

This is (IMHO) a sad hangover from C (which took it from B but not
from BCPL which used # and #x) and it appears in many
places. It sounds like you want to use leading zeroes in literals -
perhaps for spacing. I don't think there's an easy way. You just have
to be aware of it.

Note that it seems to apply to integers and not floating point
literals

>>> 012
10
>>> int("012")
12
>>> 012.5
12.5
>>>

This daft notation is recognised in some surprising places to catch
the unwary. For example, the place I first came across it was in a
windows command prompt:

s:\>ping 192.168.1.012
Pinging 192.168.1.10 with 32 bytes of data:

On B's use of the leading zero see

  http://cm.bell-labs.com/cm/cs/who/dmr/kbman.html

and note the comment: "An octal constant is the same as a decimal
constant except that it begins with a zero. It is then interpreted in
base 8. Note that 09 (base 8) is legal and equal to 011."

It maybe made sense once but this relic of the past should have been
consigned to the waste bin of history long ago.

James
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Re: Silly question

[Aahz]

In article ,
Benjamin Kaplan   wrote:
>On Thu, Aug 20, 2009 at 2:13 PM, David C Ullrich wrot=
>e:
>>
>> I just noticed that
>> sequence[i:j:k]
>
>Well, I got some good news and some bad news. According to the docs,
>it existed in 1.4 but the built-in sequences didn't support it until
>2.3. It's not used that often anyway so you haven't been missing much.

Except that it's canonical for one specific operation:

'reverseme'[::-1]
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serious conversation about type safety with a C++ programmer and keep a
straight face.  It's kind of like having a guy who juggles chainsaws
wearing body armor arguing with a guy who juggles rubber chickens wearing
a T-shirt about who's in more danger."  --Roy Smith
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Re: #elements of seq A in seq B

[Jan Kaliszewski]

20-08-2009 o 13:01:29 Neal Becker  wrote:


I meant #occurrences of characters from the set A in string B


But:

1) separately for each element of A? (see Simon's sollution with
defaultdict)

2) or total number of all occurrences of elements of A? (see below)


20-08-2009 o 14:05:12 Peter Otten <__pete...@web.de> wrote:


identity = "".join(map(chr, range(256)))
n = len(b) - len(b.translate(identity, a))


Nice, though I'd prefer Simon's sollution:

a = set(a)
n = sum(item in a for item in b)

Regards,
*j

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Re: #elements of seq A in seq B

[Jan Kaliszewski]

20-08-2009 o 04:12:14 Simon Forman  wrote:


If you want to know the count for each element you can use this:

from collections import defaultdict

def g(a, b):
a = set(a)
d = defaultdict(int)
for item in b:
if item in a:
d[item] += 1
return d

print g(A, B)

# prints defaultdict(, {' ': 1, 'e': 1, 'g': 1, 'i': 1,
'o': 1, 'n': 2, 's': 1, 'r': 2, 't': 2})


Yeah, your sollution is better (and more interesting :-)). Thanks!

*j

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Re: thread and win32com.client problem

[Martin P. Hellwig]

Christian Heimes wrote:

Ray wrote:

I already find the way to fix it. :-)


I consider it good style when people describe their solution to a 
problem, too. Other Python users may run into the same issue someday. :)


Christian


He probably used:  pythoncom.CoInitialize()

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Re: incrementing string/hex value from file and write back

[Dave Angel]

Matthias Güntert wrote:

Hello guys

I would like to read a hex number from an ASCII file, increment it and
write it back. 
How can this be performed? 


I have tried several approaches:

my file serial.txt contains: 0C 


--
f = open('serial.txt', 'r')
val = f.read()
val = val.encode('hex')
print val
--
--> 3043 


--
f = open('serial.txt', 'r')
val = f.read()  
print val

val = val+1
--
--> TypeError: cannot concatenate 'str' and 'int' objects

--
f = open('serial.txt', 'rb')
val = f.read()
val = val + 1
--
--> TypeError: cannot concatenate 'str' and 'int' objects


hm


  
You don't say much to constrain the file.  Is it always two characters 
(nibbles) long?  Or might it have a newline at the end?  If it could be 
multiple lines, is each line limited to 2 columns?  or to 8 columns?  or 
no limit?


To interpret val as an integer, trynew = int(val, 16)
Then to convert back to hex digits, try  line = "%x" % (val+1)

For fancier conversions, look at binascii.unhexlify() and hexlify().   
Look also at chr() and ord().  and str.format()


DaveA

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Re: Annoying octal notation

[Mensanator]

On Aug 20, 2:06 pm, David <71da...@libero.it> wrote:
> Hi all,
>
> Is there some magic to make the 2.x CPython interpreter to ignore the
> annoying octal notation?
> I'd really like 012 to be "12" and not "10".

Use 3.1:

>>> int('012')
12


(Just kidding! That works in 2.5 also. How are you using it where
it's coming out wrong? I can see you pulling '012' out of a text
file and want to calculate with it, but how would you use a
string without using int()? Passing it to functions that allow
string representations of numbers?)

>
> If I want an octal I'll use oct()!
>
> "Explicit is better than implicit..."
>
> TIA
> David

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Re: ncurses getch & unicode (was: decoding keyboard input when using curses)

[Iñigo Serna]

Hi again,

2009/8/20 Iñigo Serna 
>
> I have the same problem mentioned in 
> http://groups.google.com/group/comp.lang.python/browse_thread/thread/c70c80cd9bc7bac6?pli=1
>  some months ago.
>
> Python 2.6 program which uses ncurses module in a terminal configured to use 
> UTF-8 encoding.
>
> When trying to get input from keyboard, a non-ascii character (like ç) is 
> returned as 2 integers < 255, needing 2 calls to getch method to get both.
> These two integers \xc3 \xa7 forms the utf-8 encoded representation of ç 
> character.
>
> ncurses get_wch documentation states the function should return an unique 
> integer > 255 with the ordinal representation of that unicode char encoded in 
> UTF-8, \xc3a7.

Answering myself, I've copied at the bottom of this email a working
solution, but the question still remains: why win.getch() doesn't
return the correct value?

Kind regards,
Iñigo Serna


##
# test.py
import curses

import locale
locale.setlocale(locale.LC_ALL, '')
print locale.getpreferredencoding()


def get_char(win):
    def get_check_next_byte():
    c = win.getch()
    if 128 <= c <= 191:
    return c
    else:
    raise UnicodeError

    bytes = []
    c = win.getch()
    if c <= 127:
    # 1 bytes
    bytes.append(c)
    elif 194 <= c <= 223:
    # 2 bytes
    bytes.append(c)
    bytes.append(get_check_next_byte())
    elif 224 <= c <= 239:
    # 3 bytes
    bytes.append(c)
    bytes.append(get_check_next_byte())
    bytes.append(get_check_next_byte())
    elif 240 <= c <= 244:
    # 4 bytes
    bytes.append(c)
    bytes.append(get_check_next_byte())
    bytes.append(get_check_next_byte())
    bytes.append(get_check_next_byte())
    buf = ''.join([chr(b) for b in bytes])
    buf = buf.decode('utf-8')
    return buf

def getcodes(win):
    codes = []
    while True:
    try:
    ch = get_char(win)
    except KeyboardInterrupt:
    return codes
    codes.append(ch)

lst = curses.wrapper(getcodes)
print lst
for c in lst:
    print c.encode('utf-8'),
print
##
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Re: Executing untrusted code

[Emanuele D'Arrigo]

Christian, Rami and Steven, thank you all for your help. It wasn't
meant to be a challenge, I knew it ought to be easily breakable. I'm
no hacker and it just helps to have some examples to better understand
the issue.

On Aug 20, 7:42 pm, Steven D'Aprano  On a related topic, you should read this post here:
> http://tav.espians.com/a-challenge-to-break-python-security.html

Indeed I did read the post and my minimalistic test was inspired by
some of the code in it (I didn't know you could replace the
builtins!). Tav's effort kinda of ended nowhere though. My
understanding of it is that it hasn't been broken and that Tav has
submitted a patch to secure some of python's innards. But

Steven, you are perfectly right, I didn't test it and I missed the
crucial part in which I store the __builtins__ dictionary in the
dictionary of the new originalBuiltins module. My bad. Still, you did
understand my intentions and did give me a simple example of how it
could be broken. Thank you.

-However- I would suggest that conceptually the "award" goes to
Christian. ;)

In the same way the open builtin function can be replaced or removed,
also reload, file, __import__, exec, execfile and any other
potentially "unsafe" builtin can be replaced with safer versions. Or
not?

Christian's solution though, seems to be much trickier to evade. Can
the object class be replaced at runtime with a version that does not
provide a way to reach its subclasses?

Manu





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Re: incrementing string/hex value from file and write back

[Rami Chowdhury]

Of course - my apologies, I was being an idiot.

On Thu, 20 Aug 2009 14:38:08 -0700, Simon Forman   
wrote:



On Aug 20, 5:18 pm, "Rami Chowdhury"  wrote:

> val = val.encode('hex')

That's the crucial line -- it's returning a new integer, which you are  
re-binding to val. If you then did:


No, it returns another string, which still isn't the decimal
representation of the hex string.  hex C => decimal 12

In [1]: '0C'.encode('hex')
Out[1]: '3043'




--
Rami Chowdhury
"Never attribute to malice that which can be attributed to stupidity" --  
Hanlon's Razor

408-597-7068 (US) / 07875-841-046 (UK) / 0189-245544 (BD)
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Re: incrementing string/hex value from file and write back

[Ethan Furman]

[fixed top-posting]

Rami Chowdhury wrote:
On Thu, 20 Aug 2009 14:08:34 -0700, Matthias Güntert  
 wrote:



Hello guys

I would like to read a hex number from an ASCII file, increment it and
write it back.
How can this be performed?

I have tried several approaches:

my file serial.txt contains: 0C

--
f = open('serial.txt', 'r')
val = f.read()
val = val.encode('hex')


That's the crucial line -- it's returning a new integer,  which you are
re-binding to val. If you then did:

  val = val + 1

you'd be fine, and could then write val back to your file :-)



.encode('hex') is returning a string -- attempting to add one to it will 
raise the same error the OP is getting below.


To get a number you can do (after reading val from the file):

val = int(val, '16') # convert from base 16
val += 1 # increment
val = "%X" % val # back to heg digits

and then write it back out again.  Don't forget to close and reopen the 
file for writing.  :)


~Ethan~


print val
--
--> 3043





--
f = open('serial.txt', 'r')
val = f.read()
print val
val = val+1
--
--> TypeError: cannot concatenate 'str' and 'int' objects

--
f = open('serial.txt', 'rb')
val = f.read()
val = val + 1
--
--> TypeError: cannot concatenate 'str' and 'int' objects


hm


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Re: incrementing string/hex value from file and write back

[Simon Forman]

On Aug 20, 5:18 pm, "Rami Chowdhury"  wrote:
> > val = val.encode('hex')
>
> That's the crucial line -- it's returning a new integer, which you are  
> re-binding to val. If you then did:

No, it returns another string, which still isn't the decimal
representation of the hex string.  hex C => decimal 12

In [1]: '0C'.encode('hex')
Out[1]: '3043'
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Re: incrementing string/hex value from file and write back

[Simon Forman]

On Aug 20, 5:08 pm, Matthias Güntert  wrote:
> Hello guys
>
> I would like to read a hex number from an ASCII file, increment it and
> write it back.
> How can this be performed?
>
> I have tried several approaches:
>
> my file serial.txt contains: 0C
>
> --
> f = open('serial.txt', 'r')
> val = f.read()
> val = val.encode('hex')
> print val
> --
> --> 3043
>
> --
> f = open('serial.txt', 'r')
> val = f.read()  
> print val
> val = val+1
> --
> --> TypeError: cannot concatenate 'str' and 'int' objects
>
> --
> f = open('serial.txt', 'rb')
> val = f.read()
> val = val + 1
> --
> --> TypeError: cannot concatenate 'str' and 'int' objects
>
> hm


Check this out:

In [1]: val = '0C'

In [2]: val.encode('hex')
Out[2]: '3043'

That's not what you want. Try this:

In [3]: int(val, 16)
Out[3]: 12

And to convert an int to a hex string.

In [4]: '%x' % 13
Out[4]: 'd'

The interpreter has a help() function that gives you quick access to
information about python objects:

>>> help(str.encode)
Help on method_descriptor:

encode(...)
S.encode([encoding[,errors]]) -> object

Encodes S using the codec registered for encoding. encoding
defaults
to the default encoding. errors may be given to set a different
error
handling scheme. Default is 'strict' meaning that encoding errors
raise
a UnicodeEncodeError. Other possible values are 'ignore',
'replace' and
'xmlcharrefreplace' as well as any other name registered with
codecs.register_error that is able to handle UnicodeEncodeErrors.

>>> help(int)
Help on class int in module __builtin__:

class int(object)
 |  int(x[, base]) -> integer
 |
 |  Convert a string or number to an integer, if possible.  A floating
point
 |  argument will be truncated towards zero (this does not include a
string
 |  representation of a floating point number!)  When converting a
string, use
 |  the optional base.  It is an error to supply a base when
converting a
 |  non-string. If the argument is outside the integer range a long
object
 |  will be returned instead.
 |
 |  Methods defined here:
 |
...


Unfortunately you can't use it on the '%' string formatting
operator...

>>> help(%)
SyntaxError: invalid syntax

So here's a link to the docs:
http://docs.python.org/library/stdtypes.html#string-formatting-operations


HTH,
~Simon
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Re: incrementing string/hex value from file and write back

[Mark Lawrence]

Matthias Güntert wrote:

Hello guys

I would like to read a hex number from an ASCII file, increment it and
write it back. 
How can this be performed? 


I have tried several approaches:

my file serial.txt contains: 0C 


--
f = open('serial.txt', 'r')
val = f.read()
val = val.encode('hex')

val = int(val, 16) + 1
f.write('%02X' % val)

print val
--
--> 3043 


--
f = open('serial.txt', 'r')
val = f.read()  
print val

val = val+1
--
--> TypeError: cannot concatenate 'str' and 'int' objects

--
f = open('serial.txt', 'rb')
val = f.read()
val = val + 1
--
--> TypeError: cannot concatenate 'str' and 'int' objects


hm




--
Kindest regards.

Mark Lawrence.

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Re: incrementing string/hex value from file and write back

[Rami Chowdhury]

val = val.encode('hex')


That's the crucial line -- it's returning a new integer, which you are  
re-binding to val. If you then did:


  val = val + 1

you'd be fine, and could then write val back to your file :-)

On Thu, 20 Aug 2009 14:08:34 -0700, Matthias Güntert  
 wrote:



Hello guys

I would like to read a hex number from an ASCII file, increment it and
write it back.
How can this be performed?

I have tried several approaches:

my file serial.txt contains: 0C

--
f = open('serial.txt', 'r')
val = f.read()
val = val.encode('hex')
print val
--
--> 3043

--
f = open('serial.txt', 'r')
val = f.read()
print val
val = val+1
--
--> TypeError: cannot concatenate 'str' and 'int' objects

--
f = open('serial.txt', 'rb')
val = f.read()
val = val + 1
--
--> TypeError: cannot concatenate 'str' and 'int' objects


hm





--
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"Never attribute to malice that which can be attributed to stupidity" --  
Hanlon's Razor

408-597-7068 (US) / 07875-841-046 (UK) / 0189-245544 (BD)
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incrementing string/hex value from file and write back

[Matthias Güntert]

Hello guys

I would like to read a hex number from an ASCII file, increment it and
write it back. 
How can this be performed? 

I have tried several approaches:

my file serial.txt contains: 0C 

--
f = open('serial.txt', 'r')
val = f.read()
val = val.encode('hex')
print val
--
--> 3043 

--
f = open('serial.txt', 'r')
val = f.read()  
print val
val = val+1
--
--> TypeError: cannot concatenate 'str' and 'int' objects

--
f = open('serial.txt', 'rb')
val = f.read()
val = val + 1
--
--> TypeError: cannot concatenate 'str' and 'int' objects


hm

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Re: Problem with arrays in a recursive class function

[Aaron Scott]

Never mind -- ditched the attempt and implemented Dijkstra.
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[no subject]

[artur lukowicz]

6344a24de14243c76060bedd42f79bc302679dad
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Re: Annoying octal notation

[Simon Forman]

On Aug 20, 3:06 pm, David <71da...@libero.it> wrote:
> Hi all,
>
> Is there some magic to make the 2.x CPython interpreter to ignore the
> annoying octal notation?

No.  You would have to modify and recompile the interpreter. This is
not exactly trivial, see "How to Change Python's Grammar"
http://www.python.org/dev/peps/pep-0306/

However, see "Integer Literal Support and Syntax" 
http://www.python.org/dev/peps/pep-3127/

(Basically in 2.6 and onwards you can use 0oNNN notation.)

> I'd really like 012 to be "12" and not "10".
>
> If I want an octal I'll use oct()!

But that gives you a string, you're asking about literals.

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Re: thread and win32com.client problem

[Christian Heimes]

Ray wrote:

I already find the way to fix it. :-)


I consider it good style when people describe their solution to a 
problem, too. Other Python users may run into the same issue someday. :)


Christian
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Re: Annoying octal notation

[Johannes Bauer]

David schrieb:

> If I want an octal I'll use oct()! 
> 
> "Explicit is better than implicit..."

A leading "0" *is* explicit.

Implicit would be when some functions would interpret a "0" prefix as
octal and others wouldn't.

Regards,
Johannes

-- 
"Meine Gegenklage gegen dich lautet dann auf bewusste Verlogenheit,
verlästerung von Gott, Bibel und mir und bewusster Blasphemie."
 -- Prophet und Visionär Hans Joss aka HJP in de.sci.physik
 <48d8bf1d$0$7510$54022...@news.sunrise.ch>
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Problem with arrays in a recursive class function

[Aaron Scott]

I have a list of nodes, and I need to find a path from one node to
another. The nodes each have a list of nodes they are connected to,
set up like this:



class Node(object):
def __init__(self, connectedNodes):
self.connectedNodes = connectedNodes

nodes = {
1: Node([4]),
2: Node([3]),
3: Node([2, 4, 5]),
4: Node([1, 6, 3]),
5: Node([3, 7]),
6: Node([4, 9]),
7: Node([5, 8]),
8: Node([7, 9]),
9: Node([6, 8])
}



I made a quick brute-force pathfinder to solve it (in this case, a
path from node 1 to node 9). Here it is:



class PathFind(object):
def __init__(self, source, destination):
self.source = source
self.destination = destination
self.solved = []
def Search(self):
self.PathFind([self.source])
if self.solved:
print "Solutions: "
for i in self.solved:
print "\t" + str(i)
else:
print "Couldn't solve."
def PathFind(self, trail):
location = trail[-1]
if location == self.destination:
self.solved.append(trail)
print "Solution found: " + str(trail)
else:
possibilities = []
for i in nodes[location].connectedNodes:
if not i in trail: possibilities.append(i)
for i in possibilities:
trail.append(i)
self.PathFind(trail[:])
if not possibilities:
print "Dead end: " + str(trail)

finder = PathFind(1, 9)
finder.Search()



Unfortunately, it doesn't seem to be giving me the result I was after.
This is the output:



Solution found: [1, 4, 6, 9]
Dead end: [1, 4, 6, 3, 2]
Solution found: [1, 4, 6, 3, 2, 5, 7, 8, 9]
Solutions:
[1, 4, 6, 9]
[1, 4, 6, 3, 2, 5, 7, 8, 9]



The problem is the array trail[], which seems to survive from instance
to instance of PathFind(). I thought that by calling self.PathFind
(trail[:]), I was creating a new copy of trail[], but obviously
something isn't running like I expected. Is there something I'm
misunderstanding here, or is there just a stupid bug in my code I
haven't caught?
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ANN: discover 0.3.0 released, automatic test discovery for unittest

[Fuzzyman]

The discover module is a backport of the automatic test discovery from
the unittest module in Python-trunk (what will become Python 2.7 and
3.2).

The discover module should work on versions of Python 2.4 upwards:

* discover module on PyPI: http://pypi.python.org/pypi/discover

The discover module can be used to run all, or a subset, of your
unittest based tests automatically from the command line. See the PyPI
page for details.

Version 0.3.0 has two new features:

* Failing to import a file (e.g. due to a syntax error) no longer
halts discovery but is reported as an error.
* Discovery will not attempt to import test files whose names are not
valid Python identifiers, even if they match the pattern.
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Re: thread and win32com.client problem

[Ray]

I already find the way to fix it. :-)
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Re: Silly question

[David C Ullrich]

On Thu, 20 Aug 2009 14:36:35 -0400, Benjamin Kaplan wrote:

> On Thu, Aug 20, 2009 at 2:13 PM, David C Ullrich
> wrote:
>> I just noticed that
>>
>>  sequence[i:j:k]
>>
>> syntax in a post here. When did this happen?
>>
>> (I'm just curious whether it existed in 1.5.x or not. If so I'm stupid
>> - otoh if it was introduced in 2.x I'm just slow...)
>>
>>
> Well, I got some good news and some bad news. According to the docs, it
> existed in 1.4 but the built-in sequences didn't support it until 2.3.
> It's not used that often anyway so you haven't been missing much.

So I'm slow, fine. (There were several times when I was using 1.5.3
and wished they were there - transposing matrices, etc.)

> 
> http://www.python.org/doc/2.3.5/whatsnew/section-slices.html

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Re: Silly question

[David C Ullrich]

On Thu, 20 Aug 2009 18:41:34 +, Duncan Booth wrote:

> David C Ullrich  wrote:
> 
>> I just noticed that
>> 
>>   sequence[i:j:k]
>> 
>> syntax in a post here. When did this happen?
>> 
>> (I'm just curious whether it existed in 1.5.x or not. If so I'm stupid
>> - otoh if it was introduced in 2.x I'm just slow...)
>> 
>> 
> Googling for 'python extended slice' returns this as the first hit:
> 
> http://www.python.org/doc/2.3.5/whatsnew/section-slices.html
> 
>> 15 Extended Slices
>> 
>> Ever since Python 1.4, the slicing syntax has supported an optional
>> third ``step'' or ``stride'' argument. For example, these are all legal
>> Python syntax: L[1:10:2], L[:-1:1], L[::-1]. This was added to Python
>> at the request of the developers of Numerical Python, which uses the
>> third argument extensively. However, Python's built-in list, tuple, and
>> string sequence types have never supported this feature, raising a
>> TypeError if you tried it. Michael Hudson contributed a patch to fix
>> this shortcoming.
> 
> So extended slices have existed since Python 1.4, but builtin types only
> started to support them from 2.3.

Fine (I knew they existed in Numerical Python way back when...)


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thread and win32com.client problem

[Ray]

Hi, I have a problem with thread and win32com.client
running python 2.5 on vista (activestate python)

import win32com.client, thread
def child(test):
problem=win32com.client.Dispatch("WScript.Shell")
print 'hello from thread', test
def parent():
i=0
while 1:
i+=1
thread.start_new(child,('abc',))
if raw_input()=='q': break
parent()

above codes will give me error when I run it.
but if without the line
problem=win32com.client.Dispatch("WScript.Shell")
it just works fine.


errors are:

Unhandled exception in thread started by 
Traceback (most recent call last):
  File "C:\Users\Test\Desktop\Test\test_thread.py", line 3, in child
problem=win32com.client.Dispatch("WScript.Shell")
  File "C:\Python25\lib\site-packages\win32com\client\__init__.py",
line 95, in Dispatch
dispatch, userName = dynamic._GetGoodDispatchAndUserName
(dispatch,userName,clsctx)
  File "C:\Python25\lib\site-packages\win32com\client\dynamic.py",
line 98, in _GetGoodDispatchAndUserName
return (_GetGoodDispatch(IDispatch, clsctx), userName)
  File "C:\Python25\lib\site-packages\win32com\client\dynamic.py",
line 78, in _GetGoodDispatch
IDispatch = pythoncom.CoCreateInstance(IDispatch, None, clsctx,
pythoncom.IID_IDispatch)
pywintypes.com_error: (-2147221008, 'CoInitialize has not been
called.', None, None)
Traceback (most recent call last):
  File "C:\Users\Test\Desktop\Test\test_thread.py", line 11, in

parent()
  File "C:\Users\Test\Desktop\Test\test_thread.py", line 10, in parent
if raw_input()=='q': break


Thanks for any help.
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ANN: Wing IDE 3.2 released

[Wingware]

Hi,

Wingware has released version 3.2.0 final of Wing IDE, our integrated
development environment for the Python programming language.

*Release Highlights*

This release includes the following new features:

* Support for Python 3.0 and 3.1
* Rewritten version control integration with support for Subversion, CVS,
  Bazaar, git, Mercurial, and Perforce (*)
* Added 64-bit Debian, RPM, and tar file installers for Linux
* File management in Project view (**)
* Auto-completion in the editor obtains completion data from live runtime
  when the debugger is active (**)
* Perspectives: Create and save named GUI layouts and optionally automatically
  transition when debugging is started (*)
* Improved support for Cython and Pyrex (*.pyx files)
* Added key binding documentation to the manual
* Added Restart Debugging item in Debug menu and tool bar (**)

(*)'d items are available in Wing IDE Professional only.
(**)'d items are available in Wing IDE Personal and Professional only.

The release also contains many other minor features and bug fixes; see the
change log for details:  http://wingware.com/pub/wingide/3.2.0/CHANGELOG.txt

*Downloads*

Wing IDE Professional and Wing IDE Personal are commercial software and
require a license to run. A free trial license can be obtained directly from
the product when launched.  Wing IDE 101 can be used free of charge.

Wing IDE Pro 3.2.0http://wingware.com/downloads/wingide/3.2

Wing IDE Personal 3.2.0   http://wingware.com/downloads/wingide-personal/3.2

Wing IDE 101 3.2.0http://wingware.com/downloads/wingide-101/3.2

*About Wing IDE*

Wing IDE is an integrated development environment for the Python programming
language.  It provides powerful debugging, editing, code intelligence,
testing, version control, and search capabilities that reduce development and
debugging time, cut down on coding errors, and make it easier to understand
and navigate Python code.

Wing IDE is available in three product levels:  Wing IDE Professional is
the full-featured Python IDE, Wing IDE Personal offers a reduced feature
set at a low price, and Wing IDE 101 is a free simplified version designed
for teaching entry level programming courses with Python.

System requirements are Windows 2000 or later, OS X 10.3.9 or later for PPC or
Intel (requires X11 Server), or a recent Linux system (either 32 or 64 bit).
Wing IDE 3.2 supports Python versions 2.0.x through 3.1.x.

*Purchasing and Upgrading*

Wing 3.2 is a free upgrade for all Wing IDE 3.0 and 3.1 users. Any 2.x license
sold after May 2nd 2006 is free to upgrade; others cost 1/2 the normal price
to upgrade.

Upgrade a 2.x license: https://wingware.com/store/upgrade

Purchase a 3.x license:https://wingware.com/store/purchase

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Wingware | Python IDE
Advancing Software Development

www.wingware.com

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Annoying octal notation

[David]

Hi all,

Is there some magic to make the 2.x CPython interpreter to ignore the
annoying octal notation?
I'd really like 012 to be "12" and not "10". 

If I want an octal I'll use oct()! 

"Explicit is better than implicit..."

TIA
David
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Re: Executing untrusted code

[Steven D'Aprano]

On Thu, 20 Aug 2009 08:16:51 -0700, Emanuele D'Arrigo wrote:

> In what ways would the untrusted string be able to obtain the original,
> built-in open function and open a file for writing?

On a related topic, you should read this post here:

http://tav.espians.com/a-challenge-to-break-python-security.html


-- 
Steven
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Re: Silly question

[Duncan Booth]

David C Ullrich  wrote:

> I just noticed that
> 
>   sequence[i:j:k]
> 
> syntax in a post here. When did this happen?
> 
> (I'm just curious whether it existed in 1.5.x or not.
> If so I'm stupid - otoh if it was introduced in 2.x
> I'm just slow...)
> 
> 
Googling for 'python extended slice' returns this as the first hit:

http://www.python.org/doc/2.3.5/whatsnew/section-slices.html

> 15 Extended Slices
> 
> Ever since Python 1.4, the slicing syntax has supported an optional
> third ``step'' or ``stride'' argument. For example, these are all
> legal Python syntax: L[1:10:2], L[:-1:1], L[::-1]. This was added to
> Python at the request of the developers of Numerical Python, which
> uses the third argument extensively. However, Python's built-in list,
> tuple, and string sequence types have never supported this feature,
> raising a TypeError if you tried it. Michael Hudson contributed a
> patch to fix this shortcoming. 

So extended slices have existed since Python 1.4, but builtin types only
started to support them from 2.3. 
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Re: Executing untrusted code

[Steven D'Aprano]

On Thu, 20 Aug 2009 08:16:51 -0700, Emanuele D'Arrigo wrote:

> Fair enough. In this context, let's say I do this:
> 
> import __builtin__
> import imp
> originalBuiltins = imp.new_module("OriginalBuiltins")
> 
> def readOnlyOpen(filename):
> return originalBuiltins.open(filename, "r")
> 
> __builtin__.open = readOnlyOpen


Have you actually tested this? I don't think it works the way you think 
it does.

>>> import __builtin__
>>> import imp
>>> originalBuiltins = imp.new_module("OriginalBuiltins")
>>> originalBuiltins.open
Traceback (most recent call last):
  File "", line 1, in 
AttributeError: 'module' object has no attribute 'open'


So your strategy fails to provide read-only file access.

But moving on...

> In what ways would the untrusted string be able to obtain the original,
> built-in open function and open a file for writing?

That's hardly even a challenge.

>>> __builtin__.open = readOnlyOpen
>>> anUntrustedString = """import __builtin__
... reload(__builtin__)
... open('junk', 'w').write('a')
... """
>>> exec(anUntrustedString, {})
>>> open('junk').read()
'a'


Not only have I broken your "read only" open within the call to exec, but 
I've broken it outside as well. With a little bit more effort, I could 
probably save and restore the open, so that my untrusted string could 
write to files inside the exec(), but code outside of the exec() would 
still see the readOnlyOpen.




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Re: Silly question

[Benjamin Kaplan]

On Thu, Aug 20, 2009 at 2:13 PM, David C Ullrich wrote:
> I just noticed that
>
>  sequence[i:j:k]
>
> syntax in a post here. When did this happen?
>
> (I'm just curious whether it existed in 1.5.x or not.
> If so I'm stupid - otoh if it was introduced in 2.x
> I'm just slow...)
>

Well, I got some good news and some bad news. According to the docs,
it existed in 1.4 but the built-in sequences didn't support it until
2.3. It's not used that often anyway so you haven't been missing much.

http://www.python.org/doc/2.3.5/whatsnew/section-slices.html
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Silly question

[David C Ullrich]

I just noticed that

  sequence[i:j:k]

syntax in a post here. When did this happen?

(I'm just curious whether it existed in 1.5.x or not.
If so I'm stupid - otoh if it was introduced in 2.x
I'm just slow...)

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Re: Dictionary from a list

[iu2]

On Aug 20, 9:10 am, Peter Otten <__pete...@web.de> wrote:
> Jan Kaliszewski wrote:
> > 20-08-2009 o 02:05:57 Jan Kaliszewski  wrote:
>
> >> Or probably better:
>
> >>      from itertools import islice, izip
> >>      dict(izip(islice(li, 0, None, 2), islice(li, 1, None, 2)))
>
> > Or similarly, perhaps more readable:
>
> >      iterator = iter(li)
> >      dict((iterator.next(), iterator.next()) for i in xrange(len(li)/2))
>
> I just can't stop posting this one:
>
> >>> from itertools import izip
> >>> it = iter([1,2,3,4,5,6])
> >>> dict(izip(it, it))
>
> {1: 2, 3: 4, 5: 6}
>
> I really tried, but yours drove me over the edge.
>
> Peter

Nice.
(but looks like stepping towards the dark side ...  :-)

I also liked this one:
iterator = iter(li)
dict((iterator.next(), iterator.next()) for i in xrange(len(li)/2))

which inspired me to do something quite similar:

a=range(1, 11)
>>> a
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
>>> dict([[a.pop(0), a.pop(0)] for i in range(len(a)/2)])
{1: 2, 3: 4, 9: 10, 5: 6, 7: 8}


Thanks
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ncurses getch & unicode (was: decoding keyboard input when using curses)

[Iñigo Serna]

Hello,

I have the same problem mentioned in
http://groups.google.com/group/comp.lang.python/browse_thread/thread/c70c80cd9bc7bac6?pli=1some
months ago.

Python 2.6 program which uses ncurses module in a terminal configured to use
UTF-8 encoding.

When trying to get input from keyboard, a non-ascii character (like ç) is
returned as 2 integers < 255, needing 2 calls to getch method to get both.
These two integers \xc3 \xa7 forms the utf-8 encoded representation of ç
character.

ncurses get_wch documentation states the function should return an unique
integer > 255 with the ordinal representation of that unicode char encoded
in UTF-8, \xc3a7.


[Please, read the link above, it explains the issue much better that what I
could do.]


Any idea or update on this?


Thanks,
Iñigo Serna

PS: my system is a Linux Fedora 11 x86_64. Same happens on console,
gnome-terminal or xterm.
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Re: Executing untrusted code

[Rami Chowdhury]

They could, of course, use the file object constructor directly, e.g.:
f = file("/etc/passwd", "w")

On Thu, 20 Aug 2009 08:16:51 -0700, Emanuele D'Arrigo   
wrote:



Sorry for digging this back from the grave.
I've had to chew on it for a little while.

On Aug 8, 1:40 am, Nobody  wrote:

If you want to support restricted execution within a language, it
has to be built into the language from day one. Trying to bolt it > on  
later is a fool's errand.


Fair enough. In this context, let's say I do this:

import __builtin__
import imp
originalBuiltins = imp.new_module("OriginalBuiltins")

def readOnlyOpen(filename):
return originalBuiltins.open(filename, "r")

__builtin__.open = readOnlyOpen

exec(anUntrustedString, {})

In what ways would the untrusted string be able to obtain the
original, built-in open function and open a file for writing?

Manu





--
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"Never attribute to malice that which can be attributed to stupidity" --  
Hanlon's Razor

408-597-7068 (US) / 07875-841-046 (UK) / 0189-245544 (BD)
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Re: Executing untrusted code

[Christian Heimes]

Emanuele D'Arrigo write:

In what ways would the untrusted string be able to obtain the
original, built-in open function and open a file for writing?


Yes, if you know some tricks:


[cls for cls in object.__subclasses__() if cls.__name__ == 'file'][0]




Christian
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Re: Executing untrusted code

[Emanuele D'Arrigo]

Sorry for digging this back from the grave.
I've had to chew on it for a little while.

On Aug 8, 1:40 am, Nobody  wrote:
> If you want to support restricted execution within a language, it
> has to be built into the language from day one. Trying to bolt it > on later 
> is a fool's errand.

Fair enough. In this context, let's say I do this:

import __builtin__
import imp
originalBuiltins = imp.new_module("OriginalBuiltins")

def readOnlyOpen(filename):
return originalBuiltins.open(filename, "r")

__builtin__.open = readOnlyOpen

exec(anUntrustedString, {})

In what ways would the untrusted string be able to obtain the
original, built-in open function and open a file for writing?

Manu

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Re: Hi everyone, I get a problem when using binhex module

[Dave Angel]

Yan Jian wrote:

Below is what I copy from the Internet:

import binhex
import sys

infile = "in.txt"

binhex.binhex(infile, sys.stdout)

Every time I try to run this script, I get a message saying

Traceback (most recent call last):
  File "D:\eclipse_workspace\encode\src\binhex.sample.py", line 6, in

import binhex
  File "C:\Python25\lib\binhex.py", line 12, in 
# easy interface should work "as expected" on any platform.
TypeError: 'module' object is not callable

Does anyone encounter similar situation. Thank you for your help?

  
First question:   Are you running Python2.5 ?  And do you actually have 
it installed in c:\Python25 directory?


Do you in fact have 5 blank lines in front of the "import binhex" line?

Assuming yes for all of those, the only cause I can figure for that 
particular error string is that  binhex.pyc is out of synch with 
binhex.py.   To test that theory, try deleting it (in general that means 
renaming it temporarily, so you could restore it if I'm wrong), and 
running again.


I would also add the lines:
  import sys
  print  sys.version

in front of the import, just to make sure you're running what you think 
you are.  And then I'd get a console prompt, change directory to


D:\eclipse_workspace\encode\src\binhex

and run  sample.py  from that command prompt.

Compare the two version strings, and see if anything's different in the 
two error messages.


DaveA
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Re: difference between raw_input() and input()

[Steven D'Aprano]

On Thu, 20 Aug 2009 03:24:15 -0700, baalu aanand wrote:

> Hi,
> 
>  I have used both raw_input() and input() for a same input value.
> But these gives different output.
> 
>  I have listed below what actually I have done
> 
> >>> a = raw_input("===>")
>===> 023
> >>> a
> '023'
> 
>  I have given the same value for the input() but it gives 19 as
> result
> >>> a = input("===>")
>===>  023
> >>> a
> 19
> 
>   Is there anything hide within this. Please illustrate the difference
> between raw_input() and input()


Did you look them up in the documentation?

Did you try the interactive help?

help(input)
help(raw_input)



Perhaps you could try some further experiments:


>>> raw_input()
hello world
'hello world'
>>> input()
hello world
Traceback (most recent call last):
  File "", line 1, in 
  File "", line 1
hello world
 ^
SyntaxError: unexpected EOF while parsing


Does that give you a hint as to what is happening?

How about this?

>>> 07
7
>>> 08
  File "", line 1
08
 ^
SyntaxError: invalid token
>>> 010
8
>>> oct(8)
010




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Re: IDLE is not as interactive as Maple

[sturlamolden]

On 19 Aug, 20:22, laser  wrote:
> In the future, will Python provide programe enviroment like Maple
> does?

You might be looking for SAGE.

http://www.sagemath.org/
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Re: pypi category

[jelle]

The pypi list of categories, sorry...
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Re: Python libexpat and EXPAT are same/Different?

[Stefan Behnel]

hari wrote:
> Am very new to XML, I have a query, Does  Python libexpat and EXPAT
> are same or they are diffrent?

Depends on what you mean with "EXPAT". Python's expat module that you can
find in the standard library is the well known non-validating XML parser
originally written by James Clark.

BTW, if you are new to XML and want to use it in Python, you might want to
start with the xml.etree package.

Stefan
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Python libexpat and EXPAT are same/Different?

[hari]

Hi all,

Am very new to XML, I have a query, Does  Python libexpat and EXPAT
are same or they are diffrent?

Thanks in advance.

Regards,
Hari
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Re: IDLE is not as interactive as Maple

[Benjamin Kaplan]

On Wed, Aug 19, 2009 at 11:22 PM, laser wrote:
> In the future, will Python provide programe enviroment like Maple
> does? In Maple, you can remove anything unneeded in the editor. And
> the code execution order are not necessary in one direction. You can
> run any command line on the screen by
> push Enter key. These functions gave a lot of flaxibility for users to
> start with programming something.
> --
> http://mail.python.org/mailman/listinfo/python-list
>

Maple is a very expensive IDE that happens to have a language that
goes with it. Python is a language that happens to come with a free
text editor/integrated shell. For languages like Mathematica and
Maple, the IDE is everything- you almost never use the language
without the integrated IDE. Python focuses more on language features.
IDLE is not supposed to be a great editor on the level of Visual
Studio or Maple, it's supposed to be a convenient way to run your code
for people who are scared of the command line. I would venture a guess
that very few people on this list use IDLE for their coding. Based on
previous answers to questions, most people use Eclipse/PyDev,
Netbeans, Wing, Komodo, emacs, and vim. Wing and Komodo are the only
Python-specific IDEs on that list and neither of them are free (though
the have stripped-down free versions). If you want a better editor,
use one of those.
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Re: IDLE is not as interactive as Maple

[André]

On Aug 20, 12:22 am, laser  wrote:
> In the future, will Python provide programe enviroment like Maple
> does?

A quick, flip answer: perhaps if you design one?  Tools for Python are
designed by people scratching an itch.

That being said, have a look at reinteract:
http://www.reinteract.org/trac/wiki/Tutorial/Introduction


> In Maple, you can remove anything unneeded in the editor. And
> the code execution order are not necessary in one direction. You can
> run any command line on the screen by
> push Enter key. These functions gave a lot of flaxibility for users to
> start with programming something.

André

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Re: Data visualization in Python

[Aaron Watters]

On Aug 17, 3:10 pm, kj  wrote:
> I'm looking for a good Python package for visualizing
> scientific/statistical data.  (FWIW, the OS I'm interested in is
> Mac OS X).

Please take a look at the amcharts embedding in WHIFF

http://aaron.oirt.rutgers.edu/myapp/amcharts/doc

WHIFF is a collection of support services for WSGI
applications which allows applications to be composed
by "dropping" dynamic pages into container directories.

http://aaron.oirt.rutgers.edu/myapp/docs/W.intro

thanks, -- Aaron Watters

===
Sisyphus got ripped.
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Re: Hi everyone, I get a problem when using binhex module

[Xavier Ho]

On Thu, Aug 20, 2009 at 10:07 PM, Yan Jian  wrote:

>
> Does anyone encounter similar situation. Thank you for your help?
>

Yeah, in Python 3.1 I get this:

 Traceback (most recent call last):
  File "test.py", line 6, in 
binhex.binhex(file, sys.stdout)
  File "c:\Python31\lib\binhex.py", line 228, in binhex
ofp = BinHex(finfo, out)
  File "c:\Python31\lib\binhex.py", line 149, in __init__
ofp.write(b'(This file must be converted with BinHex 4.0)\r\r:')
TypeError: write() argument 1 must be str, not bytes

Python 2.6.2 runs fine though:

:"QPZ,R4iG!"849K82j!%!*!&&3#3"1#$6a...@%z$3t0fr*kb5ij6a*bb@%...@%
!!!:

I never used binhex however, so someone else might have a better insight.

Cheers,
Xav
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pypi category

[jelle]

Hi,

Would someone be able to inform me how a category can be added to the
pypy list of categories?
I'd like to add a CAD & Geometry category.
( I develop PythonOCC, wrappers for the OpenCASCADE CAD kernel, which
is why )

Thanks!

-jelle
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Re: #elements of seq A in seq B

[Peter Otten]

Neal Becker wrote:

> I meant #occurrences of characters from the set A in string B

If a contains "few" characters:

n = sum(b.count(c) for c in a)

If a contains "many" characters:

identity = "".join(map(chr, range(256)))
n = len(b) - len(b.translate(identity, a))

Peter


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Hi everyone, I get a problem when using binhex module

[Yan Jian]

Below is what I copy from the Internet:

import binhex
import sys

infile = "in.txt"

binhex.binhex(infile, sys.stdout)

Every time I try to run this script, I get a message saying

Traceback (most recent call last):
  File "D:\eclipse_workspace\encode\src\binhex.sample.py", line 6, in

import binhex
  File "C:\Python25\lib\binhex.py", line 12, in 
# easy interface should work "as expected" on any platform.
TypeError: 'module' object is not callable

Does anyone encounter similar situation. Thank you for your help?
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New Windows Mobile Smartphones from I-mate

[Muhammad Salman]

Windows Mobile smart phone device manufacturer, i-mate has shown off
its latest models -the Ultimate 9502 and the Ultimate 8502.for other
details http://infomobilepk.blogspot.com
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Re: PIL and Python

[MaxTheMouse]

On Aug 20, 10:23 am, catafest  wrote:
> On my photo jpg i have this :
>
> Image Type: jpeg (The JPEG image format)
> Width: 1224 pixels
> Height: 1632 pixels
> Camera Brand: Sony Ericsson
> Camera Model: W810i
> Date Taken: 2009:07:09 08:16:21
> Exposure Time: 1/19 sec.
> ISO Speed Rating: 320
> Flash Fired: Flash did not fire, compulsory flash mode.
> Metering Mode: Center-Weighted Average
> Software: R4EA031     prgCXC1250321_ORANGE_HN 4.5
>
> This is the data i want edit it to make some copyright for my site.

I don't know about PIL but you might want to try exif.py.
http://sourceforge.net/projects/exif-py/
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Re: #elements of seq A in seq B

[Neal Becker]

Jan Kaliszewski wrote:

> 20-08-2009 o 01:19:24 Neal Becker  wrote:
> 
>> What would be a time efficient way to count the number of occurrences of
>> elements of sequence A in sequence B?  (in this particular case, these
>> sequences are strings, if that matters).
> 
> If you mean: to count occurences of each element of A (separately) in B...
> 
> Hm, maybe something like this:
> 
># result as a dict {: , ...}
>dict((element, B.count(element)) for element in A)
> 
> 
> If you mean: to count non overlaping occurences of string A in B
> -- simply:
> 
>B.count(A)
> 
> 
> Regards,
> *j
> 

I meant #occurrences of characters from the set A in string B

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pexpect on QNX platform

[Asha Gowda]

Hi,

I found that pexpect is available only for linux.
But we need to port to QNX, Is pexpect is available? If yes, where can I
find it.

Thanks,
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Re: difference between raw_input() and input()

[Chris Rebert]

On Thu, Aug 20, 2009 at 3:24 AM, baalu aanand wrote:
> Hi,
>
>     I have used both raw_input() and input() for a same input value.
> But these gives different output.
>
>     I have listed below what actually I have done
>
>            >>> a = raw_input("===>")
>                   ===> 023
>            >>> a
>                    '023'
>
>     I have given the same value for the input() but it gives 19 as
> result
>            >>> a = input("===>")
>                   ===>  023
>            >>> a
>                    19
>
>  Is there anything hide within this. Please illustrate the difference
> between raw_input() and input()

input() === eval(raw_input())
eval("023") --> int("23", 8) --> 19 [an integer, not a string]

raw_input() /always/ returns a string.

Never use input() in Python 2.x. In Python 3, raw_input() was renamed
to input() because it's a better name and the old input() was hardly
ever used (correctly).

Cheers,
Chris
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Zipimport leaks memory?

[ashwin.u....@nokia.com]

Hi,

We are currently trying to identify and fix all the memory leaks by just doing 
Py_Initialize-PyRun_SimpleFile(some simple script)-Py_Finalize and found that 
there are around 70 malloc-ed blocks which are not freed. One of the 
significant contributor to this number is the 'files' object in ZipImporter.  I 
am not able to identify the reason for this leak and was wondering if anyone on 
this list would help me out here. 

So, here goes :

Since we have a zip file in our sys.path, this object is initialized and added 
to the zip_directory_cache dict during Py_Initialize. One point to note here is 
that there is no DECREF on the 'files' object after adding it to the 
zip_directory_cache dict.

When a module in a directory is imported(encoding.alias) then the reference 
count of 'files' is increased. When this module is unloaded during 
Py_Finalize-PyImport_Cleanup, the ref count of files object is decremented 
properly. So at the end of Py_Finalize the files object still has one reference 
count which is a result of it being an entry in the zip_directory_cache.

To summarize :

ZipImporter->files - zipimporter_init function:

Py_Initialize - 
Read files from zip - ref_count -1
Add files to zip_directory_cache - ref count - 2
Import some modules from different directory in zip - ref count - 3

Py_Finalze - 
PyImport_Cleanup - sub-directory - ref-count - 2
PyImport_Cleanup - main directory - ref-count - 1

So the reference count of 'files' is still 1 after Py_Finalize. The 
zip_directory_cache is the dict that has this 'files' object and this dict is 
added to the module during zipimport module initialization. This dict is 
destroyed during _PyModule_Clear(called by PyImport_Cleanup) but the 'files' 
object's reference count is not decremented. 

Please excuse me if I have misinterpreted the whole logic. Any pointers towards 
solving this would be great. 

Thank you.

~Ashwin

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difference between raw_input() and input()

[baalu aanand]

Hi,

 I have used both raw_input() and input() for a same input value.
But these gives different output.

 I have listed below what actually I have done

>>> a = raw_input("===>")
   ===> 023
>>> a
'023'

 I have given the same value for the input() but it gives 19 as
result
>>> a = input("===>")
   ===>  023
>>> a
19

  Is there anything hide within this. Please illustrate the difference
between raw_input() and input()

Thanks in advance
Baalu
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Polling a net address

[Iain]

Hi All,

I'm writing a system tray application for windows, and the app needs
to poll a remote site at a pre-defined interval, and then process any
data returned.

The GUI needs to remain responsive as this goes on, so the polling
needs to be done in the background. I've been looking into Twisted as
a way of achieving this, but can't seem to get anything to loop
successfully.

Does anyone have any pointers that they might be able to give me?

TIA.
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Re: difference between 2 arrays

[Michel Claveau - MVP]

(envoyé via news:\\news.wanadoo.fr\comp.lang.python)


Hi!

Yes, the module sets is written, in doc, like "deprecated".
But: 
  - sets exist in Python 2.6 (& 2.5 or 2.4)
  - documentation of sets (module) is better tha, documentation of set 
(builtin) 

The best: read the documentaion of the module, and use the builtin...

@-salutations 
-- 
MCI 

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Re: What file is foo in package bar in ?

[Nitebirdz]

On Thu, Aug 20, 2009 at 01:06:00AM +0200, Christian Heimes wrote:
> northof40 wrote:
>> Given an arbitary package is there some programmatic way to 'ask' what
>> file the method/function is implemented in ?
>
> Indeed, the inspect module contains several useful functions for the  
> job, for example
> http://docs.python.org/library/inspect.html#inspect.getfile
>

Stupid question from someone who ignores it all: since the OP is reading
code from an existing tree in order to learn from it, wouldn't it make
more sense to use something like Cscope?  Assuming it works with Python,
of course.  If it doesn't, is there a similar tool that can be used?  A
related question too is whether any of these tools actually help in an
object-oriented environment.  

http://cscope.sourceforge.net/

http://www.linux.com/archive/feature/114237

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Re: How to create functors?

[Steven D'Aprano]

On Thu, 20 Aug 2009 01:36:14 -0700, Paul Rubin wrote:

> Steven D'Aprano  writes:
>> As near as I can tell, a functor is just an object which is callable
>> like a function without actually being implemented as a function, e.g.:
> 
> No it's not anything like that either, at least as I'm used to the term
> in programming or in mathematics.  Maybe it's used other ways though. 

According to Wikipedia, functor can be used as a synonym for "function 
object":

http://en.wikipedia.org/wiki/Function_object

which is what I was thinking of. So it seems there are at least two 
meanings for the word, neither of which seems to apply to this thread :)



> As I'm used to it, it's a feature of certain static type systems.  The
> notion isn't that useful in Python 

I find the Haskell page entirely opaque and unintelligible. Well, perhaps 
not *entirely* opaque, but pretty close: it assumes a mathematical 
sophistication that I don't think I even had when I was getting my maths 
degree, let alone can remember two decades later. (Pity the poor VB 
coders wondering what Haskell is good for...) The Wikipedia page is a 
little better, but it's section on Examples is laughable -- the examples 
are as unintelligible to this reader as the description before them.


But let me try an example to see if I've got it right:


class Int2StrFunctor:
def map1(self, n):
if type(n) is not int:
raise TypeError('argument must be an int')
return "-"*n
def map2(self, f):
if type(f) is not type(lambda: None):
raise TypeError('argument must be a function')
# assume f takes an int, and returns another int
def inner(n):
return self.map1(f(n))
return inner


The functor can take an int and return a string:

>>> F = Int2StrFunctor()  # F is a functor
>>> F.map1(3)
'---'

It can also take a function (of int -> int) and return a new function 
(int -> str):

>>> def myfunc(n):
... return n+2
...
>>> f = F.map2(myfunc)
>>> f(3)
'-'
>>> f(4)
'--'


There's nothing special about the methods map1() and map2(), I could call 
them anything I like, or even do this:


>>> def __call__(self, arg):
... if type(arg) is int:
... return self.map1(arg)
... else:
... return self.map2(arg)
...
>>> Int2StrFunctor.__call__ = __call__
>>>
>>> F(2)
'--'
>>> F(myfunc)(0)
'--'


There are some technical restrictions on functors, relating to the sorts 
of functions and types (strictly "categories") they can accept, 
presumably to make them mathematically well-behaved.


Have I got it correct?


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Re: How to create functors?

[Paul Rubin]

Steven D'Aprano  writes:
> As near as I can tell, a functor is just an object which is 
> callable like a function without actually being implemented as a 
> function, e.g.:

No it's not anything like that either, at least as I'm used to the
term in programming or in mathematics.  Maybe it's used other ways
though.  As I'm used to it, it's a feature of certain static type
systems.  The notion isn't that useful in Python but you could
translate it something like this: imagine that the "list" datatype has
a couple extra operations:

   # lift_value turns a normal value from a base type to a 1-element list
   list.lift_value(x) = [x]

   # lift_function turns a function on a base type to a higher order
   # function that operates on a whole list
   list.lift_function(f) = partial(map, f)
   
Then given a function like

   def square(x): return x*x

you could say

   lifted_square = list.lifted_function(square)
   print lifted_square([1,2,3,4,5])

and get [1,4,9,16,25].  Similarly if you had some other type (like a
tree data structure), that type could also support a map-like
operation so you could lift functions to it (lifting a function and
applying it to a tree like [1,[2,3],4] would result in [1,[4,9],16] or
whatever).

If I remember properly, for type t to be a functor it needs the above
two lifting operations, with the property that for a given function f,

   t.lifted_value(f(x)) = (t.lifted_function(f))(t.lifted_value(x))

I guess this explanation isn't going that well but basically in a
statically typed language you'd use functors to convert the signatures
of functions to versions that operate on higher types.  The idea comes
from ML and is used explicitly in Haskell, and I think some of the C++
standard template library can be explained in terms of functors.

For the mathematical concept of functors and how they relate to
programming (at least Haskell's version), see:

   http://en.wikibooks.org/Haskell/Category_theory
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Re: PIL and Python

[catafest]

On my photo jpg i have this :

Image Type: jpeg (The JPEG image format)
Width: 1224 pixels
Height: 1632 pixels
Camera Brand: Sony Ericsson
Camera Model: W810i
Date Taken: 2009:07:09 08:16:21
Exposure Time: 1/19 sec.
ISO Speed Rating: 320
Flash Fired: Flash did not fire, compulsory flash mode.
Metering Mode: Center-Weighted Average
Software: R4EA031 prgCXC1250321_ORANGE_HN 4.5

This is the data i want edit it to make some copyright for my site.
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Re: regular expression

[Peter Otten]

Pierre wrote:

> I would like to change the string "(1 and (2 or 3))"  by  "(x[1] & (x
> [2] || x[3]))" using regular expression...
> Anyone can help me ?

>>> re.compile(r"(\d+)").sub(r"x[\1]", "(1 and (2 or 3))")
'(x[1] and (x[2] or x[3]))'
>>> re.compile("and|or").sub(lambda m, d={"and":"&", "or":"||"}: 
d[m.group()], _)
'(x[1] & (x[2] || x[3]))'

Peter


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Re: Dictionary from a list

[Peter Otten]

Steven D'Aprano wrote:

> On Thu, 20 Aug 2009 08:10:28 +0200, Peter Otten wrote:
> 
> 
>> I just can't stop posting this one:
>> 
> from itertools import izip
> it = iter([1,2,3,4,5,6])
> dict(izip(it, it))
>> {1: 2, 3: 4, 5: 6}
>> 
>> I really tried, but yours drove me over the edge.
> 
> If you want something to drive you over the edge:

I meant that figuratively...

 alist = [1, 2, 3, 4, 5, 6]
 dict(apply(zip, map(lambda n: map(lambda t: t[1], filter(lambda t:
> ((not (t[0]%2)) == 1) == n, enumerate(alist))), range(1, -1, -1
> {1: 2, 3: 4, 5: 6}

...originally.

> Enjoy :)

Not ;)

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Re: Dictionary from a list

[Tim Chase]

Peter Otten wrote:

it = iter([1,2,3,4,5,6])
dict(izip(it, it))

{1: 2, 3: 4, 5: 6}


Zip(it).  Zip(it) good.

it's-3:00am-and-i-seriously-need-to-sleep'ly yers...

-tkc



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Re: regular expression

[Steven D'Aprano]

On Thu, 20 Aug 2009 00:18:23 -0700, Pierre wrote:

> Hello,
> 
> I would like to change the string "(1 and (2 or 3))"  by  "(x[1] & (x
> [2] || x[3]))" using regular expression... Anyone can help me ?


Do you mean you want to change the string into "(x[1] & (x[2] || x[3]))" ?

Does it have to be using regular expressions? Would this be good enough?


>>> s = "(1 and (2 or 3))"
>>> for c in '123':
... s = s.replace(c, 'x[%s]'%c)
...
>>> s = s.replace('or', '||')
>>> s = s.replace('and', '&')
>>> s
'(x[1] & (x[2] || x[3]))'



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Re: How to create functors?

[Rami Chowdhury]

As near as I can tell, a functor is just an object which is
callable like a function



I believe that's how they're defined in the C++ world, in which, of  
course, functions aren't first-class objects...


-
Rami Chowdhury
"Never assume malice when stupidity will suffice." -- Hanlon's Razor
408-597-7068 (US) / 07875-841-046 (UK) / 0189-245544 (BD)




On Aug 19, 2009, at 21:11 , Steven D'Aprano wrote:


On Wed, 19 Aug 2009 18:42:32 -0700, Paul Rubin wrote:


Robert Dailey  writes:
I want to simply wrap a function up into an object so it can be  
called

with no parameters.


Nitpick: what you are asking for is called a closure.  "Functor"  
means

something completely different.



I'm glad somebody else noticed this. I would have said something  
about it

myself, except I wasn't entirely sure my understanding of functor is
correct. As near as I can tell, a functor is just an object which is
callable like a function without actually being implemented as a
function, e.g.:

class Functor:
def __call__(self):
return None

f = Functor()
result = f()



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regular expression

[Pierre]

Hello,

I would like to change the string "(1 and (2 or 3))"  by  "(x[1] & (x
[2] || x[3]))" using regular expression...
Anyone can help me ?

Thanks.



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Re: Dictionary from a list

[Steven D'Aprano]

On Thu, 20 Aug 2009 08:10:28 +0200, Peter Otten wrote:


> I just can't stop posting this one:
> 
 from itertools import izip
 it = iter([1,2,3,4,5,6])
 dict(izip(it, it))
> {1: 2, 3: 4, 5: 6}
> 
> I really tried, but yours drove me over the edge.

If you want something to drive you over the edge:


>>> alist = [1, 2, 3, 4, 5, 6]
>>> dict(apply(zip, map(lambda n: map(lambda t: t[1], filter(lambda t: 
((not (t[0]%2)) == 1) == n, enumerate(alist))), range(1, -1, -1
{1: 2, 3: 4, 5: 6}


Enjoy :)



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