Re: how to search multiple textfiles ? (Python is slow ?)

[M�ta-MCI (MVP)]

Hi !

Thanks for return.

Some infos: from a long time, I found that it's often more fast to use 
windows's command, instead of develop in high level language (and also, 
low level...)


FINDSTR is fast. OK. But internal commands are more fast. Example : DIR 
(with all his options)

And it's faster to read the result via a Pipe.
Thus, I use frequently this sort of function:


import os

def cmdone(repstart, commande, moderetour="LIST"):
   os.chdir(repstart)
   sret=''.join(os.popen(commande))
   if moderetour.upper() == "STR":
   return sret
   else:
   return sret.split('\n')

print cmdone('D:\\dev\\python','findstr /N /I ponx *.py','STR')
print
print cmdone('D:\\dev\\python','dir *.jpg /B')




Sorry for my bad english, and have a good day...
--
Michel Claveau


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Negative block sizes with file-like objects

[Steven D'Aprano]

I have a proxy class that wraps an arbitrary file-like object fp and 
reads blocks of data from it. Is it safe to assume that fp.read(-1) will 
read until EOF? I know that's true for file.read() and StringIO.read(), 
but is it a reasonable assumption to make for arbitrary file-like objects?

To put it in more concrete terms, I have a class like this:

class C(object):
# Much simplified version.
def __init__(self, fp):
self.fp = fp
def read(self, size=-1):
return self.fp.read(size)


Should I re-write the read() method like this?

def read(self, size=-1):
if size < 0:
return self.fp.read()
else:
return self.fp.read(size)



-- 
Steven
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Re: Are spams on comp.lang.python a major nuisance?

[Bob Cortopassi]

On 2008-09-26, nntpman68 <[EMAIL PROTECTED]> wrote:

> - I'm annoyed by any spam.
> It's tough to find good rules, but the incoming spams that I see 
> currently on comp.lang.python have certain criteas.
>
> - most email addresses from gmail.
...snip rest of good filter criteria...

Killing all messages with "googlegroups" in the messageid will get rid
of a vast majority of the spam.  Killing anything with a gmail.com
email address will end up killing more legitimate posters.

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All posts from Google Groups are auto-killed.
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Re: Negative block sizes with file-like objects

[Peter Otten]

Steven D'Aprano wrote:

> I have a proxy class that wraps an arbitrary file-like object fp and
> reads blocks of data from it. Is it safe to assume that fp.read(-1) will
> read until EOF? I know that's true for file.read() and StringIO.read(),
> but is it a reasonable assumption to make for arbitrary file-like objects?
> 
> To put it in more concrete terms, I have a class like this:
> 
> class C(object):
> # Much simplified version.
> def __init__(self, fp):
> self.fp = fp
> def read(self, size=-1):
> return self.fp.read(size)
> 
> 
> Should I re-write the read() method like this?
> 
> def read(self, size=-1):
> if size < 0:
> return self.fp.read()
> else:
> return self.fp.read(size)

Grepping through the python source shows that both -1 and None are used as
the default size.

# python2.5.2
>>> import tarfile
>>> open("sample", "w").write("contents-of-sample")
>>> t = tarfile.open("sample.tar", "w")
>>> t.add("sample")
>>> t.close()
>>> t = tarfile.open("sample.tar")
>>> t.extractfile("sample").read()
'contents-of-sample'
>>> t.extractfile("sample").read(-1)[:50]
'contents-of-sample\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00'

So you may fare better with the rewrite. But even that may fail:

http://docs.python.org/lib/bltin-file-objects.html#l2h-295

"""
read(  [size])
[...] If the size argument is negative or omitted, read all data until EOF
is reached. [...]
Also note that when in non-blocking mode, less data than what was requested
may be returned, even if no size parameter was given. 
"""

Peter
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Re: Are spams on comp.lang.python a major nuisance?

[Dotan Cohen]

2008/9/26 nntpman68 <[EMAIL PROTECTED]>:
> It's tough to find good rules, but the incoming spams that I see currently
> on comp.lang.python have certain criteas.
>
>
>
> - most email addresses from gmail.
> - all never posted before and then they have multiple posts within a few
> minutes  / seconds
> - the posts always contain one or more urls ( mostly cryptic names )
> - they always start a thread but never reply to one
> - the post doesn't contain python code or anything which looks only vaguely
> like source code
> - never mentions the word python
> - the amount of sexual or financial vocabulary exceeds classical python
> posts
>

I hope that the spammers don't read the list!

-- 
Dotan Cohen

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

ä-ö-ü-ß-Ä-Ö-Ü
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python for *nix system admins

[Lars Stavholm]

Hi All,

I'm new to this list and hoping that this is not off-topic.
If it is, please point me in the right direction.

I seem to recollect a python module or library for *nix sysadmins,
but I can't for the life of me find it again.

The module (or library) somehow added unix command capabilities
to the python language. It seemed like a lesser known, perhaps new,
python library or module.

Any input or ideas appreciated
/Lars Stavholm
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Re: What do you call a class not intended to be instantiated

[Ben Finney]

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

> On Fri, 26 Sep 2008 22:15:43 -0700, Aahz wrote:
> > An ordinary singleton is instantiating the class multiple times
> > yet returning the same instance object; a class singleton is
> > simply using the class directly (like a module).

Where is this "class singleton" terminology from? It seems redundant
to me. It also doesn't seem to have anything to do with what
"singleton" means as a pattern; "using a class" is simply using a
class.

> Since I now no longer think I need such a beast

That's a relief :-)

> I'd like to be able to call [a class] as if it were a function.
> Normally calling a class object returns an instance -- I wish to
> return something else.

In that case, you *don't* want a class at all; the entire point of a
class is to define behaviour for instances.

Instead, you want to define a class whose *instances* are callable, by
defining the '__call__' method to do whatever it is you want.

> This seems to works:
> 
> >>> class ClassSingleton(object):
> ... thing = (0, 1, 2)
> ... def __new__(cls, *args):
> ... return len(args+cls.thing)
> ...
> >>> ClassSingleton(1, 2, 4, 8, 16)
> 8

Horribly obfuscatory. Calling a class should return a new instance of
the class or something like it.

Instead, define it so the user instantiates the class by calling the
class, and *then* calls that non-class object, and so shouldn't expect
to get a new instance back:

>>> class CallableAppendor(object):
... thing = (0, 1, 2)
... def __call__(self, *args):
... return len(args + self.thing)
...
>>> appendor = CallableAppendor()
>>> appendor(1, 2, 4, 8, 16)
8

-- 
 \ “Pleasure's a sin, and sometimes sin's a pleasure.” —“Lord” |
  `\  George Gordon Noel Byron, _Don Juan_ |
_o__)  |
Ben Finney
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Re: python for *nix system admins

[km]

import os

HTH
KM
~~

On Sat, Sep 27, 2008 at 1:35 PM, Lars Stavholm <[EMAIL PROTECTED]> wrote:

> Hi All,
>
> I'm new to this list and hoping that this is not off-topic.
> If it is, please point me in the right direction.
>
> I seem to recollect a python module or library for *nix sysadmins,
> but I can't for the life of me find it again.
>
> The module (or library) somehow added unix command capabilities
> to the python language. It seemed like a lesser known, perhaps new,
> python library or module.
>
> Any input or ideas appreciated
> /Lars Stavholm
> --
> http://mail.python.org/mailman/listinfo/python-list
>
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Re: Running IDLE on 3.0rc1

[Terry Reedy]

Allan wrote:

Terry Reedy <[EMAIL PROTECTED]> writes:


I have not seen this posted, so...
To run IDLE with Python3.0rc1,
edit Python30/Libs/idlelib/run.py,
and change "set_daemon(True)" to "daemon = True" and save.
(This is about line 75, and the only appearance of 'daemon'.)
Otherwise, you get error message about not starting a subprocess.

Is this related to the tip at the end of the built-in help file in IDLE
regarding the `-n' command option?

No, the above is a bug fix that did not make it into rc1 but has now 
been committed.  It arose because the interface of a class in one of the 
modules was changed from .set_var(val) to .var = val and the need to 
change IDLE was not caught.  I imagine that checking that IDLE runs in 
not in the test suite.


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Re: python for *nix system admins

[Lars Stavholm]

km wrote:
> import os

Thanks, but I'm aware of the standard libraries like os, sys,
commands, and whatnot. I'm looking for a non-standard library
that acts like a wrapper for the unix commands. I have seen it,
I just can't find it again.
/L

> On Sat, Sep 27, 2008 at 1:35 PM, Lars Stavholm <[EMAIL PROTECTED]
> > wrote:
> 
> Hi All,
> 
> I'm new to this list and hoping that this is not off-topic.
> If it is, please point me in the right direction.
> 
> I seem to recollect a python module or library for *nix sysadmins,
> but I can't for the life of me find it again.
> 
> The module (or library) somehow added unix command capabilities
> to the python language. It seemed like a lesser known, perhaps new,
> python library or module.
> 
> Any input or ideas appreciated
> /Lars Stavholm
> --
> http://mail.python.org/mailman/listinfo/python-list
> 
> 

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Using the 'with' statement with cStringIO objects

[peppergrower]

I've been experimenting with the 'with' statement (in __future__), and
so far I like it.  However, I can't get it to work with a cStringIO
object.  Here's a minimum working example:

###
from __future__ import with_statement
import cStringIO

teststring='this is a test'

with cStringIO.StringIO(teststring) as testfile:
pass
###

I get the following error message:

Traceback (most recent call last):
  File "testfile.py", line 6, in 
with cStringIO.StringIO(teststring) as testfile:
AttributeError: 'cStringIO.StringI' object has no attribute '__exit__'

So, I'm guessing you can't use the 'with' statement with cStringIO
objects?  Is this a bug, or do I need to use the 'with' statement
differently to get this to work?

Thanks,
peppergrower
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Re: python for *nix system admins

[Ben Finney]

Lars Stavholm <[EMAIL PROTECTED]> writes:

> The module (or library) somehow added unix command capabilities
> to the python language. It seemed like a lesser known, perhaps new,
> python library or module.

Which particular Unix commands?

Perhaps you're thinking of the 'shutil' module
http://www.python.org/doc/lib/module-shutil>, which wraps a few
filesystem manipulation commands.

-- 
 \ “Of all classes the rich are the most noticed and the least |
  `\  studied.” —John Kenneth Galbraith, _The Age of Uncertainty_, |
_o__) 1977 |
Ben Finney
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Re: What do you call a class not intended to be instantiated

[Steven D'Aprano]

On Sat, 27 Sep 2008 18:20:17 +1000, Ben Finney wrote:

> Steven D'Aprano <[EMAIL PROTECTED]> writes:
> 
>> On Fri, 26 Sep 2008 22:15:43 -0700, Aahz wrote:
>> > An ordinary singleton is instantiating the class multiple times yet
>> > returning the same instance object; a class singleton is simply using
>> > the class directly (like a module).
> 
> Where is this "class singleton" terminology from? 

I don't know. Googling on it brings up an awful lot of C++ and Java 
source code for regular Singletons. Perhaps Aahz can shed some light on 
it?


> It seems redundant to
> me. It also doesn't seem to have anything to do with what "singleton"
> means as a pattern; "using a class" is simply using a class.


I don't see why this idiom causes such conceptual difficulty. There are 
classes with many instances; there are classes with a single instance 
(Singleton). Why should't there be classes with no instances?

A class is just an object. If you find yourself caring whether a 
particular object is a class, an instance or a function, then you have to 
ask yourself why you are worrying about the implementation details. Of 
course as the library writer, it's your job to worry about the 
implementation details, but ideally the library user shouldn't have to.

 
>> Since I now no longer think I need such a beast
> 
> That's a relief :-)
> 
>> I'd like to be able to call [a class] as if it were a function.
>> Normally calling a class object returns an instance -- I wish to return
>> something else.
> 
> In that case, you *don't* want a class at all; the entire point of a
> class is to define behaviour for instances.

Classes encapsulate state + behaviour in one package, and they allow 
inheritance. That's a lot more than merely defining behaviour of 
instances. Instances in turn have the additional capability of being able 
to over-ride the class' state and behaviour:

class C(object):
x = 'spam'

c = C()
c.x = 'ham'  # doesn't touch C.x

If your instance doesn't do something the class can't do on it's own, why 
bother with the instance?



> Instead, you want to define a class whose *instances* are callable, by
> defining the '__call__' method to do whatever it is you want.

Most of the time, sure.


 
>> This seems to works:
>> 
>> >>> class ClassSingleton(object):
>> ... thing = (0, 1, 2)
>> ... def __new__(cls, *args):
>> ... return len(args+cls.thing) ...
>> >>> ClassSingleton(1, 2, 4, 8, 16)
>> 8
> 
> Horribly obfuscatory. Calling a class should return a new instance of
> the class or something like it.

Apart from the name, which I dislike, what is obfuscatory about it? 
Haven't you ever used factory functions or class builders? It's the same 
principle. Why do you care that ClassSingleton is a class instead of a 
function?

I'm certainly not saying that we should use classes this way all the 
time, but the capability is there, and apparently not by accident. Guido 
wrote:

"__new__ must return an object. There's nothing that requires that it 
return a new object that is an instance of its class argument, although 
that is the convention. If you return an existing object of your class or 
a subclass, the constructor call will still call its __init__ method. If 
you return an object of a different class, its __init__ method will not 
be called."

http://www.python.org/download/releases/2.2.3/descrintro/



> Instead, define it so the user instantiates the class by calling the
> class, and *then* calls that non-class object, and so shouldn't expect
> to get a new instance back:
> 
> >>> class CallableAppendor(object):
> ... thing = (0, 1, 2)
> ... def __call__(self, *args):
> ... return len(args + self.thing) ...
> >>> appendor = CallableAppendor()
> >>> appendor(1, 2, 4, 8, 16)
> 8


That's the right solution when the instance is able to override the state 
and/or behaviour of the class. Most uses of classes are like that:

class Spam(object):
def __init__(self, n):
self.n = n
def sing(self):
return "spam "*self.n + " glorious SPAM!!!"

Because the behaviour (method 'sing') depends on state which is specific 
to the instance (attribute 'n'), it is right and proper to instantiate 
the class. The class 'Spam' is a constructor for instances, and the 
instances do all the work.

But my earlier example is not the same. In the example I gave, neither 
the behaviour nor the state depend on the instance: everything is 
specified in the class. Ben's variant behaves differently: the caller 
might override appendor.thing by hand. That is Ben's choice, of course, 
and it may be a valid one for many applications, but it's displaying 
different behaviour to my example.

In my example, the instance doesn't matter. I could write it like this:

>>> class CallableAppendor(object):
... thing = (0, 1, 2)
... @classmethod
... def __call__(cls, *args):
... return len(args + cls.thing)
...
>>> appendor = CallableAppendor()
>>> 

Re: Using the 'with' statement with cStringIO objects

[Fredrik Lundh]

peppergrower wrote:


teststring='this is a test'

with cStringIO.StringIO(teststring) as testfile:
pass


umm.  what exactly do you expect that code to do?



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Re: How to read a jpg bytearray from a Flash AS3 file

[Fredrik Lundh]

[EMAIL PROTECTED] wrote:


I'm trying to save an image from a Flash AS3 to my server as a jpg
file. I found some PHP code to do this, but I want to do this in
Python. I'm not quite sure how to convert the following code to
Python. It's mainly the $GLOBALS["HTTP_RAW_POST_DATA"] part I don't
know how to convert.


depends on what framework you're using.  if you're using plain CGI, you 
should be able to read the posted data from sys.stdin:


  import sys

  im = sys.stdin.read()

  f = open(name, 'wb')
  f.write(jpg)
  f.close()

to make your code a bit more robust, you may want to check the 
content-length before doing the read, e.g.


  import os

  if os.environ.get("REQUEST_METHOD") != "POST":
  ... report invalid request ...

  bytes = int(os.environ.get("CONTENT_LENGTH", 0))
  if bytes > MAX_REQUEST_SIZE:
  ... report request too large ...

  im = sys.stdin.read(bytes)

to deal with query parameters etc, see

   http://docs.python.org/lib/module-cgi.html



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Re: what does ` ` do in ' '.join([`x * x` for x in range(1, 6)])?

[alex23]

On Sep 27, 3:58 pm, r0g <[EMAIL PROTECTED]> wrote:
> Ah, just spotted the backticks - they just return whatever's inside them
> as a string.

No, they return the repr() of the object inside. The output of
__repr__ -has- to be a string, but typecasting into string isn't the
intention of repr() (or the ` operator).
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Re: How to get the filename in the right case ?

[Fredrik Lundh]

Stef Mientki wrote:


I don't think your suggestion is a good one.
If a filename has uppercase characters in it,
the END-USER has done that for some kind of reason.


I explain how pdb works and show you how to solve the specific 
comparison problem you mentioned in your post, and you start ranting 
because it doesn't solve all your problems?  what's wrong with you?




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Re: How to get the filename in the right case ?

[Michael Torrie]

Steven D'Aprano wrote:
> On Fri, 26 Sep 2008 01:46:15 +0200, Stef Mientki wrote:
> 
>> Secondly thoughtless copying of current behavior, doesn't bring any
>> progress,
>> and I think that's one of the reasons why we're still burdened by
>> inventions done 20 years ago,
>> e.g. "do you want to save your changes ?".
> 
> I click No about 50% of the time, and Yes Of Course You Stupid Machine 
> the other 50% of the time. Until they have a computer capable of reading 
> my mind, I'm curious what alternative you'd suggest.

It's well known that just using "Yes" and "No" in a dialog box is very,
very poor UI design.  In many cases it leads to confusion.  Especially
when the dialog box has both a statement and a question, which many do.
 The correct and proper way is to use only verbs in the buttons.  For
example instead of yes/no to the question of saving work before exiting,
you'd use "save" and "don't save."  That's extremely clear even if you
don't quite understand the statement and question the dialog is asking.

Certainly the human-interface guidelines on the more sane systems out
there (OS X, Gnome) disallow the use of yes/no buttons in dialog boxes.
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Re: Are spams on comp.lang.python a major nuisance?

[Aaron "Castironpi" Brady]

On Sep 26, 1:04 pm, "Aaron \"Castironpi\" Brady"
<[EMAIL PROTECTED]> wrote:
> On Sep 26, 11:43 am, "Tim Rowe" <[EMAIL PROTECTED]> wrote:
>
> > 2008/9/26 Steven D'Aprano <[EMAIL PROTECTED]>:
>
> > > I don't have any objective numbers, but subjectively it seems to me that
> > > the number of spams is significantly higher, but not so high as to be a
> > > major nuisance.
>
> > I consider *any* spam to be a major nuisance, but I don't see them as
> > being the fault of python-list which seems to do a pretty good job of
> > blocking them
>
> I think in June and July they were selling watches a lot which I
> haven't noticed recently.

Gucci 104 G-Bandeau Watches - Gucci Watches Discount Rolex Oyster
Perpetual Lady Datejust Pearlmaster 18kt Yellow Gold Diamond Ladies
Watch 80318C
Cartier Must 21 Watches - Cartier Watches Discount

I speak too soon.

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Re: Are spams on comp.lang.python a major nuisance?

[Dotan Cohen]

2008/9/27 Aaron Castironpi Brady <[EMAIL PROTECTED]>:
>> I think in June and July they were selling watches a lot which I
>> haven't noticed recently.
>
> Gucci 104 G-Bandeau Watches - Gucci Watches Discount Rolex Oyster
> Perpetual Lady Datejust Pearlmaster 18kt Yellow Gold Diamond Ladies
> Watch 80318C
> Cartier Must 21 Watches - Cartier Watches Discount
>
> I speak too soon.
>

If we start blocking users who have no previous posts and then post
many new messages at once, then we wll just push the spammers to forge
active list users and reply to threads. That would be a worse
situation then we are in now. I say leave well enough alone.

Read about the Brain Blood Barrier
(http://en.wikipedia.org/wiki/Brain_Blood_Barrier) for an example in
nature where although a method to stop an attacker exists, it is not
overused to prevent the attacker from becoming more powerful.

-- 
Dotan Cohen

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

ä-ö-ü-ß-Ä-Ö-Ü
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Regular expression help: unable to search ' # ' character in the file

[dudeja . rajat]

Hi,

Can some help me with the regular expression. I'm looking to search #
character in my file?

My file has contents:

###

Hello World

###

length = 10
breadth = 20
height = 30

###



###

Hello World

###

length = 20
breadth = 30
height = 40

###


I used the following search :

import re

fd = open(file, 'r')
line = fd.readline
pat1 = re.compile("\#*")
while(line):
mat1 = pat1.search(line)
if mat1:
print line
line = fd.readline()


But the above prints the whole file instead of the hash lines only.


Please help


Regards,
Rajat
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Re: what does ` ` do in ' '.join([`x * x` for x in range(1, 6)])?

[Roy Smith]

In article 
<[EMAIL PROTECTED]>,
 alex23 <[EMAIL PROTECTED]> wrote:

> ' '.join((str(x * x) for x in range(1,6)))

Aren't the outer set of parens redundant?  This works just as well:

' '.join(str(x * x) for x in range(1,6))
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Re: What do you call a class not intended to be instantiated

[Aaron "Castironpi" Brady]

On Sep 27, 5:33 am, Steven D'Aprano <[EMAIL PROTECTED]
cybersource.com.au> wrote:
> On Sat, 27 Sep 2008 18:20:17 +1000, Ben Finney wrote:
> > Steven D'Aprano <[EMAIL PROTECTED]> writes:
>
> >> On Fri, 26 Sep 2008 22:15:43 -0700, Aahz wrote:
> >> > An ordinary singleton is instantiating the class multiple times yet
> >> > returning the same instance object; a class singleton is simply using
> >> > the class directly (like a module).
>
> > Where is this "class singleton" terminology from?
>
> I don't know. Googling on it brings up an awful lot of C++ and Java
> source code for regular Singletons. Perhaps Aahz can shed some light on
> it?

[snip]

> In my example, the instance doesn't matter. I could write it like this:
>
> >>> class CallableAppendor(object):
>
> ...     thing = (0, 1, 2)
> ...     @classmethod
> ...     def __call__(cls, *args):
> ...         return len(args + cls.thing)
> ...>>> appendor = CallableAppendor()
> >>> appendor.thing = (1, 2, 3, 4, 5, 6, 7, 8)
> >>> appendor(1, 2, 4, 8, 16)
> 8
> >>> CallableAppendor.__call__(1,2,4,8,16)
>
> 8
>
> but what's the purpose of instantiating the class?

I've used them (class singletons, adopting the term) as a Globals
namespace, but only to the end of tidying.  It makes it easy to
reassign immutables.

It is too bad 'CallableAppendor.__call__(1,2,4,8,16)' doesn't work as
expected.  That is, 'CallableAppendor(1,2,4,8,16)' dosen't call
'__call__'.  I have a workaround, which may be just what you're
looking for.

>>> class A(type):
... def __call__( self, *ar ):
... print 'call', self, ar
...
>>> class B(object):
... __metaclass__= A
...
>>> B(3)
call  (3,)

Overriding the __call__ method of 'type' has the effect of giving you
a static __call__ method on a class-- a method which doesn't need an
instance to call.  Your behavior may be counterintuitive though, to
someone who wants to instantiate 'B', in this case, and proceed like a
normal object.  That is, they want to call a generic class and use it,
and also expect instances of B to behave as B.  You can't have both,
so either return B from B.__new__, or, to instantiate B, take the long
way and call B.__new__ directly.

>>> B.__new__(B)
<__main__.B object at 0x009FDB70>

Has anyone stepped through the C code to find out when the decision is
made to call which function, B.__new__ or A.__call__, when B is
called?  I'm happy that overriding type.__call__ produced the intended
results; it's always nice when things go right.
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Re: Build-in 'repr' function (was: what does ` ` do in ' '.join([`x * x` for x in range(1, 6)])?)

[MRAB]

On Sep 27, 4:16 am, Ben Finney <[EMAIL PROTECTED]>
wrote:
> process <[EMAIL PROTECTED]> writes:
> > ' '.join([`x * x` for x in range(1, 6)])
>
> > exactly what does this symbol do and what does it stand for?
>
> It's an obsolete, deprecated syntactic sugar for (what is now
> implemented as) the built-in 'repr' function.
>
> Instead, write the above as:
>
>     ' '.join([repr(x * x) for x in range(1, 6)])
>
I'd classify it as one of Guido's mistakes! :-)
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Re: Regular expression help: unable to search ' # ' character in the file

[Fredrik Lundh]

[EMAIL PROTECTED] wrote:


import re

fd = open(file, 'r')
line = fd.readline
pat1 = re.compile("\#*")
while(line):
mat1 = pat1.search(line)
if mat1:
print line
line = fd.readline()


I strongly doubt that this is the code you used.


But the above prints the whole file instead of the hash lines only.


"*" means zero or more matches.  all lines is a file contain zero or 
more # characters.


but using a RE is overkill in this case, of course.  to check for a 
character or substring, use the "in" operator:


for line in open(file):
if "#" in line:
print line



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Re: python for *nix system admins

[George Boutsioukis]

On Sat, 27 Sep 2008 10:05:01 +0200, Lars Stavholm wrote:

> Hi All,
> 
> I'm new to this list and hoping that this is not off-topic. If it is,
> please point me in the right direction.
> 
> I seem to recollect a python module or library for *nix sysadmins, but I
> can't for the life of me find it again.
> 
> The module (or library) somehow added unix command capabilities to the
> python language. It seemed like a lesser known, perhaps new, python
> library or module.
> 
> Any input or ideas appreciated
> /Lars Stavholm

The only modules I've come across that barely fit your description are 
python-unixtools(gzip, bzip only) and shutil(some limited capabilities). 
Running unix commands is usually done directly(os.popen, os.system) on 
*nix platforms. Why(and how) would anyone rewrite them as python modules?
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Re: Are spams on comp.lang.python a major nuisance?

[Aaron "Castironpi" Brady]

On Sep 27, 7:28 am, "Dotan Cohen" <[EMAIL PROTECTED]> wrote:
> 2008/9/27 Aaron Castironpi Brady <[EMAIL PROTECTED]>:
>
> >> I think in June and July they were selling watches a lot which I
> >> haven't noticed recently.
>
> > Gucci 104 G-Bandeau Watches - Gucci Watches Discount Rolex Oyster
> > Perpetual Lady Datejust Pearlmaster 18kt Yellow Gold Diamond Ladies
> > Watch 80318C
> > Cartier Must 21 Watches - Cartier Watches Discount
>
> > I speak too soon.
>
> If we start blocking users who have no previous posts and then post
> many new messages at once, then we wll just push the spammers to forge
> active list users and reply to threads. That would be a worse
> situation then we are in now. I say leave well enough alone.
>
> Read about the Brain Blood Barrier
> (http://en.wikipedia.org/wiki/Brain_Blood_Barrier) for an example in
> nature where although a method to stop an attacker exists, it is not
> overused to prevent the attacker from becoming more powerful.
>
> --
> Dotan Cohen
>
> http://what-is-what.comhttp://gibberish.co.il
> א-ב-ג-ד-ה-ו-ז-ח-ט-י-ך-כ-ל-ם-מ-ן-נ-ס-ע-ף-פ-ץ-צ-ק-ר-ש-ת
>
> ä-ö-ü-ß-Ä-Ö-Ü

Yow!  I forgot the radiolabeled polyethylene glycol coated
hexadecylcyanoacrylate nanospheres!

CMIIW correct me if I'm wrong.  Google Groups is a Usenet/c-l-py
gateway.  Other gateways aren't contributing to spam.  What are they
doing that G-Groups is not?
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Re: is decorator the right thing to use?

[George Sakkis]

On Sep 27, 1:44 am, "Dmitry S. Makovey" <[EMAIL PROTECTED]> wrote:

> George Sakkis wrote:
> > Although this works, the second argument to ProxyMethod shouldn't be
> > necessary, it's semantically redundant;  ideally you would like to
> > write it as "bmethod = ProxyMethod('b')".
>
> since I'm already on exploratory trail (what about that rug being pulled
> from under?) With my code I can do really dirty tricks like this (not
> necessary that I'm going to):
>
> class B_base:
> def bmethod(self):
> print 'B_base'
>
> class B(B_base):
> def bmethod(self):
> print 'B'
>
> class A:
> bmethod=ProxyMethod('b',B_base.bmethod)

Yes, that's indeed dirty; don't do it :)

> > As before, I don't think
> > that's doable without metaclasses (or worse, stack frame hacking).
> > Below is the update of my original recipe; interestingly, it's
> > (slightly) simpler than before:
>
> Out of curiosity (and trying to understand): why do you insist on
> dictionaries with strings contents ( {'bmethod' : 'b1' } ) rather than
> something more explicit ? Again, I can see that your code is working and I
> can even understand what it's doing, just trying to explore alternatives :)
>
> I guess my bias is towards more explicit declarations thus
>
>  bmethod=ProxyMethod('b',B.bmethod)
>
> looks more attractive to me, but I stand to be corrected/educated why is
> that not the right thing to do?

I see where you're coming from and I also prefer explicit reflection
mechanisms instead of strings (e.g. avoid eval/exec as much as
possible). As I mentioned, the second argument to ProxyMethod is (for
all sane purposes) redundant, so if you could implement it in a way
that "bmethod = ProxyMethod('b')" worked, I would be all for it, but
AFAIK it's not possible without a metaclass. A dict with string keys
and values to be consumed by a metaclass is perhaps the simplest thing
that could possibly work. It contains all the relevant information for
hooking the proxy to the delegate methods and nothing more; zero
boilerplate code overhead. Also note that it's not that big of a
difference; you have to provide the attribute name as a string anyway.

> Another thing that turns me away from string dictionaries is that those are
> the ones causing me more trouble hunting down typos. Maybe it's just "my
> thing" so I'm not going to insist on it. I'm open to arguments against that
> theory.

>From my experience, I am equally prone to typos for both strings and
regular attributes; I agree though that the traceback information is
often more helpful when you mistype an attribute.

> One argument I can bring in defence of more explicit declarations is IDE
> parsing when autocompletion for B.bme... pops up (suggesting bmethod and
> bmethod2) and with 'b':'bmethod' it never happens.

I don't rely on autocompleting IDEs, at least in dynamic languages, so
it's not much of an issue for me but yes, it's another small argument
against strings.

George
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Re: Using the 'with' statement with cStringIO objects

[George Boutsioukis]

> So, I'm guessing you can't use the 'with' statement with cStringIO
> objects?  Is this a bug, or do I need to use the 'with' statement
> differently to get this to work?
> 
> Thanks,
> peppergrower

Neither, just not implemented. Only classes with __enter__ and __exit__ 
methods(ie context manager types) can be used in with statements. And, 
correct me if I'm wrong, I  think it's pointless for a StringIO object to 
have those.
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Re: Regular expression help: unable to search ' # ' character in the file

[dudeja . rajat]

On Sat, Sep 27, 2008 at 1:58 PM, Fredrik Lundh <[EMAIL PROTECTED]>wrote:

> [EMAIL PROTECTED] wrote:
>
>  import re
>>
>> fd = open(file, 'r')
>> line = fd.readline
>> pat1 = re.compile("\#*")
>>while(line):
>>mat1 = pat1.search(line)
>>if mat1:
>>print line
>>line = fd.readline()
>>
>
> I strongly doubt that this is the code you used.
>
>  But the above prints the whole file instead of the hash lines only.
>>
>
> "*" means zero or more matches.  all lines is a file contain zero or more #
> characters.
>
> but using a RE is overkill in this case, of course.  to check for a
> character or substring, use the "in" operator:
>
>for line in open(file):
>if "#" in line:
>print line
>
> 
>
> --
> http://mail.python.org/mailman/listinfo/python-list
>

Thanks Fredrik, this works. Indeed  it is a much better and cleaner
approach.

-- 
Regards,
Rajat
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Re: What do you call a class not intended to be instantiated

[Aahz]

In article <[EMAIL PROTECTED]>,
Ben Finney  <[EMAIL PROTECTED]> wrote:
>Steven D'Aprano <[EMAIL PROTECTED]> writes:
>> On Fri, 26 Sep 2008 22:15:43 -0700, Aahz wrote:
>>>
>>> An ordinary singleton is instantiating the class multiple times
>>> yet returning the same instance object; a class singleton is
>>> simply using the class directly (like a module).
>
>Where is this "class singleton" terminology from? It seems redundant
>to me. It also doesn't seem to have anything to do with what
>"singleton" means as a pattern; "using a class" is simply using a
>class.

I don't remember where I picked it up, probably here some years ago.
The point of the terminology is to distinguish how the class is *used*,
in precise parallel with "module singleton".

>> I'd like to be able to call [a class] as if it were a function.
>> Normally calling a class object returns an instance -- I wish to
>> return something else.
>
>In that case, you *don't* want a class at all; the entire point of a
>class is to define behaviour for instances.

Absolutely agreed with your first clause, disagreed about the second
clause.  As I said earlier, the main point of a class singleton is to get
the effect of a module singleton without the need to create another file
on disk.  In that case there is no instance and therefore the point of
the class is no longer to define behavior for instances.

But you can't call a module, and classes have well-defined behavior for
calling them, so you shouldn't try to pervert a class singleton by
defining behavior for calling them.  In fact, I would recommend creating
an __init__() method that raises NotImplementedError precisely to prevent
this usage (or have a __new__() method that returns None, but I generally
prefer to recommend practices that work with classic classes).

One cute reason to prefer class singletons to module singletons is that
subclassing works well for creating multiple singletons.  But really,
the main reason I use class singletons is that they are the absolute
simplest way to get attribute access:

class Foo: pass
Foo.bar = 'xyz'
if data == Foo.bar:
print "!"

Once it gets much more complicated than that, I prefer to use a smarter
object.
-- 
Aahz ([EMAIL PROTECTED])   <*> http://www.pythoncraft.com/

"Argue for your limitations, and sure enough they're yours."  --Richard Bach
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Re: how to replace and string in a "SELECT ... IN ()"

[Tino Wildenhain]

Hi,

Michael Mabin wrote:

so you wouldn't object then to something like
 
' in (%)' % ','.join([str_edit_for_exploit(x) for x in aList]) 


if str_edit_for_exploit applied security edits?


Whats an security edit btw? If it is something meant to turn possibly
insecure data into 'secure' then, no I would still object.
Why? Because its a bad example of "default permit". Its always better
to have a whitelist - even more so when its so easy to do.

Its just a habit you develope - if you never do it right, how would you
know when and how to do it right when you need to?

Tino


smime.p7s
Description: S/MIME Cryptographic Signature
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Re: Time.sleep(0.0125) not available within Linux

[Grant Edwards]

On 2008-09-27, Lawrence D'Oliveiro <[EMAIL PROTECTED]> wrote:
> In message <[EMAIL PROTECTED]>, Grant
> Edwards wrote:
>
>> On 2008-09-26, Lawrence D'Oliveiro <[EMAIL PROTECTED]>
>> wrote:
>>> In message <[EMAIL PROTECTED]>, Grant Edwards
>>> wrote:
>>>
 Never assume somebody reading the article and attempting to
 help you can see the subject line.
>>>
>>> Why not?
>> 
>> Because it might not be.  It depends on the user's newsreader
>> and editor settings.
>
> So, should I not assume that they can see the content as well,
> because it might not be visible, depending on the user's
> newsreader and editor settings?

Thats seems like a bit of reductio ad absurdum.  My
observations over the years confirm the advice that you
shouldn't place information solely in the subject line.  If you
rely on people re-reading the subject line as the read and
reply to the body of the posting, you'll often get bad results.
People will miss information that was left out of the body and
placed solely in the subject line.  I've seen it happen over an
over again (this thread is an example).

If you don't care whether you get timely and accurate
responses, then do whatever you want.  Otherwise, include all
the pertinent information in the body of the posting.

-- 
Grant

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Re: EPD (Enthought Python Distribution) 4.0.300 Beta 3 available

[Christopher Brewster]

I have always thought this idea very good, but if I download it and  
install it (on my MacBook pro) will any conflicts occur with existing  
bits and pieces of Python and its libraries?


Thank you,

Christopher Brewster

*
Department of Computer Science, University of Sheffield
Regent Court, 211 Portobello Street
Sheffield   S1 4DP   UNITED KINGDOM
Web: http://www.dcs.shef.ac.uk/~kiffer/
Tel: +44(0)114-22.21967  Fax: +44 (0)114-22.21810
Skype: christopherbrewster
SkypeIn (UK): +44 (20) 8144 0088
SkypeIn (US): +1 (617) 381-4281
*
Corruptissima re publica plurimae leges. Tacitus. Annals 3.27




On 27 Sep 2008, at 07:08, Dave Peterson wrote:

Hello,

We've recently posted the third beta release of EPD (the Enthought
Python Distribution) with Python 2.5 version 4.0.300.  You may download
the beta from here:

http://www.enthought.com/products/epdbeta.php

Please help us test it out and provide feedback on the EPD Trac
instance: https://svn.enthought.com/epd  You can check out the release
notes here: http://www.enthought.com/products/epdbetareleasenotes.php


About EPD
-
The Enthought Python Distribution (EPD) is a "kitchen-sink-included"
distribution of the Python™ Programming Language, including over 60
additional tools and libraries. The EPD bundle includes NumPy, SciPy,
IPython, 2D and 3D visualization, database adapters, and a lot of
other tools right out of the box.

http://www.enthought.com/products/epd.php

It is currently available as a single-click installer for Windows XP
(x86), Mac OS X (a universal binary for OS X 10.4 and above), and
RedHat 3 and 4 (x86 and amd64).

EPD is free for academic use.  An annual subscription and installation
support are available for individual commercial use.  An enterprise
subscription with support for particular deployment environments is also
available for commercial purchase.  The beta versions of EPD are
available for indefinite free trial.


-- Dave


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  Support the Python Software Foundation:
  http://www.python.org/psf/donations.html


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Re: What do you call a class not intended to be instantiated

[Roy Smith]

In article <[EMAIL PROTECTED]>, [EMAIL PROTECTED] (Aahz) 
wrote:

> One cute reason to prefer class singletons to module singletons is that
> subclassing works well for creating multiple singletons.  But really,
> the main reason I use class singletons is that they are the absolute
> simplest way to get attribute access:
> 
> class Foo: pass
> Foo.bar = 'xyz'
> if data == Foo.bar:
> print "!"

I've often done something similar, creating a dummy class:

class Data:
   pass

just so I could create instances of it to hang attributes off of:

foo = Data()
foo.bar = 'xyz'

That's a trick I've been using since the Old Days (i.e. before new-style 
classes came along).  When I saw your example, my first thought was "That's 
silly, now that there's new-style classes, you can just create an instance 
of object!".  Unfortunately, when I tried it, I discovered it didn't work.  
You *can* instantiate object, but you don't get a class instance, so you 
can't create attributes on it.

>>> x = object()
>>> type(x)

>>> x.foo = 1
Traceback (most recent call last):
  File "", line 1, in 
AttributeError: 'object' object has no attribute 'foo'
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Re: Using the 'with' statement with cStringIO objects

[Hrvoje Niksic]

George Boutsioukis <[EMAIL PROTECTED]> writes:

> Neither, just not implemented. Only classes with __enter__ and
> __exit__ methods(ie context manager types) can be used in with
> statements. And, correct me if I'm wrong, I think it's pointless for
> a StringIO object to have those.

It's definitely superfluous, but it should still be provided, for the
same reason a "close" method is provided, to allow StringIO objects to
be treated like other file-like objects.  For example, code that does
the following:

with obj.open_file(...) as f:
...

shouldn't have to care if obj.open_file returns a built-in file
instance, or a StringIO instance.  As the above code becomes more
popular, __enter__ and __exit__ are beginning to be part of the file
interface (in the duck-typing sense) and should be implemented.

Until then, the the contextlib.closing context manager can be used
instead:

with contextlib.closing(obj.open_file(...)) as f:
...
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Re: is decorator the right thing to use?

[George Sakkis]

On Sep 27, 9:23 am, George Sakkis <[EMAIL PROTECTED]> wrote:

> On Sep 27, 1:44 am, "Dmitry S. Makovey" <[EMAIL PROTECTED]> wrote:
>
> > I guess my bias is towards more explicit declarations thus
>
> >  bmethod=ProxyMethod('b',B.bmethod)
>
> > looks more attractive to me, but I stand to be corrected/educated why is
> > that not the right thing to do?
>
> I see where you're coming from and I also prefer explicit reflection
> mechanisms instead of strings (e.g. avoid eval/exec as much as
> possible). As I mentioned, the second argument to ProxyMethod is (for
> all sane purposes) redundant, so if you could implement it in a way
> that "bmethod = ProxyMethod('b')" worked, I would be all for it, but
> AFAIK it's not possible without a metaclass.

Just for completeness, here's a metaclass version that uses
ProxyMethod declarations instead of a dict; you'll probably like this
better:

#=== usage =
from proxies import Proxy, ProxyMethod

class B(object):
def __init__(self, val): self.val = val
def bmethod(self,n): print "B::bmethod", self.val, n
def bmethod2(self,n,m): print "B::bmethod2", self.val, n, m

class C(object):
def __init__(self, val): self.val = val
def cmethod(self,x): print "C::cmethod", self.val, x
def cmethod2(self,x,y): print "C::cmethod2",self.val, x, y
cattr = 4

class A(Proxy):
def __init__(self, b1, b2, c):
print "init A()"
# must call Proxy.__init__
super(A,self).__init__(b1=b1, b2=b2, c=c)

def amethod(self,a):
print "A::mymethod",a

bmethod  = ProxyMethod('b1')
bmethod2 = ProxyMethod('b2')
cmethod  = ProxyMethod('c')


a = A(B(10), B(20), C(30))
a.amethod('foo')

print "bound proxy calls"
a.bmethod('foo')
a.bmethod2('bar','baz')
a.cmethod('foo')
try: a.cmethod2('bar','baz')
except Exception, ex: print ex

print "unbound proxy calls"
A.bmethod(a,'foo')
A.bmethod2(a,'bar','baz')
A.cmethod(a, 'foo')
try: A.cmethod2(a,'bar','baz')
except Exception, ex: print ex

#=== output 

init A()
A::mymethod foo
bound proxy calls
B::bmethod 10 foo
B::bmethod2 20 bar baz
C::cmethod 30 foo
'A' object has no attribute 'cmethod2'
unbound proxy calls
B::bmethod 10 foo
B::bmethod2 20 bar baz
C::cmethod 30 foo
type object 'A' has no attribute 'cmethod2'

#== proxies.py ==

class _ProxyMeta(type):
def __new__(meta, name, bases, namespace):
for attrname,value in namespace.iteritems():
if isinstance(value, ProxyMethod) and value.name is None:
value.name = attrname
return super(_ProxyMeta,meta).__new__(meta, name, bases,
namespace)


class ProxyMethod(object):
def __init__(self, proxy_attr, name=None):
self._proxy_attr = proxy_attr
self.name = name

def __get__(self, proxy, proxytype):
if proxy is not None:
return self.__get_target_attr(proxy)
else:
return self.__unbound_method

def __unbound_method(self, proxy, *args, **kwds):
method = self.__get_target_attr(proxy)
return method(*args, **kwds)

def __get_target_attr(self, proxy):
try:
delegate = getattr(proxy, self._proxy_attr)
return getattr(delegate, self.name)
except AttributeError:
raise AttributeError('%r object has no attribute %r' %
 (proxy.__class__.__name__,
self.name))


class Proxy(object):
__metaclass__ = _ProxyMeta

def __init__(self, **attr2delegate):
self.__dict__.update(attr2delegate)

#==

If you want to eliminate completely specifying attributes with
strings, it's easy to modify the above so that you write instead:

class A(Proxy):
...
bmethod  = ProxyMethod(lambda self: self.b1)
bmethod2 = ProxyMethod(lambda self: self.b2)

This is more verbose for the common case, but it's more flexible in
cases where the callable may be more complex than a plain getattr().
Actually you can support both, it doesn't have to be either/or; just
check whether the argument to ProxyMethod is a callable and if not,
make it:

from operator import attrgetter

class ProxyMethod(object):
def __init__(self, proxy_attr, name=None):
if not callable(proxy_attr):
proxy_attr = attrgetter(proxy_attr)
...

Remaining Implementation is left as an exercise to the reader ;)

George
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Re: text processing SOLVED

[[EMAIL PROTECTED]]

Thanks Black Jack
Working
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Re: Are spams on comp.lang.python a major nuisance?

[Skip Montanaro]

> CMIIW correct me if I'm wrong.  Google Groups is a Usenet/c-l-py
> gateway.  Other gateways aren't contributing to spam.  What are they
> doing that G-Groups is not?

Actually Google Groups appears to be just displaying the Usenet
newsgroup
comp.lang.python.  The spam filtering which is the topic of this
thread
is applied to the mailing list python-list@python.org side of things.
The
gateway between the mailing list and the Usenet newsgroup is on
mail.python.org I believe.

As to what Google Groups isn't doing, it's not clear.  I just visited
this
group and saw lots of spam.  My guess is that we on the mailing list
side
of things don't see a lot of that because of the spam filter.  It
seems
Google Groups makes it more difficult to report/eliminate spam than
other
more traditional Usenet newsgroup software might.  First you need to
view
the message (even though it's frequently obvious from the subject
alone
that it's spam), then click the "More Options" link, then the "Report
Message" link, then type something in the description field of the
form they display and click the Submit button.  After that, who knows
how long it takes for them to send out a Usenet cancel message?  Most
people probably see the subject and move on to the next message.

In short, it would appear that Google makes it harder to cancel spam
than they ought to.  Why they don't have spam filters similar to
what's
on Gmail to trap this stuff is unclear.

Skip

(Sent via Google Groups, so Grant will probably not see this...)
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Re: is decorator the right thing to use?

[George Sakkis]

On Sep 27, 11:27 am, George Sakkis <[EMAIL PROTECTED]> wrote:

> If you want to eliminate completely specifying attributes with
> strings, it's easy to modify the above so that you write instead:
>
> class A(Proxy):
> ...
> bmethod  = ProxyMethod(lambda self: self.b1)
> bmethod2 = ProxyMethod(lambda self: self.b2)

It's funny how often you come with a better solution a few moments
after htting send! The snippet above can (ab)use the decorator syntax
so that it becomes:

class A(Proxy):

@ProxyMethod
def bmethod(self):
return self.b1

@ProxyMethod
def bmethod2(self):
return self.b2

With the observation that ProxyMethod has access both to the callable
that returns the delegate and the name of the delegated method, we can
remove the need for the metaclass and the Proxy base class altogether:

class proxymethod(object):
def __init__(self, get_delegate):
self._get_delegate = get_delegate

def __get__(self, proxy, proxytype):
if proxy is not None:
return self.__get_target_attr(proxy)
else:
return self.__unbound_method

def __unbound_method(self, proxy, *args, **kwds):
method = self.__get_target_attr(proxy)
return method(*args, **kwds)

def __get_target_attr(self, proxy):
get_delegate = self._get_delegate
try: return getattr(get_delegate(proxy),
get_delegate.__name__)
except AttributeError:
raise AttributeError('%r object has no attribute %r' %
(proxy.__class__.__name__, get_delegate.__name__))


class A(object):

def __init__(self, b1, b2):
self.b1 = b1
self.b2 = b2

def amethod(self,a):
print "A::mymethod",a

@proxymethod
def bmethod(self):
return self.b1

@proxymethod
def bmethod2(self):
return self.b2


a = A(B(10), B(20))
a.amethod('foo')

print "bound proxy calls"
a.bmethod('foo')
a.bmethod2('bar','baz')

print "unbound proxy calls"
A.bmethod(a,'foo')
A.bmethod2(a,'bar','baz')

So back to the OP's original question and after a long circle.. a
decorator might well be the right thing to use after all :)

George
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Re: how to replace and string in a "SELECT ... IN ()"

[Michael Mabin]

If the inputs are edited prior to the construction of the string and these
fields are used for more than one update then it's not an exploit.  It's
simply a matter not repeating yourself when coding.
In this particular case too, we're talking about a list of integers that
gets inserted into a string.  If the list is validated prior to its
insertion into an SQL statement then there is no exploit.  If I write a
batch program (not a web program) that retrieves this list of integers from
other sources and validates the data prior to using it in an SQL statement,
that should be sufficient.

As far as wrong and right is concerned. I think it's more about doing what
is appropriate according to the circumstances.  As a rule you should only
code what is appropriate for the circumstances.  If it's appropriate to code
more simply without introducing unnecessary complexity you should do so.

I work in the data warehousing ETL world, where we have to perform field
edits or transformations to load source data into databases.  If I'm already
performing edits on these fields and if these fields are going to be used
for more updates downstream, it's wasteful to perform them again when I
build the SQL insert with the list and execute it.

Finally, whatever happened to the practice of granting appropriate
privileges to IDs that perform database operations?  Shouldn't the person
acting in the capacity of DBA ensure that the user updating or retrieving
data from the database does not have DROP, ALTER, or CREATE privileges on
that database?

On Sat, Sep 27, 2008 at 9:14 AM, Tino Wildenhain <[EMAIL PROTECTED]> wrote:

> Hi,
>
> Michael Mabin wrote:
>
>> so you wouldn't object then to something like
>>  ' in (%)' % ','.join([str_edit_for_exploit(x) for x in
>> aList])
>> if str_edit_for_exploit applied security edits?
>>
>
> Whats an security edit btw? If it is something meant to turn possibly
> insecure data into 'secure' then, no I would still object.
> Why? Because its a bad example of "default permit". Its always better
> to have a whitelist - even more so when its so easy to do.
>
> Its just a habit you develope - if you never do it right, how would you
> know when and how to do it right when you need to?
>
> Tino
>



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Borg vs Singleton vs OddClass

[Lie]

This is probably unrelated to Python, as this is more about design
pattern. I'm asking your comments about this design pattern that is
similar in functionality to Singleton and Borg: to share states.

I'm thinking about this design pattern (I don't know if anyone has
ever thought of this pattern before):

class OddClass(object):
def __init__(self):
global OddClass
OddClass = self
def __call__():
return self

The OddClass is a class that would overwrite its own class definition
at its first instantiation. OddClass defines __call__ so that
subsequent "instantiation" (technically it is no more an
instantiation, but Duck Typing says it does) of the class would return
the single instance.

It do have a problem though, that you can't do isinstance(a, OddClass)
since the name OddClass no longer refers to the OddClass class
descriptor, but to an instance of OddClass. I don't think that's much
of a problem though since using isinstance() is generally not a good
idea in python (although OddClass do use global which many people,
including me, would usually consider as bad form).

The problem with Borg is that it is not inheritable (in certain
sense[1]) and only work with old-style class (which is due to be
completely removed on py3k)[2], Singleton and OddClass is inheritable.

>>> class Singleton(object): ...
>>> s = Singleton()
>>> class A(Singleton): pass
>>> class B(Singleton): pass
>>> a = A()
>>> b = B()
>>> s.foo, a.bar = "bar", 42
>>> b.foo, b.bar
... Traceback, Attribute Error ...

>>> class OddClass(object): ...
>>> s = OddClass()
>>> class A(OddClass): pass
>>> class B(OddClass): pass
>>> a = A()
>>> b = B()
>>> s.foo, a.bar = "bar", 42
>>> b.foo, b.bar
... Traceback, Attribute Error ...

but for Borg, see [1]

[1] classes that inherits from Borg shares state not only within
children, but also with their parents and cousins. That means
inheriting from Borg is useless, and that also means one Borg code for
every state sharing classes, instead of inheriting from Singleton/
OddClass. In code:
>>> class Borg: ...
>>> class A(Borg): ...
>>> class B(Borg): ...
>>> s, a, b = Borg(), A(), B()
>>> s.foo, a.attr = "bar", 42
>>> b.foo, b.attr
"bar" 42
>>> # we want b.foo and b.attr to raise error since .foo, and .bar isn't B's 
>>> shared state, it's A's and Borg's shared state

[2] Actually in new-style class, they say Borg can use __slots__, but
they say it'd be slightly more complex
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Re: python for *nix system admins

[Michael Mabin]

import commands ?

On Sat, Sep 27, 2008 at 8:06 AM, George Boutsioukis
<[EMAIL PROTECTED]>wrote:

> On Sat, 27 Sep 2008 10:05:01 +0200, Lars Stavholm wrote:
>
> > Hi All,
> >
> > I'm new to this list and hoping that this is not off-topic. If it is,
> > please point me in the right direction.
> >
> > I seem to recollect a python module or library for *nix sysadmins, but I
> > can't for the life of me find it again.
> >
> > The module (or library) somehow added unix command capabilities to the
> > python language. It seemed like a lesser known, perhaps new, python
> > library or module.
> >
> > Any input or ideas appreciated
> > /Lars Stavholm
>
> The only modules I've come across that barely fit your description are
> python-unixtools(gzip, bzip only) and shutil(some limited capabilities).
> Running unix commands is usually done directly(os.popen, os.system) on
> *nix platforms. Why(and how) would anyone rewrite them as python modules?
> --
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>



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Re: python for *nix system admins

[Eric Wertman]

I've been growing a library of my own functions, that use the names of
unix commands.  They are just conveniences, of course, but I'd suggest
the same for sysadmins, it's handy.
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Re: python for *nix system admins

[Sebastian Bassi]

On Sat, Sep 27, 2008 at 3:32 PM, Eric Wertman <[EMAIL PROTECTED]> wrote:
> I've been growing a library of my own functions, that use the names of
> unix commands.  They are just conveniences, of course, but I'd suggest
> the same for sysadmins, it's handy.

Can you share it?

Best,
SB.
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File modifications

[aditya shukla]

Hello folks ,

I have a file like this

/T_0_size=105((-bin-ulockmgr_server:0.99[&&NHX:C=0.195.0],(((-bin-hostname:0.00
[&&NHX:C=200.0.0],
(-bin-dnsdomainname:0.00[&&NHX:C=200.0.0],(-bin-domainname:0.00[&&NHX:C=200.0.0],(-bin-nisdomainname:0.00[&&NHX:C=200.0.0],-bin-ypdomainname:0.00[&&NHX:C=200.0.0]):0.00):0.00):0.00):0.98

,(-bin-iptables-xml:0.97[&&NHX:C=0.183.0],(-bin-dbus-send:0.78[&&NHX:C=0.94.0],-bin-dbus-monitor:0.78[&&NHX:C=0.94.0]):0.97):0.98):0.99.

I wanna get the file in this format

((-bin-ulockmgr_server:0.99,(((-bin-hostname:0.00,(-bin-dnsdomainname:0.00,(-bin-domainname:0.00,(-bin-nisdomainname:0.00,-bin-ypdomainname:0.00):0.00):0.00):0.00):0.98

,(-bin-iptables-xml:0.97,(-bin-dbus-send:0.78,-bin-dbus-monitor:0.78):0.97):0.98):0.99

ie , remove /T_0_size , [&&NHC:C=0.195.0] , [&&NHX:C=200.0.0] and so  on ,
how should i handle this after reading the file?

Thanks


Aditya
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Re: how to replace and string in a "SELECT ... IN ()"

[Tino Wildenhain]

Hi,

Michael Mabin wrote:
If the inputs are edited prior to the construction of the string and 
these fields are used for more than one update then it's not an exploit. 
 It's simply a matter not repeating yourself when coding.


In python we do not fear that.

In this particular case too, we're talking about a list of integers that 
gets inserted into a string.  If the list is validated prior to its 


Its a list, if it indeed has integers in it is uncertain. It is so very
easy to check that that it doesnt even make sense to write such lengthy
emails about how bad you want to avoid it. Just do it. And even more so
if you are telling others how to do things make sure they do not so easy
shoot themselfes in their feet.

insertion into an SQL statement then there is no exploit.  If I write a 
batch program (not a web program) that retrieves this list of integers 
from other sources and validates the data prior to using it in an SQL 
statement, that should be sufficient.  


This might be well true but if you have a look at your original 
contribution you see that all these your asumtions are just not in.


As far as wrong and right is concerned. I think it's more about doing 
what is appropriate according to the circumstances.  As a rule you 


If its easy to do, why not just doing it correctly (or robust) in all
circumstances to just avoid overlooking a case?

should only code what is appropriate for the circumstances.  If it's 
appropriate to code more simply without introducing unnecessary 
complexity you should do so.


But you did not tell us about your asumtations about the circumstances.

I work in the data warehousing ETL world, where we have to perform field 
edits or transformations to load source data into databases.  If I'm 


Thats wrong. You do not "edit" fields. You have a validating type path 
and _always_ the database is most authoritative about what it accepts.

Any other concept is just wrong and outright dangerous. There are
many examples of how this works out (just check bugtraq)

already performing edits on these fields and if these fields are going 
to be used for more updates downstream, it's wasteful to perform them 
again when I build the SQL insert with the list and execute it. 


I still don't know what you mean by "edit" ;) If you mean filter out
special chars with for example replace("bad stuff","good stuff") check
your idea again, this is not going to work. (google for default permit)

Finally, whatever happened to the practice of granting appropriate 
privileges to IDs that perform database operations?  Shouldn't the 
person acting in the capacity of DBA ensure that the user updating or 
retrieving data from the database does not have DROP, ALTER, or CREATE 
privileges on that database? 


This of course is another layer which should be added - but you would
not need to - you edited the fields, right? ;)

Sorry, it was not meant to put you to the wall but you insist so much
on your still dangerous solution while top posting the hell out of
this thread I just could not ignore it ;)

T.


smime.p7s
Description: S/MIME Cryptographic Signature
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Re: What do you call a class not intended to be instantiated

[Terry Reedy]

Aahz wrote:

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

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



I'd like to be able to call [a class] as if it were a function.
Normally calling a class object returns an instance -- I wish to
return something else.

In that case, you *don't* want a class at all; the entire point of a
class is to define behaviour for instances.


Absolutely agreed with your first clause, disagreed about the second
clause.  As I said earlier, the main point of a class singleton is to get
the effect of a module singleton without the need to create another file
on disk.


In 3.0, at least, one does not need a disk file to create a module.

>>> import types
>>> me = types.ModuleType('me') # type(__builtins__) works, no import
>>> me

>>> me.a = 1
>>> me.a
1
>>> me.a + 1
2

That said, a blank class is even easier, and the representation is better.

tjr

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check if file is MS Word or PDF file

[A. Joseph]

What should I look for in a file to determine whether or not it is a
MS Word file or an Excel file or a PDF file, etc., etc.? including Zip
files

I don`t want to check for file extension.
os.path.splitext('Filename.jpg') will produce a tuple of filename and
extension, but some file don`t even have extension and can still be read by
MS Word or NotePad. i want to be 100% sure of the file.
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Abstract Base Class register function

[Mikolai Fajer]

I have been experimenting with the abc module in py3k and thought
about using the register method of an ABC as a class decorator:


import abc
class MyABC(metaclass=abc.ABCMeta):
pass

@MyABC.register
class MySub():
pass


This doesn't work because the register method returns None.  It would
be a fairly simple modification to have this work:


def register(cls, subclass):
"""Register a virtual subclass of an ABC."""
... etc ...
return subclass


What do people think of this behavior?

-- 

 -Mikolai Fajer-
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Hello boys!

[Milenko Stojadinovic Cvrcko]

Hello, this is Milenko Stojadinovic from town Banjaluka,
Bosnia and Herzegovina, also known as Cvrcko
Does anyone know of any bars in town where I can
swallow a bucket of cum? It can be either dog,
horse or human cum. Also, does anyone know of
any sex bars where people will shit in your mouth?
I also like eating shit.

--
Name: Mileno Stojadinovic - Cvrcko
Street adress: Sime Matavulja 12
Town: 78000 Banja Luka
Country: Bosnia and Herzegovina
Home phone: +38751/303-665
Cell phone: +38765/499-312
Email adress: [EMAIL PROTECTED]

~

The new pumpkin rarely pulls Terrance, it teases Sharon instead.  For
Susan the tape's sad, beside me it's unique, whereas against you it's
believing dirty.  Hey, go reject a fork!  Why did Alice open
throughout all the boats?  We can't explain poultices unless
Woody will mercilessly judge afterwards.  The frames, disks, and
shirts are all fat and fresh.  Who will we dine after Edwina
wastes the thin mirror's goldsmith?  It's very outer today, I'll
recollect strangely or Christopher will learn the teachers.
Hardly any humble brave tyrants hourly solve as the tired wrinkles
cover.

Hardly any distant buttons are short and other urban ointments are
filthy, but will Robette receive that?

Let's lift behind the deep highways, but don't promise the heavy
diets.  Who kicks badly, when Melvin burns the stale code before the
autumn?  Get your absolutely moulding barber within my cellar.  If you
will
laugh Gay's hill against porters, it will incredibly climb the
case.  Some shopkeepers arrive, irrigate, and shout.  Others
sadly expect.  To be pathetic or sticky will talk abysmal oranges to
wickedly look.

Are you healthy, I mean, moving above clever onions?  While farmers
partly taste pins, the powders often excuse against the blunt
jackets.  Generally Susanne will order the sticker, and if George
actually seeks it too, the bowl will attempt with the polite
lane.  He can hate durable kettles above the rural bad ocean, whilst
Oscar easily scolds them too.  You eventually fill against Norma when
the
kind drapers irritate among the poor summer.  As surprisingly as
Dolf converses, you can dye the cap much more familiarly.  Brion,
still
killing, behaves almost eerily, as the sauce changes on their
coffee.  You won't recommend me grasping about your lazy office.

Almost no butchers steadily live the lost signal.  Cyrus's hat
improves among our desk after we sow towards it.  Ralph measures the
weaver within hers and wanly calls.  Some cosmetic tags answer
David, and they rigidly walk Quincy too.  When Richard's elder
gardner dreams, Mark cares for weak, closed islands.  He might
strongly fear think and plays our cheap, sour painters above a
bathroom.  I creep the active yogi and cook it in back of its
dorm.  Tell Katherine it's strong loving within a tree.  Why will you
jump the angry lower exits before Murray does?  I am unbelievably
bitter, so I wander you.  How does Hector smell so regularly, whenever
Ronald likes the solid twig very slowly?

Julieta, have a hot printer.  You won't clean it.  Fucking don't
join a dryer!  She wants to nibble inner smogs under Usha's castle.
She'd rather
depart grudgingly than help with Bernadette's younger grocer.  Other
old dark cards will comb frantically alongside cans.  Try pouring the
monument's pretty cat and Oliver will attack you!  Don't try to
seek halfheartedly while you're jumping throughout a easy carpenter.

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answers quietly.  What doesn't Janet smell inadvertently?  They are
opening before the rain now, won't explain walnuts later.  Some
light long game covers pools outside Woodrow's rich film.  Why did
Oscar judge the pear with the handsome spoon?  He will talk nearly if
Julieta's tailor isn't wet.

Just looking beside a ulcer through the store is too young for
Woody to care it.  Both filling now, Alejandro and Marty irritated the
open rivers about smart envelope.  Occasionally, dusts kill beside
rude fires, unless they're sweet.  Her pen was sharp, dull, and
fears over the spring.  Zack, on floors difficult and upper,
attacks towards it, recollecting seemingly.  We measure the raw
sauce.

They are rejecting throughout quiet, towards empty, in back of
cold units.  My wide potter won't clean before I comb it.  If you'll
pour Edward's camp with aches, it'll admiringly converse the
cup.  I was promising frogs to worthwhile Corinne, who's walking
in back of the counter's stable.  It can receive clean pickles, do you
solve them?  Many jugs will be weird lean carrots.  Roger helps, then
Walt stupidly believes a ugly lentil on Catherine's road.  We
tease them, then we weekly dream Zack and Annabel's blank candle.
A lot of shallow dose or canyon, and she'll locally excuse everybody.
If the
bizarre balls can sow bimonthly, the hollow raindrop may love more
ventilators.  We laugh weekly, unless Jezebel grasps shoes outside
Jimmie's puddle.  Jimmy!  You'll mould plates.  Just now, I'll
dine the ba

Configuring pyc directory

[Robert Moore]

Is there a way to configure python to read/write compiled pyc files for
modules in a directory other than the directory containing the original py
files?

I'm trying trying to secure an Apache server running mod_python and don't
want the process compiling the pyc files to have write access to the folder
containing my site's py modules.  I realize the solution (if it exists) may
lie with mod_python rather than python itself, so I've also pinged the
mod_python mailing list for help.  I'm checking here as well, though, just
in case there's some solution built into python.

Thanks,
Robert
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Re: check if file is MS Word or PDF file

[Chris Rebert]

On Sat, Sep 27, 2008 at 2:43 PM, A. Joseph <[EMAIL PROTECTED]> wrote:
> What should I look for in a file to determine whether or not it is a
> MS Word file or an Excel file or a PDF file, etc., etc.? including Zip
> files
>
> I don`t want to check for file extension.
> os.path.splitext('Filename.jpg') will produce a tuple of filename and
> extension, but some file don`t even have extension and can still be read by
> MS Word or NotePad. i want to be 100% sure of the file.

Well, if you're on unix, you could run the 'file' command and check
its output using the 'subprocess' module, but it sounds like you're on
Windows...

Regards,
Chris
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>
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Re: Using the 'with' statement with cStringIO objects

[peppergrower]

Thanks for the help.  I'm fairly new to programming (which you
probably could have guessed...).  When I realized that you could use a
StringIO instance as if it were a file, I wanted to try some of the
same techniques on it as I would with a file.  In this case, I wanted
to use a "for line in testfile" construction to iterate over the
StringIO instance.  (I did find a better way for my particular case,
one that didn't involve StringIO at all.)  When I got that particular
error, I suspected that it had something to do with the relative
newness of the 'with' statement.

If this is something that should be considered for addition in the
future, is there somewhere specific I should suggest that?
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Re: multiprocessing eats memory

[redbaron]

> When processing data in parallel you will use up as muchmemoryas
> many datasets you are processing at any given time.
Worker processes eats 2-4 times more than I pass to them.


>If you need to
> reducememoryuse then you need to start fewer processes and use some
> mechanism to distribute the work on them as they become free. (see
> recommendation that uses Queues)
I don't understand how could I use Queue here? If worker process
finish computing, it puts its' id into Queue, in main process I
retrieve that id and how could I retrieve result from worker process
then?

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Re: check if file is MS Word or PDF file

[Michael Crute]

On Sat, Sep 27, 2008 at 5:43 PM, A. Joseph <[EMAIL PROTECTED]> wrote:
> What should I look for in a file to determine whether or not it is a
> MS Word file or an Excel file or a PDF file, etc., etc.? including Zip
> files
>
> I don`t want to check for file extension.
> os.path.splitext('Filename.jpg') will produce a tuple of filename and
> extension, but some file don`t even have extension and can still be read by
> MS Word or NotePad. i want to be 100% sure of the file.

You could use the mimetypes module...

<<< import mimetypes
<<< mimetypes.guess_type("LegalNotices.pdf")
>>> ('application/pdf', None)

-mike

-- 

Michael E. Crute
http://mike.crute.org

God put me on this earth to accomplish a certain number of things.
Right now I am so far behind that I will never die. --Bill Watterson
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Re: Hello boys!

[default]

On Sat, 27 Sep 2008 14:56:07 -0700 (PDT), Milenko Stojadinovic Cvrcko
<[EMAIL PROTECTED]> wrote:

>Hello, this is Milenko Stojadinovic from town Banjaluka,
>Bosnia and Herzegovina, also known as Cvrcko
>Does anyone know of any bars in town where I can
>swallow a bucket of cum? It can be either dog,
>horse or human cum. Also, does anyone know of
>any sex bars where people will shit in your mouth?
>I also like eating shit.

Come to the US and park your mouth in front of George Bush - all the
Bshit you can eat - and it keeps on coming!

I have a buddy in Bosna - he's normal.

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Re: Hello boys!

[Jim Thompson]

On Sat, 27 Sep 2008 18:47:16 -0400, default <[EMAIL PROTECTED]>
wrote:

>On Sat, 27 Sep 2008 14:56:07 -0700 (PDT), Milenko Stojadinovic Cvrcko
><[EMAIL PROTECTED]> wrote:
>
>>Hello, this is Milenko Stojadinovic from town Banjaluka,
>>Bosnia and Herzegovina, also known as Cvrcko
>>Does anyone know of any bars in town where I can
>>swallow a bucket of cum? It can be either dog,
>>horse or human cum. Also, does anyone know of
>>any sex bars where people will shit in your mouth?
>>I also like eating shit.
>
>Come to the US and park your mouth in front of George Bush - all the
>Bshit you can eat - and it keeps on coming!
>
>I have a buddy in Bosna - he's normal.

Now you know why I blanket kill-file googlegroups.

...Jim Thompson
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Re: check if file is MS Word or PDF file

[Chris Rebert]

On Sat, Sep 27, 2008 at 3:42 PM, Michael Crute <[EMAIL PROTECTED]> wrote:
> On Sat, Sep 27, 2008 at 5:43 PM, A. Joseph <[EMAIL PROTECTED]> wrote:
>> What should I look for in a file to determine whether or not it is a
>> MS Word file or an Excel file or a PDF file, etc., etc.? including Zip
>> files
>>
>> I don`t want to check for file extension.
>> os.path.splitext('Filename.jpg') will produce a tuple of filename and
>> extension, but some file don`t even have extension and can still be read by
>> MS Word or NotePad. i want to be 100% sure of the file.
>
> You could use the mimetypes module...
>
> <<< import mimetypes
> <<< mimetypes.guess_type("LegalNotices.pdf")
 ('application/pdf', None)

Looking at the docs for the mimetypes module, it just guesses based on
the filename (and extension), not the actual contents of the file, so
it doesn't really help the OP, who wants to make sure their program
isn't misled by an inaccurate extension.

Regards,
Chris
-- 
Follow the path of the Iguana...
http://rebertia.com

>
> -mike
>
> --
> 
> Michael E. Crute
> http://mike.crute.org
>
> God put me on this earth to accomplish a certain number of things.
> Right now I am so far behind that I will never die. --Bill Watterson
> --
> http://mail.python.org/mailman/listinfo/python-list
>
--
http://mail.python.org/mailman/listinfo/python-list

Re: Hello boys!

[default]

On Sat, 27 Sep 2008 15:56:39 -0700, Jim Thompson
<[EMAIL PROTECTED]> wrote:


>Now you know why I blanket kill-file googlegroups.
>
>...Jim Thompson
I knew that!

Every now and then one groper will make it back to the scene of his
crime - but, granted, there was no hope for this one.
-- 


== Posted via Pronews.Com - Unlimited-Unrestricted-Secure Usenet News==
http://www.pronews.com The #1 Newsgroup Service in the World! >100,000 
Newsgroups
---= - Total Privacy via Encryption =---
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Re: EPD (Enthought Python Distribution) 4.0.300 Beta 3 available

[Robert Kern]

Disclosure: I work for Enthought.

Christopher Brewster wrote:
I have always thought this idea very good, but if I download it and 
install it (on my MacBook pro) will any conflicts occur with existing 
bits and pieces of Python and its libraries?


For the Mac distribution, we have tried very carefully to keep EPD's Python 
separate from any previous installation. I believe the only thing that will get 
"overwritten" is that our bin/ directory inside our version of Python.framework 
will get prepended to your $PATH environment variable. This will be added to 
your ~/.bash_profile with a a descriptive comment. When you type


  $ python

at your Terminal prompt, you will get EPD's Python. To uninstall EPD, you can 
remove those lines in your ~/.bash_profile, delete 
/Library/Frameworks/Python.framework/Versions/4.0.300/, and delete 
"/Applications/EPD /". Then your previous Python 
installation should be usable again.


To just use your previous Python installation without uninstalling EPD, just 
comment out our addition to ~/.bash_profile.


If you have more questions about EPD, please join us on the enthought-dev 
mailing list:


  https://mail.enthought.com/mailman/listinfo/enthought-dev

--
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
 that is made terrible by our own mad attempt to interpret it as though it had
 an underlying truth."
  -- Umberto Eco

--
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Re: Hello boys!

[Cydrome Leader]

In rec.crafts.metalworking Jim Thompson <[EMAIL PROTECTED]> wrote:
> 
> On Sat, 27 Sep 2008 18:47:16 -0400, default <[EMAIL PROTECTED]>
> wrote:
> 
>>On Sat, 27 Sep 2008 14:56:07 -0700 (PDT), Milenko Stojadinovic Cvrcko
>><[EMAIL PROTECTED]> wrote:
>>
>>>Hello, this is Milenko Stojadinovic from town Banjaluka,
>>>Bosnia and Herzegovina, also known as Cvrcko
>>>Does anyone know of any bars in town where I can
>>>swallow a bucket of cum? It can be either dog,
>>>horse or human cum. Also, does anyone know of
>>>any sex bars where people will shit in your mouth?
>>>I also like eating shit.
>>
>>Come to the US and park your mouth in front of George Bush - all the
>>Bshit you can eat - and it keeps on coming!
>>
>>I have a buddy in Bosna - he's normal.
> 
> Now you know why I blanket kill-file googlegroups.

So you and everybody can talk about them nonstop?
--
http://mail.python.org/mailman/listinfo/python-list

Re: What do you call a class not intended to be instantiated

[Terry Reedy]

Aaron "Castironpi" Brady wrote:


class A(type):

... def __call__( self, *ar ):
... print 'call', self, ar
...

class B(object):

... __metaclass__= A
...

B(3)

call  (3,)

Overriding the __call__ method of 'type' has the effect of giving you
a static __call__ method on a class-- a method which doesn't need an
instance to call.  Your behavior may be counterintuitive though, to
someone who wants to instantiate 'B', in this case, and proceed like a
normal object.  That is, they want to call a generic class and use it,
and also expect instances of B to behave as B.  You can't have both,
so either return B from B.__new__, or, to instantiate B, take the long
way and call B.__new__ directly.


B.__new__(B)

<__main__.B object at 0x009FDB70>

Has anyone stepped through the C code to find out when the decision is
made to call which function, B.__new__ or A.__call__, when B is
called?  


For Python coded objects, ob(*args) in code translates to internal 
execution of type(ob).__call__(ob, *args) (without further 
translation!).  The interpreter compiles a statement at a time, without 
looking back to do type inferencing, and so does not know what type is 
being called or if it is even callable.


For B, B(*args) == type(B).__call__(B, *args) == A.__call__(B, *args). 
So there is no decision.


For C coded objects, I believe ob(*args) in Python code translate to a C 
call of the C equivalent of type(ob).tp_call (or something like that). 
From observation, type.tp_call acts something like this:


def __call__(cls, *args):
  if cls == type:
if len(*args):
  return arg[0].__class__
elif len(*args) == 3:
  return type.__new__(type, *args) # or maybe not pass type?
else:
  raise TypeError('type() takes 1 or 3 arguments')
  else:
return cls.__new__(cls, *args)

So, for a normal class C (an instance of type), type.__call__ calls 
C.__new__.


Terry Jan Reedy


--
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Re: What do you call a class not intended to be instantiated

[Aaron "Castironpi" Brady]

On Sep 27, 6:16 pm, Terry Reedy <[EMAIL PROTECTED]> wrote:
> Aaron "Castironpi" Brady wrote:
>  class A(type):
> > ...     def __call__( self, *ar ):
> > ...             print 'call', self, ar
> > ...
>  class B(object):
> > ...     __metaclass__= A
> > ...
>  B(3)
> > call  (3,)
>
> > Overriding the __call__ method of 'type' has the effect of giving you
> > a static __call__ method on a class-- a method which doesn't need an
> > instance to call.  Your behavior may be counterintuitive though, to
> > someone who wants to instantiate 'B', in this case, and proceed like a
> > normal object.  That is, they want to call a generic class and use it,
> > and also expect instances of B to behave as B.  You can't have both,
> > so either return B from B.__new__, or, to instantiate B, take the long
> > way and call B.__new__ directly.
>
>  B.__new__(B)
> > <__main__.B object at 0x009FDB70>
>
> > Has anyone stepped through the C code to find out when the decision is
> > made to call which function, B.__new__ or A.__call__, when B is
> > called?  
>
> For Python coded objects, ob(*args) in code translates to internal
> execution of type(ob).__call__(ob, *args) (without further
> translation!).  The interpreter compiles a statement at a time, without
> looking back to do type inferencing, and so does not know what type is
> being called or if it is even callable.
>
> For B, B(*args) == type(B).__call__(B, *args) == A.__call__(B, *args).
> So there is no decision.
>
> For C coded objects, I believe ob(*args) in Python code translate to a C
> call of the C equivalent of type(ob).tp_call (or something like that).
>  From observation, type.tp_call acts something like this:
>
> def __call__(cls, *args):
>    if cls == type:
>      if len(*args):
>        return arg[0].__class__
>      elif len(*args) == 3:
>        return type.__new__(type, *args) # or maybe not pass type?
>      else:
>        raise TypeError('type() takes 1 or 3 arguments')
>    else:
>      return cls.__new__(cls, *args)
>
> So, for a normal class C (an instance of type), type.__call__ calls
> C.__new__.
>
> Terry Jan Reedy

Oh, I see.  Then it's the class statement that calls type.__new__.

class A: ...
-> A= type( 'A', ... )
-> A= type.__call__( type, 'A', ... )
-> A= type.__new__( type, 'A', ... )

Plus an iteration over the contents of 'namespace', to search for
properties that themselves have a __get__ method.  And returns an
unboundmethod instance "of" it, for a value of "of" that's hard to
concentrate on.  I jest.

Perhaps what Steven is looking for is a subclass of 'type' that does
not give this default behavior of 'unboundmethoding' everything it
can.  That is, defaulting to 'staticmethod' or 'classmethod', and
perhaps offering a 'boundmethod' decorator for the exceptions.

For the case of '__call__', which he does want to control, that could
merely call B.__call__, instead of B.__new__.  Untested:

>>> class A(type):
... def __call__( self, *ar ):
... return self.__call__( *ar )

or

... return self.__call__( self, *ar )

Which would come through to 'B' as:

>>> class B(object):
... __metaclass__= A
... def __call__( cls, *ar ).

This is because self == B in the example.  This makes me scowl.  Very
odd.
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Re: check if file is MS Word or PDF file

[Sean DiZazzo]

On Sep 27, 4:01 pm, "Chris Rebert" <[EMAIL PROTECTED]> wrote:
> On Sat, Sep 27, 2008 at 3:42 PM, Michael Crute <[EMAIL PROTECTED]> wrote:
> > On Sat, Sep 27, 2008 at 5:43 PM, A. Joseph <[EMAIL PROTECTED]> wrote:
> >> What should I look for in a file to determine whether or not it is a
> >> MS Word file or an Excel file or a PDF file, etc., etc.? including Zip
> >> files
>
> >> I don`t want to check for file extension.
> >> os.path.splitext('Filename.jpg') will produce a tuple of filename and
> >> extension, but some file don`t even have extension and can still be read by
> >> MS Word or NotePad. i want to be 100% sure of the file.
>
> > You could use the mimetypes module...
>
> > <<< import mimetypes
> > <<< mimetypes.guess_type("LegalNotices.pdf")
>  ('application/pdf', None)
>
> Looking at the docs for the mimetypes module, it just guesses based on
> the filename (and extension), not the actual contents of the file, so
> it doesn't really help the OP, who wants to make sure their program
> isn't misled by an inaccurate extension.
>
> Regards,
> Chris
> --
> Follow the path of the Iguana...http://rebertia.com
>
>
>
> > -mike
>
> > --
> > 
> > Michael E. Crute
> >http://mike.crute.org
>
> > God put me on this earth to accomplish a certain number of things.
> > Right now I am so far behind that I will never die. --Bill Watterson
> > --
> >http://mail.python.org/mailman/listinfo/python-list

Check http://sourceforge.net/project/showfiles.php?group_id=23617

for the 'file' command for Windows.

~Sean
--
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Re: how to replace and string in a "SELECT ... IN ()"

[Michael Mabin]

I'm exhausted, so I'll just shut up about this after a few final words.
1.  "edits" is used in data warehousing to describe data scrubbing or
filtering of fields in records that are used as input sources for loading
into data warehouses. It's a term that goes way back to batch processing on
the mainframe, so it's been used this way for a long time. Sometimes we use
'validation' interchangeably with 'edit' but our use of validation usually
involves a check of input data against business rules and not type or range
checking which we consider 'edits'.  So maybe you're not used to hearing the
term used this way, but it is a variation perhaps of what you're used to.

2.  The data warehousing world is quite different from the web world in many
respects.  I appreciate the fact that web application developers must always
be mindful of the 'barbarians at the gates' but our batch environments are
locked down, especially our databases.  We have secured batch IDs. Our
programs are run using an automated schedule.  Our databases are secured to
begin with so not even our batch IDs have alter, create or drop permissions
on the database.  There's no way this exploit would ever enter this
environment because those servers aren't accessible through the web or
online.

3.  When you say 'in python we don not fear that' it's curious, because it
assumes that all Python users must think as you do.  And yet, clearly I
don't think as you do.  I really like this language and praise the
Netherlands each day I wake up that they gave us someone as brilliant as
Guido to make programming fun and not such a chore.  But I think there are
valid reasons for taking different approaches to security, data validation
and dare I say it -- field editing -- despite the claims of many who say
that in Python - TOOWTDI.

4. It's also curious that I was obliged to state my assumptions about batch
programming vs. web programming.  There is nothing in the OP to suggest that
the problem was related to web programming.  It's a question about how to
interpolate the values in a list with format specifiers in a SQL statement.
 Still, if this list is not the result of user input but was derived within
the body of the program, which by itself has no malicious intent, are we
still going to code this as if it were input by a user that might be a
hacker?  This seems retarded and paranoid to me.  And where in that post
does it say that the list is from web input?  Although to be fair maybe most
of the Python community is doing web development.

Thanks for the stimulating and educational discussion.

On Sat, Sep 27, 2008 at 4:30 PM, Tino Wildenhain <[EMAIL PROTECTED]> wrote:

> Hi,
>
> Michael Mabin wrote:
>
>> If the inputs are edited prior to the construction of the string and these
>> fields are used for more than one update then it's not an exploit.  It's
>> simply a matter not repeating yourself when coding.
>>
>
> In python we do not fear that.
>
>  In this particular case too, we're talking about a list of integers that
>> gets inserted into a string.  If the list is validated prior to its
>>
>
> Its a list, if it indeed has integers in it is uncertain. It is so very
> easy to check that that it doesnt even make sense to write such lengthy
> emails about how bad you want to avoid it. Just do it. And even more so
> if you are telling others how to do things make sure they do not so easy
> shoot themselfes in their feet.
>
>  insertion into an SQL statement then there is no exploit.  If I write a
>> batch program (not a web program) that retrieves this list of integers from
>> other sources and validates the data prior to using it in an SQL statement,
>> that should be sufficient.
>>
>
> This might be well true but if you have a look at your original
> contribution you see that all these your asumtions are just not in.
>
>  As far as wrong and right is concerned. I think it's more about doing what
>> is appropriate according to the circumstances.  As a rule you
>>
>
> If its easy to do, why not just doing it correctly (or robust) in all
> circumstances to just avoid overlooking a case?
>
>  should only code what is appropriate for the circumstances.  If it's
>> appropriate to code more simply without introducing unnecessary complexity
>> you should do so.
>>
>
> But you did not tell us about your asumtations about the circumstances.
>
>  I work in the data warehousing ETL world, where we have to perform field
>> edits or transformations to load source data into databases.  If I'm
>>
>
> Thats wrong. You do not "edit" fields. You have a validating type path and
> _always_ the database is most authoritative about what it accepts.
> Any other concept is just wrong and outright dangerous. There are
> many examples of how this works out (just check bugtraq)
>
>  already performing edits on these fields and if these fields are going to
>> be used for more updates downstream, it's wasteful to perform them again
>> when I build the SQL insert with the list and execute

Re: Not fully OO ?

[Tim Rowe]

2008/9/27 Aaron Castironpi Brady <[EMAIL PROTECTED]>:

> No way.  It's *zero* instead of one, if so, because the only thing C#
> has is a bunch of handcuffs and implicit 'self'.  You have a line
> like:

You don't follow what I said, and from your tone I get the feeling you
don't *want* to follow what I'm saying, not because I'm criticising
Python (I'm not), but because I'm guilty of the heresy of suggesting
that it's not actually simultaneoulsy optimised for every possible
use.

My point is that there are zero parameters as far as I am concerned
because I don't actually touch most of the GUI code.  There could
actually be hundreds of parameters, for all I care. They're not my
concern. Most of the time I like that -- the tools are doing my work
for me.

-- 
Tim Rowe
--
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Re: check if file is MS Word or PDF file

[Michael Crute]

On Sat, Sep 27, 2008 at 7:01 PM, Chris Rebert <[EMAIL PROTECTED]> wrote:
> Looking at the docs for the mimetypes module, it just guesses based on
> the filename (and extension), not the actual contents of the file, so
> it doesn't really help the OP, who wants to make sure their program
> isn't misled by an inaccurate extension.

One other way to detect a pdf is to just read the first 4 bytes from
the file. Valid pdf files start with "%PDF-". Something similar can be
done with Word docs but I don't know what the magic bytes are. This
approach is pretty similar to what the file command does but is
probably a better approach if you have to support multiple platforms.

-mike

-- 

Michael E. Crute
http://mike.crute.org

God put me on this earth to accomplish a certain number of things.
Right now I am so far behind that I will never die. --Bill Watterson
--
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Re: Borg vs Singleton vs OddClass

[Miles]

Lie wrote:
> This is probably unrelated to Python, as this is more about design
> pattern. I'm asking your comments about this design pattern that is
> similar in functionality to Singleton and Borg: to share states.
>
> I'm thinking about this design pattern (I don't know if anyone has
> ever thought of this pattern before):
>
> class OddClass(object):
>def __init__(self):
>global OddClass
>OddClass = self
>def __call__():

I'll change this to def __call__(self):

>return self
>
> The OddClass is a class that would overwrite its own class definition
> at its first instantiation. OddClass defines __call__ so that
> subsequent "instantiation" (technically it is no more an
> instantiation, but Duck Typing says it does) of the class would return
> the single instance.

This seems like a terrible idea to me, but then I never really
understood the appeal of the Singleton pattern, especially in Python.

> Singleton and OddClass is inheritable.
>
 class OddClass(object): ...
 s = OddClass()
 class A(OddClass): pass

Traceback (most recent call last):
  File "", line 1, in 
TypeError: Error when calling the metaclass bases
__init__() takes exactly 1 argument (4 given)

Oops!  And assuming you carefully ordered your code so that OddClass
will never be instantiated before it is subclassed (which seems
fragile), you get behavior like this:

>>> s = OddClass()
>>> s is OddClass()
True
>>> a = A()
>>> s is OddClass()
False
>>> a is OddClass()
True
>>> a is A()
False
>>> a is OddClass()
False

-Miles
--
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Re: Not fully OO ?

[Aaron "Castironpi" Brady]

On Sep 27, 6:55 pm, "Tim Rowe" <[EMAIL PROTECTED]> wrote:
> 2008/9/27 Aaron Castironpi Brady <[EMAIL PROTECTED]>:
>
> > No way.  It's *zero* instead of one, if so, because the only thing C#
> > has is a bunch of handcuffs and implicit 'self'.  You have a line
> > like:
>
> You don't follow what I said, and from your tone I get the feeling you
> don't *want* to follow what I'm saying, not because I'm criticising
> Python (I'm not), but because I'm guilty of the heresy of suggesting
> that it's not actually simultaneoulsy optimised for every possible
> use.
>
> My point is that there are zero parameters as far as I am concerned
> because I don't actually touch most of the GUI code.  There could
> actually be hundreds of parameters, for all I care. They're not my
> concern. Most of the time I like that -- the tools are doing my work
> for me.
>
> --
> Tim Rowe

flamewar.avert( ), please.  Yes, I agree, I did not follow every
word.  It's a fundamental disagreement about successful ways to
communicate, and, for the philosophers, successful communication,
whether I should have nitpicked first thing, or tried to go along with
the gist.  I tried the latter.  In your case, I guessed wrong.  Sorry.

Before I tried wxFormBuilder, I imagined that C# would be vastly
faster to develop than Python, for anything requiring any non-trivial
graphical interface.  I've done extensive VB, so I can attest to that
personally.  It is not.  The difference in dev times is about the time
it takes to write:

def onClick( event ):
   ...
controlA.bind( wx.MOUSEDOWN, onClick )

perhaps several times, which, , is not long.  You do
get the IDE, true, and that code is auto-crafted for you.  But 'wx'
does give you data in an XML file, instead of a script.  And talk
about a difference in identifiers:


  
 20,30
 gray
  


vs.

form.button.pos= 20, 30
form.button.color= gray

You can come up with examples that favor either.  But the opposite of
statistical is anecdotal.  Sorry again.

The last time I 'checked in' at your post, your claim was "an hour or
so" vs. "ages".  Hence my responses.  You could probably sneak by by
claiming a factor of *two*, but if you were exaggerating, please say
so at any time.

Penultimately, forgive my sarcasm--- I'm a bit feisty right now.  I
was distinguishing between arguments in particular, and identifiers in
general.

And lastly, "simultaneoulsy optimised for every possible use" is a
bold claim that I didn't make, at least, to come forward, in so many
words.  I do believe, and it shows, as of today, and you can quote me
on this, that it's "pretty generally applicable", though I reserve the
right to change my mind on the matter with or without notice.
Especially if I learn something.  I do not believe that C# is pretty
generally applicable.  I maintain that I will adjust that estimate if
I ever get any facts about C#, since I don't have very many.  (In
fact, outside of my VB, COM, and MFC experience, you could say I have
no clue.  Very tongue in cheek.)

In fact, do a Google for 'castironpi "every possible"'.  You get a
"can't ... every possible", and your post, and something else.  That's
it.

Python has a lot of things C# doesn't.  Can we agree on that?


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Re: Hello boys!

[default]

On Sat, 27 Sep 2008 23:12:59 + (UTC), Cydrome Leader
<[EMAIL PROTECTED]> wrote:

>In rec.crafts.metalworking Jim Thompson <[EMAIL PROTECTED]> wrote:
>> 
>> On Sat, 27 Sep 2008 18:47:16 -0400, default <[EMAIL PROTECTED]>
>> wrote:
>> 
>>>On Sat, 27 Sep 2008 14:56:07 -0700 (PDT), Milenko Stojadinovic Cvrcko
>>><[EMAIL PROTECTED]> wrote:
>>>
Hello, this is Milenko Stojadinovic from town Banjaluka,
Bosnia and Herzegovina, also known as Cvrcko
Does anyone know of any bars in town where I can
swallow a bucket of cum? It can be either dog,
horse or human cum. Also, does anyone know of
any sex bars where people will shit in your mouth?
I also like eating shit.
>>>
>>>Come to the US and park your mouth in front of George Bush - all the
>>>Bshit you can eat - and it keeps on coming!
>>>
>>>I have a buddy in Bosna - he's normal.
>> 
>> Now you know why I blanket kill-file googlegroups.
>
>So you and everybody can talk about them nonstop?

If you mean Google Groups the condemnation is justified.

Who is "them?"  Real people do occasionally wander in to GG - or those
without news servers - or without understanding of Usenet.

Basically, in the engineering groups (in particular) outsiders are
welcome.  Engineers are smart, creative and tolerant as a general
rule.  

Lighten up.  Who are you defending?  and Who goes into Usenet with a
thin skin?  Expect ridicule, expect condemnation - "water off a duck's
back."

You may think your viewpoint is the only one, the right one, the valid
one - but a few million others may disagree.  And you ain't started to
deal with culture shock - some countries place emphasis on diplomacy _
you know the "how are you?" stuff, others don't, and seem very cold.

Adapt.
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Docstrings for attributes?

[Roy Smith]

Is there any way to attach a docstring to an attribute?  I see that PEP-257 
talks about attribute docstrings, but it references PDP-258, which was 
rejected.

I suppose I could eschew plain attributes in favor of getter functions, 
because those give me a place to hang a docstring, but that feels like the 
wrong thing to do.
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what's difference usage?

[momobear]

while as I try to wrap a function using boost-python, I find a strange
situation.
#include 
#include 
#include 
#include 
#include 

using namespace boost::python;

int printlist(list &l){
std::vector a;
a.push_back("c++");
a.push_back("javascript");
for (std::vector::iterator p = a.begin(); p != a.end(); +
+p)
l.append(*p);
   return 0;
}

BOOST_PYTHON_MODULE(wlist){
   def("printlist", printlist);
}

in the up code,"int printlist(list &l)" at first time I missed add &
left of l. but when I run the following python code,
#!/usr/local/bin/python
a = list()
a.append('linux')
import wlist
wlist.printlist(a)
print a

they get the same result.
linux
c++
javascript

anyone help me figure out what's wrong here. thanks.
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Re: Docstrings for attributes?

[alex23]

On Sep 28, 11:50 am, Roy Smith <[EMAIL PROTECTED]> wrote:
> Is there any way to attach a docstring to an attribute?  I see that PEP-257
> talks about attribute docstrings, but it references PDP-258, which was
> rejected.
>
> I suppose I could eschew plain attributes in favor of getter functions,
> because those give me a place to hang a docstring, but that feels like the
> wrong thing to do.

There were a couple of solutions provided - including the use of
properties - when this question came up earlier this week:
http://groups.google.com/group/comp.lang.python/browse_frm/thread/18a8c3f09ac02f85#
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Re: Borg vs Singleton vs OddClass

[Steven D'Aprano]

On Sat, 27 Sep 2008 11:12:00 -0700, Lie wrote:

> This is probably unrelated to Python, as this is more about design
> pattern. I'm asking your comments about this design pattern that is
> similar in functionality to Singleton and Borg: to share states.
> 
> I'm thinking about this design pattern (I don't know if anyone has ever
> thought of this pattern before):
> 
> class OddClass(object):
> def __init__(self):
> global OddClass
> OddClass = self
> def __call__():
> return self


I don't think that pattern works as you give it. I suggest you read the 
thread "What do you call a class not intended to be instantiated", 
started by me on the 21st of September, which covers a similar pattern.

I'm afraid it's a rather long thread, with a lot of people 
misunderstanding what I was asking, but still worth reading. If you only 
have time to read one post, I suggest you read my reply to Ben Finney, 
posted yesterday.

My own feeling is that both your OddClass and my class without instances 
are probably solutions looking for a problem. Well, actually, no, that's 
too strong: I think the concept of "Class Singleton" is a perfectly valid 
solution to certain problems, but it competes with more well-known 
solutions like modules and Borg (in Python) and Singletons (the hammer 
available in Java and C++). As for which is better, that's partly a 
matter of personal taste and partly a matter of familiarity.


> It do have a problem though, that you can't do isinstance(a, OddClass)

But you can say "a is OddClass", which is more appropriate for a 
Singleton.

> The problem with Borg is that it is not inheritable (in certain
> sense[1]) and only work with old-style class (which is due to be
> completely removed on py3k)[2]

No, there is a new-style Borg. Read the comments here:
http://code.activestate.com/recipes/66531/

The new-style Borg is hardly more complicated than old-style: 6 lines 
versus 4.

I like Luke Plant's comment:

"classes and modules are singletons. You don't need singletons in python 
simply because classes and modules are always singletons, and they are 
also first class objects. They can have everything instances have, and as 
import statements don't make copies there is only ever one of them. We 
don't need no stinkin' design patterns."



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Re: What do you call a class not intended to be instantiated

[Steven D'Aprano]

On Sat, 27 Sep 2008 17:41:42 -0400, Terry Reedy wrote:

> In 3.0, at least, one does not need a disk file to create a module.
> 
>  >>> import types
>  >>> me = types.ModuleType('me') # type(__builtins__) works, no import
>  >>> me
> 
>  >>> me.a = 1
>  >>> me.a
> 1
>  >>> me.a + 1
> 2

Seems to work for Python 2.5 as well.


> That said, a blank class is even easier, and the representation is
> better.

And modules aren't callable. I've often thought they should be.


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Re: Hello boys!

[Jim Thompson]

On Sat, 27 Sep 2008 23:12:59 + (UTC), Cydrome Leader
<[EMAIL PROTECTED]> wrote:

>In rec.crafts.metalworking Jim Thompson <[EMAIL PROTECTED]> wrote:
>> 
>> On Sat, 27 Sep 2008 18:47:16 -0400, default <[EMAIL PROTECTED]>
>> wrote:
>> 
>>>On Sat, 27 Sep 2008 14:56:07 -0700 (PDT), Milenko Stojadinovic Cvrcko
>>><[EMAIL PROTECTED]> wrote:
>>>
Hello, this is Milenko Stojadinovic from town Banjaluka,
Bosnia and Herzegovina, also known as Cvrcko
Does anyone know of any bars in town where I can
swallow a bucket of cum? It can be either dog,
horse or human cum. Also, does anyone know of
any sex bars where people will shit in your mouth?
I also like eating shit.
>>>
>>>Come to the US and park your mouth in front of George Bush - all the
>>>Bshit you can eat - and it keeps on coming!
>>>
>>>I have a buddy in Bosna - he's normal.
>> 
>> Now you know why I blanket kill-file googlegroups.
>
>So you and everybody can talk about them nonstop?

You're gone also ;-)

...Jim Thompson
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| Analog Innovations, Inc. | et  |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |manus|
| Phoenix, Arizona  85048Skype: Contacts Only  | |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
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design pattern: MVC in python

[甜瓜]

Howdy,

I am working on a small PC game by using pygame. Since there are many
graphical objects to display and intensive user interactions, I would
like to employ MVC pattern to keep the system maintainable.
However, I cannot find a good article which discussing the general
knowledge about MVC, especially:
1. How to decouple M-V-C? That is, which function should be assigned
to which part.
2. How to communicate each other while keeping M-V-C decoupled?
3. Do I need to create Interface/Proxy class for each component?
4. What is the general principle for designing the interface of M-V-C?
As my previous experience, if without special care on the principle,
the MVC pattern would gradually become messy and the boundary between
each component becomes unclear.

Could you give me any advice? In addition, can we take the advantage
of python language to make MVC easy-to-build and easy-to-use?

Thank you in advance.

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Re: Abstract Base Class register function

[Benjamin]

On Sep 27, 4:50 pm, "Mikolai Fajer" <[EMAIL PROTECTED]> wrote:
> I have been experimenting with the abc module in py3k and thought
> about using the register method of an ABC as a class decorator:
>
> 
> import abc
> class MyABC(metaclass=abc.ABCMeta):
>     pass
>
> @MyABC.register
> class MySub():
>     pass
> 
>
> This doesn't work because the register method returns None.  It would
> be a fairly simple modification to have this work:
>
> 
>     def register(cls, subclass):
>         """Register a virtual subclass of an ABC."""
>         ... etc ...
>         return subclass
> 
>
> What do people think of this behavior?

It's probably better to just inherit from your metclass. register is
really for use with extension types that implement an interface.
>
> --
>
>      -Mikolai Fajer-

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Re: is decorator the right thing to use?

[Dmitry S. Makovey]

George Sakkis wrote:
> It's funny how often you come with a better solution a few moments
> after htting send! The snippet above can (ab)use the decorator syntax
> so that it becomes:
> 
> class A(Proxy):
> 
> @ProxyMethod
> def bmethod(self):
> return self.b1
> 
> @ProxyMethod
> def bmethod2(self):
> return self.b2

That is outstanding! This code looks very clean to me (just a touch cryptic
around declarations in A, but that was unavoidable anyway). Seems like the
right way to read it would be bottom up (or is it only my mind so
perverted?). By the looks of it - it does exactly what I needed with great
number of possibilities behind it and is very lightweight and transparent.
Now I regret I haven't come up with it myself :-D

George, at this point I'm out of rugs - so no more rug pulling from under
your feet for me. 

Now I'm going to apply all this knowledge to my code, see how that goes and
come back with more questions later.

Thank you (all) very much for a great discussion. This thread educated me
quite a bit on descriptors and why one would need them, and decorators -
just as subject line suggested, were not forgotten. 


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closures and dynamic binding

[Aaron "Castironpi" Brady]

Hello all,

To me, this is a somewhat unintuitive behavior.  I want to discuss the
parts of it I don't understand.

>>> f= [ None ]* 10
>>> for n in range( 10 ):
... f[ n ]= lambda: n
...
>>> f[0]()
9
>>> f[1]()
9

I guess I can accept this part so far, though it took a little getting
used to.  I'm writing some code and found the following workaround,
but I don't think it should give different results.  Maybe I'm not
understanding some of the details of closures.

>>> f= [ None ]* 10
>>> for n in range( 10 ):
... f[ n ]= (lambda n: ( lambda: n ) )( n )
...
>>> f[0]()
0
>>> f[1]()
1

Which is of course the desired effect.  Why doesn't the second one
just look up what 'n' is when I call f[0], and return 9?
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how to make smtplib.SMTP('localhost') work on window xp

[zxo102]

Hi,
 I am trying to use python module smtplib to send my email out on
window xp (localhost).

import smtplib
server = smtplib.SMTP('localhost')

but I got the error information as follows:

Traceback (most recent call last):
  File "", line 1, in ?
  File "c:\python24\lib\smtplib.py", line 244, in __init__
(code, msg) = self.connect(host, port)
  File "c:\python24\lib\smtplib.py", line 311, in connect
(code, msg) = self.getreply()
  File "c:\python24\lib\smtplib.py", line 355, in getreply
raise SMTPServerDisconnected("Connection unexpectedly closed")
SMTPServerDisconnected: Connection unexpectedly closed

I am not sure what is wrong with it. Should I configure my window xp
somewhere to run smtplib.SMTP('localhost')?

Thanks in advance.

ouyang
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str() should convert ANY object to a string without EXCEPTIONS !

[est]

>From python manual

str( [object])

Return a string containing a nicely printable representation of an
object. For strings, this returns the string itself. The difference
with repr(object) is that str(object) does not always attempt to
return a string that is acceptable to eval(); its goal is to return a
printable string. If no argument is given, returns the empty string,
''.


now we try this under windows:

>>> str(u'\ue863')
Traceback (most recent call last):
  File "", line 1, in 
UnicodeEncodeError: 'ascii' codec can't encode character u'\ue863' in
position 0
: ordinal not in range(128)

FAIL.

also almighty Linux

Python 2.3.4 (#1, Feb  6 2006, 10:38:46)
[GCC 3.4.5 20051201 (Red Hat 3.4.5-2)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> str(u'\ue863')
Traceback (most recent call last):
  File "", line 1, in ?
UnicodeEncodeError: 'ascii' codec can't encode character u'\ue863' in
position 0: ordinal not in range(128)

Python 2.4.4 (#2, Apr  5 2007, 20:11:18)
[GCC 4.1.2 20061115 (prerelease) (Debian 4.1.1-21)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> str(u'\ue863')
Traceback (most recent call last):
  File "", line 1, in ?
UnicodeEncodeError: 'ascii' codec can't encode character u'\ue863' in
position 0: ordinal not in range(128)

Python 2.5 (release25-maint, Jul 20 2008, 20:47:25)
[GCC 4.1.2 20061115 (prerelease) (Debian 4.1.1-21)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> str(u'\ue863')
Traceback (most recent call last):
  File "", line 1, in 
UnicodeEncodeError: 'ascii' codec can't encode character u'\ue863' in
position 0: ordinal not in range(128)


The problem is, why the f**k set ASCII encoding to range(128) 
while str() is internally byte array it should be handled in
range(256) !!

http://bugs.python.org/issue3648

One possible solution(Windows Only)

>>> str(u'\ue863'.encode('mbcs'))
'\xfe\x9f'
>>> print u'\ue863'.encode('mbcs')
��


I now spending 60% of my developing time dealing with ASCII range(128)
errors. It was PAIN!!

Please fix this issue.

http://bugs.python.org/issue3648

Please.
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Re: str() should convert ANY object to a string without EXCEPTIONS !

[Lawrence D'Oliveiro]

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

> The problem is, why the f**k set ASCII encoding to range(128) 

Because that's how ASCII is defined.

> while str() is internally byte array it should be handled in
> range(256) !!

But that's for random bytes. How would you convert an arbitrary object to
random bytes?
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Re: str() should convert ANY object to a string without EXCEPTIONS !

[Marc 'BlackJack' Rintsch]

On Sat, 27 Sep 2008 22:37:09 -0700, est wrote:

> The problem is, why the f**k set ASCII encoding to range(128) 

Because that's how ASCII is defined.  ASCII is a 7-bit code.

> while str() is internally byte array it should be handled in range(256)
> !!

Yes `str` can handle that, but that's not the point.  The point is how to 
translate the contents of a `unicode` object into that range.  There are 
many different possibilities and Python refuses to guess and tries the 
lowest common denominator -- ASCII -- instead.

> I now spending 60% of my developing time dealing with ASCII range(128)
> errors. It was PAIN!!
> 
> Please fix this issue.
> 
> http://bugs.python.org/issue3648
> 
> Please.

The issue was closed as 'invalid'.  Dealing with Unicode can be a pain 
and frustrating, but that's not a Python problem, it's the subject itself 
that needs some thoughts.  If you think this through, the relationship 
between characters, encodings, and bytes, and stop dreaming of a magic 
solution that works without dealing with this stuff explicitly, the pain 
will go away -- or ease at least.

Ciao,
Marc 'BlackJack' Rintsch
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Re: Not fully OO ?

[Lawrence D'Oliveiro]

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

> On Fri, Sep 26, 2008 at 8:20 AM, Lawrence D'Oliveiro
> <[EMAIL PROTECTED]> wrote:
>
>> Object orientation IS procedural.
> 
> Correction: OOP is Imperative.

No, "procedural".

The functional unit is called an "expression", the encapsulation of which is
called a "function". Hence "functional".

Similarly, the procedural unit is commonly called a "statement", the
encapsulation of which is a "procedure", not an "imperator".
Hence "procedural".
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Re: Not fully OO ?

[Lawrence D'Oliveiro]

In message
<[EMAIL PROTECTED]>,
Aaron "Castironpi" Brady wrote:

> I understand that formal proof systems, as well as automated
> theorem provers, have been difficult to develop.

The basic problem is: having proved that a program satisfies certain
formally-specified criteria, how do you prove that those formal criteria
specifications actually correspond to the original problem you were trying
to solve? The proof just pushes the correctness problem back another level.
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Re: closures and dynamic binding

[Marc 'BlackJack' Rintsch]

On Sat, 27 Sep 2008 21:43:15 -0700, Aaron \"Castironpi\" Brady wrote:

> To me, this is a somewhat unintuitive behavior.  I want to discuss the
> parts of it I don't understand.
> 
 f= [ None ]* 10
 for n in range( 10 ):
> ... f[ n ]= lambda: n
> ...
 f[0]()
> 9
 f[1]()
> 9

`n` is looked up at the time ``f[0]`` is called.  At that time it is 
bound to 9.

 f= [ None ]* 10
 for n in range( 10 ):
> ... f[ n ]= (lambda n: ( lambda: n ) )( n ) ...
 f[0]()
> 0
 f[1]()
> 1
> 
> Which is of course the desired effect.  Why doesn't the second one just
> look up what 'n' is when I call f[0], and return 9?

It *does* look up `n` at the time you call ``f[0]`` but this time it's 
the local `n` of the outer ``lambda`` function and that is bound to 
whatever the function was called with.  At the time it was called the 
global `n` was bound to 0.  Maybe it get's more clear if you don't name 
it `n`:

In [167]: f = [None] * 10

In [168]: for n in xrange(10):
   .: f[n] = (lambda x: lambda: x)(n)
   .:

In [169]: f[0]()
Out[169]: 0

Ciao,
Marc 'BlackJack' Rintsch
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Re: design pattern: MVC in python

[Mikolai Fajer]

The following link directly discusses using MVC and pygame.

http://ezide.com/games/writing-games.html

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