twitter: comp.lang.python - 25 new messages in 13 topics

comp.lang.python
http://groups.google.com/group/comp.lang.python?hl=en

comp.lang.python@googlegroups.com

Today's topics:

==============================================================================
TOPIC: ctypes errcheck question
http://groups.google.com/group/comp.lang.python/t/365079f0e22f1e12?hl=en
==============================================================================

== 1 of 1 ==
Date: Wed, Apr 21 2010 12:56 pm
From: Brendan Miller

According to the ctypes docs: http://docs.python.org/library/ctypes.html

An errcheck function should return the args tuple when used with out
parameters (section 15.15.2.4. Function prototypes). However, in other
cases it says to return the result, or whatever result you want
returned from the function.

I have a single errcheck function that checks result codes and throws
an exception if the result indicates an error. I'd like to reuse it
with a number of different function, some of which are specified with
out parameters, and some of which are specified in the normal method:

func = my_lib.func
func.restype = c_long
func.argtypes = [c_int, etc]

So, my question is can do I have my errcheck function return the args
tuple in both cases? The documentation seems kind of ambiguous about
how it will behave if a function loaded without output parameters
returns the arguments tuple from errcheck.

Thanks,
Brendan

==============================================================================
TOPIC: Deleting more than one element from a list
http://groups.google.com/group/comp.lang.python/t/f2a8d8bf92392d12?hl=en
==============================================================================

== 1 of 5 ==
Date: Wed, Apr 21 2010 1:12 pm
From: Simon Brunning

On 21 April 2010 20:56, candide <candide@free.invalid> wrote:
> Is the del instruction able to remove _at the same_ time more than one
> element from a list ?

Yup:

>>> z=[45,12,96,33,66,'ccccc',20,99]
>>> del z[:]
>>> z
[]

--
Cheers,
Simon B.

== 2 of 5 ==
Date: Wed, Apr 21 2010 1:40 pm
From: Gary Herron

candide wrote:
> Is the del instruction able to remove _at the same_ time more than one
> element from a list ?
>
>
> For instance, this seems to be correct :
>
>
> >>> z=[45,12,96,33,66,'ccccc',20,99]
> >>> del z[2], z[6],z[0]
> >>> z
> [12, 33, 66, 'ccccc', 20]
> >>>
>
>
> However, the following doesn't work :
>
> >> z=[45,12,96,33,66,'ccccc',20,99]
> >>> del z[2], z[3],z[6]
> Traceback (most recent call last):
> File "<stdin>", line 1, in <module>
> IndexError: list assignment index out of range
> >>>
>
>
> Does it mean the instruction
>
> del z[2], z[3],z[6]
>
> to be equivalent to the successive calls
>
>
> del z[2]
> del z[3]
> del z[6]

Yes, those are equivalent. The reason it fails is that, by the time it
gets around to the third delete, there is no longer in index [6] in the
list. The element you were thinking of is now at index [4].

This, however, will work as you expected:

del z[6], z[3],z[2]

--
Gary Herron, PhD.
Department of Computer Science
DigiPen Institute of Technology
(425) 895-4418

== 3 of 5 ==
Date: Wed, Apr 21 2010 1:49 pm
From: Mensanator

On Apr 21, 2:56 pm, candide <cand...@free.invalid> wrote:
> Is the del instruction able to remove _at the same_ time more than one
> element from a list ?
>
> For instance, this seems to be correct :
>
> >>> z=[45,12,96,33,66,'ccccc',20,99]
> >>> del z[2], z[6],z[0]
> >>> z
> [12, 33, 66, 'ccccc', 20]
> >>>
>
> However, the following doesn't work :
>
> >> z=[45,12,96,33,66,'ccccc',20,99]
> >>> del z[2], z[3],z[6]
> Traceback (most recent call last):
> File "<stdin>", line 1, in <module>
> IndexError: list assignment index out of range
> >>>
>
> Does it mean the instruction
>
> del z[2], z[3],z[6]
>
> to be equivalent to the successive calls
>
> del z[2]
> del z[3]
> del z[6]

That's part of the problem. Let's look at a better example.

>>> z = [0,1,2,3,4,5,6]
>>> del z[0],z[3],z[6]
Traceback (most recent call last):
File "<pyshell#1>", line 1, in <module>
del z[0],z[3],z[6]
IndexError: list assignment index out of range
>>> z
[1, 2, 3, 5, 6]

Yes, the error was caused by the list shrinking between calls,
so the 6 did not get deleted. But notice that 3 is still there
and 4 is missing.

If you must delete this way, do it bottom up so that the index
remains valid for the subsequent calls:

>>> z = [0,1,2,3,4,5,6]
>>> del z[6],z[3],z[0]
>>> z
[1, 2, 4, 5]

>
> ?

== 4 of 5 ==
Date: Wed, Apr 21 2010 1:57 pm
From: Emile van Sebille

On 4/21/2010 12:56 PM candide said...
> Is the del instruction able to remove _at the same_ time more than one
> element from a list ?
>
>
> For instance, this seems to be correct :
>
>
> >>> z=[45,12,96,33,66,'ccccc',20,99]

Not as I see it -- watch your index values - they change after each
delete is completed. It'll work if you order them backwards though.

>>> a = range(10)
>>> del a[0],a[2],a[4],a[6]
>>> a
[1, 2, 4, 5, 7, 8]
>>> a = range(10)
>>> del a[6],a[4],a[2],a[0]
>>> a
[1, 3, 5, 7, 8, 9]
>>>

Emile

== 5 of 5 ==
Date: Wed, Apr 21 2010 3:45 pm
From: candide

Thanks for your reponses.

==============================================================================
TOPIC: Windows debugging symbols for python 2.5.4 and pywin32 214
http://groups.google.com/group/comp.lang.python/t/b55f663b9e22c097?hl=en
==============================================================================

== 1 of 1 ==
Date: Wed, Apr 21 2010 2:23 pm
From: Alexandre Fayolle

Hi everyone,

I have a production server running a Windows Service written in Python, which
uses python 2.5.4 (yes I know it is old, but I am somewhat stuck with this for
now) and pywin32 214.

Given a set of manipulations, I get a stack overflow in the service, and a bad
crash. The same operation when running without
win32serviceutil.ServiceFramework does not trigger the bug. I'm looking for
some debugging tools (debug build of the interpreter and the pywin32
libraries) that some good soul could have kept from a previous debugging
session to try to get a C stack trace and understand what causes this.

Any hint towards what could cause that stack overflow would be welcome too.
The application is multithreaded (and uses pyro and twisted). I can provide
more information for the curious.

Many thanks.

--
Alexandre Fayolle
Logilab, Paris, France.

==============================================================================
TOPIC: Looking for registration package
http://groups.google.com/group/comp.lang.python/t/1825049a2a4f5529?hl=en
==============================================================================

== 1 of 1 ==
Date: Wed, Apr 21 2010 2:42 pm
From: kj

I'm looking for a Python-based, small, self-contained package to
hand out API keys, in the same spirit as Google API keys.

The basic specs are simple: 1) enforce the "one key per customer"
rule; 2) be robot-proof; 3) be reasonably difficult to circumvent
even for humans.

(This is for a web service we would like to implement; the goal is
to be able to control the load on our servers. Therefore, if the
package includes an automated log-analysis component, all the
better, but this is not necessary.)

Any suggestions would be appreciated.

Thanks!

==============================================================================
TOPIC: ctypes: delay conversion from c_char_p to string
http://groups.google.com/group/comp.lang.python/t/a6e1c551a1bc2630?hl=en
==============================================================================

== 1 of 2 ==
Date: Wed, Apr 21 2010 3:15 pm
From: Brendan Miller

I have a function exposed through ctypes that returns a c_char_p.
Since I need to deallocate that c_char_p, it's inconvenient that
ctypes copies the c_char_p into a string instead of giving me the raw
pointer. I believe this will cause a memory leak, unless ctypes is
smart enough to free the string itself after the copy... which I
doubt.

Is there some way to tell ctypes to return an actual c_char_p, or is
my best bet to return a c_void_p and cast to c_char_p when I'm reading
to convert to a string?

Thanks
Brendan

== 2 of 2 ==
Date: Wed, Apr 21 2010 3:29 pm
From: Brendan Miller

Here's the method I was using. Note that tmp_char_ptr is of type
c_void_p. This should avoid the memory leak, assuming I am
interpreting the semantics of the cast correctly. Is there a cleaner
way to do this with ctypes?

def get_prop_string(self, prop_name):
# Have to work with c_void_p to prevent ctypes from copying to a string
# without giving me an opportunity to destroy the original string.
tmp_char_ptr = _get_prop_string(self._props, prop_name)
prop_val = cast(tmp_char_ptr, c_char_p).value
_string_destroy(tmp_char_ptr)
return prop_val

On Wed, Apr 21, 2010 at 3:15 PM, Brendan Miller <catphive@catphive.net> wrote:
> I have a function exposed through ctypes that returns a c_char_p.
> Since I need to deallocate that c_char_p, it's inconvenient that
> ctypes copies the c_char_p into a string instead of giving me the raw
> pointer. I believe this will cause a memory leak, unless ctypes is
> smart enough to free the string itself after the copy... which I
> doubt.
>
> Is there some way to tell ctypes to return an actual c_char_p, or is
> my best bet to return a c_void_p and cast to c_char_p when I'm reading
> to convert to a string?
>
> Thanks
> Brendan
>

==============================================================================
TOPIC: Python-URL! - weekly Python news and links (Mar 9)
http://groups.google.com/group/comp.lang.python/t/d7c14ea356fcba84?hl=en
==============================================================================

== 1 of 1 ==
Date: Wed, Apr 21 2010 3:16 pm
From: Cameron Laird

QOTW: "I used to think anonymous functions (AKA blocks, etc...) would
be a
nice feature for Python.

Then I looked at a stack trace from a different programming language
with
lots of anonymous functions. (I believe it was perl.)

I became enlightened." - Jonathan Gardner, apparently echoing Guido's
criterion of debuggability in language design
http://groups.google.com/group/comp.lang.python/msg/3ebe7a0b78086acf

Editor Cameron Laird apologizes for the following three entries, which
appeared in the last installment only in an unusably garbled form:
There is no module in the standard library to handle filesystem
paths
in an OO way - but why?
http://groups.google.com/group/comp.lang.python/t/f580fb3763208425/

A "History Channel" special: how the way a TAB key was interpreted
changed over time
http://groups.google.com/group/comp.lang.python/t/82d9181fcd31ffe4/

After a false start, finally we get our first "Is it Call-By-Value
or
Call-By-Reference?" thread of the year!
http://groups.google.com/group/comp.lang.python/t/fd36962c4970ac48/
---------------------------------------------------------------------------
Back in the present,
Three new preliminary Python versions are now available for
testing:
Python 2.7 alpha 4
http://groups.google.com/group/comp.lang.python/t/779e761d934dbc1a/
Python 3.1.2 release candidate
http://permalink.gmane.org/gmane.comp.python.general/656887
Python 2.6.5 release candidate 1
http://permalink.gmane.org/gmane.comp.python.devel/111319

Forget those Java recipes when implementing the Singleton pattern:
http://groups.google.com/group/comp.lang.python/t/9228a3763eb552b3/

How to obtain a module docstring without actually importing it:
http://groups.google.com/group/comp.lang.python/t/ca97d63ace6ea81d/

Do something only if a certain module is already in use by the
current
program:
http://groups.google.com/group/comp.lang.python/t/ee22c223fa73a429/

Functions, bound methods, unbound ones: what are their differences?
http://groups.google.com/group/comp.lang.python/t/72ab93ba395822ed/

Automatically adding global names to a module: how to do that, and
alternatives to use when it's not a good idea:
http://groups.google.com/group/comp.lang.python/t/40837c4567d64745/

Raymond Hettinger on the rationale behind the collections.Counter
class:
http://groups.google.com/group/comp.lang.python/t/64d0fe87f7ea9e6/

How Tk 8.5 + ttk (the version that ships with Python 2.6) compares
to
other GUI toolkits:
http://groups.google.com/group/comp.lang.python/t/d8d24eacf022ed75/

The actual behavior of slicing like L[n::-1] is not properly
documented:
http://groups.google.com/group/comp.lang.python/t/add9aa920b55eacc/

Documenting a function with #comments instead of a proper docstring
is
silly, isn't it? How does that affect source code quality?
(Including
historical disgression going back to the PDP-8, the Altair and even
nanocomputers...)
http://groups.google.com/group/comp.lang.python/t/dea5c94f3d058e26/

Coming from Perl, one has to unlearn (bad?) habits and embrace
Python's
"rigid flexibility":
http://groups.google.com/group/comp.lang.python/t/4bfdc60d3f58c960/
http://groups.google.com/group/comp.lang.python/t/24bfa00b428f868f/

And for those perl-like oneliner fans, here is dos2unix:
http://groups.google.com/group/comp.lang.python/t/c4b63debe91d51c7/

Perl has CPAN. Python has PyPI + easy_install, but they lack many
important features. How could we improve that?
http://groups.google.com/group/comp.lang.python/t/c2c452cc4aaa6e98/

The pysandbox project provides a sandbox where untrusted code
cannot
modify its environment; now looking for someone to find holes in
it:
http://groups.google.com/group/comp.lang.python/t/87bf10f8acede7c3/

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

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

PythonWare complements the digest you're reading with the
marvelous daily python url
http://www.pythonware.com/daily

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

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

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

comp.lang.python.announce announces new Python software. Be
sure to scan this newsgroup weekly.
http://groups.google.com/group/comp.lang.python.announce/topics

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

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

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

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

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

The Summary of Python Tracker Issues is an automatically generated
report summarizing new bugs, closed ones, and patch submissions.
http://search.gmane.org/?author=status%40bugs.python.org&group=gmane.comp.python.devel&sort=date

nullege is an interesting search Web application, with the
intelligence
to distinguish between Python code and comments. It provides what
appear to be relevant results, and demands neither Java nor CSS be
enabled:
http://www.nullege.com

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

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

The Cookbook is a collaborative effort to capture useful and
interesting recipes.
http://code.activestate.com/recipes/langs/python/

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

Among several Python-oriented RSS/RDF feeds available, see:
http://www.python.org/channews.rdf
For more, see:
http://www.syndic8.com/feedlist.php?ShowMatch=python&ShowStatus=all
The old Python "To-Do List" now lives principally in a
SourceForge reincarnation.
http://sourceforge.net/tracker/?atid=355470&group_id=5470&func=browse
http://www.python.org/dev/peps/pep-0042/

del.icio.us presents an intriguing approach to reference
commentary.
It already aggregates quite a bit of Python intelligence.
http://del.icio.us/tag/python

Enjoy the *Python Magazine*.
http://pymag.phparch.com/

*Py: the Journal of the Python Language*
http://www.pyzine.com

Dr.Dobb's Portal is another source of Python news and articles:
http://www.ddj.com/TechSearch/searchResults.jhtml?queryText=python
and Python articles regularly appear at IBM DeveloperWorks:
http://www.ibm.com/developerworks/search/searchResults.jsp?searchSite=dW&searchScope=dW&encodedQuery=python&rankprofile=8

Previous - (U)se the (R)esource, (L)uke! - messages are listed here:
http://search.gmane.org/?query=python+URL+weekly+news+links&group=gmane.comp.python.general&sort=date
http://groups.google.com/groups/search?q=Python-URL!+group%3Acomp.lang.python&start=0&scoring=d&
http://lwn.net/Search/DoSearch?words=python-url&ctype3=yes&cat_25=yes

There is *not* an RSS for "Python-URL!"--at least not yet. Arguments
for and against are occasionally entertained.

Suggestions/corrections for next week's posting are always welcome.
E-mail to <Python-URL@phaseit.net> should get through.

To receive a new issue of this posting in e-mail each Monday morning
(approximately), ask <claird@phaseit.net> to subscribe. Mention
"Python-URL!". Write to the same address to unsubscribe.

-- The Python-URL! Team--

Phaseit, Inc. (http://phaseit.net) is pleased to participate in and
sponsor the "Python-URL!" project. Watch this space for upcoming
news about posting archives.

==============================================================================
TOPIC: Python-URL! - weekly Python news and links (Mar 17)
http://groups.google.com/group/comp.lang.python/t/a61081f46c167510?hl=en
==============================================================================

== 1 of 1 ==
Date: Wed, Apr 21 2010 3:17 pm
From: Cameron Laird

QOTW: "... [T]hat kills yet another usage of C ..." - Maciej
Fijalkowski
http://morepypy.blogspot.com/2009/11/some-benchmarking.html

Making operations in the Fraction class automatically return a
subclass
instance when called with subclass arguments:
http://groups.google.com/group/comp.lang.python/t/2512697a901d4752/

Providing alternate constructors for an existing class:
http://groups.google.com/group/comp.lang.python/t/99e87afb58f3ef3d/

Checking existence of files matching a certain pattern:
http://groups.google.com/group/comp.lang.python/t/a95183b7ae931b7a/

How to gracefully exit the current process, when there are multiple
threads, on Windows:
http://groups.google.com/group/comp.lang.python/t/5a6a7bcfd30fb7ce/

How inspect.stack()/sys._getframe() interact with local variables
and
references:
http://groups.google.com/group/comp.lang.python/t/fc8bf697fa9a01a4/

Alternatives to the re module when looking for a large set of
constant
strings:
http://groups.google.com/group/comp.lang.python/t/63e6e177be7dea21/

Why does Python syntax allow "break" from no more than a single
loop
at one time?
http://groups.google.com/group/comp.lang.python/t/96f3407480ed39ab/

Trying to start a new Python meeting group is not easy:
http://groups.google.com/group/comp.lang.python/t/a24bf882c72c555/

Bad interactions between cmd.exe code page (Windows), Popen, and
the
UTF-8 encoding:
http://groups.google.com/group/comp.lang.python/t/2da1f1de573e5663/

An example showing how to use the locale module to format a number
with
thousand separators:
http://groups.google.com/group/comp.lang.python/t/42e63e3a53f03593/

How non-ASCII characters get entered from the Python interactive
console:
http://groups.google.com/group/comp.lang.python/t/77271907fb195aca/

Raymond Hettinger on the rationale behind the collections.Counter
class:
http://groups.google.com/group/comp.lang.python/t/64d0fe87f7ea9e6/

You could not go to PyCon Atlanta? No problem - many PyCon talks
from
the last two years are available here:
httppycon.blip.tv/
http://python.mirocommunity.org/

An interesting problem: find out the the algorithm used to compute
a
given CRC
http://groups.google.com/group/comp.lang.python/t/b22db1e3e63db596/

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

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

PythonWare complements the digest you're reading with the
marvelous daily python url
http://www.pythonware.com/daily

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

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

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

comp.lang.python.announce announces new Python software. Be
sure to scan this newsgroup weekly.
http://groups.google.com/group/comp.lang.python.announce/topics

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

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

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

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

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

The Cookbook is a collaborative effort to capture useful and
interesting recipes.
http://code.activestate.com/recipes/langs/python/

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

del.icio.us presents an intriguing approach to reference
commentary.
It already aggregates quite a bit of Python intelligence.
http://del.icio.us/tag/python

Enjoy the *Python Magazine*.
http://pymag.phparch.com/

*Py: the Journal of the Python Language*
http://www.pyzine.com

There is *not* an RSS for "Python-URL!"--at least not yet. Arguments
for and against are occasionally entertained.

Suggestions/corrections for next week's posting are always welcome.
E-mail to <Python-URL@phaseit.net> should get through.

To receive a new issue of this posting in e-mail each Monday morning
(approximately), ask <claird@phaseit.net> to subscribe. Mention
"Python-URL!". Write to the same address to unsubscribe.

-- The Python-URL! Team--

Phaseit, Inc. (http://phaseit.net) is pleased to participate in and
sponsor the "Python-URL!" project. Watch this space for upcoming
news about posting archives.

==============================================================================
TOPIC: Python-URL! - weekly Python news and links (Feb 9)
http://groups.google.com/group/comp.lang.python/t/180100739e5a10f1?hl=en
==============================================================================

== 1 of 1 ==
Date: Wed, Apr 21 2010 3:18 pm
From: Cameron Laird

QOTW: "You see? That's what I like about the Python community: people
even
apologise for apologising :)" - Tim Golden
http://groups.google.com/group/comp.lang.python/msg/858d1c31d0c2adff

The third alpha version of Python 2.7 is ready for testing:
http://groups.google.com/group/comp.lang.python/t/6f49dacfe8759508/

How to enumerate all possible strings matching a given regular
expression:
http://groups.google.com/group/comp.lang.python/t/1b78346c6661ac4f/

Which language features do you like most?
http://groups.google.com/group/comp.lang.python/t/599b3c9772421ece/

Implementing a two-dimensional array in a simple way seems to
actually
be more efficient than other, more sophisticated alternatives:
http://groups.google.com/group/comp.lang.python/t/55e595d6dc4ca3f4/

The new GIL (to be implemented in Python 3.2) will provide less
overhead,
especially in multicore CPUs:
http://groups.google.com/group/comp.lang.python/t/586ef2d3685fa7ea/

In Python 3, 'exec' inside a function does not have the same effect
as before:
http://groups.google.com/group/comp.lang.python/t/7a046e4ede9c310a/

Using Queue objects to feed and synchronize several worker threads:
http://groups.google.com/group/comp.lang.python/t/32256dd608c9c02/

New generation IDEs should provide much better and integrated
refactoring tools:
http://groups.google.com/group/comp.lang.python/t/e019614ea149e7bd/

There is no module in the standard library to handle filesystem
paths
in an OO way - but why?
http://groups.google.com/group/comp.lang.pythonf580fb3763208425ece/

A "History Channel" special: how the way a TAB key was interpreted
changed over time
http://groups.google.com/group/comp.lang.python82d9181fcd31ffea3f4/

After a false start, finally we get our first "Is it Call-By-Value
or
Call-By-Reference?" thread of the year!
http://groups.google.com/group/comp.lang.pythonfd36962c4970ac487ea/

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

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

PythonWare complements the digest you're reading with the
marvelous daily python url
http://www.pythonware.com/daily

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

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

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

comp.lang.python.announce announces new Python software. Be
sure to scan this newsgroup weekly.
http://groups.google.com/group/comp.lang.python.announce/topics

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

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

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

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

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

The Cookbook is a collaborative effort to capture useful and
interesting recipes.
http://code.activestate.com/recipes/langs/python/

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

del.icio.us presents an intriguing approach to reference
commentary.
It already aggregates quite a bit of Python intelligence.
http://del.icio.us/tag/python

Enjoy the *Python Magazine*.
http://pymag.phparch.com/

*Py: the Journal of the Python Language*
http://www.pyzine.com

There is *not* an RSS for "Python-URL!"--at least not yet. Arguments
for and against are occasionally entertained.

Suggestions/corrections for next week's posting are always welcome.
E-mail to <Python-URL@phaseit.net> should get through.

To receive a new issue of this posting in e-mail each Monday morning
(approximately), ask <claird@phaseit.net> to subscribe. Mention
"Python-URL!". Write to the same address to unsubscribe.

-- The Python-URL! Team--

Phaseit, Inc. (http://phaseit.net) is pleased to participate in and
sponsor the "Python-URL!" project. Watch this space for upcoming
news about posting archives.

==============================================================================
TOPIC: Code redundancy
http://groups.google.com/group/comp.lang.python/t/00286d4686672e21?hl=en
==============================================================================

== 1 of 4 ==
Date: Wed, Apr 21 2010 3:33 pm
From: Ryan Kelly

On Tue, 2010-04-20 at 14:43 +0100, Alan Harris-Reid wrote:
> Hi,
>
> During my Python (3.1) programming I often find myself having to repeat
> code such as...
>
> class1.attr1 = 1
> class1.attr2 = 2
> class1.attr3 = 3
> class1.attr4 = 4
> etc.
>
> Is there any way to achieve the same result without having to repeat the
> class1 prefix? Before Python my previous main language was Visual
> Foxpro, which had the syntax...
>
> with class1
> .attr1 = 1
> .attr2 = 2
> .attr3 = 3
> .attr4 = 4
> etc.
> endwith
>
> Is there any equivalent to this in Python?

Please don't take this as in invitation to disregard the excellent
advice already received in this thread - I just want to point out that
python can usually be bent to your will. Observe:

from withhacks import namespace

with namespace(class1):
attr1 = 1
attr2 = 2

This will do pretty much what you get from the "with" statement in
javascript (I assume it's similar to Visual Foxpro).

But don't use this in any real code. Seriously, don't even think about
it. You don't want to know the kind of abuses that go on under the
covers to make this kind of syntax hacking work...

Cheers,

Ryan

--
Ryan Kelly
http://www.rfk.id.au | This message is digitally signed. Please visit
ryan@rfk.id.au | http://www.rfk.id.au/ramblings/gpg/ for details

== 2 of 4 ==
Date: Wed, Apr 21 2010 4:43 pm
From: python@bdurham.com

Ryan,

Your withhacks module looks very interesting.
http://pypi.python.org/pypi/withhacks

What are your specific concerns about its use? Are there portability
concerns?

Malcolm

== 3 of 4 ==
Date: Wed, Apr 21 2010 4:55 pm
From: Ryan Kelly

On Wed, 2010-04-21 at 19:43 -0400, python@bdurham.com wrote:
> Ryan,
>
> Your withhacks module looks very interesting.
> http://pypi.python.org/pypi/withhacks
>
> What are your specific concerns about its use? Are there portability
> concerns?

It combines two things you just don't see in respectable python programs
- bytecode hacking and trace-function hacking. And I'm sure its
performance is less than stellar, although much of that could be fixed
with some careful bytecode caching.

I'd be surprised if it runs under alternative python implementations,
and not surprised if it doesn't even work on Python 3 - although I
haven't tried it to confirm either way.

Having said that, it should work as advertised on Python 2.X with
minimal fuss. So if you don't care about portability or about that dirty
feeling you get from messing with the Python internals, then have at
it :-)

Cheers,

Ryan

--
Ryan Kelly
http://www.rfk.id.au | This message is digitally signed. Please visit
ryan@rfk.id.au | http://www.rfk.id.au/ramblings/gpg/ for details

== 4 of 4 ==
Date: Wed, Apr 21 2010 6:09 pm
From: python@bdurham.com

Ryan,

> So if you don't care about portability or about that dirty feeling you get from messing with the Python internals, then have at it :-)

Warnings aside, its very clever code. Thanks for sharing!

Malcolm

==============================================================================
TOPIC: Python-URL! - weekly Python news and links (Apr 21)
http://groups.google.com/group/comp.lang.python/t/d63eeffe7729c0cd?hl=en
==============================================================================

== 1 of 1 ==
Date: Wed, Apr 21 2010 4:09 pm
From: Cameron Laird

QOTW: "There's no RightAnswer(tm), just our best guess as to what is
the most
useful behavior for the most number of people." - Raymond Hettinger
http://groups.google.com/group/comp.lang.python/msg/e7f78ef27811781b

First beta version of Python 2.7 is available:
http://groups.google.com.ar/group/comp.lang.python/t/d036954e11a264dd/

Why still a 2.7 release, when 3.1 is already out?
http://groups.google.com.ar/group/comp.lang.python/t/f8a5028affe772ed/

Deciding when to pass around a parameter, and when to keep it as an
instance attribute:
http://groups.google.com.ar/group/comp.lang.python/t/6f51302327b58aac/

A class is more than just a container for functions and attributes:
http://groups.google.com.ar/group/comp.lang.python/t/5525bd981dd9ece6/

Lie Ryan tries to explain the various escaping levels of a regular
expression string:
http://groups.google.com.ar/group/comp.lang.python/t/3a27b819307c0cb6/

Peter Otten shows how to make string.Template resolve dotted.names
from
nested dictionaries:
http://groups.google.com.ar/group/comp.lang.python/t/d482f74d16fcbbb2/

Simple string operations, regular expressions, and a full blown
parser:
the right tools for different jobs
http://groups.google.com.ar/group/comp.lang.python/t/888b3fe934e2c5e2/

The list comprehension loop variable, nested scopes, and common
sense
applied to programming languages:
http://groups.google.com.ar/group/comp.lang.python/t/2b64b9a9069a324f/

Performance of list vs. set equality operations -- later:
encapsulation,
the Open/Closed principle, and why overriding __special__ methods
may
not affect certain built-in type operations:
http://groups.google.com.ar/group/comp.lang.python/t/818d143c7e9550bc/

__del__ methods are not the same as C++ destructors; they might not
even
be called:
http://groups.google.com.ar/group/comp.lang.python/t/6c875525954df888/

Abstract Base Classes affect the way issubclass() works -- it's not
based only on the chain of MRO anymore:
http://groups.google.com.ar/group/comp.lang.python/t/bd97c8e475e4da67/

wxPython and a bad example of 'property' usage:
http://groups.google.com.ar/group/comp.lang.python/t/d88a38bbbb7b5dca/

Keeping client expectations realistic and avoiding scope creep:
http://www.gossamer-threads.com/lists/python/python/819932

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

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

PythonWare complements the digest you're reading with the
marvelous daily python url
http://www.pythonware.com/daily

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

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

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

comp.lang.python.announce announces new Python software. Be
sure to scan this newsgroup weekly.
http://groups.google.com/group/comp.lang.python.announce/topics

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

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

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

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

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

The Cookbook is a collaborative effort to capture useful and
interesting recipes.
http://code.activestate.com/recipes/langs/python/

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

del.icio.us presents an intriguing approach to reference
commentary.
It already aggregates quite a bit of Python intelligence.
http://del.icio.us/tag/python

Enjoy the *Python Magazine*.
http://pymag.phparch.com/

*Py: the Journal of the Python Language*
http://www.pyzine.com

There is *not* an RSS for "Python-URL!"--at least not yet. Arguments
for and against are occasionally entertained.

Suggestions/corrections for next week's posting are always welcome.
E-mail to <Python-URL@phaseit.net> should get through.

To receive a new issue of this posting in e-mail each Monday morning
(approximately), ask <claird@phaseit.net> to subscribe. Mention
"Python-URL!". Write to the same address to unsubscribe.

-- The Python-URL! Team--

Phaseit, Inc. (http://phaseit.net) is pleased to participate in and
sponsor the "Python-URL!" project. Watch this space for upcoming
news about posting archives.

==============================================================================
TOPIC: when should I explicitly close a file?
http://groups.google.com/group/comp.lang.python/t/af8041d4cf076178?hl=en
==============================================================================

== 1 of 3 ==
Date: Wed, Apr 21 2010 5:53 pm
From: Lawrence D'Oliveiro

In message <4bc9aadb$1@dnews.tpgi.com.au>, Lie Ryan wrote:

> Since in python nothing is guaranteed about implicit file close ...

It is guaranteed that objects with a reference count of zero will be
disposed. In my experiments, this happens immediately.

== 2 of 3 ==
Date: Wed, Apr 21 2010 6:03 pm
From: Chris Rebert

On Wed, Apr 21, 2010 at 5:53 PM, Lawrence D'Oliveiro wrote:
> In message <4bc9aadb$1@dnews.tpgi.com.au>, Lie Ryan wrote:
>
>> Since in python nothing is guaranteed about implicit file close ...
>
> It is guaranteed that objects with a reference count of zero will be
> disposed.

> In my experiments, this happens immediately.

Experiment with an implementation other than CPython and prepare to be
surprised.

Cheers,
Chris
--
http://blog.rebertia.com

== 3 of 3 ==
Date: Wed, Apr 21 2010 9:03 pm
From: Steven D'Aprano

On Thu, 22 Apr 2010 12:53:51 +1200, Lawrence D'Oliveiro wrote:

> In message <4bc9aadb$1@dnews.tpgi.com.au>, Lie Ryan wrote:
>
>> Since in python nothing is guaranteed about implicit file close ...
>
> It is guaranteed that objects with a reference count of zero will be
> disposed.

Not all Python implementations have reference counts at all, e.g. Jython
and IronPython. Neither of those close files immediately.

> In my experiments, this happens immediately.

Are your experiments done under PyPy, CLPython, or Pynie?

--
Steven

==============================================================================
TOPIC: Download Proprietary Microsoft Products Now
http://groups.google.com/group/comp.lang.python/t/65e34924e7d42c90?hl=en
==============================================================================

== 1 of 3 ==
Date: Wed, Apr 21 2010 5:59 pm
From: Lawrence D'Oliveiro

In message <mailman.1949.1271443668.23598.python-list@python.org>, "Martin
v. Löwis" wrote:

> Brian Blais wrote:
>
>> On Apr 12, 2010, at 16:36 , Martin v. Loewis is wrote:
>>
>>> If you are planning to build Python extension modules in the next five
>>> years, I recommend that you obtain a copy of VS Express
>>
>> Am I missing something here? I have heard this before, but I have built
>> extension modules many times under windows (using Cython) and never once
>> used a MS product.
>
> It's fine if your package supports being compiled with Mingw32. A lot of
> source code can't be compiled this way, either because gcc doesn't
> support some of the MS extensions (in particular wrt. COM) ...

But then such code will not be portable to anything but Windows.

> ... or because Mingw32 doesn't provide the header files (in particular
> wrt. C++), or because linking with a library is necessary that uses the
> MSVC mangling, not the g++ one (again, for C++).

Again, that would be code that's not portable off Windows.

== 2 of 3 ==
Date: Wed, Apr 21 2010 6:06 pm
From: Lawrence D'Oliveiro

In message <4bc8547e$1@dnews.tpgi.com.au>, Lie Ryan wrote:

> ... so you should get the full installer if you want to insure yourself
> from Microsoft pulling the plug out.

I wonder how many Windows users will be able to figure that out...

== 3 of 3 ==
Date: Wed, Apr 21 2010 7:56 pm
From: David Cournapeau

On Thu, Apr 22, 2010 at 9:59 AM, Lawrence D'Oliveiro
<ldo@geek-central.gen.new_zealand> wrote:

>> ... or because Mingw32 doesn't provide the header files (in particular
>> wrt. C++), or because linking with a library is necessary that uses the
>> MSVC mangling, not the g++ one (again, for C++).
>
> Again, that would be code that's not portable off Windows.

Not really, part of the issue is that mingw uses ancient gcc (3.x
series), and g++ 3.x has poor C++ support compared to MSVC (or gcc
4.x).

There is also the issue that gcc debugging symbols are totally
incompatible with MSVC, so you cannot debug things from anything but
gdb. Gcc for win64 is also not that stable yet - when porting numpy
and scipy on windows 64, I got numerous issues with it.

None of this has anything to do with portability.

cheers,

David

==============================================================================
TOPIC: MAKE A TON OF MONEY!!!
http://groups.google.com/group/comp.lang.python/t/66e96c278ed934c7?hl=en
==============================================================================

== 1 of 1 ==
Date: Wed, Apr 21 2010 7:58 pm
From: Krushbrook

A little while back, I was browsing these newsgroups, just like you

are now, and came across an article similar to this that said you

could make thousands of dollars within weeks with only an initial

investment of $5.00 ! So I thought, "Yeah, right, this must be a

scam", like most of us, but I was curious, like most of us, so I kept

reading. Anyway, it said that you send $1.00 to each of the 5 names

and address stated in the article. You then place your own name and

address in the bottom of the list of #5, and post the article in at

least 200 newsgroups.(There are thousands) No catch, that was it.

So after thinking it over, and talking to a few people first, I

thought about trying it. I figured what I have got to lose except 5

stamps and $5.00, right?

Like most of us I was a little skeptical and a little worried about

the legal aspects of it all. So I checked it out with U.S. Post

Office(1-800-725-2161) and they confirmed that it is indeed lega!

Then I invested the measly $5.00................

\Well GUESS WHAT! !..... With in 7 days, I started getting money in

the mail! I was shocked! I still figured it end soon, and didn't give

it another thought. But the money just coming in. In my first week, I

made about $20.00 to $30.00 dollars. By the end of the second week I

had made total of over $1,000.00!!!!!! In the third week I had over

$10,000.00 and it's still growing. This is now my fourth week and I

have made a total of just over $42,000.00 and it's still comming in

....... It's certainly worth $5.00, and 5 stamps, I spent more than

that on the lottery!!

Let me tell you how this works and most importantly, Why it works....

also, make sure you print a copy of this article NOW, so you can get

the information of it as you need it. The process is very simple and

consists of 3 easy steps :

STEP 1 : Get 5 separate pieces of paper and write the following on

each piece of paper "PLEASE PUT ME ON YOUR MAILING LIST." now get 5

$1.00 bills and place ONE inside EACH of the 5 pieces of paper so the

bill will not be seen through the envelopes to prevent thievery. Next,

place on paper in each of the 5 envelopes and seal them. You should

now have 5 sealed envelopes, each with a piece of paper stating the

above phrase and a $1.00 bill. What you are doing is creating a

service by this. THIS IS PERFECTLY LEGAL!

Mail the 5 envelopes to the following addresses :

#1 Occupant
P.O. Box 54230
Houston, Tx.
77272-1193
U.S.A.

#2 Kevin Michael
1006 Abercorn Place
Sherwood, AR 72120
U.S.A.

#3 Chang
P.O.Box 502651
San Diego CA 92150-2651
U.S.A.

#4 Belchior Mira
R. Jose Dias Coelho, 7, 1 DT
Bom-Sucesso, ALVERCA
2615
PORTUGAL

#5 Kylen Rushbrook
P.O. Box 2
Danforth IL, 60930
U.S.A

STEP 2 : Now take the #1 name off the list that you see above, move

the other names up ( 5 becomes 4, 4 becomes 3, etc...) and add YOUR

Name as number 5 on the list.

STEP 3 : Change anything you need to, but try to keep this article as

close to original as possible. Now, post your mended article to at

least 200 newsgroups. (I think there are close to 18,000 groups) All

you need is 200, but remember, the more you post, the more money you

make! Don't know How post in the newsgroups? Well do exactly the

following :

FOR NETSCAPE USERS,

1) Click on any newsgroups, like normal. Then click on "To News",

which is in the top left corner of the newsgroups page. This will

bring up a message box.

2) Fill in the SUBJECT with a flashy title, like the one I used,

something to catch the eye!!!

3) Now go to the message part of the box and retype this letter

exactly as it tis here, with exception of your few changes. (remember

to add your name to number 5 and move the rest up)

4) When you're done typing in the WHOLE letter, click on 'FILE'

above the send button. Then, 'SAVE AS..' DO NOT SEND YOUR ARTICLE

UNTIL YOU SAVE IT. (so you don't have to type this 200 times :-)

5) Now that you have saved the letter, go ahead and send your

first copy! (Click the 'SEND' button in the top left corner)

6) This is where you post all 200! OK, go to ANY newsgroup

article and click the 'TO NEWS' button again. Type in your flashy

subject in the 'SUBJECT BOX', then go to the message and place your

cursor here. Now click on 'ATTACHMENT' which is right below the

'SUBJECT BOX'. Click on attach file then find your letter wherever you

saved it. Click once on your file then click 'OPEN' then click 'OK'.

If you did this right, you should see your filename in the 'ATTACHMENT

BOX' and it will be shaded.

NOW POST AWAY!!

IF YOU'RE USING INTERNET EXPLORER :

It's just as easy, holding down the left mouse button, highlight

this entire article, then press the 'CTRL' key and 'C' key at the same

time to copy this article. Then print the article for your records to

have the names of those you will be sending $1.00 to.

Next, go to the newsgroups and press 'POST AN ARTICLE' type in

your flashy subject and click the large window below. Press 'CTRL' and

'V' and the article will appear in the message window. **BE SURE TO

MAKE YOUR ADDRESS CHANGES TO THE 5 NAMES.**. Now re-highlight the

article andre-copy it so you have the changes..... then all you have

to do for each newsgroups is 'CTRL' and 'V' and press 'POST'. It's

that easy!!!

THAT'S IT! ALL you have to do is jump to different newsgroups and post

away, after you get the hang of it, it will take about 30 seconds for

each newsgroup! **REMEMBER, THE MORE NEWSGROUPS YOU POST IN, THE MORE

MONEY YOU WILL MAKE!! BUT YOU HAVE TO POST A MINIMUM OF 200 **

That's it! you will begin receiving money from around the world within

day's! You may eventually want to rent a P.O.Box due to the large

amount of mail you receive. If you wish to stay anonymous, you can

invent a name to use, as long as the postman will deliver it. ** JUST

MAKE SURE ALL THE ADDRESS ARE CORRECT. **

Now the WHY part :

Out of 200 postings, say I receive only 5 replies (a very low

example). So then I made $5.00 with my name at #5 on the letter. Now,

each of the 5 persons who just sent me $1.00 make the MINIMUM 200

postings, each with my name at #4 and only 5 persons respond to each

of the original 5, that is another $25.00 for me, now those 25 each

make 200 MINIMUM postings with my name at #3 and only 5 replies each,

I will bring in an additional $125.00! Now, those 125 persons turn

around and post the MINIMUM 200 with my name at #2 and only receive 5

replies each, I will make an additional $625.00! OK, now here is the

fun part, each of those 625 persons post a MINIMUM 200 letters with my

name #1 and the each only receive 5 replies, that just made me

$3,125.00!!! With a original investment of only $5.00! AMAZING! And as

I said 5 respones is actually VERY LOW! Average is probable 20 to 30!

So lets put those figures at just 15 responses per person. Here is

what you will make :

at #5 $15.00

at #4 $225.00

at #3 $3,375.00

at #2 $50,625.00

at #1 $759,375.00

When your name is no longer on the list, you just take the latest

posting in the newsgroups, and send out another $5.00 to names on the

list, putting your name at number 5 again. And start posting again.

the thing to remember is, do you realize that thousands of people all

over the world are joining the internet and reading these articles

everyday, JUST LIKE YOU are now!! So can you afford $5.00 and see if

it really works?? I think so... People have said, "What if the plan

is played out and no one sends you the money? So what! What are the

chances of that happening when there are tons of new honest users and

new honest people who are joining the internet and newsgroups everyday

and are willing to give it a try? Estimates are at 20,000 to 50,000

new users, every day, with thousands of those joining the actual

internet. Remember, play FAIRLY and HONESTLY and this will work. You

just have to be honest. Make sure you print this article out RIGHT

NOW, also. Try to keep a list of everyone that sends you money and

always keep an eye on the newsgroups to make sure everyone is playing

fairly. Remember, HONESTY IS THE BEST POLICY. You don't need to cheat

the basic idea to make the money!!

GOOD LUCK to all and please play fairly and reap the huge rewards from

this, which is tons of extra CASH. ** By the way, if you try to

deceive people by posting the message with your name in the list and

not sending the money to the rest of the people already on the list,

you will NOT get as much. Someone I talked to knew someone who did

that and he only made about $150.00, and that's after seven or eight

weeks! Then he sent the 5 $1.00 bills, people added him to their

lists, and in 4-5 weeks he had over $10k. This is the fairest and most

honest way I have ever seen to share the wealth of the world with

costing anything but our time!!! You also may want to but mailing and

e-mail lists for future dollars.

Please remember to declare your extra income. Thanks once again....

==============================================================================

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Wednesday, April 21, 2010

comp.lang.python - 25 new messages in 13 topics - digest

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