Re: python3: 'where' keyword

[Carl Banks]

Nick Coghlan wrote:
> Andrey Tatarinov wrote:
> > Hi.
> >
> > It would be great to be able to reverse usage/definition parts in
> > haskell-way with "where" keyword. Since Python 3 would miss lambda,
that
> > would be extremly useful for creating readable sources.
> >
> > Usage could be something like:
> >
> >  >>> res = [ f(i) for i in objects ] where:
> >  >>> def f(x):
> >  >>> #do something
>
[snip]
> For compound statements, a where clause probably isn't appropriate,
as it would
> be rather unclear what the where clause applied to.

Right.  But you know that as soon as you add this to simple
expressions, a bunch of people are going to come here whining about how
they don't get to use where with if-expressions.

Frankly, they might have a point here.  Although we have replacing
lambda expressions on our minds, I have in mind a different problem
that a where-statement would solve perfectly.  But it would have to be
used with an if-expression.

However, I think it might not be so hard.  Let's take Paul Rubin's
advice and precede the if statement with where.  Let's also allow
"elif" clauses to be replaced with "else where ... if" clauses.  That
which is bound in the while-block would be visible in both the
if-expression and if-block.

Then we could do this:

. where:
. m = someregexp.match(somestring)
. if m:
. blah blah blah
. else where:
. m = someotherregexp.match(somestring)
. if m:
. blah blah blah

We might want to spell "else where" instead as "elwhere", to match
"elif", but that's not important now.  This would take away one of the
major minor annoyances of Python.  (In fact, I've suggested something
like this as a solution to the set-and-test idiom, which Python makes
difficult, only I used the keyword "suppose" instead of "where".)

Ok, but if you do that, now you have people whining that "where" comes
after some expressions, and before others.  (This would not bother me
one bit, BTW, but I'm pretty sure I'd lose the popular vote on this
one.)

So, let's go all out and say that while could precede any statement.
We now have consistency.  Well, that really wouldn't work for the
if-statement, though, because then how could we apply a different
while-block to an else clause?  We'd have to treat if-statements
specially anyways.  So we don't have consistency.

My solution would be to propose two different where statements: a
where...do statement, and a separate where...if statement.  The
where...do statement would look like this:

. where:
. def whatever(): pass
. do:
. blah blah use whatever blah

It has the advantage of being able to apply the where bindings to
several statements, and is, IMO, much cleaner looking than simply
applying where's bindings to the single following unindented statement.

I would recommend against where...while and where...for statements.
They can't accomplish anything you couldn't do with a break statement
inside the block, and it's not obvious whether the where clause gets
executed once or for each loop (since it's physically outside the loop
part).

One question: what do you do with a variable bound inside a while-block
that has the same name as a local variable?  (Or, horrors, a
surrounding while-block?)  I'm inclined to think it should be illegal,
but maybe it would be too restrictive.
Anyways, I like this idea a lot.

+1


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Re: "A Fundamental Turn Toward Concurrency in Software"

[michele . simionato]

>  So I've always had it in
> the back of my mind that languages that can easily support massive
> (especially automatic) parallelization will have their day in the
sun,
> at least someday.

and the language of the future will be called ... FORTRAN!

:-)

(joking, but it is the only language I know supporting massive
parallelization ...)


Michele Simionato

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Re: How to read/write blobs with mysqldb?

[Paul Rubin]

"Christopher J. Bottaro" <[EMAIL PROTECTED]> writes:
> That doesn't sound very efficient to me.  What if my computer only has 64 MB
> of memory and the data I want to insert is 128 MB?

Don't use such large blobs.
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Re: Software archeology (was Re: Developing Commercial Applications in Python)

[Aahz]

In article <[EMAIL PROTECTED]>,
Stephen Waterbury  <[EMAIL PROTECTED]> wrote:
>Aahz wrote:
>> In article <[EMAIL PROTECTED]>,
>> Stephen Waterbury  <[EMAIL PROTECTED]> wrote:
>>>
>>>Also see Python Success Stories:  http://pythonology.org/success
>>>
>>>A notable example is Verity's search engine -- see
>>>http://python.oreilly.com/news/PythonSS.pdf
>> 
>> Actually, your statement is slightly inaccurate.  The Verity search
>> engine is more than fifteen years old in its core technology; it was
>> started as a LISP project at IIRC MIT.  (At one point I was much amused
>> to look at the C source code and find car() and cdr() functions.)  As of
>> my last information, Python isn't used at all in or with the Verity
>> search engine.  What you're referring to is the Verity Ultraseek engine,
>> originally written and owned by Infoseek before getting transferred to
>> Verity through a series of dot-bomb transactions.  The Ultraseek engine
>> doesn't use Python, but Python is used to control the engine, and I think
>> much of the spider is written in Python.
>
>Actually, Aahz didn't add anything useful that wasn't explained better
>in the article itself, pointing to which was the purpose of my post,
>but he is correct:  Python was *not* used to write the Verity search
>engine ... how the hell do these stupid rumors get started anyhow?? ;).
>Just read the article, dammit! :)

You're quite correct that I added little useful information, but seeing
as I used to work at Verity, I couldn't resist adding some hopefully
interesting and/or amusing trivia.  Especially the LISP bit.
-- 
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"19. A language that doesn't affect the way you think about programming,
is not worth knowing."  --Alan Perlis
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Re: Other notes

[Nick Coghlan]

Bengt Richter wrote:
IOW, I think there is a fix: keep tokenizing greedily and tokenize floating 
point as
a sequence of integers and operators, and let  be 
translated by
the compiler to floating point, and  be translated to 
the
appropriate generator expression implementation.
That would be:
 -> float( + "." + )
 -> getattr(int(), )
 -> xrange(, )
However, the problem comes when you realise that 1e3 is also a floating point 
literal, as is 1.1e3.

Cheers,
Nick.
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Getting List Of All Filesystem Mounts

[Tim Daneliuk]

Is there some pure Python/portable way to get a list
of all currently mounted filesystems?

Tim Daneliuk [EMAIL PROTECTED]
PGP Key: http://www.tundraware.com/PGP/
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Re: Python Operating System???

[Roose]

"Michael Hobbs" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
> David Brown <[EMAIL PROTECTED]> wrote:
> > Hello. I recently came across a free operating system called Unununium
(or
> > something like that) and it was developed in Python and Assembly.
> >
> > Now, I have been looking for a way to make an operating system for a
long
> > long time and the only possibilities I could find were C++ and assembly.
>
> The problem when using Python instead of C for OS development is that
> C was *specifically designed* to create an OS, while Python was designed
> for completely different purposes. If you want to write an OS, it would
> be wise to use a language that is suited for that purpose. If you
> dislike C so much and prefer Python so much more, your first step should
> be to design a Python dialect that is more appropriate for writing OS's.

Yes, that sounds pretty realistic : )  For someone who is choosing the wrong
language to write an OS, and who I would guess doesn't understand interrupt
programming and the like -- their first task should be to redesign Python!!



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Re: python3: accessing the result of 'if'

[Nick Coghlan]

Carl Banks wrote:
Right.  But you know that as soon as you add this to simple
expressions, a bunch of people are going to come here whining about how
they don't get to use where with if-expressions.
Frankly, they might have a point here.  Although we have replacing
lambda expressions on our minds, I have in mind a different problem
that a where-statement would solve perfectly.  But it would have to be
used with an if-expression.
I have a different suggestion for this.
'as' is used for renaming in import statements. 'as' will be used for exception 
naming in Python 3k.

So let's use it for expression naming in 'if' statements, too.
if someregexp.match(s) as m:
  # blah using m
elif someotherregexp.match(s) as m:
  # blah using m
Cheers,
Nick.
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Re: "A Fundamental Turn Toward Concurrency in Software"

[Nick Coghlan]

Steve Horsley wrote:
But my understanding is that the current Python VM is single-threaded 
internally,
so even if the program creates multiple threads, just one core will be 
dividing
its time between those "threads".
Not really.
The CPython interpreter does have a thing called the 'Global Interpreter Lock' 
which synchronises access to the internals of the interpreter. If that wasn't 
there, Python threads could corrupt the data structures. In order to do anything 
useful, Python code must hold this lock, which leads to the frequent 
misapprehension that Python is 'single-threaded'.

However, the threads created by the Python threading mechanism are real OS 
threads, and the work load can be distributed between different cores.

In practice, this doesn't happen for a pure Python program, since any running 
Python code must hold the interpreter lock. The Python threads end up getting 
timesliced instead of running in parallel. Genuine concurrency with pure Python 
requires running things in separate processes (to reliably get multiple 
instances of the Python interpreter up and running).

Python threads are mainly intended to help deal with 'slow' I/O operations like 
disk and network access - the C code that implements those operations *releases* 
the GIL before making the slow call, allowing other Python threads to run while 
waiting for the I/O call to complete. This behaviour means threading can give 
*big* performance benefits on even single-CPU machines, and is likely to be the 
biggest source of performance improvements from threading.

However, on multi-processor machines, it is also handy if a CPU-intensive 
operation can be handled on one core, while another core keeps running Python code.

Again, this is handled by the relevant extension releasing the GIL before 
performing its CPU-intensive operations and reacquiring the GIL when it is done.

So Python's concurrency is built in a couple of layers:
Python-level concurrency:
  Multiple processes for true concurrency
  Time-sliced concurrency within a process (based on the GIL)
C-level concurrency:
  True concurrency if GIL is released when not needed
In some cases, problems with multi-threading are caused by invocation of 
extensions which don't correctly release the GIL, effectively preventing *any* 
other Python threads from running (since the executing extension never releases it).

As an example, I frequently use SWIG to access hardware API's from Python. My 
standard 'exception translator' (which SWIG automatically places around every 
call to the extension) now looks something like:

%exception {
  Py_BEGIN_ALLOW_THREADS
  try {
$action
  } except (...) {
Py_BLOCK_THREADS
SWIG_exception(SWIG_RuntimeError, "Unexpected exception")
  }
  Py_END_ALLOW_THREADS
}
The above means that every call into my extension releases the GIL 
automatically, and reacquires it when returning to Python. I usually don't call 
the Python C API from the extension, but if I did, I would need to reacquire the 
GIL with PyGILState_Ensure() before doing so.

Without those threading API calls in place, operations which access the hardware 
always block the entire program, even if the Python program is multi-threaded.

See here for some more info on Python's threading:
http://www.python.org/doc/2.4/api/threads.html
Cheers,
Nick.
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Re: Python Operating System???

[Roose]

> But I thought Python was an all-purpose language.  After all, OS's
> have been written in Lisp before too.

It is a general purpose APPLICATION language.  I am surprised that this
hasn't been mentioned on this thread.

An OS is NOT an application.  It is a completely different kind of program.
Do you guys understand the difference between user and kernel mode?  Do you
know what address spaces and hardware interrupts are?  Python is not
equipped to handle these things.  You would end up doing so much in C
extensions that it could barely be called Python.

I am not trying to be insulting... but unless someone would like to educate
me otherwise, the idea of an OS written in Python is almost ludicrous.  As I
said, I think you might mean an OS SHELL, which would be a reasonable
(although maybe unconventional) thing to write in python.

Also I am no threading expert, but I would imagine it would be very hard to
write a task scheduler in Python given that it has the whole GIL thing.  (As
I said that isn't my domain of expertise but I'm sure someone here could
expound on that.)


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Re: Getting List Of All Filesystem Mounts

[Roel Schroeven]

Tim Daneliuk wrote:
Is there some pure Python/portable way to get a list
of all currently mounted filesystems?
Check out MtPython: http://bebop.bigasterisk.com/python/docs/MtPython
--
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Roel Schroeven
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Re: Python Operating System???

[Paul Rubin]

"Roose" <[EMAIL PROTECTED]> writes:
> An OS is NOT an application.  It is a completely different kind of program.
> Do you guys understand the difference between user and kernel mode?  Do you
> know what address spaces and hardware interrupts are?  Python is not
> equipped to handle these things.  You would end up doing so much in C
> extensions that it could barely be called Python.

You'd need some library functions to let Python access device registers
and you'd need some low level code to dispatch interrupts into Python code.

> I am not trying to be insulting... but unless someone would like to educate
> me otherwise, the idea of an OS written in Python is almost ludicrous.

Is an OS written in Lisp also ludicrous?  Because it's been done.

When Unix was first written, people thought implementing an OS in C
was ludicrous.  Everyone knew OS's had to be written in assembler.

> Also I am no threading expert, but I would imagine it would be very hard to
> write a task scheduler in Python given that it has the whole GIL thing.  (As
> I said that isn't my domain of expertise but I'm sure someone here could
> expound on that.)

The GIL is not part of the Python language.  It's just an artifact of
one particular implementation.  
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Re: python3: accessing the result of 'if'

[Paul Rubin]

Nick Coghlan <[EMAIL PROTECTED]> writes:
> So let's use it for expression naming in 'if' statements, too.
> 
> if someregexp.match(s) as m:
># blah using m
> elif someotherregexp.match(s) as m:
># blah using m

Certainly an improvement over what we have now.
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Another look at language comparisons

[Pierre Quentel]

http://khason.biz/blog/2004/12/why-microsoft-can-blow-off-with-c.html
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Re: python3: 'where' keyword

[AdSR]

Nick Coghlan wrote:
Killer app for this keyword:
class C(object):
  x = property(get, set) where:
def get(self):
  return "Silly property"
def set(self, val):
  self.x = "Told you it was silly"
Hey, this is super-elegant!
AdSR
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Re: python3: 'where' keyword

[Paul Rubin]

AdSR <[EMAIL PROTECTED]> writes:
> > Killer app for this keyword:
> > class C(object):
> >   x = property(get, set) where:
> > def get(self):
> >   return "Silly property"
> > def set(self, val):
> >   self.x = "Told you it was silly"
> 
> Hey, this is super-elegant!

Heh, even further:

z = C() where:
   class C(object):
  ...

Lets you make anonymous classes and singleton objects.
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Re: Getting rid of "self."

[Terry Reedy]

"BJörn Lindqvist" <[EMAIL PROTECTED]> wrote in message 
news:[EMAIL PROTECTED]
>I think it would be cool if you could refer to instance variables
>without prefixing with "self."

Others have expressed such a wish -- this comes up perhaps once a year. 
The bottom line is that as long as Python has separate instance and local 
namespaces with possibly duplicate names, then there must be a way to tell 
which namespace a name should be looked up in.  The current system is 
completely consistent with Python's object.attribute system.  It would be 
odd if instance attributes were referred to differently in module level 
code and function level code.

Terry J. Reedy



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Re: Other notes

[Bengt Richter]

On Sat, 08 Jan 2005 18:22:53 +1000, Nick Coghlan <[EMAIL PROTECTED]> wrote:

>Bengt Richter wrote:
>> IOW, I think there is a fix: keep tokenizing greedily and tokenize floating 
>> point as
>> a sequence of integers and operators, and let  be 
>> translated by
>> the compiler to floating point, and  be translated 
>> to the
>> appropriate generator expression implementation.
>
>That would be:
>
> -> float( + "." + )
> -> getattr(int(), )
> -> xrange(, )
>
>However, the problem comes when you realise that 1e3 is also a floating point 
>literal, as is 1.1e3.
>
Ok, that requires a little more imagination ;-)

I think it can be solved, but I haven't explored it all the way through ;-)

The key seems to be to be to condition the recognition of tokens as if 
recognizing
an old potentially floating point number, but emitting number-relevant separate 
tokens
so long as there is no embedded spaces. When a number ends, emitting an end 
marker should
permit the compiler to deal with the various compositions.

We still aren't looking ahead more than one, but we are carrying context, just 
as we do
to accumulate digits of an integer or characters of a name, but the context may 
continue
and determine what further tokens are emitted. E.g. the 'e' in the embedded 
numeric context,
becomes  rather than a name. In the following,  :== end of number 
token

   1.1 -> <1><1>
   1 .1 -> <1><1>
   1.e1 -> <1><1> 
   1 .e1 -> <1>
   1.2e3 -> <1><2><3>
   1..2 -> <1><1>
   1. .2 -> <1><2> (syntax error)
   1 ..2 -> <1><1>

I just have the feeling that there is a solution, whatever the hiccups ;-)

Regards,
Bengt Richter
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Re: Another look at language comparisons

[Michael Sparks]

Pierre Quentel wrote:

> http://khason.biz/blog/2004/12/why-microsoft-can-blow-off-with-c.html

I almost didn't look at this, but I'm glad I did - quite a fun comparison,
nicely arbitrary and reminds me of RFC in a similar vein :)


Michael.
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Re: python3: 'where' keyword

[Bengt Richter]

On Sat, 08 Jan 2005 16:42:16 +1000, Nick Coghlan <[EMAIL PROTECTED]> wrote:

>Nick Coghlan wrote:
>> It also allows the necessary but uninteresting setup for an expression 
>> to be moved "out of the way", bringing the expression that does the real 
>> work to prominence.
>
>Killer app for this keyword:
>
>class C(object):
>
>   x = property(get, set) where:
> def get(self):
>   return "Silly property"
> def set(self, val):
>   self.x = "Told you it was silly"
>

Yes, that is cool and it _is_ an interesting idea. Are suites nestable? E.g., 
is this legal?

   x = term1 + term2 where:
   term1 = a*b where:
   a = 123
   b = 456
   term2 = math.pi

Reminds me of some kind of weird let ;-)

And, is the whole thing after the '=' an expression? E.g.,

  x = ( foo(x) where:
 x = math.pi/4.0
  ) where:
 def foo(x): print 'just for illustration', x

or is this legal?

  for y in ([foo(x) for x in bar] where:
 bar = xrange(5)
): baz(y) where:
def baz(arg): return arg*2

Not trying to sabotage the idea, really, just looking for clarification ;-)

Regards,
Bengt Richter
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Re: python3: 'where' keyword

[Andrey Tatarinov]

Bengt Richter wrote:
It also allows the necessary but uninteresting setup for an expression 
to be moved "out of the way", bringing the expression that does the real 
work to prominence.
Killer app for this keyword:
class C(object):
 x = property(get, set) where:
   def get(self):
 return "Silly property"
   def set(self, val):
 self.x = "Told you it was silly"
Yes, that is cool and it _is_ an interesting idea. Are suites nestable? E.g., is this legal?
...
And, is the whole thing after the '=' an expression? E.g.,
  x = ( foo(x) where:
 x = math.pi/4.0
  ) where:
 def foo(x): print 'just for illustration', x
or is this legal?
  for y in ([foo(x) for x in bar] where:
 bar = xrange(5)
): baz(y) where:
def baz(arg): return arg*2
Not trying to sabotage the idea, really, just looking for clarification ;-)
yes, all your examples are correct. And that's the way I'd like to use 
this feature.
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Re: python3: 'where' keyword

[Andrey Tatarinov]

Nick Coghlan wrote:
It also allows the necessary but uninteresting setup for an expression 
to be moved "out of the way", bringing the expression that does the 
real work to prominence.
Killer app for this keyword:
class C(object):
  x = property(get, set) where:
def get(self):
  return "Silly property"
def set(self, val):
  self.x = "Told you it was silly"
oh, that's great! I can't imagine prettier example
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Re: OT: google groups bug, or worse?

[aaronwmail-usenet]

Bengt Richter wrote:
> What did you google with? Is this it?
>
http://groups-beta.google.com/groups?hl=en&ie=UTF-8&q=%22The+xsdbXML+framework+provides+a+flexible+and+well+defined+infrastructure%22&qt_s=Search+Groups

That was my *reply* to one of the original posts using Google,
which I faked up when I couldn't find it (posted using google).
The two originals aren't there.

hmmm.   -- Aaron Watters
===
You'd be paranoid too, if everyone was out to get you!

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Re: Another look at language comparisons

[beliavsky]

>From the web site:
"Why Microsoft can Blow-Off with C#? These people have thought up
programming languages Fortran, Prologue, Ada."

The author is ignorant. Fortran was invented by IBM in the late 1950s,
long before Microsoft existed. Ada was commissioned by the U.S.
Department of Defense in the 1970s. The Prolog programming language is
not spelled "Prologue".

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tuples vs lists

[worzel]

I get what the difference is between a tuple and a list, but why would I 
ever care about the tuple's immuutability?
Also, do you say 'too-ple' or 'chu-ple' - if you get my drift. (tomato or 
tomato kind of thing)
TIA 


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Re: Another look at language comparisons

[Jan Dries]

[EMAIL PROTECTED] wrote:
From the web site:
"Why Microsoft can Blow-Off with C#? These people have thought up
programming languages Fortran, Prologue, Ada."
The author is ignorant. Fortran was invented by IBM in the late 1950s,
long before Microsoft existed. Ada was commissioned by the U.S.
Department of Defense in the 1970s. The Prolog programming language is
not spelled "Prologue".
I don't think that "these people" is refering to Microsoft. Instead, it 
is refering to the three pictures below the text. I assume they are the 
pictures of the respective authors of these languages.

The bottom line of the article is that languages authored by men with 
beards are more successful than those authored by people without beards.
At least the anecdotical evidence to that is overwhelming :-)

And there is hope for Python, as Guido has recently been seen with a 
beard :-)
http://www.tbray.org/ongoing/When/200x/2004/12/08/-big/IMG_3061.jpg

Regards,
Jan
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The best way to do web apps with Python?

[worzel]

What is the best way 
to web developemnt with Python? Is there anything close to PHP style in-page 
script placement that can create and use other Python objects? I am not really 
interested in Zope (I believe that is more a CMS than anything else?) I am also 
looking for something a little more structured than a series of CGI 
Scripts.
 
While on the topic - what is the expectataion of 
Python for this kind of stuff? Would one use Python for certain other things but 
turn to PHP for web apps - or would one use their Python skills in place of PHP? 

 
TIA
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Re: Pre/Postconditions with decorators

[rittersporn]

Thank you very much. It is really a very elegant piece of code :-)

Eiffel (language) has both type checking and design by contract.
Python lacks both.
Your module tackles type checking, I
tried to execute arbitrary code before
and after function execution to realize
runtime assertions.

I wonder if this should be separated in a Python
"checker"-module.
Both are part of the interface "contract".

Ciao

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Re: The best way to do web apps with Python?

[Paul Rubin]

"worzel" <[EMAIL PROTECTED]> writes:
> What is the best way to web developemnt with Python? Is there
> anything close to PHP style in-page script placement that can create
> and use other Python objects? I am not really interested in Zope (I
> believe that is more a CMS than anything else?) I am also looking
> for something a little more structured than a series of CGI Scripts.

Basically, yes, there are various Python template systems similar to
PHP.  I won't name them because other people more knowledgeable than
me will do a better job than I could.  I'll say that Python is a
better language than PHP, but getting a basic dynamic web app running
in PHP is much simpler than it is in Python.  Python's advantage
starts to shine once the app gets complicated.

> While on the topic - what is the expectataion of Python for this
> kind of stuff? Would one use Python for certain other things but
> turn to PHP for web apps - or would one use their Python skills in
> place of PHP?  TIA

It's sort of a difficult trade-off and it depends a lot on your
application, who will develop and maintain it, who will use it, where
it will be deployed, etc.  Lots more people know PHP than Python, PHP
is easier to get started with, and cheap PHP hosting is available all
over.  So if you're building some simple app that you want to
distribute widely and run everywhere, PHP is attractive.  If you're
building a complex system which you'll run on a server that you have
more control over, and you'll have relatively high-powered developers
on hand to maintain the code, Python beats PHP.
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Re: The limitation of the Photon Hypothesis

[Steve Horsley]

bill wrote:
Please reply to [EMAIL PROTECTED], thank you !
No - I'll reply to the newsgroup, if you don't mind.
The limitation of the Photon Hypothesis

THE UNCERTAINTY PRINCIPLE IS UNTENABLE

You cannot use classical theory to disprove quantum theory that easily.
The uncertainty is quantum in origin, and not just an artifact of
classical mechanics applied to clumsy measurement.
You don't convince me.
Also, I think you probably accidentally posted to the wrong newsgroup.
Steve
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Re: tuples vs lists

[Bruno Desthuilliers]

worzel a écrit :
I get what the difference is between a tuple and a list, but why would I 
ever care about the tuple's immuutability?
Because, from a purely pratical POV, only an immutable object can be 
used as kay in a dict. So you can use tuples for 'composed key'.

Bruno
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Re: Pre/Postconditions with decorators

[Skip Montanaro]

>> Eiffel (language) has both type checking and design by contract.
>> Python lacks both.

Actually, Python is strongly typed.  It's just dynamically instead of
statically typed.

Skip
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Re: "A Fundamental Turn Toward Concurrency in Software"

[Lee Harr]

>> [http://www.gotw.ca/publications/concurrency-ddj.htm]. It argues that the 
>> continous CPU performance gain we've seen is finally over. And that future 
>> gain would primary be in the area of software concurrency taking advantage 
>> hyperthreading and multicore architectures.
>>

> Well, yes. However, it's not as bad as it looks. I've spent a good part
> of my professional life with multiprocessors (IBM mainframes) and
> I have yet to write a multi-thread program for performance reasons.
> All of those systems ran multiple programs, not single programs
> that had to take advantage of the multiprocessor environment.
> Your typical desktop is no different. My current system has 42
> processes running, and I'd be willing to bet that the vast majority
> of them aren't multi-threaded.
>


Exactly. If every one of your processes had its own 2 Ghz processor
running nothing else, I think you would be pretty happy. Your OS
had better be well-written to deal with concurrent access to
memory and disks, but I think for general application development
there will be huge speed boosts with little need for new
programming paradigms.
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Re: Python/Qt Problem

[Lee Harr]

On 2005-01-08, Michael <[EMAIL PROTECTED]> wrote:
> Hi,
>
> I am experiencing something very weird with PyQt. I have created several 
> windows based on QWidget using Designer. I can easily hide and show 
> these with the hide and show methods. However I have just created a new 
> window with Designer and the show method works in my main script but not 
> inside the button action method (not using proper temrinology, sorry) of 
> another window. Why is that? This works fine for the other windows.
>


If you do not get a satisfactory answer here, you should try
the dedicated PyQt mailing list:
http://mats.imk.fraunhofer.de/mailman/listinfo/pykde

The other thing I would suggest is to post some code along
with your description of what you believe it should do.
I do not think anyone will be able to diagnose the problem
without seeing the code.

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Re: tuples vs lists

[Steve Horsley]

worzel wrote:
I get what the difference is between a tuple and a list, but why would I 
ever care about the tuple's immuutability?
Mainly for security and speed. Many library functions return info by 
returning
a reference to an internally held tuple, and could be damaged / compromised
/ corrupted if that internal data was modified by malicious code. If tuples
were mutable (lists) then it would be necessary to return a copy instead.
Also, do you say 'too-ple' or 'chu-ple' - if you get my drift. (tomato or 
tomato kind of thing)
Try 'Two-pull'.
Steve
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Re: The best way to do web apps with Python?

[Pierre Quentel]

worzel a écrit :
What is the best way to web developemnt with Python? Is there anything 
close to PHP style in-page script placement that can create and use 
other Python objects? I am not really interested in Zope (I believe that 
is more a CMS than anything else?) I am also looking for something a 
little more structured than a series of CGI Scripts.
 
There are quite a few web frameworks in Python, see 
http://www.python.org/moin/WebProgramming

I'm biaised in favour of Karrigell (http://karrigell.sourceforge.net), 
the "Python Inside HTML" pages look and behave very much like PHP

Regards,
Pierre
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Re: why not datetime.strptime() ?

[Lee Harr]

On 2005-01-07, Skip Montanaro <[EMAIL PROTECTED]> wrote:
>
> josh> Shouldn't datetime have strptime?
>
> Sure, but it's not quite as trivial to implement as was strftime() support.
> While strftime() is a C library function and thus easily called from within
> the datetime C code, strptime() is implemented in Python as part of the time
> module for portability (strptime(3) is not universally available).  You'd
> need to import the time module, call its strptime() function with the input
> string and format, then use the tuple it returns to initialize a new
> datetime object.
>


Not sure this is exactly related, but I was using datetime
the other day to make timestamps:

>>> import datetime
>>> ts = datetime.datetime.now().isoformat()
>>> ts
'2005-01-08T09:45:16.896805'


and figured there would be an easy way to reverse that.
Something along the lines of:
dt = datetime.datetime.fromisoformat(ts)
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Re: DOS problem (simple fix??)

[Raymond L. Buvel]

Robert Brewer wrote:
Gavin Bauer wrote:
My DOS window (running in windows ME) closes the second it finishes
running my programs. As you can imagine, this makes it hard to see the
results. I've gotten in the habit of putting raw_input("Press enter to
exit") at the end of every program, and in addition to being pain in
the butt, it often fails to work. Being new to programming in general,
I make more mistakes than most people. My programs often have errors
before they get to my raw_input command. They then display the error
and immediately close. It is naturally a lot easier to fix an error
when you know what the error is. This makes debugging even more
annoying than it ordinarily would be, if you can imagine that. I've
heard that it should be a simple preference fix, but I've asked around
and no one seems to know how.
Thank you, and please make all answers simple enough to be understood
by a highschool student and his father :) .

For another solution try:
http://www.24help.info/showthread.php?t=149725
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Re: tuples vs lists

[worzel]

Cheers - thanks for the feedback guys - pretty much answers the question for 
me.

'Two-Pull' it is then, thanks.


"Steve Horsley" <[EMAIL PROTECTED]> wrote in message 
news:[EMAIL PROTECTED]
> worzel wrote:
>> I get what the difference is between a tuple and a list, but why would I 
>> ever care about the tuple's immuutability?
>
> Mainly for security and speed. Many library functions return info by 
> returning
> a reference to an internally held tuple, and could be damaged / 
> compromised
> / corrupted if that internal data was modified by malicious code. If 
> tuples
> were mutable (lists) then it would be necessary to return a copy instead.
>
>> Also, do you say 'too-ple' or 'chu-ple' - if you get my drift. (tomato or 
>> tomato kind of thing)
>
> Try 'Two-pull'.
>
> Steve 


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Re: The best way to do web apps with Python?

[JZ]

Dnia Sat, 8 Jan 2005 21:11:49 +0800, worzel napisał(a):

> What is the best way to web developemnt with Python? 

Hmm. :) I prefer http://cherrypy.org + http://cheetahtemplate.org/. Very
easy to learn and develop, yet powerfull.

> Is there anything close to PHP style in-page script 
> placement that can create and use other Python objects? 

Check http://spyce.sourceforge.net 
or http://nick.borko.org/pse

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http://zabiello.om
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Re: Other notes

[beliavsky]

Bengt Richter wrote:

>OTOH, there is precedent in e.g. fortran (IIRC) for named operators of
the
>form .XX. -- e.g., .GE. for >= so maybe there could be room for both.

Yes, but in Fortran 90 "==", ">="  etc. are equivalent to ".EQ." and
".GE.". It is also possible to define operators on native and
user-defined types, so that

Y = A .tx. B

can be written instead of the expression with the F90 intrinsic
functions

Y = matmul(transpose(A),B)

The Fortran 95 package Matran at
http://www.cs.umd.edu/~stewart/matran/Matran.html uses this approach to
simplify the interface of the Lapack library and provide syntax similar
to that of Matlab and Octave.

I don't know if the syntax of your idea clashes with Python, but it is
viable in general.

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Re: "A Fundamental Turn Toward Concurrency in Software"

[Jp Calderone]

On Sat, 08 Jan 2005 14:22:30 GMT, Lee Harr <[EMAIL PROTECTED]> wrote:
>>> [http://www.gotw.ca/publications/concurrency-ddj.htm]. It argues that the 
> >> continous CPU performance gain we've seen is finally over. And that future 
> >> gain would primary be in the area of software concurrency taking advantage 
> >> hyperthreading and multicore architectures.
> >>
> 
> > Well, yes. However, it's not as bad as it looks. I've spent a good part
> > of my professional life with multiprocessors (IBM mainframes) and
> > I have yet to write a multi-thread program for performance reasons.
> > All of those systems ran multiple programs, not single programs
> > that had to take advantage of the multiprocessor environment.
> > Your typical desktop is no different. My current system has 42
> > processes running, and I'd be willing to bet that the vast majority
> > of them aren't multi-threaded.
> >
> 
> Exactly. If every one of your processes had its own 2 Ghz processor
> running nothing else, I think you would be pretty happy. Your OS
> had better be well-written to deal with concurrent access to
> memory and disks, but I think for general application development
> there will be huge speed boosts with little need for new
> programming paradigms.

  Not likely.  How often do you run 4 processes that are all 
bottlenecked on CPU?  It's not a common usage pattern.  If you
have 16 CPUs, and 15 of them are running mostly idle processes
and that *one* process you'd wish would hurry the heck up and 
finish has the 16th pegged at 100% usage, you are not a happy 
camper.

  For the case where you do have a lot of competing unrelated 
processes, no doubt SMP is a big win automatically, but there 
will still need to be language innovations to make it easier 
to develop software which can benefit from the additional 
hardware for the more common case of individual CPU hungry 
processes.

  Jp
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Re: "A Fundamental Turn Toward Concurrency in Software"

[Skip Montanaro]

Jp> How often do you run 4 processes that are all bottlenecked on CPU?

In scientific computing I suspect this happens rather frequently.

"More is never enough." -- Bob Saltzman

Skip
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Re: python3: 'where' keyword

[André]

At the risk of generating controversy, here's another type of example:

def gcd(a, b):
where:
a: int, b: int
return c where:
c: int
while a:
a, b = b%a, a
return b

More can be found at http://aroberge.blogspot.com

Andre

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Re: "A Fundamental Turn Toward Concurrency in Software"

[Philippe C. Martin]

I remember a _few_ year ago when all specialists (Intel's) included
agreed that the 100MHZ barrier would never be passed - so, at least, we
did get free lunch for a couple of years :-)

I also must add that in my 17 years of realtime/embedded programming,
the problem usually was not the CPU speed - since you know _prior_ to
the design of your software whether your CPU will change context on time
when the hardware IRQ comes in - but rather the fact that all the
software/peripherals had to share the same bus ==> that usually was
where the bottleneck was.

I guess my point is to not focus the performance of a system solely on
its CPU's.




Regards,

Philippe




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***
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SnakeCard LLC
www.snakecard.com
***

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Re: "A Fundamental Turn Toward Concurrency in Software"

[Aahz]

In article <[EMAIL PROTECTED]>,
 <[EMAIL PROTECTED]> wrote:
>Michele deleted an attribution:
>>
>>  So I've always had it in
>> the back of my mind that languages that can easily support massive
>> (especially automatic) parallelization will have their day in the sun,
>> at least someday.
>
>and the language of the future will be called ... FORTRAN!
>
>:-)
>
>(joking, but it is the only language I know supporting massive
>parallelization ...)

Less of a joke than you think, perhaps.  Back in the early 1980s, a
family friend said something like, "In the year 2000, there will be a
programming language.  I don't know what it will look like, and I don't
know what it will do.  But I do know one thing: it will be called
FORTRAN."

After all, FORTRAN 2003 contains OOP support
-- 
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"19. A language that doesn't affect the way you think about programming,
is not worth knowing."  --Alan Perlis
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Re: python3: 'where' keyword

[André]

Darn space-eater google groups :-(   Here is it again, at teh risk of
generating controversy

.def gcd(a, b):
.where:
.a: int, b: int
.return c where:
.c: int
.while a:
.a, b = b%a, a
.return b
more examples can be found at aroberge.blogspot.com

André

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Re: Returning same type as self for arithmetic in subclasses

[Max M]

Tim Peters wrote:
Yes, and all builtin Python types work that way.  For example,
int.__add__ or float.__add__ applied to a subclass of int or float
will return an int or float; similarly for a subclass of str.  This
was Guido's decision...
I will not discuss it with him. He is usually right :-s

Generally speaking, no.  But I'm sure someone will torture you with a
framework that purports to make it easy .
Apparently not... But here is my solution.
If anybody is interrested. It should also be obvious what I am working on.
Btw. I really love doctests ... Unittests are a nice idea. But doctest 
is a really practical solution.

###
class vDatetime(datetime):
"""
A subclass of datetime, that renders itself in the iCalendar datetime
format.
>>> dt = vDatetime(1970, 1,1, 12, 30, 0)
>>> str(dt)
'19700101T123000'
>>> dt2 = vDatetime(1970, 1,1, 0, 0, 0)
>>> str(dt - dt2)
'PT12H30M'
Adding is not allowed
>>> dt + dt2
Traceback (most recent call last):
...
AttributeError: 'NotImplementedType' object has no attribute 'days'
"""
def __init__(self, *args, **kwargs):
datetime.__init__(self, *args, **kwargs)
self.params = Params()
def __add__(self, other):
return self._to_vdatetime(datetime.__add__(self, other))
def __sub__(self, other):
return self._to_vdatetime(datetime.__sub__(self, other))
def _to_vdatetime(self, result):
if hasattr(result, 'timetuple'):
return vDatetime(*result.timetuple()[:6])
return vDuration(result.days, result.seconds)
def fromstring(st):
"Class method that parses"
try:
timetuple = map(int, ((
st[:4], # year
st[4:6],# month
st[6:8],# day
st[9:11],# hour
st[11:13],# minute
st[13:15],# second
)))
except:
raise ValueError, 'Wrong format'
return vDatetime(*timetuple)
fromstring = staticmethod(fromstring)
def __str__(self):
return self.strftime("%Y%m%dT%H%M%S")

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http://www.mxm.dk/
IT's Mad Science
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Re: Another look at language comparisons

[Max M]

Jan Dries wrote:
[EMAIL PROTECTED] wrote:
And there is hope for Python, as Guido has recently been seen with a 
beard :-)
http://www.tbray.org/ongoing/When/200x/2004/12/08/-big/IMG_3061.jpg
LOL, he is working on linux, isn't he?
So it was about bloody time.
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http://www.mxm.dk/
IT's Mad Science
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Re: The best way to do web apps with Python?

[Rob Emmons]

> 
> 
> 
> 
> 
> 
> 
> What is 

Just FYI -- the post you posted was in HTML -- you might want to avoid
this in the future.  99% of all posts to news groups are in text, not
html.  Html is hard for everyone to read with normal news readers and not
usually of any extra value.  It's also more of a security risk to read it --
because there is more potential for exploitation.

Anyway, just thought I'd mention it if you didn't know.

Take care,
Rob
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Re: Python Operating System???

[David Brown]

So how would I make an OS Shell?


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Re: Tkinter: passing parameters to menu commands

[Kent Johnson]

Philippe C. Martin wrote:
menu.add_cascade(label="File", menu=filemenu)
filemenu.add_command(label="New", command=lambda: callback('New'))
filemenu.add_command(label="Open...", command=lambda:

Of course you could do this with named forwarding functions if you
prefer
I'm not sure what 'named forwarding functions' 
Bad choice of terminology, I just mean you can explicitly define
def handleNew:
  callback('New')
etc.
are but I'm actually in a
class and when applying your suggestion in the following manner,
everything works (THANKS!)

def __Dec(self,p_string):
  for i in p_string:
self.__Insert(i)
.
.
.
#menu creation
l_dec.add_command(label = 'ATR', command=lambda: self.__Dec('ATR'))
l_dec.add_command(label = 'IN', command=lambda:self.__Dec('IN'))
.
.
.

Yet I have a question:
If I replace the menu creation code as below, and since __Insert appends
the string p_string into a text widget that is created _after_ the menu
creation; the method __Dec seems to be called at the menu creation and
I get an error in __Insert because the test widget is equal to None.
My reflexes of C programmer tell me that command=self.__Dec just
passes a method pointer (sorry I said it) to add_command - yet it does
not seem to be so.
>
> What is actually going on ?
>
>
> #menu creation
> l_dec.add_command(label = 'ATR', command=self.__Dec('ATR'))
> l_dec.add_command(label = 'IN', command=self.__Dec('IN'))
self.__Dec is a reference to the function. It is similar to a method pointer so you don't need to 
apologize ;) The name of a function without the () is a reference. When you append () it becomes a 
call to the referenced function.

The command parameter for the menu must be a reference to a function. The function is called with no 
arguments when the menu is invoked.

So, you need a function of no arguments to handle the command. For example,
def handleMenu():
  print 'Handled'
filemenu.add_command(label="New", command=handleMenu)
Note there is no () after handleMenu. 'command' is bound to the function object; the function is not 
called until later.

OK, now suppose you want to pass a parameter to handleMenu?
def handleMenu(menuName):
  print 'Handled', menuName
Now what do you put in the command parameter? This won't work because you are *calling* handleMenu 
and assigning the result of the call (in this case the value None) to 'command':

filemenu.add_command(label="New", command=handleMenu('New')) # WRONG
You need a new function of zero arguments to bind to 'command'. Here is one way 
to do it:
def handleNew():
  handleMenu('New')
filemenu.add_command(label="New", command=handleNew) # OK
Note, again, no () after handleNew. 'command' is bound to the function object 
again.
OK, what about lambda? lambda is a way to create a simple anonymous function. One simple use of 
lambda is to make a new function that binds a parameter to another function.

lambda: handleMenu('New')
defines a function that does the same thing as handleNew. The value of the lambda expression is the 
function object. So

filemenu.add_command(label="New", command=lambda: handleMenu('New')) # OK
is another way to get the result you want.
Kent
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there's a socket.sendall(), so why no socket.recvall()?

[Irmen de Jong]

Subject says it all;
there's a socket.sendall(), so why no socket.recvall()?
I know that I can use the MSG_WAITALL flag with recv(),
but this is not implemented on all platforms, most
notably windows.
--Iremn
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Re: python3: 'where' keyword

[oren]

When I first saw this I thought: "hmmm... this seems as redundant as
adding a repeat/until loop to Python; there's no chance in hell it will
ever be accepted by the community or Guido, but I actually kinda like
it".  It's nice to see mostly positive reactions to this idea so far.

I think it's a really ingenious solution to the the anonymous function
problem - don't make it anonymous! A short, throwaway name with a very
localized scope is as good as a truly anonymous function and feels more
Pythonic to me. We thought we wanted a better syntax than lambda for
anonymous functions but Andrey shows that perhaps it wasn't what we
really need. What we need is a solution to quickly and cleanly generate
bits of callable code without polluting the containing namespace,
without having to think too hard about unique names and while making
their temporary and local nature clear from the context. Anonymity
isn't one of the requirements.

I really liked Nick Coghlan's property example. The names 'get' and
'set' are too short and generic to be used without a proper scope but
with this syntax they are just perfect.

Here's another example:

w = Widget(color=Red, onClick=onClick, onMouseOver=onMouseOver) where:
.   def onClick(event): do_this(event.x, event.y, foo)
.   def onMouseOver(event): someotherwidget.do_that()

The "onClick=onClick" part seems a bit redundant, right? So how about
this:

w = Widget(**kw) where:
.   color = Red
.   def onClick(event): do_this(event.x, event.y, blabla)
.   def onMouseOver(event): someotherwidget.do_that()
.   x, y = 100, 200
.   kw = locals()

I'm not really sure myself how much I like this. It has a certain charm
but also feels like abuse of the feature. Note that "w =
Widget(**locals()) where:" would produce the wrong result as it will
include all the values in the containing scope, not just those defined
in the where block. 

   Oren

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Re: "A Fundamental Turn Toward Concurrency in Software"

[Donn Cave]

Quoth Skip Montanaro <[EMAIL PROTECTED]>:
|
| Jp> How often do you run 4 processes that are all bottlenecked on CPU?
|
| In scientific computing I suspect this happens rather frequently.

I think he was trying to say more or less the same thing - responding
to "(IBM mainframes) ... All those systems ran multiple programs ...
My current system has 42 processes running ...", his point was that
however many processes on your desktop, on the rare occasion that
your CPU is pegged, it will be 1 process.  The process structure of
a system workload doesn't make it naturally take advantage of SMP.
So "there will still need to be language innovations" etc. -- to
accommodate scientific computing or whatever.  Your 4 processes are
most likely not a natural architecture for the task at hand, but
rather a complication introduced specifically to exploit SMP.

Personally I wouldn't care to predict anything here.  For all I know,
someday we may decide that we need cooler and more efficient computers
more than we need faster ones.

Donn Cave, [EMAIL PROTECTED]
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Installing IPython on win2k

[Dave Merrill]

Hi, I'm new to python, and ipython, but not to programming, having trouble
getting ipython installed on windows 2000, python 233. Any help would be
much appreciated; I'm sure I'm being some basic flavor of dense...

First downloaded and installed PythonWin, readline and ctypes. They're all
pretty clearly here and working, because I can run PythonWin, and from
there, importing readline and ctypes works.

Then downloaded ipython-0.6.6.zip and unzipped it. When I double-click
setup.py, I get only a brief wait cursor; nothing else happens, and
importing ipython as a test fails.

I tried moving the whole unzipped dir to site-packages, no difference.

Both files in the scripts dir, ipython and pycolor, have no filename
extension, which seems odd to my newbie eye. I tried renaming them to .py,
still no difference.

My apologies for this basic question, and my no doubt ignorant flailing
about. Very much looking forward to getting this working.

Thanks,

Dave Merrill


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Real Election Reform

[D Flint]

What do you think about this and have you seen this popular site before?

This was taken from a web site
http://www.afvr.org

How can we safeguard the integrity of each vote?
Today we have technology that protects our financial systems, military
weapon systems and national intelligent organizations. These proven systems
can be combined in a way to issue serialized equipment to authorize
personnel for the dates and hours needed. Each would have their own level of
clearance to perform the tasks they are responsible for. Each action would
be recorded and verified with a higher levels of network authority and
again, only available during the hours and dates needed. Ballots would only
be printed after the voter has cast their vote but before they leave the
booth. If the voter made a mistake he could put the printed ballot into the
booth's scanner for correction. All ballots scanned at the booth would go
into a shredder and the voter could then correct his ballot on the screen
and reprint his ballots. Once the voter accepts the printed ballot he
submits his vote on the screen and takes the two ballots to the depository.
So two computer generated, serialized and scanner perfect receipts of the
completed ballot are printed.* One for the voter and one for the public
record. This would eliminate all the extra ballots that could be used for
unauthorized voting as well as any question of voter intent.  Each piece of
equipment involved in the issuing of the receipt would be linked to the
serial# of that ballot and an electronic document would be generated that
exactly matched the two printed receipts. So the voter themselves has
validate the printed ballots, keeping one for themselves, while the other
electronic time-stamped document is deposited into an optical scanner used
as a secure depository. This second scanned count which should always match
the electronic count. This paper ballot could also be used for recounts if
needed. The voter could use the receipt to inquire about their vote in the
future. The stuffing of the ballot box or "finding ballots" would be
eliminated.  With this system, if you find a ballot, you have to find the
voter that cast that ballot too. This is not so in any of the current
systems in place today nor have we ever heard such a system ever proposed.
  http://www.afvr.org











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Re: "A Fundamental Turn Toward Concurrency in Software"

[John Roth]

"Donn Cave" <[EMAIL PROTECTED]> wrote in message 
news:[EMAIL PROTECTED]
Quoth Skip Montanaro <[EMAIL PROTECTED]>:
|
| Jp> How often do you run 4 processes that are all bottlenecked on 
CPU?
|
| In scientific computing I suspect this happens rather frequently.

I think he was trying to say more or less the same thing - responding
to "(IBM mainframes) ... All those systems ran multiple programs ...
My current system has 42 processes running ...", his point was that
however many processes on your desktop, on the rare occasion that
your CPU is pegged, it will be 1 process.  The process structure of
a system workload doesn't make it naturally take advantage of SMP.
So "there will still need to be language innovations" etc. -- to
accommodate scientific computing or whatever.  Your 4 processes are
most likely not a natural architecture for the task at hand, but
rather a complication introduced specifically to exploit SMP.
Exactly. I wasn't addressing some of the known  areas where one
can take advantage of multiple processors, or where one can take
advantage of threading on a single processor to avoid delays.
At this point in time, though, I see multithreading for compute
intensive tasks to be an intermediate step. The final step is to
restructure it so it can take advantage of cluster architectures.
Then you can simply ignore all of the complexity of threads.
That still leaves putting long running tasks (such as printing)
into the background so the UI stays responsive.
Personally I wouldn't care to predict anything here.  For all I know,
someday we may decide that we need cooler and more efficient computers
more than we need faster ones.
Chuckle. I basically think of shared memory multiprocessing
as being perverse: the bottleneck is memory, not compute
speed, so adding more processors accessing the same memory
doesn't strike me as exactly sane. Nor does pushing compute
speed up and up and up when it just stressed the memory
bottleneck.
Donn Cave, [EMAIL PROTECTED] 
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Re: OT: spacing of code in Google Groups

[Peter Hansen]

JanC wrote:
Have a look at: 
They have native win32 builds of many of the GNU commandline utilities...
Thanks, everyone, for all your kind help.
(Uh, I thought it was clear I didn't actually *want* a
method of cutting columns, since I have needed the
functionality once in the last ten years, but on behalf
of those who do what it and didn't know how to get it,
I give you thanks. ;-)
-quite-happy-with-simple-editors-and-a-command-line-ly y'rs,
 Peter
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windows mem leak

[Bob Smith]

Does the Win32 port of Python have a memory leak? I have some code that 
runs flawlessly on Linux, but bombs after a few hours on Windows. It's 
threaded and uses a lot of memory.

Thanks!
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Re: sorting on keys in a list of dicts

[Peter Hansen]

Nick Coghlan wrote:
Stability in sorting is a property not to be sneezed at - it means 
switching to sorting by a second key gives the effect of "sort by key 1, 
then by key 2", whereas that doesn't hold with an unstable sort 
Assuming "key 1" refers to the first key, and "key 2" to the second
key, then I believe you meant "gives the effect of 'sort by key 2
then by key 1'".
In other words, if you have a stable sort algorithm and do one sort
operation using key 2, then a second sort operation using key 1,
it's the same as doing a single sort with the key combination "key 1, key 2",
not the other way around.
-Peter
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Re: 2 versions of python on 1 machine

[Peter Hansen]

flupke wrote:
I used the 2 batch files technique and removed c:\python23 from my
path var and all is fine now.
Where did you find more info on PYTHONHOME and PYTHONPATH because
the docs don't seem to contain a whole lot of info.
Typing "python -h" gives a good start.  I'm sorry, I don't recall
where else there is useful info on those, though I'm pretty sure
Google could help.  (I'm not sure there's much to add to what the
"-h" option tells you, however.)
-Peter
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Re: python3: 'where' keyword

[Peter Hansen]

Andrey Tatarinov wrote:
 >>> print words[3], words[5] where:
 >>> words = input.split()
- defining variables in "where" block would restrict their visibility to 
one expression
Then your example above doesn't work...  print takes a
sequence of expressions, not a tuple as you seem to think.
-Peter
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Re: Python Operating System???

[Peter Hansen]

Paul Rubin wrote:
When Unix was first written, people thought implementing an OS in C
was ludicrous.  Everyone knew OS's had to be written in assembler.
Actually, when Unix was first written that belief was entirely
correct, and OSes *did* have to be written in assembler.
That is, pure C did not have the capability to handle all
that was required.  I recall it taking a good decade before it
became *common* to find C compilers with, for example, @interrupt
support to let the compiler generate code that properly saved
all registers and used RTI instead of RTS (or whatever it might
have been called one one's particular flavour of CPU).
Now, once you added a few tiny interrupt handlers, and some context
switching (stack manipulation) routines, pretty much everything else
*could* be done in C, but that doesn't invalidate the point.
I think it's safe to say that none of pure C, pure Lisp, or pure Python
are really capable of being used as the *sole* language to build
an operating system.
It's also safe to say that this is a largely irrelevant point.
It would probably only be of academic interest to try to do
something like that.  Any practical attempt would not think more
than twice of resorting to a little "glue" in assembler or in
the form of "canned" byte sequences built by hand and stuck
into the appropriate places in memory...
-Peter
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Re: OT: google groups bug, or worse?

[Peter Hansen]

[EMAIL PROTECTED] wrote:
I'm concerned that google groups is not correctly reflecting the
python lists.  A month ago I announced the xsdbXML framework to the
python list and the python-announce list.  As you can see from the
links
below the python announce submission was approved by the moderators
(thanks!)
and the python list submission also went out, but the messages cannot
be found at google groups.
http://mail.python.org/pipermail/python-list/2004-December/254479.html
http://mail.python.org/pipermail/python-announce-list/2004-December/003583.html
Is it a google bug?  Or is it something darker, like an anti-Python
conspiracy at google?
You didn't post via Google, right?  Just sent to the mailing list?
I believe that Google knows nothing about mailing lists, but
watches a news feed, so if the list/Usenet gateway failed to
deliver those messages, Google would never see them.
Furthermore, news delivery is not necessarily guaranteed.
(Actually, I don't recall how reliable the protocol is,
but I doubt it's foolproof.)  If any one of the news
servers between yours and Google's happened to drop some
messages, it's quite possible Google would never see
them.
Given the "architecture" of Usenet, I wouldn't be surprised
if Google missed messages consistently, a very small percentage
of the time.
-Peter
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Re: "A Fundamental Turn Toward Concurrency in Software"

[Peter Hansen]

John Roth wrote:
I have yet to write a multi-thread program for performance reasons.
If we include in the set of things covered by the term
"performance" not only throughput, but also latency, then
I suspect you actually have written some multithreaded programs
for "performance" reasons.
*I* certainly have: that's easily the reason for threading
in 95% of the cases I've dealt with, and I suspect those of
many others.
-Peter
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Re: Recent infoworld column

[Peter Hansen]

Dwarf Electrician wrote:
from a long time listener...
http://www.infoworld.com/article/04/12/30/01OPstrategic_1.html
Kudos for Roger Binns!
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Re: windows mem leak

[Peter Hansen]

Bob Smith wrote:
Does the Win32 port of Python have a memory leak? I have some code that 
runs flawlessly on Linux, but bombs after a few hours on Windows. It's 
threaded and uses a lot of memory.
Let's see what you're missing:
1. platform specifics
2. versions of things involved
3. any sort of detail about the code
4. how you're noticing/measuring the problem
5. what "bombs" means
6. any mention that you've checked Sourceforge to see whether
   a similar problem has been reported
There have been memory leaks in various past versions of Python,
and could easily be in the current version, but they're generally
rather specific in terms of the code that can trigger it.  Once it
was doing some particular work with a socket, once it was trying to
append (or extend?) to an empty list, and so on.
There are also a few ways you could have written your application
to cause memory to leak as a result of your own code, not as a
result of Python's.  And it's even possible that this would happen
only on one platform (though I'm trying hard to think of an example
and can't... maybe it's very unlikely.)
-Peter
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Re: Python Operating System???

[Arich Chanachai]

Peter Hansen wrote:
Paul Rubin wrote:
When Unix was first written, people thought implementing an OS in C
was ludicrous.  Everyone knew OS's had to be written in assembler.

Actually, when Unix was first written that belief was entirely
correct, and OSes *did* have to be written in assembler.
*nods*
That is, pure C did not have the capability to handle all
that was required.  I recall it taking a good decade before it
became *common* to find C compilers with, for example, @interrupt
support to let the compiler generate code that properly saved
all registers and used RTI instead of RTS (or whatever it might
have been called one one's particular flavour of CPU).
If my memory serves me, you are entirely correct.
Now, once you added a few tiny interrupt handlers, and some context
switching (stack manipulation) routines, pretty much everything else
*could* be done in C, but that doesn't invalidate the point.
*nods*
I think it's safe to say that none of pure C, pure Lisp, or pure Python
are really capable of being used as the *sole* language to build
an operating system.
*nods*
It's also safe to say that this is a largely irrelevant point.
It would probably only be of academic interest to try to do
something like that.  Any practical attempt would not think more
than twice of resorting to a little "glue" in assembler or in
the form of "canned" byte sequences built by hand and stuck
into the appropriate places in memory...
-Peter
Indeed indeed.  Once must remain focused and ask oneself what he/she is 
attempting to achieve.  In all likelihood, a little asm/c/python glue 
work won't hurt the objective, especially given that doing otherwise 
would entail a very  _low level_ reworking of Python that would take as 
much and likely more effort and skill than to resort to asm/c when 
Python falls incapable.  One could do a Python-Lisp OS w/ Lisp used for 
the Python incapable areas, but you would near entirely loose the 
benefits of Lisp in that respect--- it would have to be so low-level, 
could you call it Lisp?  (A question someone else here posed in this 
thread.)

- Arich
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Re: DOS problem (simple fix??)

[Steve Holden]

Gavin Bauer wrote:
My DOS window (running in windows ME) closes the second it finishes
running my programs. As you can imagine, this makes it hard to see the
results. I've gotten in the habit of putting raw_input("Press enter to
exit") at the end of every program, and in addition to being pain in
the butt, it often fails to work. Being new to programming in general,
I make more mistakes than most people. My programs often have errors
before they get to my raw_input command. They then display the error
and immediately close. It is naturally a lot easier to fix an error
when you know what the error is. This makes debugging even more
annoying than it ordinarily would be, if you can imagine that. I've
heard that it should be a simple preference fix, but I've asked around
and no one seems to know how.
I presume this means you are starting the program by the time-honored 
expedient of double-clicking on it. For debugging you would probably 
find it more satisfactory to run your programs from the command line, 
and there's a FAQ that explains how at

  http://www.python.org/doc/faq/windows.html
If that isn't simple enough then please let me know, as it's *supposed* 
to be.

Thank you, and please make all answers simple enough to be understood
by a highschool student and his father :) .
If you wanted to get really adventurous you could try tweaking the 
command that Windows runs when you double-click a Python script, but 
we'll leave that for another time.

Welcome to Python!
regards
 Steve
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Re: The limitation of the Photon Hypothesis

[Steve Holden]

Steve Horsley wrote:
bill wrote:
Please reply to [EMAIL PROTECTED], thank you !

No - I'll reply to the newsgroup, if you don't mind.
The limitation of the Photon Hypothesis

THE UNCERTAINTY PRINCIPLE IS UNTENABLE

You cannot use classical theory to disprove quantum theory that easily.
The uncertainty is quantum in origin, and not just an artifact of
classical mechanics applied to clumsy measurement.
You don't convince me.
Also, I think you probably accidentally posted to the wrong newsgroup.
Steve

No, he deliberately posted to the wrong newsgroup. But that's because 
there isn't a right newsgroup for this kind of twaddle (except possibly 
alt.rubbish.alternate.universe).

You have just marked yourself as a noob, since this hoary old favorite 
seems to appear about ten times a year.

Welcome to Usenet!
regards
 Steve
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RE: there's a socket.sendall(), so why no socket.recvall()?

[Robert Brewer]

Irmen de Jong wrote:
> Subject says it all;
> there's a socket.sendall(), so why no socket.recvall()?

Good question! Something like:

# Receive reply.
data = []
while True:
try:
chunk = conn.recv(8192)
except Exception, x:
if x.args[0] != 10035:
raise x
else:
if chunk == '':
break
data.append(chunk)

If you call .makefile() and then .read() the _fileobject, you get the
same behavior (only better). Adding recvall would just duplicate that, I
think. But that's desirable IMO.


Robert Brewer
MIS
Amor Ministries
[EMAIL PROTECTED]
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Re: tuples vs lists

[Steve Holden]

worzel wrote:
Cheers - thanks for the feedback guys - pretty much answers the question for 
me.

'Two-Pull' it is then, thanks.
Well, it might be "Two-Pull" in American, but in English it's "tyoopl" 
-- NOT "choopl" (blearch!). I've also heard people say "tuppl".

So, basically, say whatever you want. Language is about communication :-)
you-say-tomato-ly y'rs  - steve
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Re: Returning same type as self for arithmetic in subclasses

[Steve Holden]

Tim Peters wrote:
[Max M]
"""
I subclass datetime and timedelta
[...]
Generally speaking, no.  But I'm sure someone will torture you with a
framework that purports to make it easy .
Clearly the easy way is to have the type declaration introspect on the 
definitions of datetime and timedelta and then auto-create methods 
wrapping the base types' methods in a "myxxx" conversion.

left-as-an-exercise-for-the-reader-ly y'rs  - steve
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Weekly Python Patch/Bug Summary

[Kurt B. Kaiser]

Patch / Bug Summary
___

Patches :  267 open ( +6) /  2727 closed ( +9) /  2994 total (+15)
Bugs:  798 open ( -3) /  4748 closed (+15) /  5546 total (+12)
RFE :  165 open ( +0) /   140 closed ( +1) /   305 total ( +1)

New / Reopened Patches
__

Remove witty comment in pydoc.py  (2005-01-01)
CLOSED http://python.org/sf/1094007  opened by  Reinhold Birkenfeld

Docs for file() vs open()  (2005-01-01)
CLOSED http://python.org/sf/1094011  opened by  Reinhold Birkenfeld

Improvements for shutil.copytree()  (2005-01-01)
CLOSED http://python.org/sf/1094015  opened by  Reinhold Birkenfeld

xml.dom.minidom.Node.replaceChild(obj, x, x) removes child x  (2005-01-01)
   http://python.org/sf/1094164  opened by  Felix Rabe

os.py: base class _Environ on dict instead of UserDict  (2005-01-02)
   http://python.org/sf/1094387  opened by  Matthias Klose

add Bunch type to collections module  (2005-01-02)
   http://python.org/sf/1094542  opened by  Steven Bethard

self.button.pack() in tkinter.tex example  (2005-01-03)
   http://python.org/sf/1094815  opened by  [N/A]

fixes urllib2 digest to allow arbitrary methods  (2005-01-03)
   http://python.org/sf/1095362  opened by  John Reese

Argument passing from /usr/bin/idle2.3 to idle.py  (2003-11-30)
   http://python.org/sf/851459  reopened by  jafo

fix for trivial flatten bug in astgen  (2005-01-04)
   http://python.org/sf/1095541  opened by  DSM

exclude CVS conflict files in sdist command  (2005-01-04)
   http://python.org/sf/1095784  opened by  Wummel

Fix for wm_iconbitmap to allow .ico files under Windows.  (2005-01-05)
   http://python.org/sf/1096231  opened by  John Fouhy

Info Associated with Merge to AST  (2005-01-07)
   http://python.org/sf/1097671  opened by  Kurt B. Kaiser

Direct framework linking for MACOSX_DEPLOYMENT_TARGET < 10.3  (2005-01-07)
   http://python.org/sf/1097739  opened by  Bob Ippolito

Encoding for Code Page 273 used by EBCDIC Germany Austria  (2005-01-07)
   http://python.org/sf/1097797  opened by  Michael Bierenfeld

Patches Closed
__

locale.getdefaultlocale does not return tuple in some OS  (2004-10-21)
   http://python.org/sf/1051395  closed by  rhettinger

imghdr -- identify JPEGs in EXIF format  (2003-06-08)
   http://python.org/sf/751031  closed by  rhettinger

Remove witty comment in pydoc.py  (2005-01-01)
   http://python.org/sf/1094007  closed by  rhettinger

Docs for file() vs open()  (2005-01-01)
   http://python.org/sf/1094011  closed by  rhettinger

Improvements for shutil.copytree()  (2005-01-01)
   http://python.org/sf/1094015  closed by  jlgijsbers

a new subprocess.call which raises an error on non-zero rc  (2004-11-23)
   http://python.org/sf/1071764  closed by  astrand

Argument passing from /usr/bin/idle2.3 to idle.py  (2003-11-30)
   http://python.org/sf/851459  closed by  jafo

@decorators, including classes  (2004-08-12)
   http://python.org/sf/1007991  closed by  jackdied

Convert glob.glob to generator-based DFS  (2004-04-27)
   http://python.org/sf/943206  closed by  jlgijsbers

Make cgi.py use email instead of rfc822 or mimetools  (2004-12-06)
   http://python.org/sf/1079734  closed by  jlgijsbers

New / Reopened Bugs
___

marshal.dumps('hello',0) "Access violation"  (2005-01-03)
CLOSED http://python.org/sf/1094960  opened by  Mark Brophy

General FAW - incorrect "most stable version"  (2005-01-03)
   http://python.org/sf/1095328  opened by  Tim Delaney

Python FAQ: list.sort() out of date  (2005-01-03)
CLOSED http://python.org/sf/1095342  opened by  Tim Delaney

Bug In Python  (2005-01-04)
CLOSED http://python.org/sf/1095789  opened by  JastheAce

"Macintosh" references in the docs need to be checked.  (2005-01-04)
   http://python.org/sf/1095802  opened by  Jack Jansen

The doc for DictProxy is missing  (2005-01-04)
   http://python.org/sf/1095821  opened by  Colin J. Williams

Apple-installed Python fails to build extensions  (2005-01-04)
   http://python.org/sf/1095822  opened by  Jack Jansen

time.tzset() not built on Solaris  (2005-01-05)
   http://python.org/sf/1096244  opened by  Gregory Bond

sys.__stdout__ doco isn't discouraging enough  (2005-01-05)
   http://python.org/sf/1096310  opened by  Just van Rossum

_DummyThread() objects not freed from threading._active map  (2004-12-22)
   http://python.org/sf/1089632  reopened by  saravanand

Example needed in os.stat()  (2005-01-06)
CLOSED http://python.org/sf/1097229  opened by  Facundo Batista

SimpleHTTPServer sends wrong Content-Length header  (2005-01-06)
   http://python.org/sf/1097597  opened by  David Schachter

urllib2 doesn't handle urls without a scheme  (2005-01-07)
   http://python.org/sf/1097834  opened by  Jack Jansen

getsource and getsourcelines in the inspect module  (2005-01-07)
CLOSED http://python.org/sf/1098134  opened by  Björn Lindqvist

mailb

Re: The best way to do web apps with Python?

[Steve Holden]

worzel wrote:
What is the best way to web developemnt with Python? Is there anything 
close to PHP style in-page script placement that can create and use 
other Python objects? I am not really interested in Zope (I believe that 
is more a CMS than anything else?) I am also looking for something a 
little more structured than a series of CGI Scripts.
 
More ways than you can shake a stick at, but nowadays you should 
consider using WSGI if you want your code to be portable across many 
frameworks. The Web SIG worked very hard last year on defining this 
gateway interface, with the intention that it should become widely 
available, and implementations are available now on environments as 
diverse as mod_python and CherryPy.

You can read about it in Philip Eby's excellent PEP at
  http://www.python.org/peps/pep-0333.html
While on the topic - what is the expectataion of Python for this kind of 
stuff? Would one use Python for certain other things but turn to PHP for 
web apps - or would one use their Python skills in place of PHP?
 
Python is a real programming language, whereas PHP was originally 
intended as a simple way of scripting web content. Since then it has 
grown to encompass many of the same features as Python, but since they 
were retrofitted rather than designed in they are sometimes kind of 
clunky (as, IMHO, is Perl, although in a different way).

But there's a lot of good work been done in both PHP and Perl, and I'd 
usually recommend using existing functionality in either language over a 
just-for-the-sake-of-it rewrite in Python. But that could just be 
because I don't like re-inventing wheels.

regards
 Steve
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Re: Recent infoworld column

[Carlos Ribeiro]

On Sat, 08 Jan 2005 13:14:17 -0500, Peter Hansen <[EMAIL PROTECTED]> wrote:
> Dwarf Electrician wrote:
> > from a long time listener...
> >
> > http://www.infoworld.com/article/04/12/30/01OPstrategic_1.html
> 
> Kudos for Roger Binns!

>From Mr. Udell himself:

"""
When people talk about the heroes of open source, you tend to hear
such familiar names as Linus Torvalds, Larry Wall, Brendan Eich, Guido
van Rossum, Monty Widenius, Miguel de Icaza, and Rasmus Lerdorf. No
question about it: These people are my heroes. But so is Roger Binns,
and so are the countless other unsung heroes of open source. For
solving a host of vexing problems with quiet competence, and for doing
it in ways that invite others to stand on their shoulders, I salute
them all.
"""

That's recognition. Wow.

-- 
Carlos Ribeiro
Consultoria em Projetos
blog: http://rascunhosrotos.blogspot.com
blog: http://pythonnotes.blogspot.com
mail: [EMAIL PROTECTED]
mail: [EMAIL PROTECTED]
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Re: Weekly Python Patch/Bug Summary

[Max M]

Kurt B. Kaiser wrote:
Remove witty comment in pydoc.py  (2005-01-01)
CLOSED http://python.org/sf/1094007  opened by  Reinhold Birkenfeld
This is not a joke? :-)
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interpreter Py_Initialize/Py_Finalize mem leak?

[Roman Suzi]

In pure curiosity I tried to compile loop.c from Demo/embed
and started it with 'print 2+2'. It seems, that both 2.3 and 2.4
pythons have memory leaks in Py_Initialize/Py_Finalize calls.
(That is, interpreter doesn't clean up well after itself).

This is my setup:

gcc -fpic loop.c -DHAVE_CONFIG_H -lm -lpython2.4 \
  -lpthread -lutil -ldl \
  -I/usr/local/include/python2.4 \
  -L/usr/local/lib/python2.4/config \
  -o looptest

(It's on Linux RedHat 7.3)

I do not know if this is of any importance though. Probably it is
for embedded Python uses.

Sincerely yours, Roman Suzi
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Re: Working with recordsets

[Steve Holden]

AdSR wrote:
[EMAIL PROTECTED] wrote:
Hi.
I have one recorset that I would like to pass to 2 functions, one is
for create an CSV file and the other one is to create a HTML file. The
problem is that the recordset is totally read in the first function,
and then when I pass it to the second funtion the recordset is in the
last record.
I've read docs, but I think that one cursor doesn't have something
like movefirst() method. Anybody have an idea to solve this?
Thank's.
Try loading the whole recordset with the fetchall() method and use the 
resulting sequence in your functions. It won't be memory-efficient but 
it will be easy to do.

AdSR
Or, if this doesn't suit, try creating two separate cursors from the 
same connection and execute the same query on each. There's some chance 
that your database driver/backend combination will optimize the queries 
then.

regards
 Steve
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Re: Installing IPython on win2k

[Tim G]

Dave Merrill wrote:
> Hi, I'm new to python, and ipython, but not to programming, having
trouble
> getting ipython installed on windows 2000, python 233. Any help would
be
> much appreciated; I'm sure I'm being some basic flavor of dense...

First of all, rest assured that it does work (and quite
easily) so welcome to Python and iPython and I hope
the going's a bit smoother as you go along.

> Then downloaded ipython-0.6.6.zip and unzipped it. When I
double-click
> setup.py, I get only a brief wait cursor; nothing else happens, and
> importing ipython as a test fails.

First of all, ipython isn't really an import into python; you run
it and it runs python (if you understand me). So when you've
installed it, I think it puts an item on your start menu. On
linux, it puts an executable ipython onto your path.

I've just downloaded and run the setup.py, and it does
create a Start Menu item which will start iPython. Look
out for that and see if it does the business.

> Both files in the scripts dir, ipython and pycolor, have no filename
> extension, which seems odd to my newbie eye. I tried renaming them to
.py,
> still no difference.

This is a unixism. Some unix types decry the use of file extensions
because the information the extension gives -- which executable
program to use -- is already embedded in the first line of a file.

>
> My apologies for this basic question, and my no doubt ignorant
flailing
> about. Very much looking forward to getting this working.
> 
> Thanks,
> 
> Dave Merrill

Good luck and happy hunting

TJG

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Re: Embedding a restricted python interpreter

[Dieter Maurer]

Doug Holton <[EMAIL PROTECTED]> writes on Thu, 06 Jan 2005 20:34:31 -0600:
> ...
> Hi, there is a page on this topic here:
> http://www.python.org/moin/SandboxedPython
> 
> The short answer is that it is not possible to do this with the
> CPython, but you can run sandboxed code on other virtual machines,
> such as Java's JVM with Jython, or .NET/Mono's CLR with Boo or
> IronPython.

Zope contains a "restrictedPython" implementation.

  It uses a specialized compiler that prevents dangerous bytecode operations
  to be generated and enforces a restricted builtin environment.
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Re: "A Fundamental Turn Toward Concurrency in Software"

[aurora]

Of course there are many performance bottleneck, CPU, memory, I/O, network  
all the way up to the software design and implementation. As a software  
guy myself I would say by far better software design would lead to the  
greatest performance gain. But that doesn't mean hardware engineer can sit  
back and declare this as "software's problem". Even if we are not writing  
CPU intensive application we will certain welcome "free performace gain"  
coming from a faster CPU or a more optimized compiler.

I think this is significant because it might signify a paradigm shift.  
This might well be a hype, but let's just assume this is future direction  
of CPU design. Then we might as well start experimenting now. I would just  
throw some random ideas: parallel execution at statement level, look up  
symbol and attributes predicitively, parallelize hash function, dictionary  
lookup, sorting, list comprehension, etc, background just-in-time  
compilation, etc, etc.

One of the author's idea is many of today's main stream technology (like  
OO) did not come about suddenly but has cumulated years of research before  
becoming widely used. A lot of these ideas may not work or does not seems  
to matter much today. But in 10 years we might be really glad that we have  
tried.


aurora <[EMAIL PROTECTED]> writes:
Just gone though an article via Slashdot titled "The Free Lunch Is
Over: A  Fundamental Turn Toward Concurrency in Software"
[http://www.gotw.ca/publications/concurrency-ddj.htm]. It argues that
the  continous CPU performance gain we've seen is finally over. And
that future  gain would primary be in the area of software concurrency
taking advantage  hyperthreading and multicore architectures.
Well, another gain could be had in making the software less wasteful
of cpu cycles.
I'm a pretty experienced programmer by most people's standards but I
see a lot of systems where I can't for the life of me figure out how
they manage to be so slow.  It might be caused by environmental
pollutants emanating from Redmond.
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Re: there's a socket.sendall(), so why no socket.recvall()?

[Irmen de Jong]

Robert Brewer wrote:
Irmen de Jong wrote:
Subject says it all;
there's a socket.sendall(), so why no socket.recvall()?

[...]
If you call .makefile() and then .read() the _fileobject, you get the
same behavior (only better). Adding recvall would just duplicate that, I
think. But that's desirable IMO.
Hm, I didn't consider makefile(). But I'm not sure if that
works in all cases. Until now, I've been using a loop rather
like the one you posted.
But, as I pointed out earlier, there is the MSG_WAITALL option
on various platforms (Linux for instance).
So instead of sticking it in an explicitly programmed loop
in Python, or using an extension module such as this one:
http://mail.python.org/pipermail/python-list/2003-January/143051.html
, I'd rather have a recvall method on the socket object that
essentially uses MSG_WAITALL if available, and uses a
loop construction if not.
I may even write a patch for socketmodule.c right now :-D
--Irmen de Jong
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Re: tuples vs lists

[Irmen de Jong]

Steve Holden wrote:
Well, it might be "Two-Pull" in American, but in English it's "tyoopl" 
-- NOT "choopl" (blearch!). I've also heard people say "tuppl".
Probably the same ones who attend Tuppl-ware parties.
--Irmen
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Re: windows mem leak

[Steve Holden]

Bob Smith wrote:
Does the Win32 port of Python have a memory leak? I have some code that 
runs flawlessly on Linux, but bombs after a few hours on Windows. It's 
threaded and uses a lot of memory.

Thanks!
Yes, that's a well-known problem. Code that runs with a few errors will 
port without any trouble at all to Windows, but once it runs flawlessly 
on Linux it starts to leak memory on Windows. The PSU suspects a plot in 
Redmond, the basic details of which ar
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losing CGI variables in os.environ in Python 2.4

[jtauber]

Did something change between 2.3 and 2.4 that would affect os.environ
being populated with CGI variables when using the
BaseHTTPServer/CGIHTTPServer?

I received a bug report from someone trying to run my wiki/blog
software, Leonardo[1] under Python 2.4 on Windows 2000. I was able to
reproduce the problem under Python 2.4 on Windows XP Pro but confirmed
that it worked fine under Python 2.3.

Simply printing out os.environ at the point things like PATH_INFO are
extracted by Leonardo revealed that os.environ contained no CGI-related
variables when run under Python 2.4 but did contain them under 2.3

I can't see in the code for the http server modules that anything
changed in this area. Am I missing something?

Thanks in advance.
James Tauber
http://jtauber.com/blog/

[1] http://jtauber.com/leonardo

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Re: Installing IPython on win2k

[Dave Merrill]

"Tim G"  wrote in message
news:[EMAIL PROTECTED]
> Dave Merrill wrote:
> > Hi, I'm new to python, and ipython, but not to programming, having
> trouble
> > getting ipython installed on windows 2000, python 233. Any help would
> be
> > much appreciated; I'm sure I'm being some basic flavor of dense...
>
> First of all, rest assured that it does work (and quite
> easily) so welcome to Python and iPython and I hope
> the going's a bit smoother as you go along.

I'm having fun with python itself, but feeling a little constrained in the
IDE and debugger departments. (Not to mention the clues I haven't got...).


> > Then downloaded ipython-0.6.6.zip and unzipped it. When I
> double-click
> > setup.py, I get only a brief wait cursor; nothing else happens, and
> > importing ipython as a test fails.
>
> First of all, ipython isn't really an import into python; you run
> it and it runs python (if you understand me). So when you've
> installed it, I think it puts an item on your start menu. On
> linux, it puts an executable ipython onto your path.
>
> I've just downloaded and run the setup.py, and it does
> create a Start Menu item which will start iPython. Look
> out for that and see if it does the business.

Removed the files I'd unzipped and started over, putting a fresh unzip in
Program Files. Ran setup.py while watching the windows task list, and
pythonw ran for just a second, then disappeared. I saw no other signs of
anything running, and there's no shortcut for ipython in my start menu.


> > Both files in the scripts dir, ipython and pycolor, have no filename
> > extension, which seems odd to my newbie eye. I tried renaming them to
> .py,
> > still no difference.
>
> This is a unixism. Some unix types decry the use of file extensions
> because the information the extension gives -- which executable
> program to use -- is already embedded in the first line of a file.

So what do I do to try ipython directly, bypassing the shortcut (since I can
make my own later)? I tried right-click on scripts/ipython, Open With, and
chose python, but got only a quick DOS window.

Now what?

Thanks,

Dave Merrill


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Re: Python Operating System???

[Roose]

> Is an OS written in Lisp also ludicrous?  Because it's been done.

Can you point me to this?  I'd like to see how "truly" Lisp it is.

My first guess would be -- not very.  And I'd like to install it on my PC.


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Re: Python Operating System???

[Roose]

Well can you describe what kind of things you want to do exactly?

My guess is you are not out to develop a new algorithm for virtual memory or
task scheduling.

There are many parts to an OS shell.  An example is the command line, i.e.
bash and the like in Unix, and cmd.exe in Windows.  In Windows, Windows
Explorer could be considered part of the shell, as well as the start menu
and all that user-specific stuff.

Basically you need to pick your OS, and then find out what the API to
program the shell to would be.  e.g. in Windows you would do it with the
Win32 API.  This will let you do things like delete and create files,
interact with user structures, the registry, etc.

OR, as a first stab -- I would just write a prototype.  i.e., don't tie it
to a real OS.  Just pretend you have your own "users", your own "file
system", your own display space, etc.  This will help you get a much better
idea of what you want to do.


"David Brown" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
> So how would I make an OS Shell?
>
>


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Re: EOF for binary?

[Marc 'BlackJack' Rintsch]

In <[EMAIL PROTECTED]>, flamesrock
wrote:

> os.path.getsize(infile) <= infile.tell()
> 
> Because that returns the error:
> #  File "/usr/lib/python2.3/posixpath.py", line 142, in getsize
> #return os.stat(filename).st_size
> #TypeError: coercing to Unicode: need string or buffer, file found
> for me.

This error message gives a good hint what's wrong with your code snippet.

>>> f = open('tmp.txt')
>>> os.path.getsize(f)
Traceback (most recent call last):
  File "", line 1, in ?
  File "/usr/lib/python2.3/posixpath.py", line 142, in getsize
return os.stat(filename).st_size
TypeError: coercing to Unicode: need string or buffer, file found

Something expected a string instead of a file object.

>>> os.path.getsize("tmp.txt")
28190L

Ciao,
Marc 'BlackJack' Rintsch
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Re: escape string for command line

[Marc 'BlackJack' Rintsch]

In <[EMAIL PROTECTED]>, Ksenia
Marasanova wrote:

> I have a simple ecard creation script on a website, where user can add
> text to a graphic. I use ImageMagick for it:
> 
> # template_file => path to image template file
> # new_file => path to generated file
> # text => user input
> command = '''convert %s -font OfficinaSanITC-BookOS -pointsize 12
> -fill "#8C2F48" -draw "gravity north text 0,26 '%s'" %s''' % (
> template_file, text, new_file)
> system(command)
> 
> I was wondering, is there a general way to escape the string entered
> by the user, to prevent code injection into command line?

Take a look at the "string-escape" encoding:

>>> evil = "'; rm -rf /;"
>>> command = "echo '%s'"
>>> print command % evil.encode('string-escape')
echo '\'; rm -rf /;'

> Will it
> always be safe, even when binary data is submitted through POST?

Don't know if it's always safe.  Unprintable bytes like 0x00 will be
escaped as '\x00'.

Ciao,
Marc 'BlackJack' Rintsch
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Re: Installing IPython on win2k

[Dave Merrill]

Fernando replied to a similar post of mine on the IPython list, and had a
suggestion that for some unknown reason, worked. Or rather, what's unknown
is why normal setup failed.

For the benefit of anyone else who has this issue, I unzipped the files into

  C:\Program Files\ipython-0.6.6

...then opened a DOS window, and did the following two cmds:

  cd C:\Program Files\ipython-0.6.6
  "C:\Program Files\Python23\python.exe" setup.py install

Tons of DOS cmds spat out, the shortcut was created, and launching it
brought up the config wizard, then ipython.

I'd really love it if ipython could be invoked in the current debugger
context in PyDev under Eclipse. Is there any way to do that?

Thanks again,

Dave Merrill


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Re: "A Fundamental Turn Toward Concurrency in Software"

[John Roth]

"Peter Hansen" <[EMAIL PROTECTED]> wrote in message 
news:[EMAIL PROTECTED]
John Roth wrote:
I have yet to write a multi-thread program for performance reasons.
If we include in the set of things covered by the term
"performance" not only throughput, but also latency, then
I suspect you actually have written some multithreaded programs
for "performance" reasons.
*I* certainly have: that's easily the reason for threading
in 95% of the cases I've dealt with, and I suspect those of
many others.
Actually, I've never written a multi-threaded program for
any reason. There were only two times I had to deal with concurrency:
one was a very nice co-routine implementation (HASP,
the predecessor to the JES2 subsystem on MVS), and
the other was event driven (on an IBM SP). The former
system didn't have a threading library, let alone a lightweight
one, and the event driven design was a lot simpler for the
second application - and I did consider all three options.
John Roth
-Peter 
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Documenting data members

[Frans Englich]

Hello,

I have a custom module which among others contains a dictionary, acting as a 
"constant". I want to document it, but no matter what I do, it doesn't show 
up in `pydoc`. For example, the following doesn't work:

"""
A dictionary of the namespaces.
"""
xmlns = {
...
}

or

xmlns = {
"""
A dictionary of the namespaces.
"""
...
}

Bottom line: how do I document data members?

I also have another documentation question:

In a module which I install, the file starts with a comment containing a 
license header, to then be followed by a Python documentation string("""this 
module ..."""). The problem is that in pydoc, I get the uninteresting license 
header as documentation, instead of the doc string. I want to have the 
license header at the top.
Is this somehow fixable? That the doc string, instead of the license header, 
shows up in pydoc despite the latter being first in the file?


Cheers,

Frans


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Re: escape string for command line

[Ksenia Marasanova]

> >
> > I was wondering, is there a general way to escape the string entered
> > by the user, to prevent code injection into command line?
> 
> Take a look at the "string-escape" encoding:
> 
> >>> evil = "'; rm -rf /;"
> >>> command = "echo '%s'"
> >>> print command % evil.encode('string-escape')
> echo '\'; rm -rf /;'

Cool, thanks! Next time I'll study stdlib better before asking the question :)

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Re: Python Operating System???

[jtauber]

My experiment, Cleese, was making progress before I got distracted by
other things.

The approach was a micro-kernel in C made up of the CPython bytecode
interpreter with the file-related calls to libc ripped out and some
bare-metal port read/writes and memory operations exposed to Python as
built-in functions.

Everything else could then be written in pure Python. Dave Long was
able to write a VGA driver in Python and an implementation of Sokoban
that used it. You could then boot your machine to Sokoban :-)

I should probably get back to it at some stage.

see http://cleese.sourceforge.net/
James Tauber
http://jtauber.com/blog/

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Python Installation

[brolewis]

I need to install Python on a number of laptop computers (at least a
dozen). I am needing to install Python 2.4, pycrypto, win32all,
wxPython, and pyCurl. Can anyone tell me an easy way to install these
onto the laptops? Ideally I would like to have a single executable to
handle everything for me. I have also looked into using NSIS to handle
the installation, but am still unaware how to install the modules that
I need easily. Does anyone have any suggestions?

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Re: Python Installation

[brolewis]

For what its worth, I am running Windows XP Pro on all of these
machines.

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Re: Documenting data members

[Marc 'BlackJack' Rintsch]

In <[EMAIL PROTECTED]>, Frans Englich
wrote:

> I have a custom module which among others contains a dictionary, acting as a 
> "constant". I want to document it, but no matter what I do, it doesn't show 
> up in `pydoc`. For example, the following doesn't work:

I'm using epydoc_ for my documentation and there the module level and
class level variables are documented in the module/class docstring with
special markup.

> """
> A dictionary of the namespaces.
> """
> xmlns = {
> ...
> }

Will become:

""" (Module description)

:var xmlns: A dictionary of the namespaces.
"""

Ciao,
Marc 'BlackJack' Rintsch

.. _epydoc: http://epydoc.sourceforge.net/
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