date:20081003


Steven D'Aprano wrote:


We agree that the restriction is artificial, and I think irrational


I think it's irrational for another reason, too -- it's
actually vacuous. There's nothing to prevent you creating
a set of patches that simply say Delete all of the original
source and replace it with the following.

Then you're effectively distributing the modified source in
its entirety, just with a funny header at the top of each
source file that serves no useful purpose.

--
Greg
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Re: questions from a lost sheep

2008-10-03 Thread Michele Simionato

On Oct 2, 11:08 pm, johannes raggam [EMAIL PROTECTED] wrote:
 statically typed language: A language in which types are fixed at
 compile time. Most statically typed languages enforce this by requiring
 you to declare all variables with their datatypes before using them.
 Java and C are statically typed languages.

 dynamically typed language: A language in which types are discovered at
 execution time; the opposite of statically typed. VBScript and Python
 are dynamically typed, because they figure out what type a variable is
 when you first assign it a value.

 strongly typed language: A language in which types are always enforced.
 Java and Python are strongly typed. If you have an integer, you can't
 treat it like a string without explicitly converting it.

 weakly typed language: A language in which types may be ignored; the
 opposite of strongly typed. VBScript is weakly typed. In VBScript, you
 can concatenate the string '12' and the integer 3 to get the string
 '123', then treat that as the integer 123, all without any explicit
 conversion.

I have always considered this argument rather weak.
It is true, we Pythonista we are in a better position
that Perl and VBScript users, but still how strong is
strong typing really? When I can never know the types
accepted by a function at compile time?
When I can change the class of
an object at runtime?
Dynamic typing has its advantages, but calling it strong is
ridicolous for people coming from a background in ML or Haskell. The
definitions change
according to the circles you frequent, so there will be always
confusions on the terminology, unfortunately.

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Re: python-2.6

2008-10-03 Thread luca . ciciriello

Strange things happens.

I've download the installer package for Mac of Python 2.6 and I've launched
it. When finished, I've launched from a terminal the command Python and
all worked fine The response was Python 2.6 etc Now I've launched
IDLE. Nothing. IDLE icon blinked a couple of time in dock and then
disapeared. I've disabled any firewall in the system but the behavior was
the same. I've repared the privilege and restarted the system. 
A disaster. The system was dramatically slow and IDLE was still not
starting. Then I've reinstalled Python 2.5.2 an all was working fine again
(included IDLE and System speed).  

What is wrong with Python 2.6 on my system (MacOS X 10.4.11 PPC)?


- Original Message 
Da: Terry Reedy [EMAIL PROTECTED]
To: python-list@python.org python-list@python.org
Oggetto: Re: python-2.6
Data: 03/10/08 03:41

 
 
 
 [EMAIL PROTECTED] wrote:
  Hi all.
  
  I've installed on may MacOS X 10.4.11 (PPC) Python-2.5.2, numpy and
scipy.
  Now I'm interested to insall Python-2.6. My question is: What will
happen to
  may scientific modules if now I jump fro 2.5.2 to 2.6? I've to reinstall
  numpy and scipy?
 
 Keep your 2.5.2 install intact until you have everything you need and 
 want in a 2.6 install.
 
 --
 http://mail.python.org/mailman/listinfo/python-list
 
 
  
 --
 Email.it, the professional e-mail, gratis per te: http://www.email.it/f
 
 Sponsor:
 CheBanca! La prima banca che ti dà gli interessi in anticipo.
Fino al 4,70% sul Conto Deposito, zero spese e interessi subito. Aprilo!
 Clicca qui: http://adv.email.it/cgi-bin/foclick.cgi?mid=7919d=20081003


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Conditionally subclassing based on Import

2008-10-03 Thread David Pratt

Hi, just want to conditionally base a class on another if it can be  
imported,  otherwise base it on object. Does the following look ok   
for this?


try:
 import foo.bar
except ImportError:
MyBase = foo.bar.Baz
else:
MyBase = object

class Something(MyBase):

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RE module question

2008-10-03 Thread aditya shukla

Hello folks :

i have a string -bin-ulockmgr_server:0.99[NHX:C=0.195.0] from which i
want to delete [NHX:C=0.195.0] .
I wrote a regular expression for [NHX:C=0.195.0] as
\[(\w)+:\w=((-)?(\d|\d\d|\d\d\d)\.)+\d\]

now when i do

p = re.compile('\[(\w)+:\w=((-)?(\d|\d\d|\d\d\d)\.)+\d\]')
m =p.search(-bin-ulockmgr_server:0.99[NHX:C=0.195.0])
print m
_sre.SRE_Match object at 0x01314EE8
 print m.group()
[NHX:C=0.195.0]

So i guess i am able to find the substring , my question is how can i delete
this substring from the original string? ie
-bin-ulockmgr_server:0.99 should be my output.

thanks

Aditya
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Re: Comparing float and decimal


Mark Dickinson wrote:


Option (2) appeals to me, but I can't see how to
implement it.


It could be implemented for the special case of floats
and Decimals by keeping flags in each set indicating
whether any elements of those types have been added.

But doing this just for those two types would be
rather hackish, and wouldn't do anything for any
other incomparable types that might come along.

--
Greg
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Re: Conditionally subclassing based on Import

2008-10-03 Thread Gary Herron

David Pratt wrote:
 Hi, just want to conditionally base a class on another if it can be
 imported,  otherwise base it on object. Does the following look ok 
 for this?

 try:
  import foo.bar
 except ImportError:
 MyBase = foo.bar.Baz
 else:
 MyBase = object

 class Something(MyBase):

 -- 
 http://mail.python.org/mailman/listinfo/python-list

Ahhh...   I believe you've got that backwards.

try:
import foo.bar
MyBase = foo.bar.Baz
except ImportError:
MyBase = object

or
   
try:
import foo.bar
except ImportError:
MyBase = object
else:
MyBase = foo.bar.Baz


Gary Herron

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Re: Comparing float and decimal


Terry Reedy wrote:

Documenting the problem properly would mean changing the set 
documentation ... from their current 
math set based definitions to implementation based definitions


It could be documented that the mathematical definitions
hold only if the equality relations between all the elements
involved are transitive, and leave the semantics in other
cases undefined.

Then in the Decimal module it could be warned that the
equality relations between int-float and int-Decimal are
not transitive, perhaps noting that this can cause
problems with sets and dicts.

--
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Re: What is not objects in Python?


Gabriel Genellina wrote:

Had Python used the more generic size and __size__ from the beginning,  
we'd be all happy now :)


Not necessarily -- len is slightly shorter, and more
comfortable to type on a qwerty keyboard.

But in any case, size-likers have an easy solution:

  size = len

:-)

(BTW, try doing that with the x.len() notation!)

--
Greg


 But it's too late to change things.



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Re: What is not objects in Python?


Aaron Castironpi Brady wrote:


How do you have a yellow dog,


It's not a yellow dog, it's a dog yellow. Attention pay! :-)

--
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Re: del and sets proposal

2008-10-03 Thread George Sakkis

On Oct 2, 6:20 pm, Larry Bates [EMAIL PROTECTED] wrote:

 You can do the following:

 a = [1,2,3,4,5]
 del a[0]

 and

 a = {1:'1', 2: '2', 3: '3', 4:'4', 5:'5'}
 del a[1]

 why doesn't it work the same for sets (particularly since sets are based on a
 dictionary)?

 a = set([1,2,3,4,5])
 del a[1]

 Yes I know that sets have a remove method (like lists), but since dictionaries
 don't have a remove method, shouldn't sets behave like more like dictionaries
 and less like lists?  IMHO del for sets is quite intuitive.  I guess it is too
 late to change now.

Funny, I would welcome a change in the opposite direction: drop
completely the del a[i] syntax from the language and use an explicit
(non-special) method name, e.g. a.delete(i) or a.remove(i). Having
some functionality exposed through methods and some through function
builtins (e.g. len()) is more than enough; having a third way through
the del statement is unnecessarily perl-ish.

George
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Re: Ctypes behave differenty on windows 2000 and windows XP


En Thu, 02 Oct 2008 10:17:01 -0300, [EMAIL PROTECTED] escribió:


Im facing a strange problem with ctypes module on windows 2000. I did not
face this problem with the windows Xp.

The problem is  this code and specifically c_long which behave  
differently

on win2000 and winxp

from ctypes import *
h = windll.LoadLibrary(C:\\Windows\\System32\\myDll.dll)
print h
ver = getattr(h, myDll_GetVersion)
versionArr = c_long * 4
version = versionArr(0, 0, 0, 0)
print ver(version)
dllVersionStr = v%d.%d.%d.%d % tuple(version)
print dllVersionStr

The same code appears to work on windows xp with dllVersionStr printing  
as

v1.3.5.0
But on wIindows 2000 it prints v0.0.0.0


For myDll_GetVersion you should define its arguments and return type using  
.argtypes and .restype - else ctypes assumes int


--
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Re: Event-driven framework (other than Twisted)?

2008-10-03 Thread James Mills

On 10/2/08, Phillip B Oldham [EMAIL PROTECTED] wrote:
 On Oct 2, 1:32 am, James Mills [EMAIL PROTECTED] wrote:
   http://hg.shortcircuit.net.au/index.wsgi/pymills/file/b7498cd4c6a4/ex...

  Thanks for the example, but its not loading.

Sorry my VPS has been down for quite
some time today :/ Not happy!

Here is the sample:

code
#!/usr/bin/env python
# -*- coding: utf-8 -*-
# vim: set sw=3 sts=3 ts=3

import optparse

from pymills import event
from pymills.event import manager
from pymills.net.sockets import TCPServer
from pymills.event.core import listener, Component
from pymills.net.http import HTTP, Response, Dispatcher
from pymills import __version__ as systemVersion

USAGE = %prog [options] [path]
VERSION = %prog v + systemVersion

###
### Functions
###

def parse_options():
   parse_options() - opts, args

   Parse any command-line options given returning both
   the parsed options and arguments.
   

   parser = optparse.OptionParser(usage=USAGE, version=VERSION)

   parser.add_option(-b, --bind,
 action=store, default=0.0.0.0:8000, dest=bind,
 help=Bind to address:port)

   opts, args = parser.parse_args()

   return opts, args

###
### Components
###

class Test(Component):

   channel = /

   @listener(index)
   def onINDEX(self, request, response):
  self.send(Response(response), response)

   @listener(hello)
   def onHello(self, request, response):

  if request.cookie.get(seen, False):
 response.body = Seen you before!
  else:
 response.body = Hello World!
 response.cookie[seen] = True

  self.send(Response(response), response)

   @listener(test)
   def onTEST(self, request, response):
  response.body = OK
  self.send(Response(response), response)

class WebServer(TCPServer, HTTP): pass

###
### Main
###

def main():
   opts, args = parse_options()

   if : in opts.bind:
  address, port = opts.bind.split(:)
  port = int(port)
   else:
  address, port = opts.bind, 80

   server = WebServer(port, address)
   dispatcher = Dispatcher()

   event.manager += server
   event.manager += Test()
   event.manager += dispatcher

   while True:
  try:
 manager.flush()
 server.poll()
  except KeyboardInterrupt:
 break

###
### Entry Point
###

if __name__ == __main__:
   main()
/code

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Re: One class per file?


Bruno Desthuilliers wrote:

OTHO, 'one class per file' is a standard idiom in Java and IIRC in C++ 
(which both have namespaces one way or another)


In Java you don't get a choice, because the compiler
assumes a class can be found in the correspondingly
named file.

While C++ has namespaces, they don't have any defined
relationship to source files, so they don't help you
find which file something is defined in.

--
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Re: 2.6 multiprocessing and pdb

En Thu, 02 Oct 2008 18:14:07 -0300, Aaron Castironpi Brady  
[EMAIL PROTECTED] escribió:



I'm trying to step through a subprocess I launch with
multiprocessing.  Does anyone know what hack to add?  The actual call
comes in forking.Popen.__init__, Windows version, forking.py, line
222:

hp, ht, pid, tid = _subprocess.CreateProcess(
_python_exe, cmd, None, None, 1, 0, None, None, None
)


to step through a subprocess means that you are using a debugger (pdb?)  
to execute the parent process, and want to debug the child process too?
You'll have to modify the command line (the cmd argument), so the child is  
run thru the debugger too. I don't think pdb has any remote capabilities.


--
Gabriel Genellina

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Re: code critique requested - just 60 lines

2008-10-03 Thread Terrence Brannon

On Oct 2, 11:56 am, [EMAIL PROTECTED] wrote:
 Terrence Brannon, I suggest you to shorten a lot some of those very
 long lines.

yes, I wanted to, but was not sure how to continue a line on the next
line in Python.


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Re: Odd Errors


Steven D'Aprano wrote:

Side-effect has the technical meaning in functional languages of any 
change of state that isn't the creation and return of a function result.


Actually, the term has that meaning for all programming
languages. The main distinguishing feature of functional
languages is that there are *no* side effects.

The confusing thing is that in everyday English the term
implies something bad or unwanted (e.g. side effects of
a drug). That's not necessarily true of the technical
meaning -- often the side effect is exactly what we want,
as in the case of append.

--
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Re: Professional quality scripts/code


robean a écrit :

I have been learning Python for the last 3 months or so and I have a
working (but somewhat patchy) sense of the the language. I've been
using a couple of the more popular Python books as well as online
resources.

A question for experienced Python programmers: can you recommend
resources where I can look at high quality Python code and scripts?


Well... Not everything is 'high quality' in it[1], but why not start 
with the stdlib ? Most of it is pure Python, opensource code and is 
already installed on your machine, isn't it ?-)


[1] IIRC, last time I had a look at the zipfile module's code, it was 
more of a QD hack than anything else - now as long as it works fine for 
what I do with it and I don't have to maintain it, well, that's fine.



I've spent some time at http://code.activestate.com/recipes/ but am
concerned that the quality of what is posted there can be somewhat hit
and miss.


Indeed.


 What I have in mind is a site like cpan, where one can look
at the actual source code of many of the modules and learn a thing or
two about idiomatic Perl programming from studying the better ones.
Any sites like that for Python?


Lurking here is probably a good way to see a lot of code reviews. And 
even possibly to submit snippets of your own code to review. Some (if 
not most) of us here like to show how good we are at improving the poor 
newbies code !-)

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Re: tkinter textwidget problem

2008-10-03 Thread Eric Brunel


On Thu, 02 Oct 2008 21:57:01 +0200, kib2 [EMAIL PROTECTED] wrote:

Hi,

In a tkinter TextWidget I would like to retrieve the last typed word.

I've tried this with the 'wordstart' Expression [From the effbot site,  
wordstart and wordend moves the index to the beginning (end) of the  
current word. Words are sequences of letters, digits, and underline, or  
single non-space characters.], but it fails :


#!/usr/bin/env python
# -*- coding: utf-8 -*-

from Tkinter import *
root = Tk()
text = Text(root, font=(Calibri))
text.pack()

# Insert some text inside (13 chars long)
text.insert(INSERT, one two three)

# idx_st : the position of the cursor
# idx_ed : same but translated to the beginning of the last word ?
idx_st = text.index( insert ) # returns 1.13
idx_ed = text.index( insert wordstart ) # returns 1.13 too : why ?


Tk/Tkinter apparently considers the position 1.13 to be after the last  
word in the text. You get the same problem if you set the insertion point  
just after the word 'two' for example: text.index('insert') returns 1.7  
and text.index('insert wordstart') returns 1.7 too...


My solution would simply be to go back one character before asking the  
word start: text.index('insert - 1 chars wordstart') Don't know if that'll  
do what you want if there are spaces at the end of the text. And BTW, if  
you actually want the *last* word in the text, you may want to use  
text.index('end - 2 chars wordstart'). Here, you have to use '- 2 chars'  
because end points to the first non-existent index (2.0 in your case...).


HTH
--
python -c print ''.join([chr(154 - ord(c)) for c in  
'U(17zX(%,5.zmz5(17l8(%,5.Z*(93-965$l7+-'])

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Re: del and sets proposal

On Thu, 02 Oct 2008 22:27:04 -0500, Larry Bates wrote:

 Maybe dictionaries should have had a .remove method then things would be
 more consistent?

But why should sets be consistent with dictionaries? There are a few 
similarities, but also differences.

Personally, I'd rather see dictionaries grow methods like 
symmetric_difference, union, etc. than worry about whether you use del or 
remove to remove elements from a set.


-- 
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Re: code critique requested - just 60 lines

En Fri, 03 Oct 2008 05:07:41 -0300, Terrence Brannon [EMAIL PROTECTED]  
escribió:



On Oct 2, 11:56 am, [EMAIL PROTECTED] wrote:

Terrence Brannon, I suggest you to shorten a lot some of those very
long lines.


yes, I wanted to, but was not sure how to continue a line on the next
line in Python.


Having ANY open () or [] or {} is enough to implicitely continue a line  
(being it a function call, a list definition, a generator expression,  
whatever...)


tags = { 'S':  'Small',
 'M':  'Medium',
 'L':  'Large',
 'XL': 'Extra large',
   }

Also, you may use \ as the LAST character (immediately preceding the  
newline) to continue the logical line on the next physical line:


result = coef[0] * sum_deliverd + \
 coef[1] * max_income + \
 coef[2] * min_delay

--
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Re: closures and dynamic binding


jhermann wrote:


I didn't see this mentioned in the thread yet: the double-lambda is
unnecessary (and a hack).


Well, the alternative -- abusing default argument values --
is seen by many to be a hack as well, possibly a worse one.
It doesn't work in general, e.g. it fails if the function
needs to be called with a variable number of arguments.

The double lambda is conceptually more sound in some
ways, and can be made to work correctly in all cases.

The root of the problem actually has nothing to do with
lambdas or static vs. non-static scoping. It's the fact
that Python's for-loop doesn't create a new environment
for the loop variable each time around, but re-uses a
slot in the containing environment.

Contrast this with Scheme, where the equivalent of a
for-loop *does* create a new environment for each
value of the loop variable. Effectively it's using a
double lambda, except that one of the lambdas is
folded into the syntax of the loop, so you don't
notice it.

So if anything were to be done to the language to
fix this, it really should be focused on fixing the
semantics of the for-loop. Unfortunately, the
fact that the loop variable leaks out of the scope
of the loop is regarded as a feature, so anything
which changes that seems to be a non-starter.

--
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Re: javascript to python

2008-10-03 Thread lkcl

On Oct 2, 7:42 pm, Bruno Desthuilliers
[EMAIL PROTECTED] wrote:
 lkcl a écrit :



  On Oct 2, 5:54 pm, Joe Hrbek [EMAIL PROTECTED] wrote:
  Could someone help me translate to something that would close to it in
  python?  The anonymous functions are giving me problems.

  class dataListener:
  def __init__(self):
  data = 
  def onStartRequest(self, request, context):
  pass
  def onStopRequest(self, request, context, status):

  # TODO: pass these three in to dataListener as
  # params to the constructor, so it's
  # def __init__(self, instream, outstream, listener)
  # and do self.instream = instream

  global instream
  global outstream
  global listener

 Since you don't rebind them, you don't need the global statement for
 these three identifiers

  instream.close()
  outstream.close()
  listener.finished(self.data)

  def onDataAvailable(self, request, context, inputStream,
  offset, count):

  global instream

 idem

  self.data += instream.read(count)

 And then you have a class. Calling instance methods on the class won't
 work. Looks like there's something missing...

  question.

  why are request and context being ignored?
  why is there an inputStream argument to onDataAvailable, yet
  there's a global variable (in the javascript) called
  instream?  is it the same?

  all this, and more, thanks to the awfulness that is javascript :)

 None of this, and more is because of javascript. You'll find bad code
 in every language (and without more context, you can't tell if it's bad
 code - might as well be the right thing to do).

 FWIW, javascript is a very interesting and powerful language.

  for fits and giggles, compile the above python using
  pyjs.py, the python-to-javascript compiler
  (seehttp://pyjamas.sf.net) and compare the
  resultant javascript to your original code-fragment.

  l.

 I did. Here's the result:

 ok - these are the important bits.  notice that the pyjamas
compiler is doing a little bit more than your original code: it's
overriding the prototype of dataListener, making it a true class
object.

this is where there's a key departure from the original code and the
translation to python: the original code isn't actually a class, at
all - it's more like a c struct that has function pointers in it.

by declaring a python class, the javascript equivalent is to add to
prototypes.


  __dataListener.prototype.__init__ = function() {
  var data = '';
  };

[ ... so for example here, now when you declare _any number_ of
dataListeners, each and every one will have its __init__ function
called.  in your original example, you're effectively making one and
only one dataListener.  you're kinda... it's a bit like having a
lambda-class (nameless class) and declaring one and only one instance
of that python class... ]


  __dataListener.prototype.onStopRequest = function(request, context,
 status) {
  instream.close();
  outstream.close();
  listener.finished(this.data);
  };

  __dataListener.prototype.onDataAvailable = function(request,
 context, inputStream, offset, count) {
  this.data += instream.read(count);
  };

so - yeah, you can see that (apart from the .prototype, which is
necessary to make a class a la javascript) it's a pretty accurate
translation back to the original javascript.


 All this, and more, thanks to the strange idea that it would be better
 to write javascript in Python instead of writing it in javascript !-)

  *lol* :)   fortunately, pyjs.py does that translation for you ha
ha.  like they say on brainiac, STOP!  we do these experiments, so
you don't have to.

  yes - it's because in the translated python, dataListener was
declared as a class, whereas in the original javascript, the
corresponding concept (prototypes) are not made use of.

if you wanted to experiment, you could try this:

def onStartRequest(this, request, context):
pass

def onStopRequest(this, request, context, status):
instream.close()
oustream.close()
listener.finished(this.data)

def onDataAvailable(this, request, context,
  inputStream, offset, count):
this.data += instream.read(count)

class dataListener:
def __init__(self):
self.data = ''
self.onStartRequest = onStartRequest
self.onStopRequest = onStopRequest
self.onDataAvailable = onDataAvailable

which you will find to be more accurately representative of the
original javascript, conceptually.  i.e taking into account that in
the _original_ javascript, you don't have any prototypes.

but - i don't believe it to be what you actually want, even though
it's a slightly more accurate representation.

l.
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Re: RE module question

En Fri, 03 Oct 2008 03:59:18 -0300, aditya shukla  
[EMAIL PROTECTED] escribió:



Hello folks :

i have a string -bin-ulockmgr_server:0.99[NHX:C=0.195.0] from which i
want to delete [NHX:C=0.195.0] .
I wrote a regular expression for [NHX:C=0.195.0] as
\[(\w)+:\w=((-)?(\d|\d\d|\d\d\d)\.)+\d\]

now when i do

p = re.compile('\[(\w)+:\w=((-)?(\d|\d\d|\d\d\d)\.)+\d\]')
m =p.search(-bin-ulockmgr_server:0.99[NHX:C=0.195.0])
print m
_sre.SRE_Match object at 0x01314EE8

print m.group()

[NHX:C=0.195.0]

So i guess i am able to find the substring , my question is how can i  
delete

this substring from the original string? ie
-bin-ulockmgr_server:0.99 should be my output.


Instead of p.search, use p.sub
Or, if you need the match for other purposes, delete the characters from  
m.start() to m.end()


See http://docs.python.org/library/re.html#regular-expression-objects

--
Gabriel Genellina

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Re: What is not objects in Python?

2008-10-03 Thread Marc 'BlackJack' Rintsch

On Fri, 03 Oct 2008 19:10:27 +1200, greg wrote:

 But in any case, size-likers have an easy solution:
 
size = len
 
 :-)
 
 (BTW, try doing that with the x.len() notation!)

def size(obj):
return obj.len()

or

size = operator.methodcaller('len')

in Python 2.6 and up.

:-)

Ciao,
Marc 'BlackJack' Rintsch
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Re: del and sets proposal

2008-10-03 Thread Carl Banks

On Oct 2, 8:02 pm, Marc 'BlackJack' Rintsch [EMAIL PROTECTED] wrote:
 On Thu, 02 Oct 2008 15:39:55 -0700, Chris Rebert wrote:
  On Thu, Oct 2, 2008 at 3:20 PM, Larry Bates [EMAIL PROTECTED]
  wrote:
  a = set([1,2,3,4,5])
  del a[1]

  Sets don't support subscripting, so if you can't go 'a_set[something]',
  why would you expect to be able to be able to 'del' such an expression?
  What would the subscription even mean without the 'del'? It doesn't make
  sense and would just be inconsistent.

 Then add subscription access too.  By aliasing `__getitem__()` to
 `__contains__()`.  And `__setitem__()` could be implemented to add or
 remove objects by assigning truth values.  So hypothetically:

  a = set([1, 2, 3])
  a[1]
 True
  a[4]
 False
  a[2] = False
  a
 set([1, 3])
  a[4] = True
  a
 set([1, 3, 4])
  del a[1]
  a

 set([3, 4])

 I wouldn't want that addition to `set`\s but at least it can be
 implemented without introducing inconsistencies.


If set behaved that way then del a[1] wouldn't behave like del
anymore.  Normally, del whatever means that you can no longer use
whatever; in this proposal you can.


Carl Banks
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Re: Python arrays and sting formatting options

I'm not sure if our views are moving closer together or further apart, 
but here goes... 


On Thu, 02 Oct 2008 23:49:16 +, Marc 'BlackJack' Rintsch wrote:

 On Thu, 02 Oct 2008 14:51:29 +, Steven D'Aprano wrote:
 
 On Wed, 01 Oct 2008 10:38:12 +, Marc 'BlackJack' Rintsch wrote:
 
 Even if newbies don't understand all the details they should be
 introduced to ``with`` right away IMHO.  Because if you explain all
 the details, even if they understand them, they likely will ignore the
 knowledge because doing it right is a lot of boiler plate code.  So
 usually people write less robust code and ``with`` is a simple way to
 solve that problem.
 
 So what you're saying is that we should encourage cargo-cult coding.
 Write this boilerplate, because I tell you that if you do, good things
 will happen.
 
 It's not cargo cult programming if you tell people to use the ``with``
 statement to make sure the file will be closed after the block is left,
 for whatever reason the block was left.

You are right. If you explain what with blocks do, it isn't cargo cult 
programming. 



 Why on earth has everything to be guessable for someone who doesn't
 know Python or even programming at all?
 
 Oh please. Don't take my words out of context. I'm not talking about
 everything, and I'm not suggesting that advanced programming features
 should be prohibited and we should write to the level my grandmother
 would understand.
 
 The context was that a Fortran programmer asked for some help in
 writing a piece of code in Python. Your answer was entirely opaque and
 undecipherable to the OP. If your intention in answering was to teach
 the OP how to write Python code, you failed, because the OP couldn't
 understand your code! You can argue with me until Doomsday and it won't
 change that basic fact.
 
 My intention wasn't to teach the OP how to write Python but to give a
 concise, easy and straight forward solution in Python.  Yes, I really
 believe I have written such thing.  I'm well aware that a Fortran
 programmer will not understand this without learning Python.

I'm curious what the point of answering the OP's question was if you knew 
he wouldn't understand the answer. You might have saved us both a lot of 
time if you started your post with You aren't expected to understand 
this.



 Your answer may have solved the OP's *technical* problem, but it didn't
 do anything to solve the OP's *actual* problem, which was that he
 didn't know enough basic Python techniques to solve a simple problem.
 And that's the issue I was commenting on.
 
 If he doesn't know enough basic Python techniques to solve *a simple
 problem* I think this is the wrong forum and he should work through the
 tutorial from the documentation to learn the basics first.  The tutorial
 includes `map()`, list comprehensions, methods in strings, the fact that
 files are iterable, and generator expressions.

Then you should have said so.



 [more snippage]
  Nevertheless, for people coming from less dynamic languages than
  Python (such as Fortran), it is a common idiom to never use the same
  variable for two different things.  It's not a bad choice really:
  imagine reading a function where the name lines started off as an
  integer number of lines, then became a template string, then was
  used for a list of character positions...
 
 Which I'm not doing at all.  It has the same duck type all the time:
 iterable of lines.
 
 It has nothing to do with duck typing and everything to do with re-use
 of variables (or in Python, names) for different things. Just because
 lines has the same duck-type doesn't mean they are conceptually the
 same things.
 
 Of course it means they are the same things, that is what duck typing
 is about.

No, you still don't understand me. Let me give you a more extreme example 
to help clarify:

average_age = 64.7
width_of_page = 20.2
speed_of_car = 35.2
concentration_of_acid = 1.03
children_per_family = 2.3

All of the above have not just the same duck-type, but the same actual 
type (floats), and yet they are COMPLETELY different things. Imagine a 
piece of code like this:

def foo():
x = 64.7  # x is the average age of a person
... more lines of code here
x = 2.3  # x is now the average number of children per family
...
return something


Would you defend the above code on the basis that x had the same duck-
type in both places? I hope not.

A decade or so ago, one of the Mars spaceships crashed because a coder 
used a variable that was a float in inches when they were supposed to use 
a variable that was a float in millimetres (or vice versa, I forget). 
Because of this mistake, the retro-rockets fired too late, and the 
spaceship flew into the surface of Mars at some thousands of miles an 
hour. And yet both variables were not just the same duck-type, but the 
same actual type. You cannot conclude that two things are the same kind 
of thing just because they have the same type.

The difference

Re: closures and dynamic binding

2008-10-03 Thread Michele Simionato

On Oct 3, 10:44 am, greg [EMAIL PROTECTED] wrote:
 So if anything were to be done to the language to
 fix this, it really should be focused on fixing the
 semantics of the for-loop. Unfortunately, the
 fact that the loop variable leaks out of the scope
 of the loop is regarded as a feature, so anything
 which changes that seems to be a non-starter.

And Guido stated many times in the past that he is happy with the for
loop as it is,
so I don't think this will never change, even if the question keep
getting asked here
and there.
Notice that even generator expressions, where the loop variable does
not leak outside the loop,
have the same behavior.
The behavior of the list comprehension is a good test of how much
functional a language is;
Common Lisp and Python behaves in the same way (there is a single loop
variable which is
mutated at each iteration) wherea Scheme and Haskell introduce a new
binding at each iteration.
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Re: code critique requested - just 60 lines

2008-10-03 Thread Terrence Brannon

On Oct 2, 11:09 am, Steven D'Aprano [EMAIL PROTECTED]
cybersource.com.au wrote:
 On Thu, 02 Oct 2008 07:51:30 -0700, Terrence Brannon wrote:


  Basically, using non-strict dictionary keys can lead to bugs, so that
  worried me.

 What's a non-strict dictionary key?


In Perl, you can pre-define what keys are allowed in a dictionary.
That way, mis-spelling the dict key doesnt lead to accessing something
didnt mean to.

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Re: del and sets proposal

On Fri, 03 Oct 2008 02:18:53 -0700, Carl Banks wrote:

 On Oct 2, 11:27 pm, Larry Bates [EMAIL PROTECTED] wrote:
 I didn't mean to imply that del a[1] would delete the first thing in
 the set, but rather the item with a value of 1.  Just as when we use it
 on a dictionary:

 del a[1]

 doesn't mean delete the first dictionary entry but rather delete the
 entry in the object with a value of 1, which IMHO would be perfectly
 logical for a set (which is why I started this discussion).
 
 
 It's not logical at all.  In all current uses of del, the thing that
 follows del is a valid expression.  With sets, that's not the case.


I think Larry is suggesting that elements of sets should be removed in 
the same way that keys of dictionaries are removed:

d = {57: foo}
s = set([57])


He's suggesting that del s[57] should work just like del d[57] works.

The fact that sets don't have a __getitem__ method doesn't mean that they 
couldn't have a __delitem__ method:

class DelSet(set):
def __delitem__(self, element):
self.remove(element)


 s = DelSet([1, 2, 3, 4, 5])
 s
DelSet([1, 2, 3, 4, 5])
 del s[4]
 del s[5]
 s
DelSet([1, 2, 3])




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Re: What is not objects in Python?


Boris Borcic a écrit :

42, for instance.

Proof :

  42 is not object
True

QED



Lol.
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Re: Inheritance but only partly?


[EMAIL PROTECTED] wrote:


class Mask(object):
def m3(self): raise NotImplementedError
def m4(self): raise NotImplementedError



What's the name of this python design pattern? :-)


Don't know. Perhaps we could call it the FigLeaf pattern
(covering up what you don't want seen)?

There's another possibility that's even more pythonish
(I won't say pythonic, since it's not necessarily
a *recommended* thing to do):

class A:
  m1 = B.__dict__['m1']
  m2 = B.__dict__['m2']
  ...

I propose calling this the Magpie pattern (stealing
the shiny baubles you want and hiding them away in
your own nest).

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Re: closures and dynamic binding

2008-10-03 Thread Hrvoje Niksic

greg [EMAIL PROTECTED] writes:

 The root of the problem actually has nothing to do with lambdas or
 static vs. non-static scoping. It's the fact that Python's for-loop
 doesn't create a new environment for the loop variable each time
 around, but re-uses a slot in the containing environment.

 Contrast this with Scheme, where the equivalent of a for-loop *does*
 create a new environment for each value of the loop variable.

Note that Python's semantics of for regarding closures are not
unique to Python.  Common Lisp behaves similar to Python in this
regard:

* (loop for i from 0 to 2 collect (lambda () i))
(#CLOSURE... {A86F3CD} #CLOSURE... {A86F3E5} #CLOSURE... {A86F3FD})
* (mapcar #'funcall *)
(3 3 3)

Other looping constructs, such as do, behave in equivalent fashion.

 So if anything were to be done to the language to fix this, it
 really should be focused on fixing the semantics of the
 for-loop. Unfortunately, the fact that the loop variable leaks out
 of the scope of the loop is regarded as a feature, so anything which
 changes that seems to be a non-starter.

I don't think it has anything to do with variable leaking out of the
loop.  Common Lisp doesn't leak the loop variable, and it behaves the
same.  It is more a result of the different views of what iteration
is.  Common Lisp and Python define iteration in terms of repeating the
same instructions over and over, not different from what C does, in
which case it makes sense to reuse the same environment for all loop
passes.  (Python's language ref defines that a standard assignment
is done for each new iteration.)  In contrast, Scheme regards
iteration as a special case of recursion, and R5RS do prescribes
assigning loop variables to fresh locations to match what recursion
normally does.  In most cases both definitions exhibit the same
behavior, but unfortunately not when closures are created inside the
loop.
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Re: Inheritance but only partly?

2008-10-03 Thread Peter Otten

greg wrote:

 class Mask(object):
 def m3(self): raise NotImplementedError
 def m4(self): raise NotImplementedError
 
 What's the name of this python design pattern? :-)
 
 Don't know. Perhaps we could call it the FigLeaf pattern
 (covering up what you don't want seen)?

Braghettone ;)
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Re: Python arrays and sting formatting options

2008-10-03 Thread Marc 'BlackJack' Rintsch

On Thu, 02 Oct 2008 18:15:59 -0700, bearophileHUGS wrote:

 What's a range(n)? A function that returns a list of n items, from 0 to
 n. This is easy to understand, while xrange(n) is a bit less easy to
 understand (a generator or generators).

nitpick

`xrange()` doesn't return a generator or iterator but an object that 
implements the sequence protocol:

In [159]: a = xrange(0, 10, 2)

In [160]: len(a)
Out[160]: 5

In [161]: a[0]
Out[161]: 0

In [162]: a[2]
Out[162]: 4

/nitpick

Ciao,
Marc 'BlackJack' Rintsch
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Re: Python style: exceptions vs. sys.exit()

On Fri, 03 Oct 2008 17:09:07 +1200, greg wrote:

 Lawrence D'Oliveiro wrote:
 In message [EMAIL PROTECTED], Steven
 D'Aprano wrote:
 
  (2) Even when the source is available, it is sometimes a legal trap
  to read it with respect to patents and copyright.
 
 That's not how patents work.
 
 I don't think that's how copyrights work either. As far as I know,
 whether something is deemed a derivative work is judged on the basis of
 how similar it is to another work, not whether its author had knowledge
 of the other work. As long as you express an idea in an original way, it
 shouldn't matter where you got the idea from.

That is absolutely not the case with patents. It is *supposed* to be the 
case with copyrights, but in practice the courts are interpreting 
derivative work more and more broadly these days.

As for Microsoft Shared Source licences, there are two which are approved 
by the FSF, but the others are a whole different story.

You will note that both the GNU project and the Mono project warn against 
reading proprietary source code before contributing. Mono even goes so 
far as to say that if you have read the source code to .NET, they cannot 
accept your contributions:

If you have looked at Microsoft's implementation of .NET or
their shared source code, you will not be able to contribute 
to Mono. 
In general, be careful when you are implementing free software 
and you have access to proprietary code. We need to make sure 
that we are not using someone else's copyrighted code 
accidentally.

http://www.mono-project.com/Contributing



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Re: del and sets proposal

2008-10-03 Thread Carl Banks

On Oct 2, 11:27 pm, Larry Bates [EMAIL PROTECTED] wrote:
 I didn't mean to imply that del a[1] would delete the first thing in the set,
 but rather the item with a value of 1.  Just as when we use it on a 
 dictionary:

 del a[1]

 doesn't mean delete the first dictionary entry but rather delete the entry in
 the object with a value of 1, which IMHO would be perfectly logical for a set
 (which is why I started this discussion).


It's not logical at all.  In all current uses of del, the thing that
follows del is a valid expression.  With sets, that's not the case.


Carl Banks
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Re: What is not objects in Python?

2008-10-03 Thread Tim Rowe

2008/9/30 Lie Ryan [EMAIL PROTECTED]:

 Actually str.len and len(str) is just like saying the string's length
 and the length of the string. There is no difference between the two
 except for personal preference. (I am no linguist-- not even a native
 speaker of English --but I think there is a subtle difference on
 emphasis, the string's length emphasizes on the length being string's
 property, while the length of the string emphasizes on the length
 itself, am I correct?)

Well, I'm doing a linguistics degree, so I'm not a linguist /yet/, but
I think I know this one. There is the difference in emphasis that you
mention, but there may be something more significant. In both forms,
length is what linguists call the head of the noun phrase: it's
the actual thing being talked about.  In The string's length the
head is only pre-modified (the string's comes before the head and
there's nothing after the head). The length of the string has both
pre- and post- modification (The before, of the string after).
Post modification in noun phrases has been measured to be much less
frequent in spoken English than in written English, and it gets
progressively more common as the writing style gets more formal.  That
suggests that the string's length is an easier phrase to produce and
understand, but the length of the string sounds more official.

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Re: javascript to python


lkcl a écrit :

On Oct 2, 7:42 pm, Bruno Desthuilliers
[EMAIL PROTECTED] wrote:

lkcl a écrit :

(snip)


for fits and giggles, compile the above python using
pyjs.py, the python-to-javascript compiler
(seehttp://pyjamas.sf.net) and compare the
resultant javascript to your original code-fragment.
l.

I did. Here's the result:


 ok - these are the important bits.  notice that the pyjamas
compiler is doing a little bit more than your original code:


Not 'mine' - I'm not the OP. And as far as I'm concerned, the point is 
exactly here : it's doing a little bit more than the original code. 
This little bit requires 6 times the original code (cf below), and is 
actually useless for the OP's use case (else the OP's code wouldn't use 
litteral object notation but a full-blown prototype).



it's
overriding the prototype of dataListener, making it a true class
object.


There's nothing like a notion of class in javascript - as you of 
course already know.



this is where there's a key departure from the original code and the
translation to python: the original code isn't actually a class,  at
all


Indeed. Why would it need to be ?


- it's more like a c struct that has function pointers in it.


It's an object. What's wrong with objects ?


by declaring a python class, the javascript equivalent is to add to
prototypes.


Indeed. But the point is that Python - while close to a prototype-based 
language in many aspects - is still class-based. The closer Python 
translation of the OP's javascript snippet is probably the one I gave 
using a 'class singleton' - that is, using the class itself as an 
object. But retranslating this to javascript using a 
python-source-to-javascript-source tool like pyjamas won't give you back 
the original javascript snippet (which is by no mean a criticism of 
pyjamas - it would just be way too complicated to automatize such a 
translation).





 __dataListener.prototype.__init__ = function() {
 var data = '';
 };


[ ... so for example here, now when you declare _any number_ of
dataListeners,


What for ? In the original snippet, there's clearly only a need for a 
single one - and that's a *very* common pattern in browser-side 
javascript scripting. The original snippet is 12 lines, 29 words, 369 
bytes long (according to wc). The pyjamas translation of the Python 
translation of the original javascript snippet  is 49 lines, 126 words, 
2285 bytes long. That's 6 times more code (to download and parse) - for 
an unneeded feature. Often, less is better.



each and every one will have its __init__ function
called.  in your original example,


my ? I repeat : I'm *not* the OP.


you're effectively making one and
only one dataListener.


s/you/the OP/

And yes, indeed, there's only one dataListener object. What makes you 
think there's a need for more than one ?



 you're kinda... it's a bit like having a
lambda-class (nameless class) and declaring one and only one instance
of that python class... ]


It's like having an object. period. While most OOPLs are class-based, 
classes are by no mean a requirement of OO.



so - yeah, you can see that (apart from the .prototype, which is
necessary to make a class a la javascript) it's a pretty accurate
translation back to the original javascript.


I don't mean it's not working. I mean that it's a lot of unnecessary 
code for an unnecessary feature. Believe me, 6 times more code makes a 
*huge* difference when it comes to browser-side scripting and 
user-experience.


Also and IMHO, it's trying to forcefit alien idioms in javascript. Being 
prototype-based is by design - it's not a shortcoming.





All this, and more, thanks to the strange idea that it would be better
to write javascript in Python instead of writing it in javascript !-)


  *lol* :)   fortunately, pyjs.py does that translation for you ha
ha.  like they say on brainiac, STOP!  we do these experiments, so
you don't have to.


fortunately is judgement call. As far as I'm concerned, and despite a 
couple warts (but hey, no language is wart-free, and Python has it's own 
share, isn't it ?), I like javascript as a language, and enjoy coding in 
javascript almost as much as I enjoy coding in Python.



  yes - it's because in the translated python, dataListener was
declared as a class, whereas in the original javascript, the
corresponding concept (prototypes) are not made use of.


There's probably a reason why the OP didn't use a full blown prototype, 
isn't it ?-)



if you wanted to experiment, you could try this:

def onStartRequest(this, request, context):
pass

def onStopRequest(this, request, context, status):
instream.close()
oustream.close()
listener.finished(this.data)

def onDataAvailable(this, request, context,
  inputStream, offset, count):
this.data += instream.read(count)

class dataListener:
def __init__(self):
self.data = ''
self.onStartRequest = onStartRequest
self.onStopRequest

Re: Python arrays and sting formatting options

Marc 'BlackJack' Rintsch:
 bearophile
 while xrange(n) is a bit less easy to
  understand (a generator or generators).

I meant a generator of generators, a typo, sorry. -.-

Bye,
bearophile
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Re: Fun with reverse sorts

Chris Rebert:
 So the improved code is:
 your_list.sort(key=lambda elem: (elem[3], elem[2]), reverse=True)

Better (untested):
from operator import itemgetter
...
your_list.sort(key=itemgetter(3, 2), reverse=True)

Bye,
bearophile
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Re: Inheritance but only partly?

2008-10-03 Thread Michele Simionato

On Oct 2, 10:16 pm, process [EMAIL PROTECTED] wrote:
 Let's say I have a class X which has 10 methods.

 I want class Y to inherit 5 of them.

 Can I do that? Can I do something along the lines of super(Y, exclude
 method 3 4 7 9 10) ?

Don't use inheritance, use delegation or just copy the methods you
need:

class A(object):
  def meth_a(self):
 pass

class B(object):
   meth_a = A.meth_a.im_func


IMO, if you have methods that you want to use in different classes,
this is hint that
you are in need of generic functions. See this blog post for an
example:

http://www.artima.com/weblogs/viewpost.jsp?thread=237764
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Re: del and sets proposal

Steven D'Aprano:
 Personally, I'd rather see dictionaries grow methods like
 symmetric_difference, union, etc. than worry about whether you use del or
 remove to remove elements from a set.

I have functions for all those operations, so I think they can be
useful, but in practice I don't use them often. I think it's a matter
of keeping data structures separated in the mind.

Another problem is that with those operations you have to find a way
to manage values too, are they part of the uniqueness, etc? So there
can be different semantics of a single operation, and this may lead to
people that have a wrong image model of the purpose of some of those
methods.

Bye,
bearophile
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Re: javascript to python

2008-10-03 Thread lkcl

On Oct 3, 10:29 am, Bruno Desthuilliers bruno.
[EMAIL PROTECTED] wrote:
 lkcl a écrit : On Oct 2, 7:42 pm, Bruno Desthuilliers
  [EMAIL PROTECTED] wrote:
  lkcl a écrit :
 Not 'mine' - I'm not the OP.

 whoops, yes - i missed that.  sorry!

 And as far as I'm concerned, the point is
 exactly here : it's doing a little bit more than the original code.

 yeah, i know.  and that bit more gets you a proper representation
of the python class concept.

 i was merely pointing out that if you want to _really_ translate the
original code into python - _really_ strictly - it's not actually
possible.  because python doesn't have the concept of non-prototyping
(but... see below: i believe i may stand corrected on that)


 [..snip..] and is
 actually useless for the OP's use case (else the OP's code wouldn't use
 litteral object notation but a full-blown prototype).

 i know :)

  it's
  overriding the prototype of dataListener, making it a true class
  object.

 There's nothing like a notion of class in javascript - as you of
 course already know.

 okay,okay :)  class-like :)


 Indeed. But the point is that Python - while close to a prototype-based
 language in many aspects - is still class-based. The closer Python
 translation of the OP's javascript snippet is probably the one I gave
 using a 'class singleton' - that is, using the class itself as an
 object.

 oh is _that_ how you do it.  thanks.  i always wondered how you did
class singletons in python.

 python-source-to-javascript-source tool like pyjamas won't give you back
 the original javascript snippet (which is by no mean a criticism of
 pyjamas - it would just be way too complicated to automatize such a
 translation).

 well... you _say_ that... but... actually, if that's the real way to
represent class singletons, and it's an accurate representation of the
OP's javascript, and a good example, then _yes_, pyjs should
definitely have that added as a feature - to understand that a class
singleton _can_ get mapped to the much more efficient javascript
example you gave.

not that many people would _want_ to do that, so it goes onto the
diminishing returns TODO list, but...

 Nope. You defined functions outside the object's scope, and you still
 have to instanciate dataListener. Also, this above code just won't work
 - unless you explicitely pass the dataListener instance to the
 functions, ie:

 d = dataListener()
 d.onDataAvailable(d, ...)

 yeah - i didn't realise what the python class singleton thing was.
 It seem you didn't read my other translation proprosal, so I repost it here:

 class dataListener(object):
 data = ''

 i did - i just didn't understand its significance.

 so - to get this straight: when you do class clsname(object), and you
have the indentation and declaration of variables (e.g. data, above)
at the same level as the functions, it means that there's only one of
them? (i.e. a singleton)?

so, if i do this:

d = dataListener()
e = dataListener()

d.data = fred

print f.data

will return fred?

l.
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Re: Inheritance but only partly?

2008-10-03 Thread Tim Rowe

2008/10/2 process [EMAIL PROTECTED]:
 Let's say I have a class X which has 10 methods.

 I want class Y to inherit 5 of them.

 Can I do that?

As others have said, no. What nobody seems to have said yet is why. If
Y descends from X, you are saying that Y is an X; that a Y can be used
anywhere an X can. If Y doesn't support some methods of X then it is
*not* an X, and *can't* be used anywhere an X can.

Rather than looking at workarounds, as others have, I think you need
to go back to your design and work out what's gone wrong that you
/want/ to descend Y from X. Your present design is wrong, plain and
simple. Working around it won't fix that.

-- 
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lxml and schema validation

2008-10-03 Thread hrishy

Hi

I am validating a xmlfile against a xsd (My.xsd) but i notice that the xsd has 
a include which includes another xsd (My1.xsd)

I have written a simple program that to validate this

from lxml import etree
xmlschemadoc=etree.parse(My.xsd)
xmlschema=etree.XMLSchema(xmlschemadoc)
xmldoc=etree.parse(My.XML)
xmlschema.assertValid(xmldoc)

will my program validate against My.xsd and My1.xsd both ?

I also would like my program to continue validation against the xsd and not 
stope at the first failure .
my question would be how do i do that in python ?

regards
Hrishy


  
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Re: windows help files ?

2008-10-03 Thread Stef Mientki


Martin v. Löwis wrote:

1. how can I launch the windows help file (CHM), from python  with a
keyword as argument ?



Run hh.exe. If you want it to navigate to specific page, also pass that
page on the command line (finding out the exact syntax is left as an
exercise)

  

That's one way,
in the meanwhile I found win32help.py,
which I finally got to work.
The whole hh.exe (seems also to be a wellknown virus) and win32help 
documentation is very hard to find.

2. now when my program should also run under Linux/Mac,  how should I
call the help file  under Linux/Mac.



Provide an HTML tree of the documentation, and use the webbrowser module
to start a browser on it.
  

Yes, but for context sensitive help that's a little bit primitive.
I'm now working on the idea of offering 3 levels of context sensitive 
help (through F1, shift-F1, ctrl-F1):

- standard doc ( chm-keyword  / html-tag )
- search on google
- help from a user defined location ( chm / html / search engine / txt / 
pdf )


thanks again,
cheers,
Stef

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SQLite

2008-10-03 Thread Matthias Huening


Hi,

This is probably trivial, but I cannot find a solution right now.
With MySQLdb, I could test the success of a deleting action like this:

sql = DELETE FROM table WHERE name='xxx'
res = cur.execute(sql)
if res == 1:
 print 'Okay'
else:
 print 'nothing deleted'


This seems not to work with sqlite3. How can I test whether deletion was 
sussessful or not?


Thanks,
Matthias
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[BaseHTTPServer/SimpleHTTPServer] Remove Server: header

2008-10-03 Thread [EMAIL PROTECTED]

Hello.


I'm using SimpleHTTPServer (work well) but it always sends Server
header in response:
Server: SimpleHTTP/0.6 Python/2.5.1

How can I remove that ?

I tried:
self.server_version = 
self.sys_version  = 

but the header is still sent, empty.

I there a way to remove the Server: header completely ?



Thanks.
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Re: Inheritance but only partly?

2008-10-03 Thread Simon Brunning

2008/10/3 Tim Rowe [EMAIL PROTECTED]:

 As others have said, no. What nobody seems to have said yet is why. If
 Y descends from X, you are saying that Y is an X; that a Y can be used
 anywhere an X can. If Y doesn't support some methods of X then it is
 *not* an X, and *can't* be used anywhere an X can.

See http://en.wikipedia.org/wiki/Liskov_substitution_principle.

-- 
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Simon B.
[EMAIL PROTECTED]
http://www.brunningonline.net/simon/blog/
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Re: SQLite

2008-10-03 Thread gordyt

Howdy Matthias!

The delete operation will set the rowcount member of your cursor.
Let's assume you have an sqlite3 database with a table called 'test'
with an id column.  It does have a record with id=1.  It does not have
a record with id=2.

 import sqlite3
 connection = sqlite3.connect('test.sqlite3')
 cursor = connection.cursor()
 cursor.execute('delete from test where id=1')
sqlite3.Cursor object at 0x7f3450
 print cursor.rowcount
1
 cursor.execute('delete from test where id=2')
sqlite3.Cursor object at 0x7f3450
 print cursor.rowcount
0
 cursor.close()
 connection.close()


--gordy
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tkinter question

2008-10-03 Thread [EMAIL PROTECTED]

I saw this (close to this anyway) lieing around on the internet and
was wanting to use it to define a start point exc but I need the
graphics to stay within a set y coords and I am not realy sure how to
do that.  I have no idea on how to bind a min/max y to it.  (the
concept is inspired by the java csound blue).


#!/usr/bin/python
from Tkinter import *
import csoundroutines as cs


root = Tk()


global canv
xx = {}

def makeFrame(root):
   global canv
   test = cs.csdInstrumentlist3('bay-at-night.csd')
   canv = Canvas (root, height = 200, width = 350)

   for i in range (0, len(test.instr_number)):
 canv.create_text(10, i *10, text=str(test.instr_number[i]) +
'...', tags=('movable'))
 xx[i] = canv.tag_bind('movable', 'B1-Motion', slide) #B1-motion
is a drag with left button down
 canv.pack()


def slide (event):
   '''
   triggered when something is dragged on the canvas - move thing
under
mouse ('current') to new position
   '''
   newx = event.x
   if event.y  10 and event.y  0:
 newy = event.y
 canv.coords('current', newx, newy)


makeFrame(root)
root.mainloop()
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Re: del and sets proposal

2008-10-03 Thread Marc 'BlackJack' Rintsch

On Fri, 03 Oct 2008 02:09:09 -0700, Carl Banks wrote:

 On Oct 2, 8:02 pm, Marc 'BlackJack' Rintsch [EMAIL PROTECTED] wrote:
 Then add subscription access too.  By aliasing `__getitem__()` to
 `__contains__()`.  And `__setitem__()` could be implemented to add or
 remove objects by assigning truth values.  So hypothetically:

  a = set([1, 2, 3])
  a[1]
 True
  a[4]
 False
  a[2] = False
  a
 set([1, 3])
  a[4] = True
  a
 set([1, 3, 4])
  del a[1]
  a

 set([3, 4])

 I wouldn't want that addition to `set`\s but at least it can be
 implemented without introducing inconsistencies.
 
 
 If set behaved that way then del a[1] wouldn't behave like del
 anymore.  Normally, del whatever means that you can no longer use
 whatever; in this proposal you can.

Then there should be no ``del`` for `collections.defaultdict`:

In [169]: from collections import defaultdict

In [170]: d = defaultdict(int)

In [171]: d[42]
Out[171]: 0

In [172]: del d[42]

In [173]: d[42]
Out[173]: 0

Ciao,
Marc 'BlackJack' Rintsch
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processing email with Python on Windows?

2008-10-03 Thread Beliavsky

I work for a financial company where we run Windows XP and read email
using Microsoft Outlook 2003. I get daily files that come as email
attachments from various counterparties. I save them as h:\firm_name
\mmdd.csv . Would Python be a good tool to automate the process of
saving reports, or would it be more convenient to use a Microsoft
proprietary language such as VB or C#? Of course one factor is one's
relative competence with the various languages.
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Re: javascript to python

2008-10-03 Thread lkcl

 so, if i do this:

 d = dataListener()
 e = dataListener()

 d.data = fred

 print f.data

 duh, duh - that should be print e.data :)
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execute a function before and after any method of a parent class

2008-10-03 Thread TP

Hi everybody,

I would like to be able to specialize an existing class A, so as to obtain a
class B(A), with all methods of B being the methods of A preceded by a
special method of B called _before_any_method_of_A( self ), and followed by
a special method of B called _after_any_method_of_A( self ).

The goal is to avoid to redefine explicitly in B all methods of A.

Is this possible in Python?

Thanks a lot

Julien

-- 
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(55l4('])

When a distinguished but elderly scientist states that something is
possible, he is almost certainly right. When he states that something is
impossible, he is very probably wrong. (first law of AC Clarke)
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Re: [BaseHTTPServer/SimpleHTTPServer] Remove Server: header

2008-10-03 Thread Gary M. Josack

you've got ?self.send_header('Server', self.version_string()) in the 
send_response method of the BaseHTTPRequestHandler class in the 
BaseHTTPServer module. Long story, short, it's going to be a lot of work 
to get rid of.


[EMAIL PROTECTED] wrote:

Hello.


I'm using SimpleHTTPServer (work well) but it always sends Server
header in response:
Server: SimpleHTTP/0.6 Python/2.5.1

How can I remove that ?

I tried:
self.server_version = 
self.sys_version  = 

but the header is still sent, empty.

I there a way to remove the Server: header completely ?



Thanks.
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Re: Python style: exceptions vs. sys.exit()

2008-10-03 Thread Grant Edwards

On 2008-10-03, greg [EMAIL PROTECTED] wrote:
 Lawrence D'Oliveiro wrote:
 In message [EMAIL PROTECTED], Steven D'Aprano
 wrote:
 
  (2) Even when the source is available, it is sometimes a legal trap to
  read it with respect to patents and copyright.
 
 That's not how patents work.

 I don't think that's how copyrights work either. As far as
 I know, whether something is deemed a derivative work is
 judged on the basis of how similar it is to another work,
 not whether its author had knowledge of the other work.
 As long as you express an idea in an original way, it
 shouldn't matter where you got the idea from.

IANAL, but IIRC it does matter when it comes to establishing
punative damages.  If you knowingly and intentionally infringe
a patent, I think you're libel for more damages than if you
accidentally re-invent something.  At least that's what I was
told...

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Re: windows help files ?

2008-10-03 Thread Lawrence D'Oliveiro

In message [EMAIL PROTECTED], Lie Ryan
wrote:

 ...python's docstring viewer has a less-like pager (or was it less) in
 Linux ...

It invokes whatever you define in $PAGER.
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Re: Python style: exceptions vs. sys.exit()

2008-10-03 Thread J. Cliff Dyer


On Fri, 2008-10-03 at 09:15 -0500, Grant Edwards wrote:
 On 2008-10-03, greg [EMAIL PROTECTED] wrote:
  Lawrence D'Oliveiro wrote:
  In message [EMAIL PROTECTED], Steven D'Aprano
  wrote:
  
   (2) Even when the source is available, it is sometimes a legal trap to
   read it with respect to patents and copyright.
  
  That's not how patents work.
 
  I don't think that's how copyrights work either. As far as
  I know, whether something is deemed a derivative work is
  judged on the basis of how similar it is to another work,
  not whether its author had knowledge of the other work.
  As long as you express an idea in an original way, it
  shouldn't matter where you got the idea from.
 
 IANAL, but IIRC it does matter when it comes to establishing
 punative damages.  If you knowingly and intentionally infringe
 a patent, I think you're libel for more damages than if you
 accidentally re-invent something.  At least that's what I was
 told...
 

s/libel/liable/

When talking about legal matters, it's kind of an important distinction.


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Re: execute a function before and after any method of a parent class

2008-10-03 Thread Almar Klein

Maybe you can use __getattribute__.
I tried it, but got stuck trying to let __getattribute__
work normal without calling itself.

class A(object):
def foo(self):
print hi

class B(A):
def __getattribute__(self,name):
try:
fun = A.__dict__[name]
except KeyError:
fun = None
if fun and callable(fun):
self._before_any_method_of_A()
result =  fun(self)
self._after_any_method_of_A()
return result
else:
# do some stuff to act normal
try:
# erm, this invokes __getattribute__, which will invoke
again,
# and again, and again...
return self.__dict__[name]
except KeyError:
pass
try:
return B.__dict__[name]
except KeyError:
pass


def _before_any_method_of_A(self):
print before

def _after_any_method_of_A(self):
print after


b = B()
b.foo()


greetings,
  Almar

2008/10/3 TP [EMAIL PROTECTED]

 Hi everybody,

 I would like to be able to specialize an existing class A, so as to obtain
 a
 class B(A), with all methods of B being the methods of A preceded by a
 special method of B called _before_any_method_of_A( self ), and followed by
 a special method of B called _after_any_method_of_A( self ).

 The goal is to avoid to redefine explicitly in B all methods of A.

 Is this possible in Python?

 Thanks a lot

 Julien

 --
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 (55l4('])

 When a distinguished but elderly scientist states that something is
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 impossible, he is very probably wrong. (first law of AC Clarke)
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Re: Python style: exceptions vs. sys.exit()

2008-10-03 Thread Grant Edwards

On 2008-10-03, J. Cliff Dyer [EMAIL PROTECTED] wrote:

On Fri, 2008-10-03 at 09:15 -0500, Grant Edwards wrote:
On 2008-10-03, greg [EMAIL PROTECTED] wrote:
Lawrence D'Oliveiro wrote:
In message [EMAIL PROTECTED], Steven D'Aprano
wrote:

(2) Even when the source is available, it is sometimes a legal trap to
read it with respect to patents and copyright.

That's not how patents work.

I don't think that's how copyrights work either. As far as
I know, whether something is deemed a derivative work is
judged on the basis of how similar it is to another work,
not whether its author had knowledge of the other work.
As long as you express an idea in an original way, it
shouldn't matter where you got the idea from.

IANAL, but IIRC it does matter when it comes to establishing
punative damages. If you knowingly and intentionally infringe
a patent, I think you're libel for more damages than if you
accidentally re-invent something. At least that's what I was
told...

s/libel/liable/

Of course.

When talking about legal matters, it's kind of an important
distinction.

Once again we see why a spell-checker is no substitue for
proof-reading.

A bit of googling finds that 35 USC 284 allows the court to
increase damages up to triple the compensatory value. Whether
or not the infringement was willful is often a primary
consideration in that decision.

http://www.invention-protection.com/ip/publications/docs/Damage_Relief_for_Patent_Infringement.html
http://www.ipwatchdog.com/willful_patent_infringement.html
http://www.law.duke.edu/journals/dltr/articles/2007DLTR0006.html

If the infringer never new the invention was patented, then the
infringement can't be willful.

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at I can SHOPLIFT!!
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Re: tkinter textwidget problem

2008-10-03 Thread kib2


Tk/Tkinter apparently considers the position 1.13 to be after the last
word in the text. You get the same problem if you set the insertion
point just after the word 'two' for example: text.index('insert')
returns 1.7 and text.index('insert wordstart') returns 1.7 too...



Exactly.


My solution would simply be to go back one character before asking the
word start: text.index('insert - 1 chars wordstart') Don't know if
that'll do what you want if there are spaces at the end of the text. And
BTW, if you actually want the *last* word in the text, you may want to
use text.index('end - 2 chars wordstart'). Here, you have to use '- 2
chars' because end points to the first non-existent index (2.0 in your
case...).

HTH


Good idea, it seems to work fine now.
See you.

Kib².
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ABCs - infix syntax for isinstance() ?

2008-10-03 Thread Boris Borcic


Given the ABC innovation, maybe an infix syntax for isinstance() would be good.

Possibilities :

- stealing is away from object identity. As a motivation, true use cases for 
testing object identity are rare; forcing the usage of a function or method to 
test it, would dissuade abuse.


- allowing containment tests, ie x in Number to invoke isinstance() in the 
background when the container is of type type. My brain is too muddled by flu 
at the moment, to see whether Guido's fabled time machine allowed him to already 
provide all the necessities in py26.

Any takers ?

- combining both keywords to create a third one, eg is in

Whaddyathink ?

BB

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C API type issue

2008-10-03 Thread Rich Henry

Made a simple little test program as im learning to embed python, have a
simple script that just sets x=10.0 in test.py and prints type(x). Python
prints that x is a float but PyFloat_Check() returns false. If i removed the
check and just force it to print the double value, its correct. Any ideas
why PyFloat_Check() returns false on a float? Thanks in advance.

#include Python.h
#include cstdio

int main(int argc, char** argv)
{
FILE* fp = fopen(test.py, r);
assert(fp);

Py_Initialize();

//
//create a dictionary, load the builtins and execute our file
//
PyObject *d = PyDict_New();
assert(d);
PyDict_SetItemString(d, __builtins__, PyEval_GetBuiltins());
PyRun_File(fp, test.py, Py_file_input, d, NULL);

//
//get a variable that should be in our global namespace
//
PyObject *x = PyDict_GetItemString(d, x);
assert(x);

Py_DECREF(d);

//
//determine its type and print it
//
if(PyFloat_Check(x))
{
printf(x = %lf\n, PyFloat_AS_DOUBLE(x));
}

Py_DECREF(x);

Py_Finalize();
fclose(fp);
return 0;
}
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Re: ABCs - infix syntax for isinstance() ?

Boris Borcic:
 - combining both keywords to create a third one, eg is in

A note only on syntax: isa seems better for Python. I don't comment
how useful it can be.

Bye,
bearophile
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Re: lxml and schema validation

2008-10-03 Thread Stefan Behnel

hrishy wrote:
 I am validating a xmlfile against a xsd (My.xsd) but i notice that the xsd 
 has a include which includes another xsd (My1.xsd)
 
 I have written a simple program that to validate this
 
 from lxml import etree
 xmlschemadoc=etree.parse(My.xsd)
 xmlschema=etree.XMLSchema(xmlschemadoc)

Includes/Imports will be resolved at this point.


 xmldoc=etree.parse(My.XML)
 xmlschema.assertValid(xmldoc)
 
 will my program validate against My.xsd and My1.xsd both ?

It will be validated against My.xsd, which (as you said), includes My1.xsd.
So, yes, both schemas will participate in the validation.


 I also would like my program to continue validation against the xsd and not 
 stope at the first failure.

You want to get a list of all validation errors, instead of bailing out after
the first failure, right? libxml2 doesn't support that. All you get is the
list of errors in the error log of the validator, but when libxml2 decides to
bail out from the validation, that's it.

Stefan
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Re: lxml and adding a stylesheet

2008-10-03 Thread Stefan Behnel

Sean Davis wrote:
 I have an xml document and simply need to add an xml-stylesheet to
 it.  I am using lxml to parse the xml document and then would like to
 insert the xml-stylesheet tag using the etree api.  Any suggestions?

I assume you are talking about a processing instruction here, not a tag.

Use the .addprevious() method on the root Element with a PI object.

Stefan
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Re: lxml question

2008-10-03 Thread Stefan Behnel

Uwe Schmitt wrote:
 I have to parse some text which pretends to be XML. lxml does not want
 to parse it, because it lacks a root element.
 I think that this situation is not unusual, so: is there a way to
 force lxml to parse it ?
 
 My work around is wrapping the text with root.../root before
 feeding lxmls parser.

Yes, you can do that. To avoid creating an intermediate string, you can use
the feed parser and do something like this:

parser = etree.XMLParser()
parser.feed(root)
parser.feed(your_xml_tag_sequence_data)
parser.feed(/root)
root = parser.close()

Stefan
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Re: closures and dynamic binding

2008-10-03 Thread Aaron Castironpi Brady

On Oct 3, 3:44 am, greg [EMAIL PROTECTED] wrote:
 jhermann wrote:
  I didn't see this mentioned in the thread yet: the double-lambda is
  unnecessary (and a hack).

 Well, the alternative -- abusing default argument values --
 is seen by many to be a hack as well, possibly a worse one.
 It doesn't work in general, e.g. it fails if the function
 needs to be called with a variable number of arguments.

 The double lambda is conceptually more sound in some
 ways, and can be made to work correctly in all cases.

 The root of the problem actually has nothing to do with
 lambdas or static vs. non-static scoping. It's the fact
 that Python's for-loop doesn't create a new environment
 for the loop variable each time around, but re-uses a
 slot in the containing environment.

 Contrast this with Scheme, where the equivalent of a
 for-loop *does* create a new environment for each
 value of the loop variable. Effectively it's using a
 double lambda, except that one of the lambdas is
 folded into the syntax of the loop, so you don't
 notice it.

 So if anything were to be done to the language to
 fix this, it really should be focused on fixing the
 semantics of the for-loop. Unfortunately, the
 fact that the loop variable leaks out of the scope
 of the loop is regarded as a feature, so anything
 which changes that seems to be a non-starter.

 --
 Greg

I agree that the default argument syntax is an abuse, but it
accomplishes exactly what I want: to create a copy of a namespace.  I
don't think there's a way to create a closure in Python without
another function, so you might need new syntax if you wanted to.

Otherwise, using function syntax, I want a new namespace on each
iteration that nests inside the old one, except for one variable which
overrides the outer scope.  I agree that a new variable isn't the
obviously correct meaning of a for loop, and functions are the same as
a new scope, just you have to call them, so why not use them as is?

(untested)
for i in range( 3 ):
  def f( n ):
def g( ):
  return n
  return g
  closures[ i ]= f( i )

Or:

(non-standard)
for i in range( 3 ):
  closure f( i ):
def g( ):
  return i
  return g
  closures[ i ]= f

Here the only difference is whether you call 'f' or not.  'closure'
would theoretically call itself, and make a copy of its scope upon
execution of the definition, overriding the arguments.  So, functions
are the same.
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Re: What is not objects in Python?

2008-10-03 Thread Aaron Castironpi Brady

On Oct 3, 5:10 am, Tim Rowe [EMAIL PROTECTED] wrote:
 2008/9/30 Lie Ryan [EMAIL PROTECTED]:

  Actually str.len and len(str) is just like saying the string's length
  and the length of the string. There is no difference between the two
  except for personal preference. (I am no linguist-- not even a native
  speaker of English --but I think there is a subtle difference on
  emphasis, the string's length emphasizes on the length being string's
  property, while the length of the string emphasizes on the length
  itself, am I correct?)

 Well, I'm doing a linguistics degree, so I'm not a linguist /yet/, but
 I think I know this one. There is the difference in emphasis that you
 mention, but there may be something more significant. In both forms,
 length is what linguists call the head of the noun phrase: it's
 the actual thing being talked about.  In The string's length the
 head is only pre-modified (the string's comes before the head and
 there's nothing after the head). The length of the string has both
 pre- and post- modification (The before, of the string after).
 Post modification in noun phrases has been measured to be much less
 frequent in spoken English than in written English, and it gets
 progressively more common as the writing style gets more formal.  That
 suggests that the string's length is an easier phrase to produce and
 understand, but the length of the string sounds more official.

 --
 Tim Rowe

... Unless, there is some corresponding distinction in mechanics
between speaking and writing.  That is, if something about the process
of generating writing makes it, post-modification, easier.  I'm going
to assume that it's been observed across all modes of writing too, (in
addition to across all formality levels), where in all cases it was
equally easy to go back and edit, which is impossible in speech.  And,
in the cases where the entire process of writing was observed, that
neither kind of modification occurred more frequently in revisions.
--
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Re: do you fail at FizzBuzz? simple prog test

2008-10-03 Thread Chuckk Hubbard

range(1,101), no?

On Tue, May 20, 2008 at 4:46 PM, Sells, Fred
[EMAIL PROTECTED] wrote:
 or
 for i in range(1,100):
  print ('fizz','','')[i%3] + ('buzz','','','','')[i%5] or i

 
  Write a program that prints the numbers from 1 to 100. But for
  multiples of three print Fizz instead of the number and for the
  multiples of five print Buzz. For numbers which are multiples of
  both three and five print FizzBuzz.
 
  for i in range(1,101):
  if i%3 == 0 and i%5 != 0:
  print Fizz
  elif i%5 == 0 and i%3 != 0:
  print Buzz
  elif i%5 == 0 and i%3 == 0:
  print FizzBuzz
  else:
  print i
 
 
  is there a better way than my solution? is mine ok?


 --
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-- 
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Re: execute a function before and after any method of a parent class

2008-10-03 Thread Aaron Castironpi Brady

On Oct 3, 9:03 am, TP [EMAIL PROTECTED] wrote:
 Hi everybody,

 I would like to be able to specialize an existing class A, so as to obtain a
 class B(A), with all methods of B being the methods of A preceded by a
 special method of B called _before_any_method_of_A( self ), and followed by
 a special method of B called _after_any_method_of_A( self ).

 The goal is to avoid to redefine explicitly in B all methods of A.

 Is this possible in Python?

 Thanks a lot

 Julien

 --
 python -c print ''.join([chr(154 - ord(c)) for c in '*9(9(18%.91+,\'Z
 (55l4('])

 When a distinguished but elderly scientist states that something is
 possible, he is almost certainly right. When he states that something is
 impossible, he is very probably wrong. (first law of AC Clarke)

Yes it's possible.  The exact solution depends on how much control you
want, and over what.  Do you want inheritance or delegation?  Do you
want the same pre and post method for all inherited methods?  Will you
always use single-inheritance?  Would you mind using a list of names,
as a sort of midpoint between complete redefinition and completely
dynamic?  Do you want class lookups to succeed?  If so, what do you
want them to do?

Generally, you could build the class dynamically with a metaclass, or
use __getattr__ a lookup.
--
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Re: SQLite

2008-10-03 Thread Petite Abeille



On Oct 3, 2008, at 2:33 PM, Matthias Huening wrote:


This seems not to work with sqlite3.


Before going any further... make sure that SQLite's count_change is  
enabled:


PRAGMA count_changes
PRAGMA count_changes = 0 | 1

Query or change the count-changes flag. Normally, when the count- 
changes flag is not set, INSERT, UPDATE and DELETE statements return  
no data. When count-changes is set, each of these commands returns a  
single row of data consisting of one integer value - the number of  
rows inserted, modified or deleted by the command. 


http://www.sqlite.org/pragma.html

Cheers,

--
PA.
http://alt.textdrive.com/nanoki/
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how to get a class instance name during creation?

2008-10-03 Thread dmitrey

hi all,
I have a code
z = MyClass(some_args)
can I somehow get info in MyClass __init__ function that user uses z
as name of the variable?

I.e. to have __init__ function that creates field z.name with value
z.

Thank you in advance, D.
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Exploding (**myvariable) a dict with unicode keys

2008-10-03 Thread Devin

So Python can have unicode variable names but you can't
explode (**myvariable) a dict with unicode keys? WTF?

-Devin
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Re: windows help files ?

En Fri, 03 Oct 2008 09:07:21 -0300, Stef Mientki [EMAIL PROTECTED]  
escribió:

Martin v. Löwis wrote:



1. how can I launch the windows help file (CHM), from python  with a
keyword as argument ?


Run hh.exe. If you want it to navigate to specific page, also pass that
page on the command line (finding out the exact syntax is left as an
exercise)


That's one way,
in the meanwhile I found win32help.py,
which I finally got to work.
The whole hh.exe (seems also to be a wellknown virus) and win32help  
documentation is very hard to find.


hh.exe is part of the Windows OS and is included on all non-prehistoric  
Windows versions. See http://support.microsoft.com/dllhelp/
win32help is part of the pywin32 package - but it's just a thin wrapper  
around the help API. The authoritative documentation source should be the  
Microsoft site: http://msdn.microsoft.com/en-us/library/cc196383.aspx


--
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Re: [BaseHTTPServer/SimpleHTTPServer] Remove Server: header


[EMAIL PROTECTED] wrote:

I'm using SimpleHTTPServer (work well) but it always sends Server
header in response:
How can I remove that ?


En Fri, 03 Oct 2008 11:11:34 -0300, Gary M. Josack [EMAIL PROTECTED]  
escribió:
you've got ?self.send_header('Server', self.version_string()) in the  
send_response method of the BaseHTTPRequestHandler class in the  
BaseHTTPServer module. Long story, short, it's going to be a lot of work  
to get rid of.


One can always write a customized RequestHandler, and just copy the  
send_response method omiting the offending line. (Ok, you have to check  
whether it still works with the next Python release... a warning triggered  
by a new sys.version would be enough to remember that)


--
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--
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Re: SimpleXMLRPCServer -- turning off request log?

2008-10-03 Thread mh

Vinay Sajip [EMAIL PROTECTED] wrote:
 Did you try setting logRequests to false?

Perfect, that's just what I needed.

Thanks Vinay!!
Mark

-- 
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Pixar Animation Studios
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Re: Exploding (**myvariable) a dict with unicode keys

2008-10-03 Thread Martin v. Löwis

Devin wrote:
 So Python can have unicode variable names but you can't
 explode (**myvariable) a dict with unicode keys? WTF?

That works fine for me.

Regards,
Martin
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Re: Exploding (**myvariable) a dict with unicode keys

2008-10-03 Thread Peter Otten

Martin v. Löwis wrote:

 Devin wrote:
 So Python can have unicode variable names but you can't
 explode (**myvariable) a dict with unicode keys? WTF?
 
 That works fine for me.

The OP probably means

 def f(a=1): return a
...
 f(**{a: 42})
42
 f(**{ua: 42})
Traceback (most recent call last):
  File stdin, line 1, in module
TypeError: f() keywords must be strings

Peter

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Re: Exploding (**myvariable) a dict with unicode keys

2008-10-03 Thread Devin

On Oct 3, 1:57 pm, Peter Otten [EMAIL PROTECTED] wrote:
 Martin v. Löwis wrote:
  Devin wrote:
  So Python can have unicode variable names but you can't
  explode (**myvariable) a dict with unicode keys? WTF?

  That works fine for me.

 The OP probably means

  def f(a=1): return a
 ...
  f(**{a: 42})
 42
  f(**{ua: 42})

 Traceback (most recent call last):
   File stdin, line 1, in module
 TypeError: f() keywords must be strings

 Peter

Yes, that's exactly what I mean.
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Re: execute a function before and after any method of a parent class

En Fri, 03 Oct 2008 11:03:22 -0300, TP [EMAIL PROTECTED]  
escribió:


I would like to be able to specialize an existing class A, so as to  
obtain a

class B(A), with all methods of B being the methods of A preceded by a
special method of B called _before_any_method_of_A( self ), and followed  
by

a special method of B called _after_any_method_of_A( self ).

The goal is to avoid to redefine explicitly in B all methods of A.

Is this possible in Python?


Sure. After reading this (excelent!) article by M. Simionato  
http://www.phyast.pitt.edu/~micheles/python/documentation.html you should  
be able to write a decorator to make any method into a sandwich  
(probably based on his trace example). Your code would look like this:


@decorator
def sandwich(f, self, *args, **kw):
self.before()
f(self, *args, **kw)
self.after()

class A:
  @sandwich
  def foo(self):
...

  @sandwich
  def bar(self, x):
...

Ok, but then you have to explicitely decorate every method. To avoid this,  
you may use a metaclass; this article by Michael Foord explains how:

http://www.voidspace.org.uk/python/articles/metaclasses.shtml#a-method-decorating-metaclass

That's all!

--
Gabriel Genellina

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Re: Exploding (**myvariable) a dict with unicode keys

2008-10-03 Thread Martin v. Löwis

Devin wrote:
 On Oct 3, 1:57 pm, Peter Otten [EMAIL PROTECTED] wrote:
 Martin v. Löwis wrote:
 Devin wrote:
 So Python can have unicode variable names but you can't
 explode (**myvariable) a dict with unicode keys? WTF?
 That works fine for me.
 The OP probably means

 def f(a=1): return a
 ...
 f(**{a: 42})
 42
 f(**{ua: 42})
 Traceback (most recent call last):
   File stdin, line 1, in module
 TypeError: f() keywords must be strings

 Peter
 
 Yes, that's exactly what I mean.

Hmm. Why did you say that Python can have unicode variable
names? In the version you are using, it can't. In Python
3.0, it can, but then, you can also use Unicode strings
as keys in **arguments, in Python 3.0.

Regards,
Martin
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Re: Python is slow?

2008-10-03 Thread Terry Reedy


greg wrote:

Steven D'Aprano wrote:


We agree that the restriction is artificial, and I think irrational


I think it's irrational for another reason, too -- it's
actually vacuous. There's nothing to prevent you creating
a set of patches that simply say Delete all of the original
source and replace it with the following.

Then you're effectively distributing the modified source in
its entirety, just with a funny header at the top of each
source file that serves no useful purpose.


The useful purpose is to show that you are distributing your work under 
someone else's product name, instead of making up your own as you ought to.



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[ANN] PyYAML-3.06: YAML parser and emitter for Python

2008-10-03 Thread Kirill Simonov



 Announcing PyYAML-3.06


A new bug fix release of PyYAML is now available:

http://pyyaml.org/wiki/PyYAML


Changes
===

* setup.py checks whether LibYAML is installed and if so, builds
  and installs LibYAML bindings.  To force or disable installation
  of LibYAML bindings, use '--with-libyaml' or '--without-libyaml'
  options respectively.
* Building LibYAML bindings no longer requires Pyrex installed.
* 'yaml.load()' raises an exception if the input stream contains
  more than one YAML document.
* Fixed exceptions produced by LibYAML bindings.
* Fixed a dot '.' character being recognized as !!float.
* Fixed Python 2.3 compatibility issue in constructing !!timestamp
  values.
* Windows binary packages are built against the LibYAML stable branch.
* Added attributes 'yaml.__version__' and  'yaml.__with_libyaml__'.


Resources
=

PyYAML homepage: http://pyyaml.org/wiki/PyYAML
PyYAML documentation: http://pyyaml.org/wiki/PyYAMLDocumentation

TAR.GZ package: http://pyyaml.org/download/pyyaml/PyYAML-3.06.tar.gz
ZIP package: http://pyyaml.org/download/pyyaml/PyYAML-3.06.zip
Windows installer:
http://pyyaml.org/download/pyyaml/PyYAML-3.06.win32-py2.3.exe
http://pyyaml.org/download/pyyaml/PyYAML-3.06.win32-py2.4.exe
http://pyyaml.org/download/pyyaml/PyYAML-3.06.win32-py2.5.exe
http://pyyaml.org/download/pyyaml/PyYAML-3.06.win32-py2.6.exe

PyYAML SVN repository: http://svn.pyyaml.org/pyyaml
Submit a bug report: http://pyyaml.org/newticket?component=pyyaml

YAML homepage: http://yaml.org/
YAML-core mailing list: 
http://lists.sourceforge.net/lists/listinfo/yaml-core



About PyYAML


YAML is a data serialization format designed for human readability and
interaction with scripting languages.  PyYAML is a YAML parser and
emitter for Python.

PyYAML features a complete YAML 1.1 parser, Unicode support, pickle
support, capable extension API, and sensible error messages.  PyYAML
supports standard YAML tags and provides Python-specific tags that allow
to represent an arbitrary Python object.

PyYAML is applicable for a broad range of tasks from complex
configuration files to object serialization and persistance.


Example
===

 import yaml

 yaml.load(
... name: PyYAML
... description: YAML parser and emitter for Python
... homepage: http://pyyaml.org/wiki/PyYAML
... keywords: [YAML, serialization, configuration, persistance, pickle]
... )
{'keywords': ['YAML', 'serialization', 'configuration', 'persistance',
'pickle'], 'homepage': 'http://pyyaml.org/wiki/PyYAML', 'description':
'YAML parser and emitter for Python', 'name': 'PyYAML'}

 print yaml.dump(_)
name: PyYAML
homepage: http://pyyaml.org/wiki/PyYAML
description: YAML parser and emitter for Python
keywords: [YAML, serialization, configuration, persistance, pickle]


Copyright
=

The PyYAML module is written by Kirill Simonov [EMAIL PROTECTED].

PyYAML is released under the MIT license.
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Re: SQLite

2008-10-03 Thread Matthias Huening


Thanks!
cursor.rowcount does exactly what I need.

Before going any further... make sure that SQLite's count_change is 
enabled:


PRAGMA count_changes
PRAGMA count_changes = 0 | 1

Query or change the count-changes flag. Normally, when the 
count-changes flag is not set, INSERT, UPDATE and DELETE statements 
return no data. When count-changes is set, each of these commands 
returns a single row of data consisting of one integer value - the 
number of rows inserted, modified or deleted by the command. 




Looks like this is not really necessary. My database hat count_changes 
disabled, but rowcount seems to work anyway. Are there any pitfalls?


Matthias
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Re: C API type issue

En Fri, 03 Oct 2008 12:27:50 -0300, Rich Henry [EMAIL PROTECTED]  
escribió:



Made a simple little test program as im learning to embed python, have a
simple script that just sets x=10.0 in test.py and prints type(x). Python
prints that x is a float but PyFloat_Check() returns false. If i removed  
the

check and just force it to print the double value, its correct. Any ideas
why PyFloat_Check() returns false on a float? Thanks in advance.


You got the reference count wrong. This is by far the most common source  
of errors when writting C code for Python (at least for beginners)



#include Python.h
#include cstdio

int main(int argc, char** argv)
{
FILE* fp = fopen(test.py, r);
assert(fp);

Py_Initialize();

//
//create a dictionary, load the builtins and execute our file
//
PyObject *d = PyDict_New();
assert(d);
PyDict_SetItemString(d, __builtins__, PyEval_GetBuiltins());
PyRun_File(fp, test.py, Py_file_input, d, NULL);


Instead of a bare dictionary, I'd use a module. Or the __main__ module.  
See how PyRun_SimpleFileExFlags handles this (or just use that function,  
or other variant).



//
//get a variable that should be in our global namespace
//
PyObject *x = PyDict_GetItemString(d, x);
assert(x);


This returns a borrowed reference, not a new one.


Py_DECREF(d);


This releases the only reference to d, and the dictionary is deleted. This  
in turn releases the last refrence to x, and it's deleted too.



//determine its type and print it
//
if(PyFloat_Check(x))
{
printf(x = %lf\n, PyFloat_AS_DOUBLE(x));
}


At this stage x is an invalid object.


Py_DECREF(x);


And this is wrong now.



Py_Finalize();
fclose(fp);
return 0;
}




--
Gabriel Genellina

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Tkinter setting alpha

2008-10-03 Thread Jonathan Hayward

I'm trying to make a Tkinter/Python port of the demo at http://wiki.tcl.tk/10515
, which has adjustable alpha under Windows and (I think) MacOS.

I'm not quite sure how to port:

wm attributes . -alpha [expr {$alphaLevel + 0.05} ]
set AlphaLevel [wm attributes . -alpha]

The goal is to have a screen pop that fades in and out at least on
Windows, and it would be nice if it could fade on other platforms
(including my preferred Linux).

Two questions:

1: Is Tkinter a good choice, or are there other libraries that are
easier and/or will allow cross-platform GUI work with (ideally) fading
in and out?

2: If I go with Tkinter, how can I port lines like those quoted above
to be able to get and set a Frame's alpha value?

--
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** To see an award-winning website with stories, essays, artwork,
** games, and a four-dimensional maze, why not visit my home page?
** All of this is waiting for you at http://JonathansCorner.com

++ Would you like to curl up with one of my hardcover books?
++ You can now get my books from http://CJSHayward.com
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Re: how to get a class instance name during creation?

En Fri, 03 Oct 2008 15:04:01 -0300, dmitrey [EMAIL PROTECTED]  
escribió:



I have a code
z = MyClass(some_args)
can I somehow get info in MyClass __init__ function that user uses z
as name of the variable?

I.e. to have __init__ function that creates field z.name with value
z.


No. I'd just write it as:

z = MyClass(some, args, 'z')

wich is pretty simple and readable (although you have to repeat the 'z').  
All the alternative ways I know of require too much black magic.


--
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Re: Exploding (**myvariable) a dict with unicode keys

2008-10-03 Thread Devin

On Oct 3, 2:29 pm, Martin v. Löwis [EMAIL PROTECTED] wrote:
 Devin wrote:
  On Oct 3, 1:57 pm, Peter Otten [EMAIL PROTECTED] wrote:
  Martin v. Löwis wrote:
  Devin wrote:
  So Python can have unicode variable names but you can't
  explode (**myvariable) a dict with unicode keys? WTF?
  That works fine for me.
  The OP probably means

  def f(a=1): return a
  ...
  f(**{a: 42})
  42
  f(**{ua: 42})
  Traceback (most recent call last):
    File stdin, line 1, in module
  TypeError: f() keywords must be strings

  Peter

  Yes, that's exactly what I mean.

 Hmm. Why did you say that Python can have unicode variable
 names? In the version you are using, it can't. In Python
 3.0, it can, but then, you can also use Unicode strings
 as keys in **arguments, in Python 3.0.

 Regards,
 Martin

Oh. I read somewhere that UTF-8 variable names we're supported. I
thought I even saw a colleague using Kanji.
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Re: javascript to python


lkcl a écrit :

On Oct 3, 10:29 am, Bruno Desthuilliers bruno.
[EMAIL PROTECTED] wrote:

lkcl a écrit : On Oct 2, 7:42 pm, Bruno Desthuilliers

[EMAIL PROTECTED] wrote:

lkcl a écrit :



And as far as I'm concerned, the point is
exactly here : it's doing a little bit more than the original code.


 yeah, i know.  and that bit more gets you a proper representation
of the python class concept.


Except that in most cases - at least when it comes to browser 
scripting[1]  - this concept is just useless. IOW, that's quite a lot of 
code for something you just don't need.


[1] but ask yourself how many times you end up having only one single 
instance of a given class in a python utility script...



 i was merely pointing out that if you want to _really_ translate the
original code into python - _really_ strictly - it's not actually
possible.


really strictly, nope. But mainly because there's nothing in Python 
that behave like the 'this' javascript object (and it doesn't matter in 
the OP snippet). But you can have something quite close, using the class 
as an object (which it is anyway).



 because python doesn't have the concept of non-prototyping
(but... see below: i believe i may stand corrected on that)


!-)


Indeed. But the point is that Python - while close to a prototype-based
language in many aspects - is still class-based. The closer Python
translation of the OP's javascript snippet is probably the one I gave
using a 'class singleton' - that is, using the class itself as an
object.


 oh is _that_ how you do it.  thanks.  i always wondered how you did
class singletons in python.


Note that this not really idiomatic Python - partly for cultural 
reasons, and mostly because use case and constraint differs (class 
singleton would surely become idiomatic if Python was used as 
browser-scripting language the way js is, because you then have to avoid 
any useless code to keep the site responsive).


Anyway, that's still IMHO the pythonic way to translate a litteral 
javascript object - I fail to see anything closer in Python (if there's 
some guru around ?)



python-source-to-javascript-source tool like pyjamas won't give you back
the original javascript snippet (which is by no mean a criticism of
pyjamas - it would just be way too complicated to automatize such a
translation).


 well... you _say_ that... but... actually, if that's the real way to
represent class singletons, and it's an accurate representation of the
OP's javascript, and a good example, then _yes_, pyjs should
definitely have that added as a feature - to understand that a class
singleton _can_ get mapped to the much more efficient javascript
example you gave.


I'm afraid it's going to be quite complicated. You'd have to make sure 
the class only has classmethods - including inherited methods (and 
exception made of methods inherited from object). And FWIW, even such a 
class may be a base class for 'normal' python classes, so there's just 
no reliable semantic way to make sure the class is really a class 
singleton that should map to a litteral js object.


See, the problem here is that we have two high level, highly dynamic 
languages, that are quite close on quite a lot of things but are based 
on two really different object models. So quite often, the best 
translation is obvious for a programmer with a decent knowledge of both 
languages, but almost impossible for a program because there are way too 
much imply stuff (like, for the python class singleton, the fact that 
the class is not meant to be instanciated is totally implicit).



not that many people would _want_ to do that,


Err... Do you have much experience in browser scripting ??? That's a 
*very* common js idiom.



so it goes onto the
diminishing returns TODO list, but...


Nope. You defined functions outside the object's scope, and you still
have to instanciate dataListener. Also, this above code just won't work
- unless you explicitely pass the dataListener instance to the
functions, ie:

d = dataListener()
d.onDataAvailable(d, ...)


 yeah - i didn't realise what the python class singleton thing was.


In this case, the problem I pointed out was that Python's functions 
needs to be class instances to yield instancemethods when looked up on 
an instance or class. If you set a function as an instance attribute, 
the descriptor protocol is not invoked, and you just have a plain 
function (note that this is by design).



It seem you didn't read my other translation proprosal, so I repost it here:



class dataListener(object):
data = ''


 i did - i just didn't understand its significance.

 so - to get this straight: when you do class clsname(object), and you
have the indentation and declaration of variables (e.g. data, above)
at the same level as the functions, it means that there's only one of
them? (i.e. a singleton)?


Nope. Whatever is declared within the class statement becomes a class 
attribute - that is, an attribute of the class object, shared

Re: ABCs - infix syntax for isinstance() ?


Boris Borcic a écrit :
Given the ABC innovation, maybe an infix syntax for isinstance() would 
be good.


Possibilities :

- stealing is away from object identity. As a motivation, true use 
cases for testing object identity are rare; 


x is None is a *very* common test. Using a _marker object as default 
arg value when you want to accept None as a meaningfull value is pretty 
common. Testing a class identity often happens when writing metaclasses.



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Re: Stopping a Thread with Time Slicing

2008-10-03 Thread Steve

Hi Todd,

Thanks for your suggestions on using the Event condition methods on
this thread.

Here is my updated code  :


import time
import datetime
import threading


def log(message):

  now = datetime.datetime.now().strftime(%H:%M:%S)
  print %s :  %s % (now, message)



class StoppableThread(threading.Thread):

  def __init__(self, sleep_time, function, args=[], kwargs={}):

self.sleep_time = sleep_time

threading.Thread.__init__(self)

self.function = function
self.args = args
self.kwargs = kwargs
self.finished = threading.Event()


  def run(self):

while not self.finished.isSet():# loop while condition
is true
  log('** Doing Work')
  self.function(*self.args, **self.kwargs)  # run the function
  self.finished.wait(self.sleep_time)   # put thread in wait
state


log('** Thread Has STOPPED!')


  def stop(self): # stop the thread from running
log('* Stopping Thread')
self.finished.set()
self.join()




def my_function (a, b, c):
  log('my_function running... %s' % a)


#
#T E S T
#

SMALL_SLEEP = 35
CHECK_SLEEP = 300   # sleep interval in seconds to run a timed
process


log('Create Thread')
thread_obj = StoppableThread(CHECK_SLEEP, my_function, (15,0,-1))


log('Thread Start\n')
thread_obj.start()

for current_loop in range(0,10):
  time.sleep(SMALL_SLEEP)
  log('current loop = %d \n' % current_loop)

log('Call Thread Stop')
thread_obj.stop()

log('Done!')


Test Output :

python Simple_Thread_Stop_Event.py

12:58:42 :  Create Thread
12:58:42 :  Thread Start

12:58:42 :  ** Doing Work
12:58:42 :  my_function running... 15
12:59:17 :  current loop = 0
12:59:52 :  current loop = 1
13:00:27 :  current loop = 2
13:01:02 :  current loop = 3
13:01:37 :  current loop = 4
13:02:12 :  current loop = 5
13:02:47 :  current loop = 6
13:03:22 :  current loop = 7
13:03:42 :  ** Doing Work
13:03:42 :  my_function running... 15
13:03:57 :  current loop = 8

13:04:32 :  current loop = 9

13:04:32 :  Call Thread Stop
13:04:32 :  * Stopping Thread
13:04:32 :  ** Thread Has STOPPED!
13:04:32 :  Done!


On Oct 2, 4:40 pm, Todd Whiteman [EMAIL PROTECTED] wrote:
 Steve wrote:

 A better approach for this is to use a Python Event or Condition 
 object:http://docs.python.org/library/threading.html#id5

 Example code:

 import threading
 my_stop_event = threading.Event()

        # Sleep Loop :
        #for current_loop in range(0, self.time_slice) :
        #  time.sleep(self.sleep_time / self.time_slice)

        event.wait(self.sleep_time)
        if not self.running:    # check the flag
          break                 # break out of the sleep loop

 # From another thread, you can notify the above sleeping thread using:
 my_stop_event.set()

 Cheers,
 Todd

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Re: closures and dynamic binding

2008-10-03 Thread Terry Reedy


greg wrote:

jhermann wrote:


I didn't see this mentioned in the thread yet: the double-lambda is
unnecessary (and a hack).


Well, the alternative -- abusing default argument values --
is seen by many to be a hack as well, possibly a worse one.


I disagree.  It is one way to evaluate an expression when a function is 
compiled.



It doesn't work in general, e.g. it fails if the function
needs to be called with a variable number of arguments.


So?  Many things do not work 'in general'. If one wants multiple 
closures with a variable number of arguments, one should use a def 
statement and some other binding method, such as given below


Here are four ways to get the list of closures desired:
All print 0 ... 9 with for f in lst:  print(f()) #3.0

lst = []
for i in range(10):
lst.append(eval(lambda: %d %i))

# use exec instead of eval with def statement instead of lambda expression

lst = []
def f(i): return lambda: i
for i in range(10):
lst.append(f(i))

#I would most likely use this, with a def instead of lambda inside f for 
any real, non-trivial example.


def populate(n):
  n -= 1
  if n = 0: return populate(n)+[lambda:n]
  else: return []
lst = populate(10)

# body recursion

def populate(i,n,lst):
if i  n: return populate(i+1,n,lst+[lambda:i])
else: return lst
lst = populate(0,10,[])

# tail recursion

Terry Jan Reedy

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Re: how to get a class instance name during creation?