Re: An assessment of the Unicode standard

[Hendrik van Rooyen]

On Thursday 17 September 2009 15:29:38 Tim Rowe wrote:

> There are good reasons for it falling out of favour, though. At the
> time of the Sapir-Whorf hypothesis, anthropologists were arguing that
> members of a certain remote tribe did not experience grief on the
> death of a child because their language did not have a word for grief.
> They showed all the *signs* of grief -- weeping and wailing and so on
> -- and sometimes used metaphors ("I feel as if my inside is being
> crushed"). But because of the conviction at the time that "if your
> language does not have a word for something, and you have never seen
> that object, then you "__cannot__" think about it" the anthropologists
> were convinced that this just looked and sounded like grief and wasn't
> actually grief.

This is kind of convincing, when applied to an emotion like that.  The whole 
thing is obviously a lot more complicated than the position I have taken 
here - if it weren't, then there would be no way for a language to change  
and grow, if it were literally true that you cannot think of something  that 
you have no word for.

>
> By the way, at the moment I am thinking of a sort of purple
> blob-shaped monster with tentacles and fangs, that my language doesn't
> have a word for and that I have never seen. On your theory, how come I
> am thinking about it?

I do not really believe you are thinking about a purple people eater. - you 
must be mistaken.

:-)

- Hendrik


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Re:OT - people eaters - was: An assessment of the Unicode standard

[Hendrik van Rooyen]

On Friday 18 September 2009 06:39:57 Dennis Lee Bieber wrote:

>   A one-eyed, one-horned, flying purple people eater?
>
> {Which brings up the confusing question... Is the eater purple, or does
> it eat purple people (which is why it is so rare... it only eats people
> caught in the last stages of suffocation )}

Snap (sort of). 
Does anybody know where the concept of the purple people eater comes from?
I mean is there a children's book or something?

- Hendrik

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Re: explicit call to __init__(self) in subclass needed?

[Bruno Desthuilliers]

Ethan Furman a écrit :

Andrew MacKeith wrote:

I create a class like this in Python-2.6

 >>> class Y(str):
...   def __init__(self, s):
...  pass
...
 >>> y = Y('giraffe')
 >>> y
'giraffe'
 >>>

How does the base class (str) get initialized with the value passed to 
Y.__init__() ?


Is this behavior specific to the str type, or do base classes not need 
to be explicitly initialized?


Andrew


All the immutable base types (I *think*), use __new__ for object 
creation, not __init__.


All types use __new__ for object *creation*. __init__ is for object 
initialization (which indeed happens in the __new__ method for immutable 
types, since the initializer works my mutating the newly created 
instance) !-)



~Ethan~

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specify max width to reportlab.canvas.drawString

[juanefren]

I am using reportlab to create pdf documents, everything looks fine,
how ever, is there a way to specify a max width to drawString
function ? I mean cut the sentence and continue a step down...

Cheers
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Re: SQLite or files?

[Tim Chase]

You can also make a SQLite database be in-memory, giving you
the performance benefits of skipping the disk.



Yes, I love the in-memory database -- especially for my automated 
testing in Django.  However, the OP said that memory footprint 
was a concern (granted, I don't know how much data they were 
talking about -- a couple dozen rows in 1-2 tables might make 
this an attractive option).


-tkc



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Re: explicit call to __init__(self) in subclass needed?

[Bruno Desthuilliers]

Andrew MacKeith a écrit :

I create a class like this in Python-2.6

 >>> class Y(str):
...   def __init__(self, s):
...  pass
...
 >>> y = Y('giraffe')
 >>> y
'giraffe'
 >>>

How does the base class (str) get initialized with the value passed to 
Y.__init__() ?


It happens in the __new__ method (which is the proper "constructor")

class Y(str):
def __new__(cls, value, foo="foo"):
instance = str.__new__(cls, value)
instance.foo = foo
return instance

def __repr__(self):
return "<%s(%s, %s)>" % (type(self).__name__, self, self.foo)



Is this behavior specific to the str type,  or do base classes not need
to be explicitly initialized?


When you override a method in a derived class, it's your responsability 
to call on the parent(s) class(es) implementation. __init__ is not an 
exception to that rule. The point is that since __init__ works by 
mutating the newly created instance, it makes no sense to have a 
distinct __init__ for immutable types - which have their "value" set 
once for all at creation time.

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Re: Looking for a pure Python chart drawing module

[Chris Withers]

John Nagle wrote:

   That's a wrapper for Antigrain ("http://www.antigrain.com/";), which is
a C++ library.  I'm trying hard to avoid dependencies on binary libraries
with limited support.  Builds exist only for Python 2.4 and 2.5.


Huh?

Matplotlib is a pretty phenomenal charting library, I use it routinely 
on both windows and linux, I've never had any compilation problems on 
Linux and never even needed to compile it on Windows.


Writing if off as "just a wrapper for antigrain" is pretty insulting...

Chris

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Re: Looking for a pure Python chart drawing module

[Chris Withers]

Grant Edwards wrote:

On 2009-09-16, Alan G Isaac  wrote:


Tkinter is part of the Python standard library:


That doesn't mean you can depend on it being available.  It
doesn't get installed by default on some Linux distros.


That's 'cos some linux distros feel the need to destroy python's 
packaging for their own silly reasons...


Take them out and shoot them.

Chris

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Re: recommendation for webapp testing?

[Chris Withers]

Simon Brunning wrote:

Mechanize is a superb library for its intended purpose - I use it all
the time. It's lack of support for pages with JavaScript
functionality, though, means it's not very useful at a testing tool
for modern web sites.


There's also zope.testbrowser, which is a handy wrapper around 
Mechanize. I wonder if they've done anything with JS there?


Chris

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Cross platform TTF font render from Python [was: Load TTF from pycairo under Windows]

[Laszlo Nagy]

Hi All,

I need to render antialiased PNG images using TTF font files and UTF-8 
text. It needs to be available at least on Linux and Windows. This is 
what I have tried:


#1. PIL - it has some problems and I cannot use it. Specifically, the 
ImageFont.getsize() returns bad value for some fonts, and there are some 
TTF fonts that are rendered incorrectly  (UTF-8)


#2. pycairo - very sophisticated, nice features, knows and does 
everything correctly. However, has no native support for libfreetype. I 
could write an extension in C and use it from Linux. Not available on 
windows.


#3. gdmodule - I tried to install in under windows without success. No 
binary installer available.


#4. pygame - documentation looks great, it is cross platform. But the 
first example program I had tried has been terminated, printing out 
memory dump and complaining about double freeing some memory location.


What other options do we have?

Thanks,

 Laszlo

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Re: How do I begin debugging a python memory leak?

[Chris Withers]

Matthew Wilson wrote:

I have a web app based on TurboGears 1.0.  In the last few days, as
traffic and usage has picked up, I noticed that the app went from using
4% of my total memory all the way up to 50%.

I suspect I'm loading data from the database and somehow preventing
garbage collection.

Are there any tools that might help me out with this?


http://pypi.python.org/pypi/guppy

...which will give you:

http://guppy-pe.sourceforge.net/heapy_tutorial.html

Good for finding out what's making up the memory usage.

cheers,

Chris

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Re: Creating a local variable scope.

[markol...@gmail.com]

On Sep 11, 7:36 pm, Johan Grönqvist  wrote:
> Hi All,
>
> I find several places in my code where I would like to have a variable
> scope that is smaller than the enclosing function/class/module definition.

This is one of the single major frustrations I have with Python and a
important source of bugs for me. Here is a typical situation

for i, j in visited:
a[i, j] = 1
for i in range(rows):
a[i, 0] = 1
for j in range(columns):
a[0, i] = 1

As you see the third loop has a bug (I am actually mixing two logics:
1) using i for rows and j for columns 2) using i for the first
iterator and j for the second). The result is a buggy code that is
tolerated by Python. In C++ or Perl I don't have this problem. I
wonder whether other people share this opinion and if we have ever had
PEPs trying to address that...

Marko
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Place the timer in Python script

[Vamsikrishna]

How to place the timer in python code.

I want calculate the python script execution time.

ex : Start Timer
: End Timer

Execution Time : End Timer - Start Timer.

How can we write the python code for this.

Help would be appreciable.

Thanks in Advance.

Vamsi
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Tkinter - Text - bullets

[Thomas Lehmann]

My intention is to write a small custom widget displaying text where
the text can have a simple wiki syntax. The main interest is to
support heading, bold, italic, underline, itemization and enumeration.

How can I implement itemization using the Tkinter.Text widget?
(bullets)
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Re: Cross platform TTF font render from Python [was: Load TTF from pycairo under Windows]

[Robin Becker]

Laszlo Nagy wrote:

Hi All,

I need to render antialiased PNG images using TTF font files and UTF-8 
text. It needs to be available at least on Linux and Windows. This is 
what I have tried:


#1. PIL - it has some problems and I cannot use it. Specifically, the 
ImageFont.getsize() returns bad value for some fonts, and there are some 
TTF fonts that are rendered incorrectly  (UTF-8)


#2. pycairo - very sophisticated, nice features, knows and does 
everything correctly. However, has no native support for libfreetype. I 
could write an extension in C and use it from Linux. Not available on 
windows.


#3. gdmodule - I tried to install in under windows without success. No 
binary installer available.


#4. pygame - documentation looks great, it is cross platform. But the 
first example program I had tried has been terminated, printing out 
memory dump and complaining about double freeing some memory location.



...
the reportlab graphics renderPM(_renderPM) module does most things with T1 and 
TTF and works linux/win32. We use  freetype2 internally to extract the curves 
from ttf and then draw them with libart_lgpl which does anti-aliasing.


However, we don't render the fonts using freetype so hinting etc etc don't get 
done.

I think something similar could be done directly with PIL and the antigrain 
extension.


I'm surprised when you say that libfreetype isn't available on windows. It's a 
fairly hard road, but it can be travelled; certainly we built the parts of 
freetype that we needed into our extension. That required only a static library 
from freetype. I haven't needed to do this on windows since 2.1.5 so perhaps 
it's harder now.

--
Robin Becker

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Re: Place the timer in Python script

[Avell Diroll]

Vamsikrishna wrote:

How to place the timer in python code.


timeit ...

it's in the standard library:

http://docs.python.org/library/timeit.html

Cheers,

Ju
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Re: specify max width to reportlab.canvas.drawString

[Robin Becker]

juanefren wrote:

I am using reportlab to create pdf documents, everything looks fine,
how ever, is there a way to specify a max width to drawString
function ? I mean cut the sentence and continue a step down...

Cheers

You'll get better results asking at the reportlab user group

reportlab-us...@reportlab.com

but there are some ways to do what you want just with simple string 
manipulation.


Assuming you know the initial x, y and have setup a canvas with the font and 
sizeand the maximum width you want.




from reportlab.lib.utils import simpleSplit
L = simpleSplit(text,canv._fontname,canv._fontsize,maxWidth)

for t in L:
canv.drawString(x,y,t)
y -= canv._leading


I haven't tested this code, but that's the principle anyway for direct drawing 
to the canvas.

--
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Re: How do I begin debugging a python memory leak?

[Rainer Grimm]

On 17 Sep., 02:10, Matthew Wilson  wrote:
> I have a web app based on TurboGears 1.0.  In the last few days, as
> traffic and usage has picked up, I noticed that the app went from using
> 4% of my total memory all the way up to 50%.
>
> I suspect I'm loading data from the database and somehow preventing
> garbage collection.
>
> Are there any tools that might help me out with this?

If have one of the following plattforms
X86/Linux, AMD64/Linux, PPC32/Linux, PPC64/Linux and X86/Darwin (Mac
OS X),
have a look at valgrind.
http://valgrind.org/
I used of often for searching the memory leaks in c++. It's a great
tool to analyse your memory behaviour.

Greetings
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python-win32 : cross database automation

[Threader Slash]

Hello Everybody...

I working on a client-server database solution. The system is normalized and
is using MySQL. To automate some of processes I using Python. Part of the
old database will be still running on Lotus Notes.

After working on it, it seems that the best choice to directly manipulate
Lotus is to use Python with win32COM -
http://www.boddie.org.uk/python/COM.html . I installed ActivePython 2.6
compiler, which comes with integrated win32com.

However, when I try to run.. it gives me the error:

--x--x--

ActivePython 2.6.2.2 (ActiveState Software Inc.) based on
Python 2.6.2 (r262:71600, Apr 21 2009, 15:05:37) [MSC v.1500 32 bit (Intel)]
on
win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import win32com.client
>>> sess=win32com.client.Dispatch("Lotus.NotesSession")
Traceback (most recent call last):
File "", line 1, in 
File "C:\dev\python\Py26\lib\site-packages\win32com\client\__init__.py",
line 95, in Dispatch
dispatch, userName =
dynamic._GetGoodDispatchAndUserName(dispatch,userName,clsctx)
File "C:\dev\python\Py26\lib\site-packages\win32com\client\dynamic.py", line
98, in _GetGoodDispatchAndUserN
ame
return (_GetGoodDispatch(IDispatch, clsctx), userName)
File "C:\dev\python\Py26\lib\site-packages\win32com\client\dynamic.py", line
78, in _GetGoodDispatch
IDispatch = pythoncom.CoCreateInstance(IDispatch, None, clsctx,
pythoncom.IID_IDispatch)
pywintypes.com_error: (-2147221005, 'Invalid class string', None, None)

--x--x--

Any suggestions? Some help is mostly appreciated.

I will keep working to get it fixed, after I post the working solution here.
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Re: Creating a local variable scope.

[Neal Becker]

markol...@gmail.com wrote:

> On Sep 11, 7:36 pm, Johan Grönqvist  wrote:
>> Hi All,
>>
>> I find several places in my code where I would like to have a variable
>> scope that is smaller than the enclosing function/class/module
>> definition.
> 
> This is one of the single major frustrations I have with Python and a
> important source of bugs for me. Here is a typical situation
> 
> for i, j in visited:
> a[i, j] = 1
> for i in range(rows):
> a[i, 0] = 1
> for j in range(columns):
> a[0, i] = 1
> 
> As you see the third loop has a bug (I am actually mixing two logics:
> 1) using i for rows and j for columns 2) using i for the first
> iterator and j for the second). The result is a buggy code that is
> tolerated by Python. In C++ or Perl I don't have this problem. I
> wonder whether other people share this opinion and if we have ever had
> PEPs trying to address that...
> 
> Marko

I agree.  I wish there were a convenient way to switch this 'feature' 
on/off.  I believe the vast majority of the time I do not want variable 
names leaking out into other scopes.  OTOH, sometimes it's convenient.

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ANN: Resolver One 1.6.5 released

[Giles Thomas]

We are proud to announce the release of Resolver One, version 1.6.5.
Resolver One is a Windows-based spreadsheet that integrates Python
deeply into its recalculation loop, making the models you build more
reliable and more maintainable.

For versions 1.6 and 1.6.5, we've made it easier for people to share
their spreadsheets.  A new free "player" version means you can pass
your work on to other people, and they can use it without having to
buy anything, while a new Resolverlib makes calling your spreadsheets
from IronPython programs as easy as calling a function.

You can read more about Resolver One here:



We have a 31-day free trial version, so if you would like to take a
look, you can download it from our website:



If you want to use Resolver One in an Open Source project, we offer
free licenses for that:




Best regards,

Giles
--
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giles.tho...@resolversystems.com
+44 (0) 20 7253 6372

17a Clerkenwell Road, London EC1M 5RD, UK
VAT No.: GB 893 5643 79
Registered in England and Wales as company number 5467329.
Registered address: 843 Finchley Road, London NW11 8NA, UK
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Re: class initialization problem

[Dave Angel]

rantingrick wrote:

On Sep 18, 12:24 am, "OKB (not okblacke)"
 wrote:
  

Perhaps you want to cut off the recursion at the first step, so
that the nested instance itself does not have a nested instance.  If so,
add another parameter to __init__ that flags whether you are creating a
"top-level" instance.




yes, i also figured that out just a few minutes ago.

class A():
  def __init__(self, nested=ue)
if nested:
   self.var =(nestedúlse)

I think i have been staring at code too long and my noodle just
shutdown for the evening :)

Thanks!

  
Don't forget the else: clause.  If the nested flag is not set, set 
self.var = None.  Otherwise, some user of this class has to face the 
possibility that he gets an attribute exception accessing the child.


DaveA

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Re: Looking for a pure Python chart drawing module

[Piet van Oostrum]

> Chris Withers  (CW) wrote:

>CW> John Nagle wrote:
>>> That's a wrapper for Antigrain ("http://www.antigrain.com/";), which is
>>> a C++ library.  I'm trying hard to avoid dependencies on binary libraries
>>> with limited support.  Builds exist only for Python 2.4 and 2.5.

>CW> Huh?

>CW> Matplotlib is a pretty phenomenal charting library, I use it routinely on
>CW> both windows and linux, I've never had any compilation problems on Linux
>CW> and never even needed to compile it on Windows.

>CW> Writing if off as "just a wrapper for antigrain" is pretty insulting...

*You* made up the "just" in that quote. The point was that the OP wants
something that only needs Python.
-- 
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URL: http://pietvanoostrum.com [PGP 8DAE142BE17999C4]
Private email: p...@vanoostrum.org
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Re: Looking for a pure Python chart drawing module

[Aaron Watters]

On Sep 15, 1:25 pm, John Nagle  wrote:
> I'm looking for something that can draw simple bar and pie charts
> in Python.  I'm trying to find a Python package, not a wrapper for
> some C library, as this has to run on both Windows and Linux
> and version clashes are a problem.

http://skimpygimpy.sourceforge.net includes charts and canvases
that generate PNG using pure Python.  Honestly, they aren't
very pretty though :(.

Also, if you are looking for web display also take a look
at WHIFF Flash charts (using either open flash charts or amcharts)
-- these are very pretty.

  http://aaron.oirt.rutgers.edu/myapp/docs/W1100_1600.openFlashCharts

  -- Aaron Watters

===
Tee front:
  80 minutes / 16 positions / no protection
back:
  Rutgers Rugby

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Re: Place the timer in Python script

[Dave Angel]

Vamsikrishna wrote:

How to place the timer in python code.

I want calculate the python script execution time.

ex : Start Timer
: End Timer

Execution Time : End Timer - Start Timer.

How can we write the python code for this.

Help would be appreciable.

Thanks in Advance.

Vamsi

  

import time
start = time.time()
.. DO SOME STUFF

print "Elapsed time", time.time() - start

Note that the time resolution on some OS's is better than others.  So if 
you're on a system that only gives one-second resolution, you may want 
to use a different function.


DaveA


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Re: Cross platform TTF font render from Python [was: Load TTF from pycairo under Windows]

[Laszlo Nagy]

...
the reportlab graphics renderPM(_renderPM) module does most things 
with T1 and TTF and works linux/win32. We use freetype2 internally to 
extract the curves from ttf and then draw them with libart_lgpl which 
does anti-aliasing.
I just tried reportlab and RenderPM. I got the same error others got: it 
looks impossible to use it for creating raster images. Details here:


http://osdir.com/ml/python.reportlab.user/2005-06/msg00015.html

I think something similar could be done directly with PIL and the 
antigrain extension.
PIL would be ideal because it is lightweight and works on Windows and 
Linux too. But it is buggy. It doesn't render some east european 
(iso8859-2) characters, which we deperately need. Some TTF fonts are 
rendered incorrecly in PIL. Simply it doesn't work.


I'm surprised when you say that libfreetype isn't available on 
windows. It's a fairly hard road, but it can be travelled; certainly 
we built the parts of freetype that we needed into our extension. That 
required only a static library from freetype. I haven't needed to do 
this on windows since 2.1.5 so perhaps it's harder now.
I'll try anything that might work. In fact I have already seen articles 
about windows + libfreetype on the internet, but I could not find 
statically linked libraries built against Python 2.6. If you could send 
me a few hints where to start, I would greatly appreciate it. The only 
one requirement that I do not want to start writting C code and glue 
together libraries by hand. Not because I'm lazy but because I would 
like to have something that can be installed easily on new windows 
systems, and have no dependency problems "out of the box".


Thank you for your efforts.

Laszlo

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Re: Creating a local variable scope.

[Ethan Furman]

Neal Becker wrote:

markol...@gmail.com wrote:



On Sep 11, 7:36 pm, Johan Grönqvist  wrote:


Hi All,

I find several places in my code where I would like to have a variable
scope that is smaller than the enclosing function/class/module
definition.


This is one of the single major frustrations I have with Python and a
important source of bugs for me. Here is a typical situation

for i, j in visited:
   a[i, j] = 1
for i in range(rows):
   a[i, 0] = 1
for j in range(columns):
   a[0, i] = 1

As you see the third loop has a bug (I am actually mixing two logics:
1) using i for rows and j for columns 2) using i for the first
iterator and j for the second). The result is a buggy code that is
tolerated by Python. In C++ or Perl I don't have this problem. I
wonder whether other people share this opinion and if we have ever had
PEPs trying to address that...

Marko



I agree.  I wish there were a convenient way to switch this 'feature' 
on/off.  I believe the vast majority of the time I do not want variable 
names leaking out into other scopes.  OTOH, sometimes it's convenient.




loop != scope

~Ethan~
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Re: explicit call to __init__(self) in subclass needed?

[Ethan Furman]

Bruno Desthuilliers wrote:

Ethan Furman a écrit :


Andrew MacKeith wrote:


I create a class like this in Python-2.6

 >>> class Y(str):
...   def __init__(self, s):
...  pass
...
 >>> y = Y('giraffe')
 >>> y
'giraffe'
 >>>

How does the base class (str) get initialized with the value passed 
to Y.__init__() ?


Is this behavior specific to the str type, or do base classes not 
need to be explicitly initialized?


Andrew



All the immutable base types (I *think*), use __new__ for object 
creation, not __init__.



All types use __new__ for object *creation*. __init__ is for object 
initialization (which indeed happens in the __new__ method for immutable 
types, since the initializer works my mutating the newly created 
instance) !-)



~Ethan~


Thanks for the clarification, Bruno!

~Ethan~

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Re: Creating a local variable scope.

[Wolfgang Rohdewald]

On Friday 18 September 2009, Ethan Furman wrote:
> loop != scope

true for python but in some languages the loop
counter has a scope limited to the loop


-- 
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Re: Cross platform TTF font render from Python [was: Load TTF from pycairo under Windows]

[Robin Becker]

Laszlo Nagy wrote:



...

 > looks impossible to use it for creating raster images. Details here:


http://osdir.com/ml/python.reportlab.user/2005-06/msg00015.html


OK your error occurs because we need to set up the renderPM canvas with an 
initial font (for compatibility with the PDF canvas). You can down load a zip 
file containing suitable files from http://www.reportlab.org/ftp/pfbfer.zip.


Just unzip the pfb/afm files into reportlab/fonts and stuff should work there 
after.



.
I'm surprised when you say that libfreetype isn't available on 
windows. It's a fairly hard road, but it can be travelled; certainly 
we built the parts of freetype that we needed into our extension. That 
required only a static library from freetype. I haven't needed to do 
this on windows since 2.1.5 so perhaps it's harder now.
I'll try anything that might work. In fact I have already seen articles 
about windows + libfreetype on the internet, but I could not find 
statically linked libraries built against Python 2.6. If you could send 
me a few hints where to start, I would greatly appreciate it. The only 
one requirement that I do not want to start writting C code and glue 
together libraries by hand. Not because I'm lazy but because I would 
like to have something that can be installed easily on new windows 
systems, and have no dependency problems "out of the box".


Thank you for your efforts.

Laszlo




I could send you the statically linked library that I use, but it's a 
relocatable static library ie you need to combine it with some other extension. 
I'm using it to combine with the _renderPM.c file to create a standalone pyd. I 
suspect that's not what you want.

--
Robin Becker
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Re: Looking for a pure Python chart drawing module

[Giacomo Boffi]

Piet van Oostrum  writes:

>> Chris Withers  (CW) wrote:
>
>>CW> John Nagle wrote:
 That's a wrapper for Antigrain ("http://www.antigrain.com/";),
 which is a C++ library.  I'm trying hard to avoid dependencies on
 binary libraries with limited support.  Builds exist only for
 Python 2.4 and 2.5.
>
>>CW> Huh?
>
>>CW> Matplotlib is a pretty phenomenal charting library, I use it
>>CW> routinely on both windows and linux, I've never had any
>>CW> compilation problems on Linux and never even needed to compile
>>CW> it on Windows.
>
>>CW> Writing if off as "just a wrapper for antigrain" is pretty
>>CW> insulting...
>
> *You* made up the "just" in that quote. The point was that the OP
> wants something that only needs Python.

matplotlib can be used to generate .ps, .pdf and .svg files (all
vectorial formats) without resorting to Antigrain

Antigrain is used only in rasterizing, due to its better capabilities
in the field of antialiasing, when you use matplotlib with an
interactive backend; of course, if you're truly dispising Antigrain
and are happy with a coarser display you can select interactive
backends that DO NOT use Antigrain

that's for the Antigrain wrapper

otoh, if the OP intended a plotting library that does not use binary
modules at all (then his reference to Antigrain was mostly fogging),
then matplotlib is not for him

% find matplotlib-0.99.0/| grep -v agg24 | grep '\.cpp$' | wc -l
23
% find matplotlib-0.99.0/| grep -v agg24 | grep '\.c$' | wc -l
5
% 

-- 
 I wish we'd come to our senses and see there is no truth
 In those who promote the confusion for this ever changing mood.
(people get ready people get ready people get ready people get ready)
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Re: Creating a local variable scope.

[Johan Grönqvist]

Thanks for all replies.

First, two general comments, and then my conclusions:

I did not intend to ask for new features, but my interest was in writing 
readable code that works in python 2.5, although I may upgrade to 2.6 soon.


Also, what I gave was intended as a minimal example, and not a complete 
use case.



Summarizing the answers, it seems that I will try to follow three 
suggestions:


1) In general, try to restructure the code into smaller modules and 
smaller functions.


2) When using many local variables bindings to create one larger object, 
define an inner function that hides those bindings.


3) If I define a few values intended to be used very locally, delete 
those after use.


Thanks again,

Johan

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Re: Looking for a pure Python chart drawing module

[Grant Edwards]

On 2009-09-18, Chris Withers  wrote:
> Grant Edwards wrote:
>> On 2009-09-16, Alan G Isaac  wrote:
>> 
>>> Tkinter is part of the Python standard library:
>> 
>> That doesn't mean you can depend on it being available.  It
>> doesn't get installed by default on some Linux distros.
>
> That's 'cos some linux distros feel the need to destroy
> python's packaging

What do you mean by "Python's packaging"?  I used to build
python from sources, and tcl/tk support was optional then as
well.

> for their own silly reasons...
>
> Take them out and shoot them.

I think you're overstating that a bit.  AFAIK, when building
Python from sources, tcl/tk support has always been optional as
well.

-- 
Grant Edwards   grante Yow! Being a BALD HERO
  at   is almost as FESTIVE as a
   visi.comTATTOOED KNOCKWURST.
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Re: OT - people eaters - was: An assessment of the Unicode standard

[David Robinow]

On Fri, Sep 18, 2009 at 3:26 AM, Hendrik van Rooyen
 wrote:
> Does anybody know where the concept of the purple people eater comes from?
> I mean is there a children's book or something?
> - Hendrik
http://en.wikipedia.org/wiki/Purple_People_Eater
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Re: How do I begin debugging a python memory leak?

[Paul Rubin]

Rainer Grimm  writes:
> have a look at valgrind.

Have you actually used that on Python?
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Re: Tkinter - Text - bullets

[eb303]

On Sep 18, 11:57 am, Thomas Lehmann  wrote:
> My intention is to write a small custom widget displaying text where
> the text can have a simple wiki syntax. The main interest is to
> support heading, bold, italic, underline, itemization and enumeration.
>
> How can I implement itemization using the Tkinter.Text widget?
> (bullets)

Something like this maybe?

from Tkinter import *

root = Tk()
txt = Text(root, wrap='word')
txt.pack()

txt.tag_configure('text_body', font=('Times', 18), lmargin1=0,
lmargin2=0)
txt.tag_configure('bulleted_list', font=('Times', 18), lmargin1='10m',
lmargin2='15m', tabs=['15m'])

txt.insert(END, u"This is a normal paragraph. Let's make it a bit long
to see that it wraps as expected.\n", 'text_body')
txt.insert(END, u"\u00B7\tThis is the first item in the list.\n",
'bulleted_list')
txt.insert(END, u"\u00B7\tThis is the second item in the list. Let's
make this one quite long too to see how it wraps.\n", 'bulleted_list')

root.mainloop()


HTH
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Re: multiprocessing managers and socket connection.

[Chris]

On Aug 31, 10:41 pm, Terry  wrote:
> On Aug 26, 7:25 pm, Chris  wrote:
>
>
>
> > On Aug 25, 9:11 pm, Terry  wrote:
>
> > > On Aug 25, 10:14 pm, Chris  wrote:
>
> > > > I've been using multiprocessing managers and I really like the
> > > > functionality.
>
> > > > I have a question about reconnecting to a manager. I have a situation
> > > > where I start on one machine (A) a manager that is listening and then
> > > > on another machine (B) connects to that manager and uses its proxy
> > > > object to call functions on the manager's computer; this all works as
> > > > expected. But, if the manager from A shuts down, B's application won't
> > > > notice because in the MP code it ignores socket error
> > > > errno.ECONNREFUSED. If A becomes available again or is restarted, B
> > > > doesn't automatically reconnect either and continue its operation.
> > > > It's function is basically stopped.
>
> > > > Here is the code from connection.py:
> > > > while 1:
> > > >         try:
> > > >             s.connect(address)
> > > >         except socket.error, e:
> > > >             if e.args[0] != errno.ECONNREFUSED: # connection refused
> > > >                 debug('failed to connect to address %s', address)
> > > >                 raise
> > > >             time.sleep(0.01)
> > > >         else:
> > > >             break
>
> > > > How can I have B automatically reconnect to A and continue its work
> > > > once A is available again?
>
> > > I think you need to retry repeatedly until successfully connected.
>
> > > br, Terry
>
> > I'm having issue after once connected. If the server goes down during
> > a long-running connection. I would want to be notified so I could try
> > to reconnect. I'm doing more experimenting now and will try to post an
> > example.
>
> Hi Chris,
>
> Are you sure that the proxy object keeps a permanent connection to the
> server?
>
> br, Terry

Sorry for the delay in response. I was able to find a solution by NOT
using sockets, but using PIPES instead. The socket connections to the
managers don't disconnect properly.

Here's how to reproduce the situation (yes it's a stupid example, but
that's the point):

mp_manager_test.py --> http://python.pastebin.com/m3d10e343
mp_manager_test_client.py --> http://python.pastebin.com/m7a8fda4c

run the following sequence which requires 3 shells.
shell1> python mp_manager_test.py start_server
shell2> python mp_manager_test_client.py
shell3> python mp_manager_test.py stop_server

Run the 3rd line while the client is accessing the server.
When you use the socket for a connection, it hangs.
When you use a PIPE, it throws the exception and actually exits; so I
can catch the exception and handle it properly instead of having a
hanging program. I am not sure how well a remote pipe will work though
as I have yet to try it over a network between machines.

To switch from socket to pipe, just switch the comments at the top in
the source files:
ADDY = ("127.0.0.1",9000)
ADDY2 = ("127.0.0.1",9001)
#ADDY = r'\\.\pipe\PipeName'
#ADDY2 = r'\\.\pipe\PipeName2'

Chris
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Not this one the other one, from a dictionary

[Ross]

Learning my way around list comprehension a bit.   I wonder if  
someone has a better way to solve this issue.  I have a two element  
dictionary, and I know one of the keys but not the other, and I want  
to look up the other one.


So I have this dictionary:

aDict = {'a': 'bob', 'b': 'stu'}

I know that the dictionary contains two keys/value pairs,  but I  
don't know the values nor that the keys will be 'a' and 'b'.   I  
finally get one of the keys passed to me as variable BigOne. e.g.:


BigOne = "a"

The other key, call it  littleOne remains unknown.  It might be "b"  
but could be "c", "x", etc...   I later need to access both values...


I have something that works, with list comprehension - but wonder if  
there's a more brief/elegant way to get there:


BigValu = aDict[BigOne]
temp =  [ thing for thing in aDict if thing != BigOne ]
LittleValu = aDict[ temp[0] ]

Any thoughts?

- Ross.
 
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Re: multiprocessing managers and socket connection.

[bouncy...@gmail.com]

Is this "server" something you wrote from scratch or something that is just 
being used. Some details are left out

--


--Original Message--
From: Chris 
To: 
Date: Fri, 18 Sep 2009 09:10:15 AM -0700
Subject: Re: multiprocessing managers and socket connection.

On Aug 31, 10:41 pm, Terry  wrote:
> On Aug 26, 7:25 pm, Chris  wrote:
>
>
>
> > On Aug 25, 9:11 pm, Terry  wrote:
>
> > > On Aug 25, 10:14 pm, Chris  wrote:
>
> > > > I've been using multiprocessing managers and I really like the
> > > > functionality.
>
> > > > I have a question about reconnecting to a manager. I have a situation
> > > > where I start on one machine (A) a manager that is listening and then
> > > > on another machine (B) connects to that manager and uses its proxy
> > > > object to call functions on the manager's computer; this all works as
> > > > expected. But, if the manager from A shuts down, B's application won't
> > > > notice because in the MP code it ignores socket error
> > > > errno.ECONNREFUSED. If A becomes available again or is restarted, B
> > > > doesn't automatically reconnect either and continue its operation.
> > > > It's function is basically stopped.
>
> > > > Here is the code from connection.py:
> > > > while 1:
> > > >         try:
> > > >             s.connect(address)
> > > >         except socket.error, e:
> > > >             if e.args[0] != errno.ECONNREFUSED: # connection refused
> > > >                 debug('failed to connect to address %s', address)
> > > >                 raise
> > > >             time.sleep(0.01)
> > > >         else:
> > > >             break
>
> > > > How can I have B automatically reconnect to A and continue its work
> > > > once A is available again?
>
> > > I think you need to retry repeatedly until successfully connected.
>
> > > br, Terry
>
> > I'm having issue after once connected. If the server goes down during
> > a long-running connection. I would want to be notified so I could try
> > to reconnect. I'm doing more experimenting now and will try to post an
> > example.
>
> Hi Chris,
>
> Are you sure that the proxy object keeps a permanent connection to the
> server?
>
> br, Terry

Sorry for the delay in response. I was able to find a solution by NOT
using sockets, but using PIPES instead. The socket connections to the
managers don't disconnect properly.

Here's how to reproduce the situation (yes it's a stupid example, but
that's the point):

mp_manager_test.py --> http://python.pastebin.com/m3d10e343
mp_manager_test_client.py --> http://python.pastebin.com/m7a8fda4c

run the following sequence which requires 3 shells.
shell1> python mp_manager_test.py start_server
shell2> python mp_manager_test_client.py
shell3> python mp_manager_test.py stop_server

Run the 3rd line while the client is accessing the server.
When you use the socket for a connection, it hangs.
When you use a PIPE, it throws the exception and actually exits; so I
can catch the exception and handle it properly instead of having a
hanging program. I am not sure how well a remote pipe will work though
as I have yet to try it over a network between machines.

To switch from socket to pipe, just switch the comments at the top in
the source files:
ADDY = ("127.0.0.1",9000)
ADDY2 = ("127.0.0.1",9001)
#ADDY = r'\\.\pipe\PipeName'
#ADDY2 = r'\\.\pipe\PipeName2'

Chris
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How to print without spaces?

[Peng Yu]

Hi,

I don't want to print the space between 'a' and 'b'. Could somebody
let me know how to do it?

Regards,
Peng

$ python
Python 2.5.2 (r252:60911, May 21 2008, 10:08:24)
[GCC 4.1.2 20070626 (Red Hat 4.1.2-14)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> print "a","b"
a b
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RE: How to print without spaces?

[Andreas Tawn]

> Hi,
> 
> I don't want to print the space between 'a' and 'b'. Could somebody
> let me know how to do it?
> 
> Regards,
> Peng
> 
> $ python
> Python 2.5.2 (r252:60911, May 21 2008, 10:08:24)
> [GCC 4.1.2 20070626 (Red Hat 4.1.2-14)] on linux2
> Type "help", "copyright", "credits" or "license" for more information.
> >>> print "a","b"
> a b

print "a" + "b"

Cheers,

Drea
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Re: How to print without spaces?

[Donn]

print "a"+"b"

\d
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Re: Why use "locals()"

[Simon Forman]

On Mon, Sep 14, 2009 at 1:12 AM, Sean DiZazzo  wrote:
>
> Thanks for your explanation Steven.  I see how it can be valuable, but
> it seems to always break the second rule of Zen.  I don't really want
> to get into the code of debuggers, but I guess I can see how they
> might have no other way to know what local variables have been set.
>
> ~Sean


The zeroth "rule" of zen is "don't take the rules so seriously".
"They're really more like guidelines anyway."

Regards,
~simon
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Re: multiprocessing managers and socket connection.

[Chris]

On Sep 18, 12:42 pm, "bouncy...@gmail.com" 
wrote:
> Is this "server" something you wrote from scratch or something that is just 
> being used. Some details are left out
>
> --
>
> --Original Message--
> From: Chris 
> To: 
> Date: Fri, 18 Sep 2009 09:10:15 AM -0700
> Subject: Re: multiprocessing managers and socket connection.
>
> On Aug 31, 10:41 pm, Terry  wrote:
> > On Aug 26, 7:25 pm, Chris  wrote:
>
> > > On Aug 25, 9:11 pm, Terry  wrote:
>
> > > > On Aug 25, 10:14 pm, Chris  wrote:
>
> > > > > I've been using multiprocessing managers and I really like the
> > > > > functionality.
>
> > > > > I have a question about reconnecting to a manager. I have a situation
> > > > > where I start on one machine (A) a manager that is listening and then
> > > > > on another machine (B) connects to that manager and uses its proxy
> > > > > object to call functions on the manager's computer; this all works as
> > > > > expected. But, if the manager from A shuts down, B's application won't
> > > > > notice because in the MP code it ignores socket error
> > > > > errno.ECONNREFUSED. If A becomes available again or is restarted, B
> > > > > doesn't automatically reconnect either and continue its operation.
> > > > > It's function is basically stopped.
>
> > > > > Here is the code from connection.py:
> > > > > while 1:
> > > > >         try:
> > > > >             s.connect(address)
> > > > >         except socket.error, e:
> > > > >             if e.args[0] != errno.ECONNREFUSED: # connection refused
> > > > >                 debug('failed to connect to address %s', address)
> > > > >                 raise
> > > > >             time.sleep(0.01)
> > > > >         else:
> > > > >             break
>
> > > > > How can I have B automatically reconnect to A and continue its work
> > > > > once A is available again?
>
> > > > I think you need to retry repeatedly until successfully connected.
>
> > > > br, Terry
>
> > > I'm having issue after once connected. If the server goes down during
> > > a long-running connection. I would want to be notified so I could try
> > > to reconnect. I'm doing more experimenting now and will try to post an
> > > example.
>
> > Hi Chris,
>
> > Are you sure that the proxy object keeps a permanent connection to the
> > server?
>
> > br, Terry
>
> Sorry for the delay in response. I was able to find a solution by NOT
> using sockets, but using PIPES instead. The socket connections to the
> managers don't disconnect properly.
>
> Here's how to reproduce the situation (yes it's a stupid example, but
> that's the point):
>
> mp_manager_test.py -->http://python.pastebin.com/m3d10e343
> mp_manager_test_client.py -->http://python.pastebin.com/m7a8fda4c
>
> run the following sequence which requires 3 shells.
> shell1> python mp_manager_test.py start_server
> shell2> python mp_manager_test_client.py
> shell3> python mp_manager_test.py stop_server
>
> Run the 3rd line while the client is accessing the server.
> When you use the socket for a connection, it hangs.
> When you use a PIPE, it throws the exception and actually exits; so I
> can catch the exception and handle it properly instead of having a
> hanging program. I am not sure how well a remote pipe will work though
> as I have yet to try it over a network between machines.
>
> To switch from socket to pipe, just switch the comments at the top in
> the source files:
> ADDY = ("127.0.0.1",9000)
> ADDY2 = ("127.0.0.1",9001)
> #ADDY = r'\\.\pipe\PipeName'
> #ADDY2 = r'\\.\pipe\PipeName2'
>
> Chris
> --http://mail.python.org/mailman/listinfo/python-list
>
>

No, that's a full example posted in those 2 files right there; there
is nothing else needed to run it.
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detmining name during an assignment

[Jamie Riotto]

I have an app that uses Python scripting. When a user creates a new object:

objName = newObject()

I'd like the newObject be able to use objName as its internal name.
So, if a user says:

cube1 = Cube()

 A "cube1" object should apear in the scene list. I believe this means I need
to determine that a namespace assignment is going on from inside the
object's init code
or by using properties.

I've searched the web but can't find a simple answer. Is there some
way to use the inspect
module get source code functoins? How would I get the code for "the
current interpreter line"
causing the init code to execute?

Thanks very much in advance,
Jamie Riotto
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Re: detmining name during an assignment

[Stephen Hansen]

On Fri, Sep 18, 2009 at 10:00 AM, Jamie Riotto wrote:

> I have an app that uses Python scripting. When a user creates a new object:
>
> objName = newObject()
>
> I'd like the newObject be able to use objName as its internal name.
>

Almost this exact same question came up not so long ago, which is a bit
strange.

The short of it is, you can't.


> So, if a user says:
>
> cube1 = Cube()
>
>  A "cube1" object should apear in the scene list. I believe this means I
> need
> to determine that a namespace assignment is going on from inside the
> object's init code
> or by using properties.
>

That's the thing: during the object's __init__, a "namespace assignment"
isn't going on. newObject() initializes and creates an object, returning it.
There's no way for it to tell what happens to that object after. It might
just get discarded and garbage collected immediately. Or it might get
inserted into a dictionary. Or it might end up bound to a name in a
namespace. It has no idea: all of that happens completely -after- the
__init__ is completely finished and returned.

There isn't a simple answer because Python just doesn't work like that :) An
assignment statement doesn't create a variable or a cell or anything of that
nature, it simply labels an object with a particular name that's only
meaningful in a certain namespace. A given object can have any number of
such labels and the object can't actually tell what those are.

--S
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Re: detmining name during an assignment

[Simon Forman]

On Sep 18, 1:00 pm, Jamie Riotto  wrote:
> I have an app that uses Python scripting. When a user creates a new object:
>
> objName = newObject()
>
> I'd like the newObject be able to use objName as its internal name.
> So, if a user says:
>
> cube1 = Cube()
>
>  A "cube1" object should apear in the scene list. I believe this means I need
> to determine that a namespace assignment is going on from inside the
> object's init code
> or by using properties.
>
> I've searched the web but can't find a simple answer. Is there some
> way to use the inspect
> module get source code functoins? How would I get the code for "the
> current interpreter line"
> causing the init code to execute?
>
> Thanks very much in advance,
> Jamie Riotto

Save yourself a lot of trouble and just assign a name "manually":

class foo:
def __init__(self, name):
self.name = name


some_foo = foo("some_foo")

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Re: Not this one the other one, from a dictionary

[Tim Chase]

Learning my way around list comprehension a bit.   I wonder if  
someone has a better way to solve this issue.  I have a two element  
dictionary, and I know one of the keys but not the other, and I want  
to look up the other one.


Several ways occur to me.  Of the various solutions I played 
with, this was my favorite (requires Python2.4+ for generator 
expressions):


  d = {'a': 'alice', 'b':'bob'}
  known = 'a'
  other_key, other_value = (
(k,v)
for k,v
in d.iteritems()
if k != known
).next()

If you just want one or the other, you can simplify that a bit:

  other_key = (k for k in d.iterkeys() if k != known).next()
  other_key = (k for k in d if k != known).next()

or

  other_value = (v for k,v in d.iteritems() if k != known).next()

If you're using pre-2.4, you might tweak the above to something like

  other_key, other_value = [
(k,v)
for k,v
in d.iteritems()
if k != known
][0]
  other_key = [k for k in d if k != known)[0]
  other_value = [k for k in d.iteritems if k != known][0]

Hope this helps,

-tkc





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Re: How to improve this code?

[Simon Forman]

On Sep 14, 9:08 pm, Oltmans  wrote:
> Hello,
>
> Is there someway I can improve the following code(pythonically)?
> (Copying from IDLE)
> match=[1,2,3,4,5]
>
> def elementsPresent(aList):
>         result=False
>         if not aList:
>                 return False
>         for e in aList:
>                 if e in match:
>                         result=True
>                 else:
>                         result = False
>         return result
>  elementsPresent([6,7,8,9,5]) # should return True because 5 is
> present in list named match.
>
> Is there somehow I can improve code in elementsPresent()? I'm not a
> very good programmer but I sense that idea of using a variable named
> 'result' inside elementsPresent() doesn't sound very good. Any ideas
> will be highly appreciated.
>
> Thanks,
> Oltmans

It's not really relevant to this particular task (since you want to
stop after finding an 'e' in match) but whenever you're doing
something like this:

if e in match:
result = True
else:
result = False

You can just assign the result of the boolean expression directly to
your result:

result = e in match


Regards,
~Simon
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Re: detmining name during an assignment

[Christian Heimes]

Jamie Riotto schrieb:
> I have an app that uses Python scripting. When a user creates a new object:
> 
> objName = newObject()
> 
> I'd like the newObject be able to use objName as its internal name.
> So, if a user says:
> 
> cube1 = Cube()
> 
>  A "cube1" object should apear in the scene list. I believe this means I need
> to determine that a namespace assignment is going on from inside the
> object's init code
> or by using properties.

As the others already explained to you there is no way to archive your
goal with an assignment to a local or global variable. But you can
follow a different approach:

class Scene(object):
def __setattr__(self, name, value):
super(Scene, self).__setattr__(name value)
if isinstance(value, SceneObject):
value.name = name
value.scene = self

class SceneObject(object):
pass

class Cube(SceneObject):
pass

scene = Scene()
scene.cube1 = Cube()

Have fun!

Christian

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Re: detmining name during an assignment

[Ishwor]

Jamie,
Hi.

> I have an app that uses Python scripting. When a user creates a new object:
>
> objName = newObject()

newObject should technically speaking be newClass() but nevermind :-)

> I'd like the newObject be able to use objName as its internal name.
> So, if a user says:
>
> cube1 = Cube()
>
>  A "cube1" object should apear in the scene list. I believe this means I need
> to determine that a namespace assignment is going on from inside the
> object's init code
> or by using properties.

A class's init code is like a constructor (guessing you know about
ctors here). Basically, initialising all the variables that particular
class uses. In this instance calling Cube( ) would cause it to call up
the __init__(self) function in Cube class and do whatever it does
there such as defining a variable, calling other initialisation
functions etc...

> I've searched the web but can't find a simple answer. Is there some
> way to use the inspect
> module get source code functoins? How would I get the code for "the

To get the source code for a function, you can manually inspect it. To
get the functions that a class exports, use can use
dir(object_of_a_class) in Python shell (this may not be what you want
but I write it anyway because I feel like writing today). You can also
run help(module_name_here) to see the docs+functions.

> current interpreter line"
> causing the init code to execute?

I am starting to suspect that you are very much asking for a debugger
;-) Look up pdb;a Python debugger.
-- 
Regards,
Ishwor Gurung
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Re: Not this one the other one, from a dictionary

[Ishwor]

Ross
Hi.

> So I have this dictionary:
>
> aDict = {'a': 'bob', 'b': 'stu'}

Yes.

> I know that the dictionary contains two keys/value pairs,  but I don't know
> the values nor that the keys will be 'a' and 'b'.   I finally get one of the
> keys passed to me as variable BigOne. e.g.:
>
> BigOne = "a"

Right. aDict[BigOne] will give you - 'bob' which may/maynot be what
you want by the looks of it, you want aDict[BigOne].

>>> aDict.keys()
['a', 'b']
>>> aDict.values()
['bob', 'stu']

keys() / values() return list so you do not have to worry about
explicitly getting list.

> The other key, call it  littleOne remains unknown.  It might be "b" but
> could be "c", "x", etc...   I later need to access both values...
>
> I have something that works, with list comprehension - but wonder if there's
> a more brief/elegant way to get there:

If you know the dictionary name in this case aDict (which you don't
mention you know or not), you can just traverse it using easily as
such:
>>>for k in aDict:
 print k, aDict[k];

>>> [[i,a[i]] for i in aDict]
[['a', 'bob'], ['b', 'stu']]
>>> [[i,a[i]] for i in aDict][0]
['a', 'stu']
>>> [[i,a[i]] for i in aDict][0][0]
'a'
>>> [[i,a[i]] for i in aDict][0][1]
'bob'


-- 
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Re: How to improve this code?

[Sergey Simonenko]

elements_present = lambda seq, match: any(((x in match) for x in seq))

On Mon, 14 Sep 2009 19:08:59 -0600, Oltmans  wrote:


Hello,

Is there someway I can improve the following code(pythonically)?
(Copying from IDLE)
match=[1,2,3,4,5]

def elementsPresent(aList):
result=False
if not aList:
return False
for e in aList:
if e in match:
result=True
else:
result = False
return result
 elementsPresent([6,7,8,9,5]) # should return True because 5 is
present in list named match.

Is there somehow I can improve code in elementsPresent()? I'm not a
very good programmer but I sense that idea of using a variable named
'result' inside elementsPresent() doesn't sound very good. Any ideas
will be highly appreciated.

Thanks,
Oltmans



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Python based paramiko package acting up on Linux, code works fine on windows

[flxkid]

I've tried to post to the mailing list for paramiko and contact the
author, but it seems he's having some mailing list problems.  Anyways,
I have this small example that works just fine on Windows against
Python 2.6.2, but fails on Ubuntu against 2.6.2.  Here is the code:

import subprocess
import os
import re
import paramiko
import sqlite3
import datetime
import base64
import sys
import logging
from paramiko.rsakey import RSAKey

class OpenSessions:
sshconns = []
sqlconn = sqlite3.connect('test.sqlite')

def __init__(self):
self.sqlconn.row_factory = sqlite3.Row
sqlcur = self.sqlconn.cursor()
sqlcur.execute("select host, pub_key, username, password,
private_key from ssh_hosts")
rows = sqlcur.fetchall()
for row in rows:
sshconn = paramiko.SSHClient()
sshconn._system_host_keys.add(row["host"], "ssh-rsa", 
RSAKey
(data=base64.decodestring(row["pub_key"])))
if row["private_key"] != "":
sshconn.connect(hostname=row["host"], 
username=row["username"],
pkey=RSAKey(data=base64.decodestring(row["private_key"])))
elif row["password"] != "":
sshconn.connect(hostname=row["host"], 
username=row["username"],
password=row["password"], look_for_keys=False, timeout=60)
self.sshconns.append(sshconn)

output = ""
for conn in self.sshconns:
print conn.exec_command("uname -a")[1].readline()

exit()

if __name__== '__main__':
sessions = OpenSessions()

The code fails with this trace:
Traceback (most recent call last):
  File "test.py", line 41, in 
sessions = OpenSessions()
  File "test.py", line 36, in __init__
print chan.exec_command("uname -a")[1].readline()
  File "/usr/local/lib/python2.6/dist-packages/paramiko/channel.py",
line 212, in exec_command
self._wait_for_event()
  File "/usr/local/lib/python2.6/dist-packages/paramiko/channel.py",
line 1077, in _wait_for_event
raise e
paramiko.SSHException: Channel closed.
Exception in thread Thread-1 (most likely raised during interpreter
shutdown):
Traceback (most recent call last):
  File "/usr/lib/python2.6/threading.py", line 525, in
__bootstrap_inner
  File "/usr/local/lib/python2.6/dist-packages/paramiko/transport.py",
line 1567, in run
: 'NoneType' object has no attribute
'error'

This well beyond my abilities to debug.  All I know is that it always
works on Windows, and always fails in Ubuntu (which of course is where
I need use the code).  Any suggestions?  I know the paramiko mailing
list would probably be the better spot for this, but like I said, its
got some issues right now.

OLIVER


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Re: Not this one the other one, from a dictionary

[Ross]

Thanks Tim (and Ishwor) for the suggestions, those are structures  
that somewhat new to me - looks good!  I'll play with those.At  
this rate I may soon almost know what I'm doing.


Rgds
Ross.


On 18-Sep-09, at 1:19 PM, Tim Chase wrote:

Learning my way around list comprehension a bit.   I wonder if   
someone has a better way to solve this issue.  I have a two  
element  dictionary, and I know one of the keys but not the other,  
and I want  to look up the other one.


Several ways occur to me.  Of the various solutions I played with,  
this was my favorite (requires Python2.4+ for generator expressions):


  d = {'a': 'alice', 'b':'bob'}
  known = 'a'
  other_key, other_value = (
(k,v)
for k,v
in d.iteritems()
if k != known
).next()

If you just want one or the other, you can simplify that a bit:

  other_key = (k for k in d.iterkeys() if k != known).next()
  other_key = (k for k in d if k != known).next()

or

  other_value = (v for k,v in d.iteritems() if k != known).next()

If you're using pre-2.4, you might tweak the above to something like

  other_key, other_value = [
(k,v)
for k,v
in d.iteritems()
if k != known
][0]
  other_key = [k for k in d if k != known)[0]
  other_value = [k for k in d.iteritems if k != known][0]

Hope this helps,

-tkc







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Granularity of OSError

[kj]

I've often come across the idea that good Python style deals with
potential errors using an EAFP ("easier to ask forgiveness than
permission") strategy rather than a LBYL ("look before you leap")
strategy.

For example, LBYL would look like this:

if os.path.isfile(some_file):
os.unlink(some_file)

In contrast, EAFP would look like this:

try:
os.unlink(some_file)
except OSError:
pass

But, as written, the EAFP code above is not satisfactory, because
there can be OSError's triggered for reasons other than the
non-existence of the regular file some_file.

What one needs is a finer granularity of exception, mapping to
exactly the error that one is guarding against.

Is there a standard approach to refining the granularity of exceptions
such as OSError?  The only approach I can think of is to somehow
parse the error string (assuming is available) to determine whether
the exception is indeed of the specific kind we're trying to catch.
But this strikes me as grossly inelegant.  Is there a better way?

(BTW, the problem is generic, because client code has no control
over the specificity of the exceptions raised by a library module.
If these exceptions turn out to be too broad, client code has to
somehow deal with this reality, at least in the short term.)

TIA!

kynn

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Re: explicit call to __init__(self) in subclass needed?

[Andrew MacKeith]

Bruno Desthuilliers wrote:

Andrew MacKeith a écrit :

I create a class like this in Python-2.6

 >>> class Y(str):
...   def __init__(self, s):
...  pass
...
 >>> y = Y('giraffe')
 >>> y
'giraffe'
 >>>

How does the base class (str) get initialized with the value passed to 
Y.__init__() ?


It happens in the __new__ method (which is the proper "constructor")

class Y(str):
def __new__(cls, value, foo="foo"):
instance = str.__new__(cls, value)
instance.foo = foo
return instance

def __repr__(self):
return "<%s(%s, %s)>" % (type(self).__name__, self, self.foo)



Is this behavior specific to the str type,  or do base classes not need
to be explicitly initialized?


When you override a method in a derived class, it's your responsability 
to call on the parent(s) class(es) implementation. __init__ is not an 
exception to that rule. The point is that since __init__ works by 
mutating the newly created instance, it makes no sense to have a 
distinct __init__ for immutable types - which have their "value" set 
once for all at creation time.


Thanks for the explanation, Bruno.

I have been successfully using a class derived from str, and in that
class I add a lot of extra data to the derived class instance in the
__init__ method of the derived class, so it is possible to mutate the
derived class __dict__, even if the base class data remains immutable.


See example below.

The __init__ must have the same arguments as the base class.

>>> class Y(str):
...   def __init__(self):
...  self.color = 'blue'
...
>>> y = Y('Parrot')
Traceback (most recent call last):
  File "", line 1, in 
TypeError: __init__() takes exactly 1 argument (2 given)
>>>
>>> class Y(str):
...   def __init__(self, text):
...  self.color = 'blue'
...
>>> y = Y('Parrot')
>>> y
'Parrot'
>>> y.color
'blue'
>>> y[:3]
'Par'
>>> y.size = 'small'
>>>
>>> y.__class__

>>>

But you can get bitten if you do something that returns a new object

>>> y += 'Tail'
>>> y
'ParrotTail'
>>> y.color
Traceback (most recent call last):
  File "", line 1, in 
AttributeError: 'str' object has no attribute 'color'
>>>
>>> y.__class__

>>>

Andrew
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Re: Granularity of OSError

[Sean DiZazzo]

On Sep 18, 11:54 am, kj  wrote:
> I've often come across the idea that good Python style deals with
> potential errors using an EAFP ("easier to ask forgiveness than
> permission") strategy rather than a LBYL ("look before you leap")
> strategy.
>
> For example, LBYL would look like this:
>
> if os.path.isfile(some_file):
>     os.unlink(some_file)
>
> In contrast, EAFP would look like this:
>
> try:
>     os.unlink(some_file)
> except OSError:
>     pass
>
> But, as written, the EAFP code above is not satisfactory, because
> there can be OSError's triggered for reasons other than the
> non-existence of the regular file some_file.
>
> What one needs is a finer granularity of exception, mapping to
> exactly the error that one is guarding against.
>
> Is there a standard approach to refining the granularity of exceptions
> such as OSError?  The only approach I can think of is to somehow
> parse the error string (assuming is available) to determine whether
> the exception is indeed of the specific kind we're trying to catch.
> But this strikes me as grossly inelegant.  Is there a better way?
>
> (BTW, the problem is generic, because client code has no control
> over the specificity of the exceptions raised by a library module.
> If these exceptions turn out to be too broad, client code has to
> somehow deal with this reality, at least in the short term.)
>
> TIA!
>
> kynn

You can access the exception object which gives you greater detail.

try:
os.unlink(some_file)
except OSError, e:
print e.errno
print e.strerror

if e.errno == 2:
pass
else:
raise


If it's the error you are looking for, handle it, or else raise.

~Sean
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Re: How to print without spaces?

[Tobiah]

> I don't want to print the space between 'a' and 'b'. Could somebody let me
> know how to do it?

 print "a","b"
> a b

Since you are new, you should also be aware of:

print "%s%s" % (a, b)


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Re: Granularity of OSError

[Jeff McNeil]

On Sep 18, 3:05 pm, Sean DiZazzo  wrote:
> On Sep 18, 11:54 am, kj  wrote:
>
>
>
>
>
> > I've often come across the idea that good Python style deals with
> > potential errors using an EAFP ("easier to ask forgiveness than
> > permission") strategy rather than a LBYL ("look before you leap")
> > strategy.
>
> > For example, LBYL would look like this:
>
> > if os.path.isfile(some_file):
> >     os.unlink(some_file)
>
> > In contrast, EAFP would look like this:
>
> > try:
> >     os.unlink(some_file)
> > except OSError:
> >     pass
>
> > But, as written, the EAFP code above is not satisfactory, because
> > there can be OSError's triggered for reasons other than the
> > non-existence of the regular file some_file.
>
> > What one needs is a finer granularity of exception, mapping to
> > exactly the error that one is guarding against.
>
> > Is there a standard approach to refining the granularity of exceptions
> > such as OSError?  The only approach I can think of is to somehow
> > parse the error string (assuming is available) to determine whether
> > the exception is indeed of the specific kind we're trying to catch.
> > But this strikes me as grossly inelegant.  Is there a better way?
>
> > (BTW, the problem is generic, because client code has no control
> > over the specificity of the exceptions raised by a library module.
> > If these exceptions turn out to be too broad, client code has to
> > somehow deal with this reality, at least in the short term.)
>
> > TIA!
>
> > kynn
>
> You can access the exception object which gives you greater detail.
>
> try:
>     os.unlink(some_file)
> except OSError, e:
>     print e.errno
>     print e.strerror
>
>     if e.errno == 2:
>         pass
>     else:
>         raise
>
> If it's the error you are looking for, handle it, or else raise.
>
> ~Sean

I do this myself in a lot of places, almost exactly like this. It's
slightly clearer to use 'if e.errno == errno.ENOENT' in my opinion,
but, whatever.

The only place I've run into issues with this is when dealing with
socket programming across operating systems. Python on Windows exports
all of the WSA errors when dealing with sockets, but 'WSAEHOSTUNREACH'
is not the same as 'ENETUNREACH.' In cases like that, you've got to be
careful to check for all possible variations of the same error if you
care about supporting Windows.

Thanks,

Jeff
mcjeff.blogspot.com
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Re: Granularity of OSError

[kj]

In <254eac4d-ce19-4af9-8c6a-5be8e7b0f...@u16g2000pru.googlegroups.com> Sean 
DiZazzo  writes:

>On Sep 18, 11:54=A0am, kj  wrote:
>> I've often come across the idea that good Python style deals with
>> potential errors using an EAFP ("easier to ask forgiveness than
>> permission") strategy rather than a LBYL ("look before you leap")
>> strategy.
>>
>> For example, LBYL would look like this:
>>
>> if os.path.isfile(some_file):
>> =A0 =A0 os.unlink(some_file)
>>
>> In contrast, EAFP would look like this:
>>
>> try:
>> =A0 =A0 os.unlink(some_file)
>> except OSError:
>> =A0 =A0 pass
>>
>> But, as written, the EAFP code above is not satisfactory, because
>> there can be OSError's triggered for reasons other than the
>> non-existence of the regular file some_file.
>>
>> What one needs is a finer granularity of exception, mapping to
>> exactly the error that one is guarding against.
>>
>> Is there a standard approach to refining the granularity of exceptions
>> such as OSError? =A0The only approach I can think of is to somehow
>> parse the error string (assuming is available) to determine whether
>> the exception is indeed of the specific kind we're trying to catch.
>> But this strikes me as grossly inelegant. =A0Is there a better way?
>>
>> (BTW, the problem is generic, because client code has no control
>> over the specificity of the exceptions raised by a library module.
>> If these exceptions turn out to be too broad, client code has to
>> somehow deal with this reality, at least in the short term.)
>>
>> TIA!
>>
>> kynn

>You can access the exception object which gives you greater detail.

>try:
>os.unlink(some_file)
>except OSError, e:
>print e.errno
>print e.strerror

>if e.errno =3D=3D 2:
>pass
>else:
>raise


>If it's the error you are looking for, handle it, or else raise.


Thanks, that's very handy. 

kynn
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Re: Not this one the other one, from a dictionary

[Vlastimil Brom]

2009/9/18 Ross :
>
> Learning my way around list comprehension a bit.   I wonder if someone has a
> better way to solve this issue.  I have a two element dictionary, and I know
> one of the keys but not the other, and I want to look up the other one.
>
> So I have this dictionary:
>
> aDict = {'a': 'bob', 'b': 'stu'}
>
> I know that the dictionary contains two keys/value pairs,  but I don't know
> the values nor that the keys will be 'a' and 'b'.   I finally get one of the
> keys passed to me as variable BigOne. e.g.:
>
> BigOne = "a"
>
> The other key, call it  littleOne remains unknown.  It might be "b" but
> could be "c", "x", etc...   I later need to access both values...
>
> I have something that works, with list comprehension - but wonder if there's
> a more brief/elegant way to get there:
>
> BigValu = aDict[BigOne]
> temp =  [ thing for thing in aDict if thing != BigOne ]
> LittleValu = aDict[ temp[0] ]
>
> Any thoughts?
>
> - Ross.
>
> --
> http://mail.python.org/mailman/listinfo/python-list
>

Hi,
not a list comprehension, but another useful approach to get the
complement of (a) given item(s) might be the set operations.
(As you are working with dict keys, the requirements for set elements
are automatically fulfilled.

>>> data_dict = {'a': 'bob', 'b': 'stu'}
>>> not_wanted_key = "a"
>>> other_key = (set(data_dict.iterkeys()) - set([not_wanted_key,])).pop()
>>> other_key
'b'
>>> data_dict[other_key]
'stu'
>>>

vbr
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Re: How do I begin debugging a python memory leak?

[Rainer Grimm]

On Sep 18, 5:42 pm, Paul Rubin  wrote:
> Rainer Grimm  writes:
> > have a look at valgrind.
>
> Have you actually used that on Python?
Not with python as far I can remember. But often with C++ executables,
as i mentioned it.
I you look at
http://valgrind.org/info/
there stands:
Valgrind has been used on programs written partly or entirely in C, C+
+, Java, Perl, Python, assembly code, Fortran, Ada, and many others.

It exists also a extension for python
http://blogs.gnome.org/jamesh/2008/03/24/python-valgrind/ , to get rid
of the false positiv errors.
So it should be worth a try.
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Re: detmining name during an assignment

[Gabriel Genellina]

En Fri, 18 Sep 2009 14:38:08 -0300, Christian Heimes   
escribió:

Jamie Riotto schrieb:


I have an app that uses Python scripting. When a user creates a new  
object:


objName = newObject()

I'd like the newObject be able to use objName as its internal name.


As the others already explained to you there is no way to archive your
goal with an assignment to a local or global variable. But you can
follow a different approach:

class Scene(object):
def __setattr__(self, name, value):
super(Scene, self).__setattr__(name value)
if isinstance(value, SceneObject):
value.name = name
value.scene = self

class SceneObject(object):
pass

class Cube(SceneObject):
pass

scene = Scene()
scene.cube1 = Cube()


As the OP said it's being used for scripting some application, presumably  
the application can control the environment on which the script is run.  
One may use the Scene class above as the globlal scope when executing the  
script:


scene = Scene()
code = "cube1 = Cube(); print cube1.name"
exec code in Scene

(well, not exactly, Scene should inherit from dict and override  
__setitem__ instead, but you get the idea)


--
Gabriel Genellina

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Re: How to print without spaces?

[koranthala]

On Sep 18, 9:49 pm, "Andreas Tawn"  wrote:
> > Hi,
>
> > I don't want to print the space between 'a' and 'b'. Could somebody
> > let me know how to do it?
>
> > Regards,
> > Peng
>
> > $ python
> > Python 2.5.2 (r252:60911, May 21 2008, 10:08:24)
> > [GCC 4.1.2 20070626 (Red Hat 4.1.2-14)] on linux2
> > Type "help", "copyright", "credits" or "license" for more information.
> > >>> print "a","b"
> > a b
>
> print "a" + "b"
>
> Cheers,
>
> Drea

What if I want to print 1 to 100 in a loop without spaces in between?
I think that is the OPs question.
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Re: How to print without spaces?

[Jerry Hill]

On Fri, Sep 18, 2009 at 4:16 PM, koranthala  wrote:
> What if I want to print 1 to 100 in a loop without spaces in between?
> I think that is the OPs question.

In that case I would skip using print entirely, and use something like this:

import sys
for i in xrange(100):
sys.stdout.write(str(i))
sys.stdout.write('\n')

That allows you to bypass any of the behavior of the print builtin
that you don't want.

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Re: Creating a local variable scope.

[Gabriel Genellina]

En Fri, 18 Sep 2009 10:55:47 -0300, Johan Grönqvist  
 escribió:


Summarizing the answers, it seems that I will try to follow three  
suggestions:


1) In general, try to restructure the code into smaller modules and  
smaller functions.


That's a good thing - "manageable" modules and functions.

2) When using many local variables bindings to create one larger object,  
define an inner function that hides those bindings.


I'd say, not to *hide* those bindings, but because the code fragment  
deserves logically to become a function.


3) If I define a few values intended to be used very locally, delete  
those after use.


Why bother? Unless they're big objects and you want to ensure they get  
deleted as soon as possible.


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Re: How to print without spaces?

[Wolfgang Rohdewald]

On Friday 18 September 2009, koranthala wrote:
> What if I want to print 1 to 100 in a loop without spaces in
>  between? I think that is the OPs question.

arr = ['a', 'b', 'c', 'andsoon']
print ''.join(arr)

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Re: Application-global "switches"?

[kj]

In <579a15bf-83c0-4228-9079-bbaac1222...@o13g2000vbl.googlegroups.com> Marius 
Gedminas  writes:

>On Sep 4, 9:29=A0pm, kj  wrote:
>> The only solution I can come up with is to define a "dummy module",
>> say _config.py, which contains only upper-case variables representing
>> these global switches, and is imported by all the other modules in
>> the application with the line "from _config import *". =A0During the
>> early stages of the run, the script inspects the command-line flags,
>> and if it finds a --continuing flag, it sets the variable
>> _config.CONTINUATION_MODE to True. =A0(The last point implies that
>> these variables are not strictly speaking read-only, since they
>> most be set at the beginning of the run. =A0But after this initial
>> setting, they should remain read-only.)

>Be very very careful about "from _config import *".  If you import
>a module that, in turn, imports _config this way, before you set
>the initial values, that module will already have made its own copies
>of all the variables and thus will not see the correct values.

Good point.  That's another reason for going for something like
Nick's solution earlier in this thread.

Thanks,

kynn
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Re: Why use "locals()"

[Sean DiZazzo]

On Sep 18, 9:55 am, Simon Forman  wrote:
> On Mon, Sep 14, 2009 at 1:12 AM, Sean DiZazzo  wrote:
>
> > Thanks for your explanation Steven.  I see how it can be valuable, but
> > it seems to always break the second rule of Zen.  I don't really want
> > to get into the code of debuggers, but I guess I can see how they
> > might have no other way to know what local variables have been set.
>
> > ~Sean
>
> The zeroth "rule" of zen is "don't take the rules so seriously".
> "They're really more like guidelines anyway."
>
> Regards,
> ~simon

Yeah.  I think I was just a bit randy at that moment.  I realized that
the (*args,**kwargs) idiom is very similar and I use it all the
time.

~Sean
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[ANN] pyjamas pyv8run converts python to javascript, executes under command-line

[lkcl]

just for fits and giggles and also because i'm getting fed up of using
web browsers as part of the pyjs development cycle instead of the
command-line, the pyjamas pyv8run.py has been brought back up-to-
scratch, and can now execute the pyjamas LibTest regression tests with
a 99.95% pass rate.

pyv8run is a back-to-back combination of google's v8 engine + a
library by flier liu which makes extensive use of python-boost (http://
code.google.com/p/pyv8) + the pyjamas python-to-javascript compiler.
the initial experiment some months ago, with pyjamas 0.5, produced a
python ACcellerator with a 10x performance increase; the latest
0.6~svn pyjamas compiler results in a python DEcellerator with a
[finger-in-the-air] 10x performance DEcrease, thanks to the addition
of several python strictness features.  hurrah! :)

perhaps it is the fact that the 0.5 test used google's stable x86
libv8, and the 0.6~svn test used google's alpha-release of amd64 libv8
- who knows, who cares, it's just hilarious to convert arbitrary
python code into javascript and have it do 99.95% the same job.

on the roadmap of this sub-sub-project of pyjamas is:

* to throw pyv8run at the standard http://python.org regression tests
and see what sticks

* to improve the pyjamas compiler and/or alter the adapted lib2to3
parser/AST library in order to create a stand-alone, self-bootstrapped
_javascript_ version of the pyjamas python-to-javascript compiler.
this is _mandatory_ in order to support "eval" and "exec" - execution
of python _source_ code - inside web browsers (and under a js> prompt
such as spidermonkey or d8)

this latter goal has already been hilariously achieved by the
(completely independent) skulpt project: http://skulpt.org/ whose
parser/AST code the pyjamas project has borrowed - and back-ported
from javascript to python.  you can see their demo python prompt on
the main page, and use it to mash your own web browser of choice into
submission.

the pyjamas project is taking a slightly different approach to achieve
this same goal: beat the stuffing out of the pyjamas compiler, rather
than hand-write such large sections of code in pure javascript, and
double-run regression tests (once as python, second time converted to
javascript under pyv8run, d8 or spidermonkey).

anyway, just thought there might be people who would be intrigued (or
horrified enough to care what's being done in the name of computer
science) by either of these projects.

l.
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Re: Python based paramiko package acting up on Linux, code works fine on windows

[flxkid]

On Sep 18, 11:22 am, flxkid  wrote:
> I've tried to post to the mailing list for paramiko and contact the
> author, but it seems he's having some mailing list problems.  Anyways,
> I have this small example that works just fine on Windows against
> Python 2.6.2, but fails on Ubuntu against 2.6.2.  Here is the code:
>
> import subprocess
> import os
> import re
> import paramiko
> import sqlite3
> import datetime
> import base64
> import sys
> import logging
> from paramiko.rsakey import RSAKey
>
> class OpenSessions:
>         sshconns = []
>         sqlconn = sqlite3.connect('test.sqlite')
>
>         def __init__(self):
>                 self.sqlconn.row_factory = sqlite3.Row
>                 sqlcur = self.sqlconn.cursor()
>                 sqlcur.execute("select host, pub_key, username, password,
> private_key from ssh_hosts")
>                 rows = sqlcur.fetchall()
>                 for row in rows:
>                         sshconn = paramiko.SSHClient()
>                         sshconn._system_host_keys.add(row["host"], "ssh-rsa", 
> RSAKey
> (data=base64.decodestring(row["pub_key"])))
>                         if row["private_key"] != "":
>                                 sshconn.connect(hostname=row["host"], 
> username=row["username"],
> pkey=RSAKey(data=base64.decodestring(row["private_key"])))
>                         elif row["password"] != "":
>                                 sshconn.connect(hostname=row["host"], 
> username=row["username"],
> password=row["password"], look_for_keys=False, timeout=60)
>                         self.sshconns.append(sshconn)
>
>                 output = ""
>                 for conn in self.sshconns:
>                         print conn.exec_command("uname -a")[1].readline()
>
>                 exit()
>
> if __name__== '__main__':
>         sessions = OpenSessions()
>
> The code fails with this trace:
> Traceback (most recent call last):
>   File "test.py", line 41, in 
>     sessions = OpenSessions()
>   File "test.py", line 36, in __init__
>     print chan.exec_command("uname -a")[1].readline()
>   File "/usr/local/lib/python2.6/dist-packages/paramiko/channel.py",
> line 212, in exec_command
>     self._wait_for_event()
>   File "/usr/local/lib/python2.6/dist-packages/paramiko/channel.py",
> line 1077, in _wait_for_event
>     raise e
> paramiko.SSHException: Channel closed.
> Exception in thread Thread-1 (most likely raised during interpreter
> shutdown):
> Traceback (most recent call last):
>   File "/usr/lib/python2.6/threading.py", line 525, in
> __bootstrap_inner
>   File "/usr/local/lib/python2.6/dist-packages/paramiko/transport.py",
> line 1567, in run
> : 'NoneType' object has no attribute
> 'error'
>
> This well beyond my abilities to debug.  All I know is that it always
> works on Windows, and always fails in Ubuntu (which of course is where
> I need use the code).  Any suggestions?  I know the paramiko mailing
> list would probably be the better spot for this, but like I said, its
> got some issues right now.
>
> OLIVER

Was a bug in paramiko channel.py in the _wait_for_event function.  All
fixed up now.

OLIVER
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Re: can python make web applications?

[lkcl]

On Sep 16, 7:02 pm, Paul Boddie  wrote:
> On 16 Sep, 18:31, lkcl  wrote:
>
>
>
> >http://pyjs.org/examples/timesheet/output/TimeSheet.html
>
> I get this error dialogue message when visiting the above page:
>
> "TimeSheet undefined list assignment index out of range"

 ah well spotted, thanks paul.
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Re: can python make web applications?

[lkcl]

On Sep 16, 7:02 pm, Paul Boddie  wrote:
> On 16 Sep, 18:31, lkcl  wrote:
>
>
>
> >http://pyjs.org/examples/timesheet/output/TimeSheet.html
>
> I get this error dialogue message when visiting the above page:
>
> "TimeSheet undefined list assignment index out of range"
>
> Along with the following in-page error, once the data has been
> imported:
>
> "JavaScript Error: uncaught exception: list assignment index out of
> range at line number 0. Please inform webmaster."
>
> It looks quite nice, though.
>
> Paul

DOH!  someone assuming javascript-isms in lists, and the compiler's
been improved to ban them :)

   ...
   self.date = None
   ...
   ...

   print 'setEntries:', entries
   try:
 #tt = time.localtime(time.time())
-tt = []
-tt[0] = int(self.date[:4])
-tt[1] = int(self.date[4:6])
-tt[2] = int(self.date[6:8])
+tt = [0] * 9
+if self.date:
+tt[0] = int(self.date[:4])
+tt[1] = int(self.date[4:6])
+tt[2] = int(self.date[6:8])
 tt[3] = 0
 tt[4] = 0
 tt[5] = 0
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Re: Creating a local variable scope.

[Sean DiZazzo]

On Sep 11, 10:36 am, Johan Grönqvist 
wrote:
> Hi All,
>
> I find several places in my code where I would like to have a variable
> scope that is smaller than the enclosing function/class/module definition.
>
> One representative example would look like:
>
> --
> spam = { ... }
> eggs = { ... }
>
> ham = (a[eggs], b[spam])
> --
>
> The essence is that for readability, I want spam and eggs in separate
> definitions, but for clarity, I would like to express the fact that they
> are "local to the definition of ham", i.e., they are not used outside of
>   the definition of ham.
>
> The language reference at
>  says that "The
> following are blocks: a module, a function body, and a class
> definition." (all other cases seem to refer to dynamic execution using
> eval() or similar). Python 3 and 2.6 seem to have identical scope rules.
>
> In the other languages I have used I can either use braces (C and
> descendants) or use let-bindings (SML, Haskell etc.) to form local scopes.
>
> Are there suggestions or conventions to maximize readability for these
> cases in python? (Execution time is not important in the cases I
> currently consider.)
>
> Regards
>
> Johan

I would do something like this:

>>> class Namespace(object):
... pass
...
>>> n = Namespace()
>>> n.f = 2
>>> n.g = 4
>>> print f
Traceback (most recent call last):
  File "", line 1, in ?
NameError: name 'f' is not defined
>>> print n.f
2

~Sean
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Re: detmining name during an assignment

[Jamie Riotto]

On Fri, Sep 18, 2009 at 1:10 PM, Gabriel Genellina
 wrote:
> En Fri, 18 Sep 2009 14:38:08 -0300, Christian Heimes 
> escribió:
>>
>> Jamie Riotto schrieb:
>
>>> I have an app that uses Python scripting. When a user creates a new
>>> object:
>>>
>>> objName = newObject()
>>>
>>> I'd like the newObject be able to use objName as its internal name.
>>
>> As the others already explained to you there is no way to archive your
>> goal with an assignment to a local or global variable. But you can
>> follow a different approach:
>>
>> class Scene(object):
>>    def __setattr__(self, name, value):
>>        super(Scene, self).__setattr__(name value)
>>        if isinstance(value, SceneObject):
>>            value.name = name
>>            value.scene = self
>>
>> class SceneObject(object):
>>    pass
>>
>> class Cube(SceneObject):
>>    pass
>>
>> scene = Scene()
>> scene.cube1 = Cube()
>
> As the OP said it's being used for scripting some application, presumably
> the application can control the environment on which the script is run. One
> may use the Scene class above as the globlal scope when executing the
> script:
>
> scene = Scene()
> code = "cube1 = Cube(); print cube1.name"
> exec code in Scene
>
> (well, not exactly, Scene should inherit from dict and override __setitem__
> instead, but you get the idea)
>
> --
> Gabriel Genellina
>
> --
> http://mail.python.org/mailman/listinfo/python-list
>

Thanks for the detailed clarifications and suggestions. I understand
the problem a lot better now.
However, I'll have to keep looking for a more elegant solution.
Telling a user that typing:
cube1 = Cube(name = cube1) is a good thing because its pythonic is
somehow unsatisfying.

Also, in the last suggestion about execution the script in the Scene
Handler global scope, well thats
exactly what I do, and yes, cube1=Cube, print cube1.name works great.
The issue is say perhaps that
cube then collides with something called sphere1. How does cube1 know
that it hit "sphere1" and not
just a sphere object. Since I can execute the scripts one line at a
time, I suppose I could search dictionaries
for new names pointing to the same object after every execution, but Yuck.

Perhaps the best approach is a preprossesor that looks for lines of
the form "name = class()" and adds in the
class(name = name) behind the scenes. Thanks again - jamie
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Re: pygame and py2app : big package

[TerryP]

On Sep 18, 9:28 pm, pdora...@pas-de-pub-merci.mac.com (Pierre-Alain
Dorange) wrote:
> I used py2app on Mac to build a package of my game (using pygame).
> It works fine (better than py2exe, i can'tmake work at tht time).
>
> But the package is very big.
> The biggest "thing" is numpy lib : 19 MB !
>
> numpy is very big and i doubt all is reallly needed
>
> --
> Pierre-Alain Dorange
>
> MicroWar 2.0 : kill some PC
>         

Excuse me, but what was the point? (id est, are you just saying this
or do you wish to ask a question?;)
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Re: Granularity of OSError

[Ryan Kelly]

> > You can access the exception object which gives you greater detail.
> >
> > try:
> > os.unlink(some_file)
> > except OSError, e:
> > print e.errno
> > print e.strerror
> >
> > if e.errno == 2:
> > pass
> > else:
> > raise
>
> I do this myself in a lot of places, almost exactly like this. It's
> slightly clearer to use 'if e.errno == errno.ENOENT' in my opinion,
> but, whatever.

In some cases it's also more correct.  While ENOENT is always 2, some
error codes differ between windows and posix.  In general it's better to
use the constants from the errno module.

   Ryan


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Re: pyjamas pyv8run converts python to javascript, executes under command-line

[Paul Boddie]

On 18 Sep, 23:17, lkcl  wrote:
>
> the pyjamas project is taking a slightly different approach to achieve
> this same goal: beat the stuffing out of the pyjamas compiler, rather
> than hand-write such large sections of code in pure javascript, and
> double-run regression tests (once as python, second time converted to
> javascript under pyv8run, d8 or spidermonkey).
>
> anyway, just thought there might be people who would be intrigued (or
> horrified enough to care what's being done in the name of computer
> science) by either of these projects.

I've added pyjamas to the implementations page on the Python Wiki in
the compilers section:

http://wiki.python.org/moin/implementation

The Skulpt implementation, already listed by Cameron Laird on his page
of Python implementations, is now also present, although using it is a
bit like using various 8-bit microcomputer emulators which assume a UK
keyboard and ignore the "replacement" keys on my own non-UK keyboard.

Paul
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Re: Granularity of OSError

[Christian Heimes]

kj wrote:
> For example, LBYL would look like this:
> 
> if os.path.isfile(some_file):
> os.unlink(some_file)
> 
> In contrast, EAFP would look like this:
> 
> try:
> os.unlink(some_file)
> except OSError:
> pass


The two version aren't equal. The first one suffers from a race
condition which may lead to a severe security issue. The file may be
gone or replaced by a different file in the time span between the check
and the call to unlink().

Christian

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Re: Granularity of OSError

[Sean DiZazzo]

On Sep 18, 5:23 pm, Christian Heimes  wrote:
> kj wrote:
> > For example, LBYL would look like this:
>
> > if os.path.isfile(some_file):
> >     os.unlink(some_file)
>
> > In contrast, EAFP would look like this:
>
> > try:
> >     os.unlink(some_file)
> > except OSError:
> >     pass
>
> The two version aren't equal. The first one suffers from a race
> condition which may lead to a severe security issue. The file may be
> gone or replaced by a different file in the time span between the check
> and the call to unlink().
>
> Christian

Thanks for pointing that out.  I never thought of it before.

~Sean
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Re: Substitute for KConfig in Qt4

[David Boddie]

On Thursday 17 September 2009 13:04, nusch wrote:

> I want to remove pyKDE dependencies from my app to make it pure PyQt.
> What will be the best substitute for KConfig?

What exactly do you use KConfig for in your application?

David
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Re: An assessment of the Unicode standard

[r]

On Friday 18 September 2009 06:39:57 Dennis Lee Bieber wrote:
(snip)

Snap (sort of).
Does anybody know where the concept of the purple people eater comes
from?
I mean is there a children's book or something?
- Hendrik

Where is the one eyed, one horned, lavender (antiquated) language
eater i ask! He would be a friend of mine for sure ;-)
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Re: Granularity of OSError

[Grant Edwards]

On 2009-09-19, Christian Heimes  wrote:
> kj wrote:
>> For example, LBYL would look like this:
>> 
>> if os.path.isfile(some_file):
>> os.unlink(some_file)
>> 
>> In contrast, EAFP would look like this:
>> 
>> try:
>> os.unlink(some_file)
>> except OSError:
>> pass
>
>
> The two version aren't equal. The first one suffers from a race
> condition which may lead to a severe security issue. The file may be
> gone or replaced by a different file in the time span between the check
> and the call to unlink().

IOW, just be cause you look before you leap, it doesn't mean
you're not going to land on anybody and have to ask for
forgiveness afterwards.

Since you always have to handle the error case, there's not
much point in checking first unless the error case has bad
side-effects that you're trying to avoid.  In this case,
attempting to unlink a non-existent file has no bad
side-effects, so there's no point in checking before the
unlink.

-- 
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Re: Podcast catcher in Python

[Chuck]

On Sep 12, 3:37 pm, Chuck  wrote:
> On Sep 11, 9:54 pm, Chris Rebert  wrote:
>
> > On Fri, Sep 11, 2009 at 7:43 PM, Chuck  wrote:
> > > Does anyone know how I should read/download the mp3 file, and how I
> > > should write/save it so that I can play it on a media player such as
> > > Windoze media player?  Excuse my ignorance, but I am a complete noob
> > > at this.  I downloaded the mp3, and I got a ton of hex, I think, but
> > > it could've been unicode.
>
> > urllib.urlretrieve():http://docs.python.org/library/urllib.html#urllib.urlretrieve
>
> > Cheers,
> > Chris
>
> Thanks Chris!  I will play around with this.

I am using Python 3.1, but I can't figure out why I can't use
xml.dom.minidom.  Here is my code:

from xml.dom.minidom import parse, parseString
url = 'http://minnesota.publicradio.org/tools/podcasts/
grammar_grater.xml'  #just for test purposes

doc = parse(url)  #I have also tried parseString(url), not to mention
a million other methods from xml.Etree, xml.sax etc...  all to no
avail


What the heck am I doing wrong?  How can I get this xml file and use
the toprettyxml() method.  Or something, so I can parse it.  I don't
have any books and the documentation for Python kind of sucks.  I am a
complete noob to Python and internet programming.  (I'm sure that is
obvious :) )

Thanks!

Charlie
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Re: Cross platform TTF font render from Python [was: Load TTF from pycairo under Windows]

[David Boddie]

On Friday 18 September 2009 08:54, Laszlo Nagy wrote:

> I need to render antialiased PNG images using TTF font files and UTF-8
> text. It needs to be available at least on Linux and Windows. This is
> what I have tried:

[...]

> #4. pygame - documentation looks great, it is cross platform. But the
> first example program I had tried has been terminated, printing out
> memory dump and complaining about double freeing some memory location.

I'm surprised this doesn't work. I've seen games that are distributed
with TrueType fonts, so I would expect them to work, or people would
probably say something. :-)

> What other options do we have?

PyQt4 can render Unicode text to all sorts of paint devices, and it supports
TrueType fonts, too. You basically do all the painting via a single API:

  http://www.riverbankcomputing.co.uk/static/Docs/PyQt4/html/qpainter.html

Here's a quick example of how it could be done:

  http://www.diotavelli.net/PyQtWiki/Paint%20on%20an%20image

All the relevant stuff happens in the updateImage() method.

David
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Re: Podcast catcher in Python

[Chris Rebert]

On Fri, Sep 18, 2009 at 7:34 PM, Chuck  wrote:

> I am using Python 3.1, but I can't figure out why I can't use
> xml.dom.minidom.  Here is my code:
>
> from xml.dom.minidom import parse, parseString
> url = 'http://minnesota.publicradio.org/tools/podcasts/
> grammar_grater.xml'  #just for test purposes
>
> doc = parse(url)  #I have also tried parseString(url), not to mention
> a million other methods from xml.Etree, xml.sax etc...  all to no
> avail
>
>
> What the heck am I doing wrong?  How can I get this xml file and use
> the toprettyxml() method.  Or something, so I can parse it.  I don't
> have any books and the documentation for Python kind of sucks.  I am a
> complete noob to Python and internet programming.  (I'm sure that is
> obvious :) )

Impossible to say, considering *you didn't actually state what
problem/error you're encountering*.

Cheers,
Chris
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