date:20070423

En Mon, 23 Apr 2007 02:17:49 -0300, Prateek [EMAIL PROTECTED] escribió:

 Oh dear god, I implemented this and it overall killed performance by
 about 50% - 100%. The same script (entering 3000 items) takes between
 88 - 109s (it was running in 55s earlier).

 Here is the new Set implementation:
 class SeaSet(set):
[...]

 The surprising thing is that commits *ARE* running about 50% faster
 (according to the time column in the hotshot profiler). But, now, the
 longest running operations seem to be the I/O operations which are
 taking 10 times longer! (even if they're only reading or writing a few
 bytes. Could this have something to do with the set implementation
 being in Python as opposed to C?

Hard to tell - you have posted only your SeaSet implementation, and no I/O  
is involved in that code.

 For instance, this method:
   def __readTableHeader(self, f):
   hdr = f.read(sz__TABLE_HEADER_FORMAT__)
   if len(hdr)  sz__TABLE_HEADER_FORMAT__:
   raise EOFError
   t = THF_U(hdr)
   #t = unpack(__TABLE_HEADER_FORMAT__, hdr)
   return t

 is now taking  13s when it was taking less than 0.8s before! (same
 number of calls, nothing changed except the set implementation)

I don't see where your SeaSet class is used.

-- 
Gabriel Genellina
-- 
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Re: Do other Python GUI toolkits require this?

On 2007-04-20, Paul Boddie [EMAIL PROTECTED] wrote:
 On 20 Apr, 16:34, Antoon Pardon [EMAIL PROTECTED] wrote:
 On 2007-04-20, Paul Boddie [EMAIL PROTECTED] wrote:

  You could have knowledge or accomplishment
  on the X axis and effort or work on the Y axis.

 What else is effort than the time you spent on it?

 What's the difference between watching a television programme called
 Useless Celebrity Factoids for half an hour and spending the same
 amount of time studying for an exam involving useful information where
 you might also need to show some level of understanding of the subject
 matter?

Do you want to discus principals or the practical problem in setting
up a study?

 If that's not comparing similar measures of information, what's the
 difference between studying for an exam in a subject whose
 prerequisites are familiar to you and studying for one in an
 unfamiliar field, both for the same amount of time?

Same question. If you are looking at the principals there is no
problem, those already familiar now, already have spent time/effort
at the subject. So you should calculate that time too.

In practice those setting up a study, try to pick a activity
noone is very familiar with.

-- 
Antoon Pardon
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Re: Select weirdness

2007-04-23 Thread Ron Garret

In article [EMAIL PROTECTED],
 Irmen de Jong [EMAIL PROTECTED] wrote:

 Ron Garret wrote:
  I don't understand why socketserver calling select should matter.  (And 
  BTW, there are no calls to select in SocketServer.py.  I'm using 
  Python2.5.)
 
 You don't *need* a select at all.

Yes I do, because what I'm really writing is a dispatching proxy that 
has to serve many simultaneous connections.

Here's the full story in case you're interested: We have an application 
that is currently fielded as a cgi.  We have a development server that 
needs to run multiple copies of the application at the same time.  This 
is so that developers can push changes into their private sandboxes 
for evaluation before going into the main development branch.  Each 
sandbox has its own source tree, its own database, and its own URL 
namespace.

There are a small number of URLs in the application that are performance 
bottlenecks (they are used to serve AJAX updates).  In order to 
alleviate that bottleneck without having to rewrite the whole 
application to run under mod_python or some such thing we've written a 
special dedicated server that handles only the AJAX requests.

The tricky part is that each developer needs to have their own copy of 
this server running because each developer can have different code that 
needs to run to serve those requests.  Assigning each developer a 
dedicated IP port would be a configuration nightmare, so these servers 
serve run on unix sockets rather than TCP sockets.

I have not been able to find a proxy server that can proxy to unix 
sockets, so I need to write my own.  Conceptually its a very simple 
thing: read the first line of an HTTP request, parse it with a regexp to 
extract the sandbox name, connect to the appropriate unix server socket, 
and then bidirectionally pipe bytes back and forth.  But it has to do 
this for multiple connections simultaneously, which is why I need select.

  Anyway, try the following instead:
 
  
  That won't work for POST requests.
 
 
 Why not?

Because POST requests can be very complicated.

 Just add some more code to deal with the POST request body.

I was really hoping to avoid having to write a fully HTTP-aware proxy.

 There should be a content-length header to tell you how many
 bytes to read after the header section has finished.

Not if the content-transfer-encoding is chunked.  Or if there are 
multiple file attachments.

Also, even GET requests can become very complicated (from a protocol 
point of view) in HTTP 1.1.

rg
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Re: Do other Python GUI toolkits require this?

On 2007-04-21, Diez B. Roggisch [EMAIL PROTECTED] wrote:
 Antoon Pardon schrieb:
 On 2007-04-20, Diez B. Roggisch [EMAIL PROTECTED] wrote:
 So if you have the choice between a steep or a shalow income curve
 you will prefer the shalow curve because a steep curve makes you
 think about verticale clifs and such?

 The analogy with a walk is just silly because curves are not like walks.
 Nobody will say something like: I won't invest in that company because
 it has a steep profit curve or the reverse: I'll invest in this company
 because it has an easy looking downhill going profit curve.
 Your whole argumentation bases on the fact that the result of the 
 learning process, and the success of it, has something to do with the 
 reached height - or y-axis-value - of your climb.

 Which is nonsense. The goal is to go from A - ignorance - to B - 
 knowledge - which both lie on the X-Axis.
 
 Well if you want to do it that way, nobody can stop you, but people
 in the habit of processing numbers usually put the time on the X-axis
 like in time spend learning or exercising and put the other value
 on the Y-axis. 


 You seem to live in a very limited world, where bezier-curves (note the 
 name...)
 are parametrized over t, but rendered on the x/y-axis happily going 
 forth and back and whatnot.

I'm not talking about bezier-curves or any parametric curve, because
it doesn't make sense to talk about steep and shalow curves then, since
there is no implication of hard/slow easy/fast associated then
with steep or shalow, you might as well use polar coordinates.

 If using knowledge as the x-axis and effort on the y-axis, the figure of 
 speech makes perfect sense.

That is an after the fact interpretation. There certain
rules/conventions in picking your variables when you want to draw a
curve. The association of steep and shalow of a curve with some real
world implication depends on those rules/conventions.

If you don't follow those rules/conventions don't think you can get
a message across by saying steep, because any data can be put on
a steep curve if you are allowed to pick how to draw your axes.

So your statement doesn't mean much more than: After I have played
with the paper, turned it over, rotated it a bit, the curve looks
steep.

 That is because people prefer a curve going up and down while moving
 to the right instead of going left and right while moving up.

 Which is obviously something people don't want to do in this context, 
 because going down doesn't make too much sense here, doesn't it? Or do 
 you want to cram the process of unlearning in the little figure of 
 speech as well?

Then those people shouldn't refer to curves. If people want to refer
to curves in order to bring a message accross then the message should
make sense to those familiar with curves. I can understand that some
people find that doing so, makes their message feel wrong. Not a
problem, use an other metaphor. Don't twist the metaphor to get
a message that feels all right to you but brings nonsense to those
who are familiar with the metaphor.

 But even a perfectly sense-making explanation can be found, I doubt that 
 you will ever acknowledge that you did make a mistake on this one - as 
 you always (or better never) do...

As far as I can see I don't differ from most people in this respect
on this news group.

-- 
Antoon Pardon
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Re: Python and Javascript equivalence

2007-04-23 Thread Marc 'BlackJack' Rintsch

In [EMAIL PROTECTED], Prateek wrote:

 Try creating a dict with sequential numeric keys.
 
 If you already have a list called my_list, you can do:
 
 com_array = dict(zip(range(len(my_list)), my_list))

com_array = dict(enumerate(my_list))

That doesn't create the intermediate lists.

Ciao,
Marc 'BlackJack' Rintsch
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Re: Do other Python GUI toolkits require this?

On 2007-04-22, René Fleschenberg [EMAIL PROTECTED] wrote:
 Antoon Pardon schrieb:
 Who says the axes are labeled familiarity and learning period?   I
 just assume they are labeled (y-axis) Effort and (x-axis) Knowledge
 (or skill or ).  
 
 You can assume all you want, but no serious person processing numbers
 would choose axes like that.

 The vast majority of world population is not into processing numbers,
 so why should they care?

They don't have to care at all. But if they don't care about how curves
are usually organized, maybe they are better of not using curves to
bring a message across, since it risks to bring the wrong message to
those who are familiar with curves.

-- 
Antoon Pardon
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Re: Select weirdness

En Mon, 23 Apr 2007 04:33:22 -0300, Ron Garret [EMAIL PROTECTED]  
escribió:

 I have not been able to find a proxy server that can proxy to unix
 sockets, so I need to write my own.  Conceptually its a very simple
 thing: read the first line of an HTTP request, parse it with a regexp to
 extract the sandbox name, connect to the appropriate unix server socket,
 and then bidirectionally pipe bytes back and forth.  But it has to do
 this for multiple connections simultaneously, which is why I need select.

No. This is what the *server* should do, not the *handler*. The server  
listens on incoming requests, and creates a new handler for each one.  
Inside a handler, you don't have to worry about multiple connections.
If you want to process simultaneous connections, inherit your server from  
ThreadingMixIn or ForkingMixIn (or use one of the predefined server  
classes).

-- 
Gabriel Genellina
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Re: Dictionaries and dot notation

En Mon, 23 Apr 2007 03:14:32 -0300, Martin Drautzburg  
[EMAIL PROTECTED] escribió:

 I did not notice that I can use a single class (or a module) for
 all my datastructures, because I can plug in new attributes into the
 instance without the class knowing about them.

 I was mistaken to believe that I had to know about attributes at the
 time of class creation. But your expample does not require that. Should
 have read this more carefully.

Welcome to Python and its dynamic  nature!

-- 
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Re: Do other Python GUI toolkits require this?

On 2007-04-20, Dennis Lee Bieber [EMAIL PROTECTED] wrote:
 On 20 Apr 2007 12:25:40 GMT, Antoon Pardon [EMAIL PROTECTED]
 declaimed the following in comp.lang.python:

 
 But if a wrong idea is circulating and nobody ever tries to correct it,
 people will continue with the wrong idea. All I did was make a simple
 remark, that as I suggested anyone could ignore, but that would allow
 those willing to learn, to further investigate.

   But is it a wrong idea if 999 people interpret the phrase one way,
 and just 1 insists upon an interpretation that, while correct in a small
 technical area, results in misunderstanding when speaking with the other
 999?

   The lay person sees productivity as movement on the x-axis (I'm
 here [start of job], I need to get there [end of job]).

I dare you. Give some people some data: Like the productivity of each
month in a year and ask them to put those numbers on a graph. I bet most
will put the months on the x-axis and the productivity on the y-axis.

-- 
Antoon Pardon
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Re: python cgi problem with textarea

2007-04-23 Thread placid

On Apr 23, 1:01 am, Adrian Smith [EMAIL PROTECTED] wrote:
 On Apr 22, 10:09 pm, placid [EMAIL PROTECTED] wrote:

  i just tried it and its working. here it is

 http://yallara.cs.rmit.edu.au/~bevcimen/form.html

  maybe the internal server error is because mod_python isn't installed
  assuming your using Apache as your web server

 Yeah, but it wouldn't work *at all* in that case, would it? ATM it
 seems to work as long as the textarea input has no spaces.

it doest work because the space character isnt interpreted
correctly, you need
to change the space characters too nbsp;

Cheers


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Re: python cgi problem with textarea

2007-04-23 Thread Peter Otten

Adrian Smith wrote:

 ...and I get an internal server error if I have any spaces in the
 textarea, which is really going to limit its usefulness to me. Oddly,

While debugging you should put

 #!/usr/bin/python
  
  import cgitb
  cgitb.enable()

 import cgi
 print Content-type: text/html\n
 form = cgi.FieldStorage()
 print form[essay].value

at the beginning of your cgi -- just in case the error is in the python
script.

Peter

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Two syntax questions (newbie)

2007-04-23 Thread Szabolcs


I used Mathematica for data processing a lot and I got spoiled by its
functional programming possibilities.
I was drawn to Python because it also allows for a similar programming
style (and, more importantly, it has an interactive shell, ipython,
and a lot of libraries that are useful to me, like scipy).
I am still learning the language, so please be gentle :-)

And here comes the first question:

Mathematica allows writing
result = [EMAIL PROTECTED]@[EMAIL PROTECTED]
or even
result = data//Sort//Reverse//processData
instead of
result = processData[Reverse[Sort[data]]]

In Python this would be something like
result = processData(list(reversed(sorted(data

The first two Mma alternatives are both easier to read (especially
when part of a bigger expression) and easier to type (an re-type, if
working interactively) because I don't have to jump with the cursor to
the beginning and end of the expression to insert the brackets when
adding another function call.

Is there a way to avoid typing all the parentheses in Python? Is it
possible to define a different syntax for function calls or define a
function composition operator for functions that take a single
argument?

The second question:

Of course Python is not Mathematica and not as friendly with this
style as Mma is. Sometimes it forces me to use some temporary
variables (e.g. because lines get too long and breaking lines with a
backslash is ugly). I like to get rid of these variables as soon as
they aren't needed, e.g.:

temp = data[:]
temp.sort()
temp.reverse()
result = processData(temp)
del temp

Is it possible to avoid the explicit del temp? In C/C++ I would simply
enclose the piece of code in curly brackets. Is it possible to somehow
separate a block of code from the rest of the program and make
variables local to it?

Of course none of these two things would allow me do to something that
I can not already do, but they would make work easier. And I am
curious if they are possible.

Thanks for your replies in advance,
Szabolcs

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Re: Dictionaries and dot notation

2007-04-23 Thread 人言落日是天涯，望极天涯不见家

On 2007-04-22, Martin Drautzburg [EMAIL PROTECTED] wrote:
 Daniel Nogradi wrote:


  What if I want to create a datastructure that can be used in dot
  notation without having to create a class, i.e. because those
  objects have no behavior at all?

 A class inheriting from dict and implementing __getattr__ and
 __setattr__ should do the trick...
 
 
 It can do the trick but one has to be careful with attributes that are
 used by dict such as update, keys, pop, etc. Actually it's noted in a
 comment at
 http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/361668 why the
 whole idea (attribute access of dictionaries) is a bad idea and I tend
 to agree.

 Oh thank you. So all I have to do is have my object's class implement
 __setattr__ and __getattr__, or derive it from a class that does so?
 And I could save my attributes anywhere within my instance variables.
 So I could even add a dictionary whose name does not conflict with what
 python uses and whose key/value pairs hold the attributes I want to
 access with dot notation and delegate all the python attributes to
 their native positions? Oh I see, thats tricky. I still need to be
 aware of the builtin stuff one way or the other.

Maybe you can do the opposite and create a class that implements
__getitem__ and __setitem__ in function of attribute access.

The following is an example:

class Rec(object):
 def __init__(__, **kwargs):
 for key,value in kwargs.items():
 setattr(__, key, value)

 def __getitem__(self, key):
 return getattr(self, key)

 def __setitem__ (self, key, val):
 setattr(self, key, val)


rec = Rec(a=1)

print rec.a
print rec[a]

rec.b = 2
print rec[b]

rec[c] = 3
print rec.c

-- 
Antoon Pardon
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ctypes: how to make a structure pointer to point to a buffer

first, I'm try the POINTER to convesion the pointer type. but failed.

class STUDENT(Structure):
_fields_ = [('name',  c_int),
('id',   c_int),
('addition',c_ubyte)]

buffer = c_byte * 1024
student_p = cast(buffer, POINTER(STUDENT))

The parameter of the POINTER must be ctypes type.
How could I attach the buffer pointer to the structure STUDENT ?

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Re: serializable object references

En Mon, 23 Apr 2007 03:35:42 -0300, Martin Drautzburg  
[EMAIL PROTECTED] escribió:

 Gabriel Genellina wrote:

 En Sun, 22 Apr 2007 12:47:10 -0300, Martin Drautzburg
 [EMAIL PROTECTED] escribió:

 I was thinking that it would be nice if a web application could talk
 to real objects. The client side does not need to know the internals
 of an object, it acts as a view for server-side models. All it has
 to be able to do is invoke methods on its model. So a view could
 just store its object-reference in an instance variable and pass it
 to the server, where my problem of looking it up comes in.

 This is more or less what several web frameworks do. You publish
 objects; URLs are mapped to method objects; URL parameters become
 method parameters. See http://wiki.python.org/moin/WebFrameworks

 Okay will look. I have checked out cherrypy, but it does not seem to
 support direct object references, i.e. the server-side objects are
 really stateless and all calls to an object method will see the same
 state unless you do something about it youself.

The description I wrote above aplies exactly to ZOPE: URLs map exactly to  
object methods and those objects can (and should) maintain state. (Zope  
uses an OO database, ZODB, to hold those objects).
But Zope is a big framework and not easy to grasp, so I would not recomend  
it for a small site or web application.
Using CherryPy you can keep state across requests, if you use some sort of  
session machinery; at least you could build a mapping SessionID-State (the  
state being as complex as you want).
I think TurboGears has something built in for managing sessions, but I'm  
not sure.

 I have also looked at the wonderful qooxdoo javascript framework and in
 the examples they have, the data I receive on a published object method
 on my cherrypy server is:

Never used qooxdoo...

-- 
Gabriel Genellina
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Re: Two syntax questions (newbie)

En Mon, 23 Apr 2007 05:15:26 -0300, Szabolcs [EMAIL PROTECTED] escribió:

 Mathematica allows writing
 result = [EMAIL PROTECTED]@[EMAIL PROTECTED]
 or even
 result = data//Sort//Reverse//processData
 instead of
 result = processData[Reverse[Sort[data]]]

 In Python this would be something like
 result = processData(list(reversed(sorted(data

 The first two Mma alternatives are both easier to read (especially
 when part of a bigger expression) and easier to type (an re-type, if
 working interactively) because I don't have to jump with the cursor to
 the beginning and end of the expression to insert the brackets when
 adding another function call.

 Is there a way to avoid typing all the parentheses in Python? Is it
 possible to define a different syntax for function calls

Not a different syntax.

 or define a
 function composition operator for functions that take a single
 argument?

You could use this:

def chain(*args):
   Compose functions (assoc right).
   last argument (args[-1]): argument to last function
   args[0] .. args[-2]: functions taking a single argument
   Returns args[0](args[1](...(args[-2]))(args[-1])
   
   args = list(args)
   data = args.pop(-1)
   while args:
 fn = args.pop(-1)
 data = fn(data)
   return data

import random
items = [random.randrange(100) for _ in range(20)]
print chain(list, reversed, sorted, items)


 Of course Python is not Mathematica and not as friendly with this
 style as Mma is. Sometimes it forces me to use some temporary
 variables (e.g. because lines get too long and breaking lines with a
 backslash is ugly).

I almost never use backslashes for line continuation. If you have an open  
(,[,{ continuation is implicit. If not, usually adding a heading ( is  
enough.
That is, instead of

x = a + b + \
 c - d

I'd use:

x = (a + b +
  c - d)

 I like to get rid of these variables as soon as
 they aren't needed, e.g.:

 temp = data[:]
 temp.sort()
 temp.reverse()
 result = processData(temp)
 del temp

 Is it possible to avoid the explicit del temp? In C/C++ I would simply
 enclose the piece of code in curly brackets. Is it possible to somehow
 separate a block of code from the rest of the program and make
 variables local to it?

Python does not have block scope; use a function instead. (It's hard to  
define block scopes without variable declarations). Anyway that would make  
any difference if you are using huge structures.

-- 
Gabriel Genellina
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Re: * Dr G Polya BRILLIANTLY analyses the Virgina Shooting Incident *

2007-04-23 Thread The Real Andy

On 22 Apr 2007 17:17:40 -0700, [EMAIL PROTECTED] wrote:

On Apr 22, 8:49 pm, Jim Thompson [EMAIL PROTECTED]
Web-Site.com wrote:
 Ignorant Bastard Poster

 On 22 Apr 2007 11:32:34 -0700, [EMAIL PROTECTED] wrote:

 Dr Gideon Polya published some 130 works in a 4 decade scientific
 career, most recently a huge pharmacological reference text
 Biochemical Targets of Plant Bioactive Compounds (Taylor  Francis,
 New York  London, 2003), and is currently editing a completed book on
 global avoidable mortality (numerous articles on this matter can be
 found by a simple Google search for Gideon Polya and on his
 websites:

 Here is the BRILLIANT AND INCISIVE ANALYSIS:

 http://countercurrents.org/polya230407.htm--

 Dr Polya, we are incredibly proud of you. God Bless you for your
 courage.

Note that Dr. Polya comes from Tasmania - the Australian state where I
was born.

Meanwhile, Jim's decline continues - he has now committed top posting.
Institutionalisation can't be far away.

 A few home truths, but when i read this kind of diatribe:

The past and present US mass murder and genocide is largely
un-reported by lying, racist, genocide-ignoring Mainstream media and
Racist Bush-ite (RB) America (and its lackey Racist White Australia)
are ruled by régimes locked into denial over the seriousness of global
warming

Makes me wonder about the credibility of any statement Dr Gideon Polya
makes.
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Re: Two syntax questions (newbie)

2007-04-23 Thread Szabolcs

Thanks for the reply!

On Apr 23, 10:55 am, Gabriel Genellina [EMAIL PROTECTED]
wrote:
  or define a
  function composition operator for functions that take a single
  argument?

 You could use this:

 def chain(*args):
Compose functions (assoc right).
last argument (args[-1]): argument to last function
args[0] .. args[-2]: functions taking a single argument
Returns args[0](args[1](...(args[-2]))(args[-1])

args = list(args)
data = args.pop(-1)
while args:
  fn = args.pop(-1)
  data = fn(data)
return data

 import random
 items = [random.randrange(100) for _ in range(20)]
 print chain(list, reversed, sorted, items)

This is already better. Is it possible to define function composition
as an operator and have something like ([EMAIL PROTECTED]@sorted)(items)
or (list*reversed*sorted)(items) ?

 I almost never use backslashes for line continuation. If you have an open
 (,[,{ continuation is implicit. If not, usually adding a heading ( is
 enough.
 That is, instead of

 x = a + b + \
  c - d

 I'd use:

 x = (a + b +
   c - d)

Thanks! This is very useful.

Szabolcs

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Re: Support for new items in set type

2007-04-23 Thread Prateek

 I don't see where your SeaSet class is used.

Actually that is the point. According to the hotshot profile, the
problem code doesn't use the SeaSet implementation. Yet that same code
was running much faster earlier. I tried multiple time (2-3 times).
From what I can fathom, nothing else changed - just the set
implementation.

It seems obvious that the read() call in the __readTableHeader method
is blocking for longer periods although it isn't exactly obvious why
that might be.

I was hoping someone with an idea of Python-C interaction could shed
some light on this. I'm on a different computer right now, I'll log
back in later and post more code if that helps.

Again, thanks to anyone who can help.

Prateek

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Re: When are immutable tuples essential? Why can't you just use lists everywhere instead?

2007-04-23 Thread 人言落日是天涯，望极天涯不见家

On 2007-04-20, Gabriel Genellina [EMAIL PROTECTED] wrote:
 En Fri, 20 Apr 2007 15:28:51 -0300, Bjoern Schliessmann  
[EMAIL PROTECTED] escribió:

 Luis M. González wrote:

 I don't remember exactly where I read about it, but Guido said
 once that tuples are being kept mainly for historical reasons.

 Weren't tuples added when lists already existed?

 Both listobject.c and tupleobject.c appear to had been checked in at the  
 same time:

 Revision 2167 - (view) (download) (as text) - [select for diffs]
 Added Sun Oct 14 12:07:46 1990 UTC (16 years, 6 months ago) by guido
 File length: 4965 byte(s)
 Initial revision

 And that's before the earliest tagged release I could find on svn, Python  
 0.98

But this doesn't contradict the supposed comment from guido. One can
add something later and come to the conclusion that it would have been
better not included but that in the mean time too much depend on it
to remove it. That seems a perfect description of keeping something
for historical reasons.

So it is possible that one keeps something for historical reasons
that is more recent than something one keeps for design reasons.

-- 
Antoon Pardon
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Re: ctypes: how to make a structure pointer to point to a buffer

2007-04-23 Thread Diez B. Roggisch

人言落日是天涯，望极天涯不见家 wrote:

 first, I'm try the POINTER to convesion the pointer type. but failed.
 
 class STUDENT(Structure):
 _fields_ = [('name',  c_int),
 ('id',   c_int),
 ('addition',c_ubyte)]
 
 buffer = c_byte * 1024
 student_p = cast(buffer, POINTER(STUDENT))
 
 The parameter of the POINTER must be ctypes type.
 How could I attach the buffer pointer to the structure STUDENT ?

I think it should work like this:

from ctypes import *

class STUDENT(Structure):
_fields_ = [('name',  c_int),
('id',   c_int),
('addition',c_ubyte)]

buffer = (c_byte * 1024)()
buffer_p = pointer(buffer)
student_p = cast(buffer_p, POINTER(STUDENT))

print student_p


Diez
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Re: ctypes: how to make a structure pointer to point to a buffer

On Apr 23, 5:42 pm, Diez B. Roggisch [EMAIL PROTECTED] wrote:
 人言落日是天涯，望极天涯不见家 wrote:
  first, I'm try the POINTER to convesion the pointer type. but failed.

  class STUDENT(Structure):
      _fields_ = [('name',  c_int),
                      ('id',   c_int),
                      ('addition',    c_ubyte)]

  buffer = c_byte * 1024
  student_p = cast(buffer, POINTER(STUDENT))

  The parameter of the POINTER must be ctypes type.
  How could I attach the buffer pointer to the structure STUDENT ?

 I think it should work like this:

 from ctypes import *

 class STUDENT(Structure):
     _fields_ = [('name',  c_int),
                     ('id',   c_int),
                     ('addition',    c_ubyte)]

 buffer = (c_byte * 1024)()
 buffer_p = pointer(buffer)
 student_p = cast(buffer_p, POINTER(STUDENT))

 print student_p

 Diez


yes, it should add the bracket
buffer = (c_byte * 1024)()

Thank you !

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Re: Two syntax questions (newbie)

2007-04-23 Thread Diez B. Roggisch

 This is already better. Is it possible to define function composition
 as an operator and have something like ([EMAIL PROTECTED]@sorted)(items)
 or (list*reversed*sorted)(items) ?

Not on functions, but on classes/instances. So something like this might
work for you (untested):

class FunctionComposer(object):
def __init__(self, f=None):
if f is None:
   f = lambda x: x
self._f = f

def __call__(self, *args, **kwargs):
return self._f(*args, **kwargs)

def __mul__(self, other):
def combined(*args, **kwargs):
return other(self._f(*args, **kwargs))
return FunctionComposer(combined)

fc = FunctionComposer

Then you can write

(fc() * list * reversed * sorted)(items)

Diez
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Re: recursion depth problem

2007-04-23 Thread Michael Bentley


On Apr 23, 2007, at 1:57 AM, proctor wrote:

 On Apr 22, 5:51 pm, Michael Bentley [EMAIL PROTECTED] wrote:
 Oops!  Note to self: *ALWAYS* try code before posting to a public
 forum :-(

 def binary(val, width):
 print '%10s = the sum of' % val
 for i in [2 ** x for x in range(width - 1, -1, -1)]:
 a = val / i
 print ' ' * 13 + '%s * (2 ** %s)' % (a, width)
 val -= i * a
 width -= 1

 binary(233, 8)

 hi michael,

 just a quick clarification...

 it seems to me that the self-documenting part of the code should be
 more like this:

 print ' ' * 13 + '%s * (2 ** %s)' % (a, width-1)

 instead of

 print ' ' * 13 + '%s * (2 ** %s)' % (a, width)

 is this correct, or am i mixed?


No, you're right -- actually I ended up decrementing width after the  
print instead of before it -- but didn't feel like posting yet  
another correction.  Your correction works though!



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Offer of free dedicated servers for the Python project

2007-04-23 Thread Jasper Bryant-Greene

Hi All

Please don't interpret this as spam or as a posting of a commercial
nature. I am here to point out an opportunity for the Python project to
receive some free hardware support. I'm not here to sell anything :)

My company, DirectScale, is offering 10 free dedicated servers to
open-source projects. This can be Python, or any project related to
Python, or any project at all, as long as its deliverables are licensed
under an OSI-approved open-source license.

The only requirement is that someone responsible for the project contact
us via our website (www.directscale.com) outlining what they would use
the servers for.

I encourage any project who could make good use of some free servers to
get in touch, as this opportunity will not last.

Thanks for your time.

-- 
Jasper Bryant-Greene [EMAIL PROTECTED]
Album Limited

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Re: Do other Python GUI toolkits require this?

2007-04-23 Thread Michael Bentley

OK.  In order to kill the-thread-that-would-not-die(tm), I think I  
know what I must do.  I'll print a correction:

On Apr 19, 2007, at 2:22 AM, Michael Bentley wrote:
 ... I switched to PyObjC.  The
 learning curve is rather steep IMO, but worth it.  One thing I think
 I should mention though is that if you move to PyObjC -- do some
 projects in Objective C first.  Otherwise your brain will implode.

Should be changed to:

.. I switched to PyObjC.  The
learning-effort curve is rather steep IMO, but worth it.  One thing I  
think
I should mention though is that if you move to PyObjC -- do some
projects in Objective C first.  Otherwise your brain will implode.

Hope this helps,
Michael ;-)



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The Hack of bitmask used as Predicate Parameters

2007-04-23 Thread Xah Lee

In this article, i explain how the use of bit masks is a hack in many
imperative languages.

Often, a function will need to take many True/False parameters. For
example, suppose i have a function that can draw a rainbow, and each
color of the rainbow can be turned on or off individually. My function
specification can be of this form: “rainbow(red, orange, yellow,
green, blue, violet, purple)”. Each parameter is a true or false
value. So, to draw a rainbow with only red and yellow stripes on, one
would code, for example “rainbow(t,f,t,f,f,f,f)”, where “t” stands for
true and “f” stands for false. (or, similar values for the true/false
of the language's boolean system)

The problem with this simple approach is that when a function has too
many parameters, “which position means what” becomes difficult to
remember and manage. Alternatively, a high-level language may provide
a system for named parameters. So, for example, the function may be
called like this with 2 arguments “rainbow(red:t, yellow:t)”, meaning,
give the true values to the parameters named “red” and “yellow”.
Parameters not given may automatically assumed to have false values by
default. Similarly, the language can simply have the function call
look like this: “rainbow(red, yellow)”, where omitted parameter names
simply means false.

LSL deals with this issue by using a concept of bit-mask that came
from low-level languages. From the programer's point of view, the way
to call this rainbow function would look like this: “rainbow(red|
yellow)”. On the surface, it seems just a syntax variation. But
actually, the “red” and “yellow” here are global constants of type
integer, defined by the language, and the “|” is actually a bit-wise
binary operator. To explain this to a educated person (e.g. a
mathematician) but who are not a professional programer, it gets a bit
complex as one has to drag in binary notation, boolean operation on
binary notation realized as a sequence of slots, and the compiler ease
in processing numbers as binary digits, and the compiler writer and
language designer's laziness in resorting to these instead of a high-
level interface of named parameters.

The hack of using the so-called bit-mask as a interface for functions
that need named parameters, is similar to languages using “1” and “0”
as the true/false symbols in its boolean system, and languages using
the “or” operator “||” as a method of nested “if else” program flow
constructs. The problem with these hacks, is that they jam logically
disparate semantics into the same construct. Their effects is making
the source code more difficult to read, and thus increased programer
error.



It may seem like nickpicking to say that it is a hack. However, when
many such seemingly trivially improper designs appear in a language,
adds up to the language's illness, and overall making the language
difficult to learn, difficult to read, difficult to extend, increase
programing errors, and most importantly, reduce a clear understanding
of key concepts.

Unix and C, are the primary perpetrator of this sin. Due to their
“$free$” and “speedy” and “simplistic” nature as cigarettes given to
children, have passed these designs to many imperative languages and
left programers not understanding the basic issues of a function's
parameters and named parameters.

Examples of using bitmask as a hack:

• Many functions in C. (e.g. fcntl)

• Unix's function/“command line tool”'s error values. (as bits)

• Perl's “sysopen”, “select”, and others. (if you know a perl example
that isn't related to unix, pls let me known)

• Second Life's Linden Scripting Language.
(see http://xahlee.org/sl/ls-prob.html )

A example of confusion about function's parameters is exhibited in
unix's bewildering, inconsist syntaxes in its command line tools's
ways of taking arguments. (some parameter influence other parameters.
Argument order sometimes matter, sometimes doesn't, sometimes causing
unintented output and sometimes causing syntax error. Named parameters
sometimes have the names optional(!). Named parameters that are
predicates sometimes act by their presence along, sometimes by their
value, sometimes accept both, sometimes causes syntax error. Some
defaults are supplied to unnamed parameters, and some are to named
parameters. Some parameters has synonyms. ...)

For another example in a more modern language, is Python's
“re.search()” function for text pattern matching. Its optional third
parameter is a bitmask.  ( see “Regular Expressions in Python”
http://xahlee.org/perl-python/python_re-write/lib/node111.html )

As a example of not clearly understanding a function's parameters and
the need and role of named parameters in computing languages, Python's
“sorted” function as well as its “lambda” construct are both victims.

(Further reading:
• “Sorting in Python and Perl”
http://xahlee.org/perl-python/python_doc_sort.html

• “Python Doc Problem Example: sort()”
http://xahlee.org/perl-python/sort_list.html

• “Lambda

Re: [ANN] Pythonutils 0.3.0

2007-04-23 Thread Colin J. Williams

Fuzzyman wrote:
 There is a new (and long overdue) release of the `Pythonutils module
 http://www.voidspace.org.uk/python/modules.shtml#pythonutils`_.
 This is version **0.3.0**.
 
 * `Quick Download: Pythonutils 0.3.0.zip http://www.voidspace.org.uk/
 cgi-bin/voidspace/downman.py?file=pythonutils-0.3.0.zip`_
 
 
 What is Pythonutils?
 ===
 
 Pythonutils is a collection of general utility modules that simplify
 common programming tasks in Python.
 
 
 The modules included are :
 
 * `ConfigObj http://www.voidspace.org.uk/python/configobj.html`_
 4.4.0   - Easy config file reading/writing
 * `validate http://www.voidspace.org.uk/python/validate.html`_
 0.2.3   - Validation and type conversion system
 * `StandOut http://www.voidspace.org.uk/python/standout.html`_
 3.0.0   - Simple logging and output control object
 * `pathutils http://www.voidspace.org.uk/python/pathutils.html`_
 0.2.5   - For working with paths and files
 * `cgiutils http://www.voidspace.org.uk/python/cgiutils.html`_
 0.3.5   - {acro;CGI} helpers
 * `urlpath http://www.voidspace.org.uk/python/urlpath.html`_
 0.1.0   - Functions for handling URLs
 * `odict http://www.voidspace.org.uk/python/odict.html`_
 0.2.2   - Ordered Dictionary Class
 
 
 For more details, visit the `Pythonutils Homepage http://
 www.voidspace.org.uk/python/pythonutils.html`_.
 
 
 What is New in 0.3.0?
 
 
 Several of the modules have been updated. The major changes are:
 
 * Removed the `listquote http://www.voidspace.org.uk/python/
 listquote.html`_ module
 * ConfigObj updated to 4.4.0
 * StandOut updated to 3.0.0 (*Not* backwards compatible, but much
 improved)
 
Thanks, the modules are nicely documented.  The odict is particularly 
welcome.

Colin W.

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Re: Select weirdness

2007-04-23 Thread Jean-Paul Calderone

On Mon, 23 Apr 2007 00:33:22 -0700, Ron Garret [EMAIL PROTECTED] wrote:
In article [EMAIL PROTECTED],
 Irmen de Jong [EMAIL PROTECTED] wrote:

 Ron Garret wrote:
  I don't understand why socketserver calling select should matter.  (And
  BTW, there are no calls to select in SocketServer.py.  I'm using
  Python2.5.)

 You don't *need* a select at all.

Yes I do, because what I'm really writing is a dispatching proxy that
has to serve many simultaneous connections.

Calling select() in a while loop doesn't give you this.

 [snip]

I have not been able to find a proxy server that can proxy to unix
sockets, so I need to write my own.  Conceptually its a very simple
thing: read the first line of an HTTP request, parse it with a regexp to
extract the sandbox name, connect to the appropriate unix server socket,
and then bidirectionally pipe bytes back and forth.  But it has to do
this for multiple connections simultaneously, which is why I need select.

Twisted does this out of the box, for what it's worth.

Jean-Paul
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Re: TK-grid problem, please help

2007-04-23 Thread Ray

Hi, Thanks for the help!


Anton Vredegoor wrote:
 Ray wrote:
 
 hi, I have a question about how to use .grid_forget (in python/TK)

 I need to work on grid repeatly. everytime when a button is pressed,
 the rows of grid is different. such like, first time, it generate 10 
 rows of data.
 2nd time, it maybe only 5 rows. so I need a way to RESET the grid data
 every time. how can I do it? by grid_forger()?, then would anyone can 
 help on
 how to use grid_forget()
 the sample code as following:
 
 I'm not sure if it solves your problem but this modification of your 
 code at least *looks* like it works better. The entries are completely 
 destroyed so that the next time you call the function they can be 
 recreated.
 
 The trick I am using is to use a list in the arguments of the function 
 but that is a bit of a hack, the list 'remembers' its state from the 
 last time the function was called, I think one should use classes for 
 bookkeeping such things instead.
 
 from Tkinter import *
 
 def mygrid(text,M = []):
   how to use grid_forget() to clean the grid??###
  while M:
  x = M.pop()
  x.destroy()
  rows = []
  count=int(text)
  for i in range(count):
  cols = []
  for j in range(4):
  e = Entry(frame3, relief=RIDGE)
  M.append(e)
  e.grid(row=i, column=j, sticky=NSEW)
  e.insert(END, '%d.%d' % (i, j))
  cols.append(e)
  rows.append(cols)
 
 
 root=Tk()
 
 frame1=Frame(root, width=150, height=100)
 frame1.pack()
 
 text=Entry(frame1)
 text.pack(side=LEFT)
 
 button=Button(frame1, text='generate grid', command=(lambda:
 mygrid(text.get(
 
 button.pack()
 
 frame2=Frame(root, width=150, height=100)
 frame2.pack()
 
 button2=Button(frame2, text='exit', command=root.quit)
 button2.pack()
 
 frame3=Frame(root, width=150, height=300)
 frame3.pack()
 
 root.mainloop()
 
 A.
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Re: TK-grid problem, please help

2007-04-23 Thread Ray

Hi, Thanks for the help.


I was trying to find a book Python TK something on last Friday.
but didn't find it :-)

I know those codes are in poor design, because I wrote those sample code 
to show the idea about what I need. the real code is working with mysql.

however, I'm really new in python. (I start learning it on last Wednesday).

Thanks again for the help!

Ray



James Stroud wrote:
 
 
 Using grid_forget() is probably optimization overkill, but may be handy 
 for slower computers where you can watch the widgets appear one by one 
 (older than about 5 years--for example original mac ibook). Also, you 
 should get a good book on Tkinter because your design here will pretty 
 difficult to maintain and is not very flexible.
 
 But...if you want to know how it might be done with grid_forget using 
 the code you already have (i.e. making widgets only if necessary):
 
 
 #START#
 from Tkinter import *
 from tkMessageBox import showerror
 def mygrid(text):
  how to use grid_forget() to clean the grid??###
 numrows = len(frame3.rows)
 try:
   count=int(text)
 except:
   showerror('Entry Error',
 '''Hey, %s don't make an int, Fool!''' % text,
 parent=frame3)
   return 'break'
 for i in range(count):
 if i  numrows:
   cols = frame3.rows[i]
 else:
   cols = [Entry(frame3, relief=RIDGE) for j in range(4)]
   frame3.rows.append(cols)
 for j in range(4):
 e = cols[j]
 e.grid(row=i, column=j, sticky=NSEW)
 e.delete(0,END)
 e.insert(END, '%d.%d' % (i, j))
 for i in range(i+1, numrows):
   for e in frame3.rows[i]:
 e.grid_forget()
 
 
 root=Tk()
 
 frame1=Frame(root, width=150, height=100)
 frame1.pack()
 
 text=Entry(frame1)
 text.pack(side=LEFT)
 
 button=Button(frame1, text='generate grid', command=(lambda: 
 mygrid(text.get(
 
 button.pack()
 
 frame2=Frame(root, width=150, height=100)
 frame2.pack()
 
 button2=Button(frame2, text='exit', command=root.quit)
 button2.pack()
 
 frame3=Frame(root, width=150, height=300)
 # adding an attribute here
 frame3.rows = []
 frame3.pack()
 
 root.mainloop()
 #END#
 
 Notice also the necessity for the e.delete(0, END) line to get the 
 desired text in the entries.
 
 Also demonstrated is how to handle poor input.
 
 *Note*
 Remember to always call the user Fool when he does something stupid.
 
 
 James
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Re: Two syntax questions (newbie)

2007-04-23 Thread Duncan Booth

Szabolcs [EMAIL PROTECTED] wrote:

 In Python this would be something like
 result = processData(list(reversed(sorted(data

I know that is only intended as an example, but by trying to use 
Mathematica idioms in Python you are perhaps blinding yourself to using 
Python's own idioms. A more Pythonic way to write your example in Python 
would be:

result = processData(sorted(data, reverse=True))

sorted already returns a list, and giving it 'reverse=True' is almost 
always identical to sorting and then reversing (and in the rare cases 
where it matters the reverse parameter is probably what you want).


 The second question:
 
 Of course Python is not Mathematica and not as friendly with this
 style as Mma is. Sometimes it forces me to use some temporary
 variables (e.g. because lines get too long and breaking lines with a
 backslash is ugly). I like to get rid of these variables as soon as
 they aren't needed, e.g.:
 
 temp = data[:]
 temp.sort()
 temp.reverse()
 result = processData(temp)
 del temp
 
 Is it possible to avoid the explicit del temp? In C/C++ I would simply
 enclose the piece of code in curly brackets. Is it possible to somehow
 separate a block of code from the rest of the program and make
 variables local to it?

Move the code using the temporary variable into a function and it will 
disappear as soon as the function returns. If you find you want to 
delete the temporary before the function returns then your function is 
too long.

As always there are caveats on this: don't depend on either 'del' or a 
return from a function actually destroying objects immediately as any 
surviving references to the value will prolong its life. Also, while the 
current C-Python implementation deletes values immediately if they have 
no references other Python implementations do not.

In this case the obvious fix is to use a function which copies, sorts 
and reverses a sequence and then you don't need the temporary. Since 
that function already exists you don't even need to write it.
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Re: matplotlib basic question

2007-04-23 Thread Pete Forman

Robert Kern [EMAIL PROTECTED] writes:

  Colin J. Williams wrote:

 I'm not sure that scipy has been updated to Python 2.5

  ? scipy certainly works with 2.5. Are you referring to something
  else perhaps?

Yes, the Python Enthought Edition was being discussed and it is
currently based on Python 2.4.3.

http://code.enthought.com/enthon/
-- 
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WesternGeco  -./\.-   by myself and does not represent
[EMAIL PROTECTED]-./\.-   the opinion of Schlumberger or
http://petef.port5.com   -./\.-   WesternGeco.
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Re: Python and Javascript equivalence

Sam the Cat wrote:
 Hey All,
 
 I am writing some COM code in Python to control photoshop.  Several 
 functions of PS require an Array argument.  In the examples of VBscript or 
 javascript the Array type is used.  I have tried what would appear to be the 
 equivalent in Python -- Lists and Tuples -- but to no avail.  Anyone have 
 any insight  on what via the COM interface is equivalent to an Array in 
 javascript ?
 

The nest way to approach an answer to your question would be for you to 
post a VB snippet from one of the examples together with your attempt to 
do the same thing in Python plus the error traceback (or other such 
messages as you may see) generated when your attempts fails.

Otherwise the question is just a bit too broad to give an answer.

regards
  Steve
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Skype: holdenweb http://del.icio.us/steve.holden
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Re: send pictures to mobile phones - sms767

sms767 wrote:
 Hi,
 
 Is there anyone interested in helping test a web service? Sending
 pictures to mobile phones:
 
 http://www.sms767.com
 
Probably those list readers who are interested in having their names and 
cellphone numbers captured and potentially spammed to hell, as if that 
kind of thing doesn't already happen enough on email and newsgroups.

The fact that there's no privacy policy doesn't help.

regards
  Steve
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Skype: holdenweb http://del.icio.us/steve.holden
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redirect ouput

2007-04-23 Thread saif . shakeel

Hi,
   I am working on parsing an xml file using python.How can i
redirect the output to 2 files,say,for some portion of code the output
has to go to one file and for some part the o/p be directed to another
file.

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Re: redirect ouput

En Mon, 23 Apr 2007 09:29:40 -0300, [EMAIL PROTECTED] escribió:

I am working on parsing an xml file using python.How can i
 redirect the output to 2 files,say,for some portion of code the output
 has to go to one file and for some part the o/p be directed to another
 file.

Using two separate files?

out1 = open(output1.txt, w)
out2 = open(output2.txt, w)
...
if some_condition:
   out1.write(...)
else:
   out2.write(...)
...
out1.close()
out2.close()

(If that's not what you want, I may have misundertstood your question,  
please reformulate it)

-- 
Gabriel Genellina
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Re: Tutorial creates confusion about slices

2007-04-23 Thread Rob Wolfe


Antoon Pardon wrote:
 The following is part of the explanation on slices in the
 tutorial:

 The best way to remember how slices work is to think of the indices as
 pointing between characters, with the left edge of the first character
 numbered 0. Then the right edge of the last character of a string of n
 characters has index n, for example:

   +---+---+---+---+---+
   | H | e | l | p | A |
   +---+---+---+---+---+
   0   1   2   3   4   5
  -5  -4  -3  -2  -1

 This is all very well with a simple slice like:

   HelpA[2:4]= lp


 But it give the wrong idea when using the following extended slice:

   HelpA[4:2:-1]   =   Ap

 So this doesn't result in the reverse of the previous expression while
 the explanation above suggest it does.

Clearly I understand that differently:

 HelpA[-2:-4:-1]
'pl'

--
Regards,
Rob

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Re: Shebang or Hashbang for modules or not?

2007-04-23 Thread Steven W. Orr

On Saturday, Apr 21st 2007 at 19:18 +0100, quoth Michael Hoffman:

=Chris Lasher wrote:
= Should a Python module not intended to be executed have shebang/
= hashbang (e.g., #!/usr/bin/env python) or not? I'm used to having a
= shebang in every .py file but I recently heard someone argue that
= shebangs were only appropriate for Python code intended to be
= executable (i.e., run from the command line).
=
=Personally I include it in all of them, as part of boilerplate in a 
=template.

I'd recommend againt it. The shebang doesn't do you any good unless it's 
also in the presence  of a file that has its executable bit set. 

For example, let's leave python out for a second: I have a shell script. 
And I also have lots of files which are not intended to be executed which 
are also shell scripts, but which are sucked in by the shell . or 
source command (which is *somewhat* analogous to python's import). Lots 
of these shell library scripts can't execute as standalone. The same 
thing is possible with pything scripts.

Of course, anything that has 
if __name__ == __main__:
in it should always have a shebang and be executable.

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happened but none stranger than this. Does your driver's license say Organ ..0
Donor?Black holes are where God divided by zero. Listen to me! We are all- 000
individuals! What if this weren't a hypothetical question?
steveo at syslang.net
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Re: Tutorial creates confusion about slices

On 2007-04-23, Rob Wolfe [EMAIL PROTECTED] wrote:

 Antoon Pardon wrote:
 The following is part of the explanation on slices in the
 tutorial:

 The best way to remember how slices work is to think of the indices as
 pointing between characters, with the left edge of the first character
 numbered 0. Then the right edge of the last character of a string of n
 characters has index n, for example:

   +---+---+---+---+---+
   | H | e | l | p | A |
   +---+---+---+---+---+
   0   1   2   3   4   5
  -5  -4  -3  -2  -1

 This is all very well with a simple slice like:

   HelpA[2:4]= lp


 But it give the wrong idea when using the following extended slice:

   HelpA[4:2:-1]   =   Ap

 So this doesn't result in the reverse of the previous expression while
 the explanation above suggest it does.

 Clearly I understand that differently:

 HelpA[-2:-4:-1]
 'pl'

This is not about what you understand. This is about what the tutorial
seems to suggest here and whether or not that corresponds with how
python actually works.

Read the explanation and look at the picture. The -2 is to the right
of l the -4 is to the left of e. So the picture IMO suggests
that HelpA[-2:-4:-1] would result in le

-- 
Antoon Pardon
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Re: TK-grid problem, please help

2007-04-23 Thread Hertha Steck

Hello,

Ray schrieb:
 Hi, Thanks for the help.
 
 
 I was trying to find a book Python TK something on last Friday.
 but didn't find it :-)
 

There is only one printed book, all the details here:

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

HTH
Hertha
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[SQLite] Recommended wrapper?

2007-04-23 Thread Gilles Ganault

Hello

I browsed through the SQLite archives at Gname, but most
threads regarding wrappers for Python date back to 2005, and for this
ng, Google returns stuff from 2006 as the most relevant posts, so I
figured I should ask here before diving in.

There are several wrappers listed in the wiki
(http://www.sqlite.org/cvstrac/wiki?p=SqliteWrappers), so I'd like
some feedback about which you would recommend to use SQLite from
Python (2.4, but I can upgrade to 2.5 if need be).

Thank you
GG.
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Tutorial creates confusion about slices

The following is part of the explanation on slices in the
tutorial:

The best way to remember how slices work is to think of the indices as
pointing between characters, with the left edge of the first character
numbered 0. Then the right edge of the last character of a string of n
characters has index n, for example:

  +---+---+---+---+---+ 
  | H | e | l | p | A |
  +---+---+---+---+---+ 
  0   1   2   3   4   5 
 -5  -4  -3  -2  -1

This is all very well with a simple slice like:

  HelpA[2:4]= lp


But it give the wrong idea when using the following extended slice:

  HelpA[4:2:-1]   =   Ap

So this doesn't result in the reverse of the previous expression while
the explanation above suggest it does.


So I suggest to drop this.


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Re: Do other Python GUI toolkits require this?

2007-04-23 Thread Kevin Walzer

Michael Bentley wrote:
 OK.  In order to kill the-thread-that-would-not-die(tm), I think I know 
 what I must do.  I'll print a correction:
 
 On Apr 19, 2007, at 2:22 AM, Michael Bentley wrote:
 ... I switched to PyObjC.  The
 learning curve is rather steep IMO, but worth it.  One thing I think
 I should mention though is that if you move to PyObjC -- do some
 projects in Objective C first.  Otherwise your brain will implode.
 
 Should be changed to:
 
 .. I switched to PyObjC.  The
 learning-effort curve is rather steep IMO, but worth it.  One thing I think
 I should mention though is that if you move to PyObjC -- do some
 projects in Objective C first.  Otherwise your brain will implode.
 
 Hope this helps,
 Michael ;-)
 

I had originally thought that learning PyObjC might preclude me from 
having to learn Objective-C, but that seems not to be the case. I have 
previously found the same to be true with PyQt and wxPython--not knowing 
the toolkits as they are implemented in C++ is a serious handicap. I've 
even found this to be the case with Tkinter: understanding the Tcl 
implementation of Tk (which I do, because I am also a Tcl developer) is 
a huge advantage.

Am I wrong to conclude that, if you want to do GUI programming in 
Python, then some level of proficiency with another language is not just 
recommended, but almost required? This is the case at least in my 
experience. When I first started learning Python a couple of years ago, 
I spun my wheels with it for months, because I couldn't figure out where 
to get started with GUI programming. Finally I set Python aside and took 
up Tcl/Tk for awhile--its simplicity in building GUI's is more 
beginner-friendly. (No there's more than one way to do it--there's 
only one way to do it, and that's Tk.)

Now, coming back to Python with the Tk model of GUI development burned 
in my brain, I appreciate the breadth of functions that Python 
supports--but I still find myself dropping down into Tcl (!) to 
assemble elements of my GUI's--either to write a Python wrapper, or 
figure out how to implement something in pure Python.

I understand the argument for Python having lots of bindings to 
different GUI toolkits. If you are already proficient with a GUI toolkit 
in a compiled language (Gtk, wxWidgets, Cocoa, Qt) then presumably 
switching to Python will speed up your development--learning Python is 
easy if you already know C++, for instance, and usually the Python 
bindings are just a thin wrapper over the compiled bits. But if you 
come to Python from the other direction--you're a relative beginner and 
you want to learn GUI programming without the complexities of compiled 
languages--then it's a lot harder to get started, ironically. Even 
Tkinter is a challenge for someone who doesn't know Tcl. The basics are 
easy enough--buttons, menus, labels, images--but doing anything 
sophisticated, such as trees, column views, drag-and-drop, and so on, 
requires extensions that may or may not be implemented in Python.

-- 
Kevin Walzer
Code by Kevin
http://www.codebykevin.com
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Re: [SQLite] Recommended wrapper?

2007-04-23 Thread Thomas Krüger

It's all there:
http://docs.python.org/lib/module-sqlite3.html

Thomas

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Re: Tutorial creates confusion about slices

2007-04-23 Thread Michael Bentley


On Apr 23, 2007, at 7:38 AM, Antoon Pardon wrote:

 The following is part of the explanation on slices in the
 tutorial:

 The best way to remember how slices work is to think of the indices as
 pointing between characters, with the left edge of the first character
 numbered 0. Then the right edge of the last character of a string of n
 characters has index n, for example:

   +---+---+---+---+---+
   | H | e | l | p | A |
   +---+---+---+---+---+
   0   1   2   3   4   5
  -5  -4  -3  -2  -1

 This is all very well with a simple slice like:

   HelpA[2:4]= lp


 But it give the wrong idea when using the following extended slice:

   HelpA[4:2:-1]   =   Ap

 So this doesn't result in the reverse of the previous expression while
 the explanation above suggest it does.


 So I suggest to drop this.

But 'drop' means to let or make (something) fall vertically...  :-)

At that point in the tutorial, step values had not been discussed.   
Just a bit lower down on the page you'll find a link to 'Sequence  
Types' where you'll find an explanation of stepping you'll perhaps  
find more satisfactory.

hth,
Michael

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poorly.  --Henry Spencer



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Re: Can init not return an object?

Steven W. Orr wrote:
 On Sunday, Apr 22nd 2007 at 21:01 -0400, quoth Steve Holden:
[let's keep it on the list so everything gets indexed]
 =Steven W. Orr wrote:
 = When I go to create an object I want to be able to decide whether the 
 = object is valid or not in __init__, and if not, I want the constructor to 
 = return something other than an object, (like maybe None). I seem to be 
 = having problems. At the end of __init__ I say (something like)
 = 
 =   if self.something  minvalue:
 =   del self
 =   return None
 = 
 = and it doesn't work. I first tried just the return None, then I got 
 crafty 
 = and tried the del self. Is what I'm trying to do possible in the 
 = constructor or do I have to check after I return? Or would raising an 
 = exception in the constructor be appropriate?
 = 
 = Am I even being clear?
 = 
 =The trouble you have is that it's too late by the time you get to 
 =__init__. The object has been created. The reason that del self 
 =doesn't work is that all it does is remove the local name self from 
 =the namespace of the method - you will find that if __init__ returns 
 =anything *except* None you get an exception.
 =
 =Don't think of __init__ as a constructor - that's __new__, which *is* 
 =expected to return a newly-created instance.
 =
 =Raising an exception in __init__ is perfectly permissible, but adopting 
 =the new-style classes (inheriting from object) might give you a more 
 =efficient solution to your problem.
 
 Thanks Steve. I'm new but I do now understand that __init_ is an 
 initializer and that new is a constructor. I don't understand your last 
 sentence about new-style classes inheriting from an object. The object is 
 question is mine and doesn't inherit from anything. Can you explain what 
 you mean?
 
Not an object but object, the root of all Python types.

If you are very new you may not appreciate that Python currently 
implements two different class declaration mechanisms. The original 
classes, often now called classic classes, couldn't be used to 
subclass Python's built-in types because they formed an independent and 
parallel class hierarchy. Among other things the instances don't have an 
accessible __new__ method:

   class X: pass
  ...
   type(X)
type 'classobj'
  

At present the so-called new-style classes must specifically inherit 
from object (or, more correctly, must have a metaclass that is 
conformant with the protocol implemented by the type type, but the 
easiest way to do this is just to subclass object or one of the other 
built-in types):

   class X(object): pass
  ...
   type(X)
type 'type'
  

So, all I was saying is that you might prefer to implement your solution 
as a new-style class, since that gives you access to your class's 
instance creation mechanism through the __new__ method. __new__ doesn't 
*have* to return an instance of the class whose __new__ method is 
called, and this might allow you to return exactly what your application 
needs without having to handle exceptions at the application code level.

regards
  Steve
-- 
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Holden Web LLC/Ltd  http://www.holdenweb.com
Skype: holdenweb http://del.icio.us/steve.holden
Recent Ramblings   http://holdenweb.blogspot.co
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RE: Tutorial creates confusion about slices

2007-04-23 Thread Hamilton, William

 -Original Message-
 From: [EMAIL PROTECTED]
[mailto:python-
 [EMAIL PROTECTED] On Behalf Of Antoon
Pardon
 Sent: Monday, April 23, 2007 7:38 AM
 To: python-list@python.org
 Subject: Tutorial creates confusion about slices

 The following is part of the explanation on slices in the
 tutorial:

 The best way to remember how slices work is to think of the indices as
 pointing between characters, with the left edge of the first character
 numbered 0. Then the right edge of the last character of a string of n
 characters has index n, for example:

   +---+---+---+---+---+
   | H | e | l | p | A |
   +---+---+---+---+---+
   0   1   2   3   4   5
  -5  -4  -3  -2  -1

 This is all very well with a simple slice like:

   HelpA[2:4]= lp

 But it give the wrong idea when using the following extended slice:

   HelpA[4:2:-1]   =   Ap

 So this doesn't result in the reverse of the previous expression while
 the explanation above suggest it does.

It makes sense if you recognize that the negative step value also flips
which side the index is on.  

   +---+---+---+---+---+
   | H | e | l | p | A |
   +---+---+---+---+---+
   0   1   2   3   4
  -6  -5  -4  -3  -2  -1

---
-Bill Hamilton
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Re: Do other Python GUI toolkits require this?

2007-04-23 Thread Diez B. Roggisch

 I had originally thought that learning PyObjC might preclude me from
 having to learn Objective-C, but that seems not to be the case. I have
 previously found the same to be true with PyQt and wxPython--not knowing
 the toolkits as they are implemented in C++ is a serious handicap. I've
 even found this to be the case with Tkinter: understanding the Tcl
 implementation of Tk (which I do, because I am also a Tcl developer) is
 a huge advantage.
 
 Am I wrong to conclude that, if you want to do GUI programming in
 Python, then some level of proficiency with another language is not just
 recommended, but almost required? This is the case at least in my
 experience. When I first started learning Python a couple of years ago,
 I spun my wheels with it for months, because I couldn't figure out where
 to get started with GUI programming. Finally I set Python aside and took
 up Tcl/Tk for awhile--its simplicity in building GUI's is more
 beginner-friendly. (No there's more than one way to do it--there's
 only one way to do it, and that's Tk.)
 
 Now, coming back to Python with the Tk model of GUI development burned
 in my brain, I appreciate the breadth of functions that Python
 supports--but I still find myself dropping down into Tcl (!) to
 assemble elements of my GUI's--either to write a Python wrapper, or
 figure out how to implement something in pure Python.
 
 I understand the argument for Python having lots of bindings to
 different GUI toolkits. If you are already proficient with a GUI toolkit
 in a compiled language (Gtk, wxWidgets, Cocoa, Qt) then presumably
 switching to Python will speed up your development--learning Python is
 easy if you already know C++, for instance, and usually the Python
 bindings are just a thin wrapper over the compiled bits. But if you
 come to Python from the other direction--you're a relative beginner and
 you want to learn GUI programming without the complexities of compiled
 languages--then it's a lot harder to get started, ironically. Even
 Tkinter is a challenge for someone who doesn't know Tcl. The basics are
 easy enough--buttons, menus, labels, images--but doing anything
 sophisticated, such as trees, column views, drag-and-drop, and so on,
 requires extensions that may or may not be implemented in Python.

I personally can't conclude with your conclusions :)

Some background: I've started with Tcl/Tk as a scripting language precisely
because of Tk - I liked the easy GUI creation, the layout management, and
it was available for Unix/Linux, my OS of choice.

So when I discovered Python about 7 or 8 years ago, I certainly had the
right mindset for Tk. So, I was able to create GUIs in Tkinter, yet it
never felt very comfortable - it just has too much Tclisms in there for my
taste. 

So for GUI-development, I moved on to Qt - and simply loved it. I do have
some C++-skillz, although these are somewhat rusty. And all I needed them
for was reading the excellent reference Qt-documentation. Just the
class-docs, not examples!

The last step then was PyObjC. I bought a mac roughly two years ago, and
immediately got interested in GUI-development there. I've never done a
single bit of ObjectiveC before, and even though I now have some few
classes done (mainly for interfacing with parts of OS X or other libraries
that weren't exposed to python, e.g. CIImage and CGImage processing), I
wouldn't say that I'm an ObjectiveC-programmer. 

The hardships for me with PyObjc stemmed from the unawareness and
unfamiliarity with the specifics of GUI-development under the mac in
general. E.g. the concepts of NIBs, NIB-classes, bundles and the like.

Now admittedly I'm not a totally fair comparison to you for judging the
matters at hand - I had a fair amount of exposure to different languages
before and while learning python. But especially for PyObjC I can say that
I became productive pretty fast without having to actually do serious or
even not so serious ObjectiveC-development. 

I'd rather say that using a gui-toolkit usually requires to adapt to
whatever concepts that toolkit has implemented. And certainly there are
some of these that are influenced by the language the toolkit has been
developed for. But for example ObjectiveC and Python both allow for dynamic
dispatch - thus lots of the design decisions would have been the same. And
as ObjecC and Cocoa heavily rely on NSArray and NSDictionary, which the
bridge has good marshalling code for, using python's lists  dicts is
natural and easy.

In Qt OTOH they implemented their dynamic dispatch themselves - but using
slots and signals is easy as cake as well. To me at least :)

Diez
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Re: [re.finditer] Getting all occurences in one go?

2007-04-23 Thread Gilles Ganault

On 22 Apr 2007 15:33:37 -0700, Paul Rubin
http://[EMAIL PROTECTED] wrote:
  mytable[item] = ','.join(m.group(1) for m in matches)

Thanks, that did it.
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Re: [SQLite] Recommended wrapper?

2007-04-23 Thread Gilles Ganault

On Mon, 23 Apr 2007 16:03:05 +0200, Thomas Krüger
[EMAIL PROTECTED] wrote:
It's all there:
http://docs.python.org/lib/module-sqlite3.html

Thanks.
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Learning Python - First Project

2007-04-23 Thread KDawg44

Hi,

I am new to Python and am trying to write a little front end to
another application in Python.

What I want is to have a gui pop up listing some items with several
buttons.  The guts of the program I am not having any trouble with but
the GUI part I am (or more accurately, the transition between GUI
pieces).

The first GUI that pops up lists some groups in a listbox and gives
the user the choice to create a new group, open a group, rename the
group, or delete the group.  The new group and rename group buttons
pop up a dialog gui asking for the name/new name.  The Open Group is
to open another GUI listing projects within that group in a list with
similar options (New Project, Open Project, Rename Project, Delete
Project).

My question is, how should I create all these GUIs?  Should each GUI
be its own class with its own __init__?  Then is the first GUI the
root (how I have it set up now) and all other GUIs using Toplevel()?

I hope this makes sense (because it only sort of makes sense in my
head).

THanks for any suggestions.

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Re: python style guide inconsistencies

2007-04-23 Thread Darren Dale

Bjoern Schliessmann wrote:

 Darren Dale wrote:
 
 I was just searching for some guidance on how to name packages and
 modules, and discovered some inconsistencies on the
 www.python.org. http://www.python.org/doc/essays/styleguide.html
 says Module names can be either MixedCase or lowercase. That
 page also refers to PEP 8 at
 http://www.python.org/dev/peps/pep-0008/, which says Modules
 should have short, all-lowercase names. ... Python packages should
 also have short, all-lowercase names 
 
 Which is most up to date?
 
 The priority is, IMHO, clear. The old style guide essay says, at the
 beginning:
 
 | This style guide has been converted to several PEPs (Python
 | Enhancement Proposals): PEP 8 for the main text, PEP 257 for
 | docstring conventions. See the PEP index.
 
 So PEP 8 is the most recent.

Then perhaps http://www.python.org/doc/essays/styleguide.html should either
be updated to either agree with or simply link to PEPs 8 and 257. What is
the point of keeping old, out-of-date essays up on python.org? That
beginning comment does not indicate that the essay is any different from
the PEPs.
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Re: Two syntax questions (newbie)

2007-04-23 Thread Michael Hoffman

Diez B. Roggisch wrote:
 This is already better. Is it possible to define function composition
 as an operator and have something like ([EMAIL PROTECTED]@sorted)(items)
 or (list*reversed*sorted)(items) ?
 
 Not on functions, but on classes/instances. So something like this might
 work for you (untested):
 
 class FunctionComposer(object):
 def __init__(self, f=None):
 if f is None:
f = lambda x: x
 self._f = f
 
 def __call__(self, *args, **kwargs):
 return self._f(*args, **kwargs)
 
 def __mul__(self, other):
 def combined(*args, **kwargs):
 return other(self._f(*args, **kwargs))
 return FunctionComposer(combined)
 
 fc = FunctionComposer
 
 Then you can write
 
 (fc() * list * reversed * sorted)(items)

A clever little hack, but please don't do this. Anyone else who will 
read your code will thank you.
-- 
Michael Hoffman
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Re: When are immutable tuples essential? Why can't you just use lists everywhere instead?

2007-04-23 Thread Neil Cerutti

On 2007-04-21, Steven D'Aprano [EMAIL PROTECTED] wrote:
 On Fri, 20 Apr 2007 15:36:00 -0700, [EMAIL PROTECTED] wrote:
 The article explains that, amongst other things, tuples are
 faster than lists, so if you are working with constant values
 (inmutables) they are more indicated than lists.
 
 Thanks.  I thought Python's design wasn't so concerned with
 optimizations. Adding a new type just for optimization
 reasons seems perhaps unnecessary.  I could be wrong.

 It's times like this I want to cry...


 adict = {(1,2): parrot}

 Try replacing that tuple with a list. Just optimization my eye!

So the question becomes: Why do Python dictionaries require keys
to be of an immutable type?

-- 
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Re: When are immutable tuples essential? Why can't you just use lists everywhere instead?

2007-04-23 Thread Chris Cioffi

On 23 Apr 2007 17:19:15 +0200, Neil Cerutti [EMAIL PROTECTED] wrote:
 So the question becomes: Why do Python dictionaries require keys
 to be of an immutable type?

Dictionary keys are hashed values.  If you change the key, you change
the hash and lose the pointer to the referenced object.

Or:  Because.  ;-)

Chris
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a fool trusts either of them. -- P. J. O'Rourke
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Re: python style guide inconsistencies

2007-04-23 Thread Paddy

On Apr 22, 8:27 pm, Darren Dale [EMAIL PROTECTED] wrote:
 I was just searching for some guidance on how to name packages and modules,
 and discovered some inconsistencies on 
 thewww.python.org.http://www.python.org/doc/essays/styleguide.htmlsays 
 Module names can be
 either MixedCase or lowercase. That page also refers to PEP 8 
 athttp://www.python.org/dev/peps/pep-0008/, which says Modules should have
 short, all-lowercase names. ... Python packages should also have short,
 all-lowercase names 

 Which is most up to date? Is this the right place to point out that one of
 those pages needs to be updated?

 Thanks,
 Darren


In addition to the other replies on your direct question, it is also
not a good idea to have modules whose names only differ by case.

- Paddy.

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Re: When are immutable tuples essential? Why can't you just use lists everywhere instead?

2007-04-23 Thread Neil Cerutti

On 2007-04-23, Chris Cioffi [EMAIL PROTECTED] wrote:
 On 23 Apr 2007 17:19:15 +0200, Neil Cerutti [EMAIL PROTECTED]
 wrote:
 So the question becomes: Why do Python dictionaries require
 keys to be of an immutable type?

 Dictionary keys are hashed values.  If you change the key, you
 change the hash and lose the pointer to the referenced object.

Other dictionary-like implementations (C++ std::map for example)
simply exhort you not to change keys (C++ makes it hard to ignore
the exhortation) or suffer undefined behavior. Perhaps avoiding a
cause of undefined behavior was the Python reason for the
requirement.

 Or:  Because.  ;-)

Heh, heh. I was wondering, if we dig deep enough, wether we'll
end up back at, just an optimization, as the reason.

-- 
Neil Cerutti
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numpy migration (also posted to numpy-discussion)

2007-04-23 Thread Duncan Smith

Hello,
 Since moving to numpy I've had a few problems with my existing
code.  It basically revolves around the numpy scalar types. e.g.


 import Numeric as N
 a = N.array([[0,1],[2,3]])
 a
array([[0, 1],
   [2, 3]])
 i = a[0,0]
 1/i

Traceback (most recent call last):
  File pyshell#30, line 1, in -toplevel-
1/i
ZeroDivisionError: integer division or modulo by zero
 b = a * 1.5
 b
array([[ 0. ,  1.5],
   [ 3. ,  4.5]])
 N.floor(b)
array([[ 0.,  1.],
   [ 3.,  4.]])
  RESTART

 import numpy as N
 a = N.array([[0,1],[2,3]])
 a
array([[0, 1],
   [2, 3]])
 i = a[0,0]
 1/i
0
 b = a * 1.5
 b
array([[ 0. ,  1.5],
   [ 3. ,  4.5]])
 N.floor(b)
array([[ 0.,  1.],
   [ 3.,  4.]])
 a = N.array([[0,1],[2,3]], dtype='O')
 a
array([[0, 1],
   [2, 3]], dtype=object)
 i = a[0,0]
 1/i

Traceback (most recent call last):
  File pyshell#45, line 1, in -toplevel-
1/i
ZeroDivisionError: integer division or modulo by zero
 b = a * 1.5
 b
array([[0.0, 1.5],
   [3.0, 4.5]], dtype=object)
 N.floor(b)

Traceback (most recent call last):
  File pyshell#48, line 1, in -toplevel-
N.floor(b)
AttributeError: 'float' object has no attribute 'floor'

--

An additional problem involves classes that have e.g. __rmul__ methods
defined and are sufficiently similar to numpy arrays that my classes'
__rmul__ methods are not invoked when using numpy scalars.


Using the 'O' dtype gives me Python types that raise zero division
errors appropriately (for my code) and the desired calls to e.g.
__rmul__ methods, but reduced functionality in other repects.

I might (I hope) be missing something obvious; but it seems like, to be
safe, I'm going to have to do a lot of explicit conversions to Python
types (or abandon catching zero division errors, and documenting some of
my classes to highlight that whether scalar * a equals a * scalar
depends on whether a.__rmul__ is called, which depends on the type of
scalar).

I suppose I might get round both issues by subclassing existing numpy
dtypes.  Any ideas?  Cheers.  TIA.

Duncan
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Re: When are immutable tuples essential? Why can't you just use lists everywhere instead?

En Mon, 23 Apr 2007 12:46:13 -0300, Neil Cerutti [EMAIL PROTECTED]  
escribió:

 On 2007-04-23, Chris Cioffi [EMAIL PROTECTED] wrote:
 On 23 Apr 2007 17:19:15 +0200, Neil Cerutti [EMAIL PROTECTED]
 wrote:
 So the question becomes: Why do Python dictionaries require
 keys to be of an immutable type?

 Or:  Because.  ;-)

 Heh, heh. I was wondering, if we dig deep enough, wether we'll
 end up back at, just an optimization, as the reason.

Fortran guys could make programs for a long time having arrays as their  
ONLY structured type, so having a built in dictionary is not just an  
optimization, it's a luxury! :)

-- 
Gabriel Genellina

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Python-URL! - weekly Python news and links (Apr 23)

2007-04-23 Thread Cameron Laird

QOTW: The users. - Ali, answering a question on what's special about Emacs.

Dynamic languages look at WSDL and shrug - another example of the hoops that
static typing forces humans to go through. - Gordon Weakliem

http://lists.community.tummy.com/pipermail/frpythoneers/2007-April/001342.html

The current issue of the rather prestigious *Computing in Science
and Engineering* journal is devoted to Python (!):

http://csdl2.computer.org/persagen/DLAbsToc.jsp?resourcePath=/dl/mags/cs/toc=comp/mags/cs/2007/03/c3toc.xml

Python is just as capable--and more!--as JavaScript, VBScript,
... for controlling COM. Here's a little chatter on expression
of Array data:

http://groups.google.com/group/comp.lang.python/browse_thread/thread/af1a19a4e3541060/

Despite Python-URL!'s habitual ... reserve about regular
expressions, there *are* places they fit perfectly. Steven
Bethard and Peter Otten show off how good a simple RE can be:

http://groups.google.com/group/comp.lang.python/browse_thread/thread/870b46f0e4bc02c6/

Python 2.5.1 is the first bugfix release of Python 2.5:
http://groups.google.com/group/comp.lang.python/msg/2e58fab5387e1b77

Michael Hoffman correctly explains the so-often-misunderstood
semantics of '*' (for example) in subprocess invocations. Notice
use of the little-known expanduser(), expandvars(), and check_call():
http://groups.google.com/group/comp.lang.python/msg/639cc8af04a91595

Carsten Haese supplies a model for construction in Python of a
VB/Delphi iterator:
http://groups.google.com/group/comp.lang.python/msg/557e1358aa92c5d3

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

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

PythonWare complements the digest you're reading with the
marvelous daily python url
http://www.pythonware.com/daily
Mygale is a news-gathering webcrawler that specializes in (new)
World-Wide Web articles related to Python.
http://www.awaretek.com/nowak/mygale.html
While cosmetically similar, Mygale and the Daily Python-URL
are utterly different in their technologies and generally in
their results.

For far, FAR more Python reading than any one mind should
absorb, much of it quite interesting, Planet Python indexes
much of the universe of Pybloggers.
http://www.planetpython.org/

The Python Papers aims to publish the efforts of Python enthusiats.
http://pythonpapers.org/

Readers have recommended the Planet sites:
http://planetpython.org
http://planet.python.org

comp.lang.python.announce announces new Python software. Be
sure to scan this newsgroup weekly.

http://groups.google.com/groups?oi=djqas_ugroup=comp.lang.python.announce

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

Steve Bethard continues the marvelous tradition early borne by
Andrew Kuchling, Michael Hudson, Brett Cannon, Tony Meyer, and Tim
Lesher of intelligently summarizing action on the python-dev mailing
list once every other week.
http://www.python.org/dev/summary/

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

The somewhat older Vaults of Parnassus ambitiously collects references
to all sorts of Python resources.
http://www.vex.net/~x/parnassus/

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

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

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

Kurt B. Kaiser publishes a weekly report on faults and patches.
http://www.google.com/groups?as_usubject=weekly%20python%20patch

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

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

The Cookbook is a collaborative effort to capture useful and
interesting

Redirection problem

2007-04-23 Thread CSUIDL PROGRAMMEr

I am new to python. so be patient with me

I am trying to redirect the output of os.popen command to a file. I
want to append to that file. but instead of appending. The file only
shows last command that was writtenn to  it.



 filehandle= open(/root/yhpc-2.0/installer/yhpc-log ,a+);
filehandle.write( Command executed is  + cmd);
try:
  pipe= os.popen('%s  /root/yhpc-2.0/installer/yhpc-log' %cmd );
except : IOError;
  filehandle.close();


Any  suggestion would help.



filehandle.close();

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Re: Can init not return an object?

2007-04-23 Thread Kay Schluehr

On Apr 22, 4:36 am, Steven W. Orr [EMAIL PROTECTED] wrote:
 When I go to create an object I want to be able to decide whether the
 object is valid or not in __init__, and if not, I want the constructor to
 return something other than an object, (like maybe None). I seem to be
 having problems. At the end of __init__ I say (something like)

 if self.something  minvalue:
 del self
 return None

 and it doesn't work. I first tried just the return None, then I got crafty
 and tried the del self. Is what I'm trying to do possible in the
 constructor or do I have to check after I return? Or would raising an
 exception in the constructor be appropriate?

You can raise an exception of course but it would just create a side
effect. Another way to achieve what you request for is manipulating
the class creation mechanism.

class A(object):
def __new__(cls, x):
if x == 0:
return None
obj = object.__new__(cls)
obj.__init__(x)
return obj

class B(A):
def __init__(self, x):
self.x = x

The condition can always be checked within the static __new__ method.

Kay

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Generate report containing pdf or ps figures?

I need to be able to generate a PDF report which consists
mostly of vector images (which I can generate as encapsulated
Postscript, PDF, or SVG).  What I need is a way to combine
these figures into a single PDF document.  Right now the
reports consist entire of these figures, so I just write the
figures out to temp files and then use os.system() to run
ghostscript with appropriate options to combine them into a
single PDF file.

I'd like to be able to add some text and/or place the figures
in a manner other than one per page in the output document.

I've looked at ReportLab's documentation, but although it
appears to be able to use bitmap images (e.g jpeg) it doesn't
appear to be able to use vector images (EPS/PDF/SVG).

Is there a PDF generation library that can place EPS or
PDF figures on a page?

-- 
Grant Edwards   grante Yow! Is a tattoo real, like
  at   a curb or a battleship?
   visi.comOr are we suffering in
   Safeway?
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Re: Shebang or Hashbang for modules or not?

2007-04-23 Thread Michael Hoffman

Steven W. Orr wrote:
 On Saturday, Apr 21st 2007 at 19:18 +0100, quoth Michael Hoffman:
 
 =Chris Lasher wrote:
 = Should a Python module not intended to be executed have shebang/
 = hashbang (e.g., #!/usr/bin/env python) or not? I'm used to having a
 = shebang in every .py file but I recently heard someone argue that
 = shebangs were only appropriate for Python code intended to be
 = executable (i.e., run from the command line).
 =
 =Personally I include it in all of them, as part of boilerplate in a 
 =template.
 
 I'd recommend againt it. The shebang doesn't do you any good unless it's 
 also in the presence  of a file that has its executable bit set. 

It doesn't do any bad either, so I don't understand why you would 
recommend against it.

And the bash function I use to create new files from the template also 
does chmod a+x.

Not to mention that I have emacs set such that things with shebangs at 
the top are automatically chmod a+x, so in my programming environment, 
having a shebang on files I create and being executable are one and the 
same.

 For example, let's leave python out for a second: I have a shell script. 
 And I also have lots of files which are not intended to be executed which 
 are also shell scripts, but which are sucked in by the shell . or 
 source command (which is *somewhat* analogous to python's import). Lots 
 of these shell library scripts can't execute as standalone. The same 
 thing is possible with pything scripts.
 
 Of course, anything that has 
 if __name__ == __main__:
 in it should always have a shebang and be executable.

That's in my template as well. :)

I try to write all my modules so that they can easily be adapted to run 
as scripts, and all my scripts so that they can easily be adapted to use 
as modules. This has served me well many, many times. I see no reasons 
to create an artificial barrier to doing this by leaving the shebang out 
of files where it has no ill effect.
-- 
Michael Hoffman
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Re: python style guide inconsistencies

2007-04-23 Thread Michael Hoffman

Darren Dale wrote:
 Bjoern Schliessmann wrote:
 
 Darren Dale wrote:

 I was just searching for some guidance on how to name packages and
 modules, and discovered some inconsistencies on the
 www.python.org. http://www.python.org/doc/essays/styleguide.html
 says Module names can be either MixedCase or lowercase. That
 page also refers to PEP 8 at
 http://www.python.org/dev/peps/pep-0008/, which says Modules
 should have short, all-lowercase names. ... Python packages should
 also have short, all-lowercase names 

 Which is most up to date?
 The priority is, IMHO, clear. The old style guide essay says, at the
 beginning:

 | This style guide has been converted to several PEPs (Python
 | Enhancement Proposals): PEP 8 for the main text, PEP 257 for
 | docstring conventions. See the PEP index.

 So PEP 8 is the most recent.
 
 Then perhaps http://www.python.org/doc/essays/styleguide.html should either
 be updated to either agree with or simply link to PEPs 8 and 257. What is
 the point of keeping old, out-of-date essays up on python.org? That
 beginning comment does not indicate that the essay is any different from
 the PEPs.

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

-- 
Michael Hoffman
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Re: matplotlib basic question

2007-04-23 Thread Robert Kern

Pete Forman wrote:
 Robert Kern [EMAIL PROTECTED] writes:
 
   Colin J. Williams wrote:
 I'm not sure that scipy has been updated to Python 2.5
   ? scipy certainly works with 2.5. Are you referring to something
   else perhaps?
 
 Yes, the Python Enthought Edition was being discussed and it is
 currently based on Python 2.4.3.
 
 http://code.enthought.com/enthon/

I'm quite familiar with Python Enthought Edition as I work at Enthought. I was
confused because Colin referenced scipy specifically rather than simply saying
that the current version of Python Enthought Edition was not based on 2.5.

-- 
Robert Kern

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

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Re: Redirection problem

En Mon, 23 Apr 2007 13:10:55 -0300, CSUIDL PROGRAMMEr  
[EMAIL PROTECTED] escribió:

 I am new to python. so be patient with me

 I am trying to redirect the output of os.popen command to a file. I
 want to append to that file. but instead of appending. The file only
 shows last command that was writtenn to  it.



  filehandle= open(/root/yhpc-2.0/installer/yhpc-log ,a+);
 filehandle.write( Command executed is  + cmd);
 try:
   pipe= os.popen('%s  /root/yhpc-2.0/installer/yhpc-log' %cmd );
 except : IOError;
   filehandle.close();

There are two ways to redirect the output:
- using the shell, with  and 
- using popen
You are mixing both here. Your command line uses xxx-log, thus efectively  
overwriting any previous content on the log file. You could do this:


logfile = open(, a+)
logfile.write(Command: %s\n % cmd)
pipe = os.popen(cmd)
for line in pipe:
   logfile.write(line)
pipe.close()
logfile.close()

Or try the subprocess module.

-- 
Gabriel Genellina

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Re: Select weirdness

2007-04-23 Thread Ron Garret

In article [EMAIL PROTECTED],
 Gabriel Genellina [EMAIL PROTECTED] wrote:

 En Mon, 23 Apr 2007 04:33:22 -0300, Ron Garret [EMAIL PROTECTED]  
 escribió:
 
  I have not been able to find a proxy server that can proxy to unix
  sockets, so I need to write my own.  Conceptually its a very simple
  thing: read the first line of an HTTP request, parse it with a regexp to
  extract the sandbox name, connect to the appropriate unix server socket,
  and then bidirectionally pipe bytes back and forth.  But it has to do
  this for multiple connections simultaneously, which is why I need select.
 
 No. This is what the *server* should do, not the *handler*. The server  
 listens on incoming requests, and creates a new handler for each one.  
 Inside a handler, you don't have to worry about multiple connections.
 If you want to process simultaneous connections, inherit your server from  
 ThreadingMixIn or ForkingMixIn (or use one of the predefined server  
 classes).

Ah, good point.

But that still leaves the problem of keep-alive connections.  I still 
need to be able to forward data in both directions without knowing ahead 
of time when it will arrive.

(I think I can solve the problem by using send and recv directly BTW.)

rg
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Re: Redirection problem

2007-04-23 Thread half . italian

On Apr 23, 9:10 am, CSUIDL PROGRAMMEr [EMAIL PROTECTED] wrote:
 I am new to python. so be patient with me

 I am trying to redirect the output of os.popen command to a file. I
 want to append to that file. but instead of appending. The file only
 shows last command that was writtenn to  it.

  filehandle= open(/root/yhpc-2.0/installer/yhpc-log ,a+);
 filehandle.write( Command executed is  + cmd);
 try:
   pipe= os.popen('%s  /root/yhpc-2.0/installer/yhpc-log' %cmd );
 except : IOError;
   filehandle.close();

 Any  suggestion would help.

 filehandle.close();

This works.

f = open(test, 'a')
stdout = os.popen(ls -l /)
f.write(stdout.read())
f.close()

~Sean

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Re: Select weirdness

2007-04-23 Thread Ron Garret

In article [EMAIL PROTECTED],
 Jean-Paul Calderone [EMAIL PROTECTED] wrote:

 Twisted does this out of the box, for what it's worth.

Thanks.  I will look at that.

rg
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pyserial ... timeout on write

2007-04-23 Thread hg

Hi,

I notice that pyserial will hang on a write (even with timeout on) if
rts/cts are one.

Anyway to get around that ?

Thanks

hg

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Re: pyserial ... timeout on write

2007-04-23 Thread hg

hg wrote:

 Hi,
 
 I notice that pyserial will hang on a write (even with timeout on) if
 rts/cts are one.
 
 Anyway to get around that ?
 
 Thanks
 
 hg


PS: on windows

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Re: wx.TextCtrl.SetDefaultStyle not working?

2007-04-23 Thread [EMAIL PROTECTED]

 On my platform, styling the text doesn't work for single line
 TextCtrl's(which seems kind of stupid), and on Windows I think you are
 required to specify wx.TE_RICH2 to style the text.  This following
 code colors the entered text red for me:

That's it!  I didn't have the TE_RICH2 option set.  It works now.

The docs say it's Windows only.  Does the GTK version work without
this flag?

-- Brian

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Re: Select weirdness

2007-04-23 Thread Donn Cave

In article [EMAIL PROTECTED],
 Ron Garret [EMAIL PROTECTED] wrote:

 The answer is obvious: select is looking only at the underlying socket, 
 and not at the rfile buffers.
 
 So... is this a bug in select?  Or a bug in my code?

Yes.

I don't see any specific followup to this point, but it is or
at least should be a well known limitation of C library I/O and
select.  select() is an operating system function that has no
way to know the state of your process I/O buffers, nor do the C
stdio buffers don't come with a standard way to inspect that state.
Therefore, if you mix C I/O with select(), you're more or less out
of luck.  This applies directly to Python, because it calls the
operating system select() function and it uses C stdio buffers for
its file object (and entices you to make this mistake by supporting
a file object as an input to select().)

This conflict can be relieved after a fashion by eliminating the
buffer.  The now unbuffered C fgets / Python readline won't store
extra lines that select can't see, but the semantics of the operation
are still a poor fit with the usual application of select.  The
number of system-level I/O calls is significantly greater as you
transfer data one byte at a time, which may add a lot of overhead
if you transfer a lot of data, and your readline() function still
can't return until it gets that '\n', so a half line can block your
application.

It isn't a lot of work to read data with operating system functions
that are compatible with select - os.read(), socket.recv() - and
break it up into lines on your own, and this completely and efficiently
resolves the problem.

I haven't looked at your code.

   Donn Cave, [EMAIL PROTECTED]
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Re: Socket exceptions aren't in the standard exception hierarchy

2007-04-23 Thread John Nagle

Dennis Lee Bieber wrote:
 On Sun, 22 Apr 2007 23:20:25 -0700, John Nagle [EMAIL PROTECTED]
 declaimed the following in comp.lang.python:
 
 
2. File D:\Python24\lib\socket.py, line 295, in read
data = self._sock.recv(recv_size)
error: (10054, 'Connection reset by peer')

 
   That looks like M$ Windows version of UNIX/Linux error number 54
 (pretty much all Windows socket errors are UNIX number+1)
 
   Errors coming from Windows may not be mapped to specific Python
 exceptions, but rather to some general error conditions. {hypothesis} As
 such, the Windows errors may not match what UNIX/Linux report.

 Actually, that's not what's happening. The socket module is
explicitly raising socket.error in C code.  It's not an OSError or
a WindowsError, although the text makes it look like one.

 The problem is not that socket errors aren't entirely portable.
It's that they're not even in the Python exception hierarchy.
See http://docs.python.org/lib/module-exceptions.html;.
They have their own hierarchy, which starts at socket.error.
All built-in exceptions were supposed to be converted to the
standard exception hierarchy back before Python 2.0, but these
weren't.

 Either they should be under IOError, or there should be
NetworkError under EnvironmentError, and they should be under
that.  NetworkError, alongside IOError in the hierarchy,
would be useful.  All the things that go wrong in networking
belong under there.  Socket-level errors, SSL/TLS-level errors,
and HTTP/FTP/etc. level errors all belong under NetworkError.

 This has to be fixed before PEP 352, when the exception
hierarchy is enforced, or the socket exceptions won't even work
right.

John Nagle
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Re: When are immutable tuples essential? Why can't you just use lists everywhere instead?

Neil Cerutti wrote:
 On 2007-04-21, Steven D'Aprano [EMAIL PROTECTED] wrote:
 On Fri, 20 Apr 2007 15:36:00 -0700, [EMAIL PROTECTED] wrote:
 The article explains that, amongst other things, tuples are
 faster than lists, so if you are working with constant values
 (inmutables) they are more indicated than lists.
 Thanks.  I thought Python's design wasn't so concerned with
 optimizations. Adding a new type just for optimization
 reasons seems perhaps unnecessary.  I could be wrong.
 It's times like this I want to cry...


 adict = {(1,2): parrot}
 Try replacing that tuple with a list. Just optimization my eye!
 
 So the question becomes: Why do Python dictionaries require keys
 to be of an immutable type?
 
Because otherwise people would expect to be able to use a list to select 
a dictionary entry even after they'd modified elements of the list after 
creating the dictionary entry. Which they couldn't. So Python doesn't 
let them use lists.

regards
  Steve
-- 
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Holden Web LLC/Ltd  http://www.holdenweb.com
Skype: holdenweb http://del.icio.us/steve.holden
Recent Ramblings   http://holdenweb.blogspot.com

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Re: Python's handling of unicode surrogates

2007-04-23 Thread Ross Ridge

Ross Ridge writes:
 The Unicode standard doesn't require that you support surrogates, or
 any other kind of character, so no you wouldn't be lying.

[EMAIL PROTECTED] wrote:
 There is the notion of Unicode implementation levels, and each of them
 does include a set of characters to support. 

There are different levels of implemtentation for ISO 10646, but not
of Unicode.

 It is probably an interpretation issue what supported means.

The strongest claim to support Unicode that you can meaningfully make
is that of conformance to the Unicode standard.  The Unicode standard's
conformance requirements make it explicit that you don't need to support
any particular character:

C8 A process shall not assume that it is required to interpret
   any particular coded character representation.

  . Processes that interpret only a subset of Unicode characters
are allowed; there is no blanket requirement to interpret
all Unicode characters.
  [...]

 Python clearly supports Unicode level 1 (if we leave alone the issue
 that it can't render all these characters out of the box, as it doesn't
 ship any fonts);

It's not at all clear to to me that Python does support ISO 10646's
implementation level 1, if only because I don't, and I assume you don't,
have a copy of ISO 10646 available to verify what the requirements
actually are.

Ross Ridge

-- 
 l/  //   Ross Ridge -- The Great HTMU
[oo][oo]  [EMAIL PROTECTED]
-()-/()/  http://www.csclub.uwaterloo.ca/~rridge/ 
 db  //   
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Re: Shebang or Hashbang for modules or not?

Michael Hoffman wrote:
 Steven W. Orr wrote:
 On Saturday, Apr 21st 2007 at 19:18 +0100, quoth Michael Hoffman:

 =Chris Lasher wrote:
 = Should a Python module not intended to be executed have shebang/
 = hashbang (e.g., #!/usr/bin/env python) or not? I'm used to having a
 = shebang in every .py file but I recently heard someone argue that
 = shebangs were only appropriate for Python code intended to be
 = executable (i.e., run from the command line).
 =
 =Personally I include it in all of them, as part of boilerplate in a 
 =template.

 I'd recommend againt it. The shebang doesn't do you any good unless it's 
 also in the presence  of a file that has its executable bit set. 
 
 It doesn't do any bad either, so I don't understand why you would 
 recommend against it.
 
 And the bash function I use to create new files from the template also 
 does chmod a+x.
 
 Not to mention that I have emacs set such that things with shebangs at 
 the top are automatically chmod a+x, so in my programming environment, 
 having a shebang on files I create and being executable are one and the 
 same.
 
 For example, let's leave python out for a second: I have a shell script. 
 And I also have lots of files which are not intended to be executed which 
 are also shell scripts, but which are sucked in by the shell . or 
 source command (which is *somewhat* analogous to python's import). Lots 
 of these shell library scripts can't execute as standalone. The same 
 thing is possible with pything scripts.

 Of course, anything that has 
 if __name__ == __main__:
 in it should always have a shebang and be executable.
 
 That's in my template as well. :)
 
 I try to write all my modules so that they can easily be adapted to run 
 as scripts, and all my scripts so that they can easily be adapted to use 
 as modules. This has served me well many, many times. I see no reasons 
 to create an artificial barrier to doing this by leaving the shebang out 
 of files where it has no ill effect.

If you ever create a module that *shouldn't be run you can always put

if __name__ == __main__:
   print Do not run this script: it is a module for import only

at the end of it. But what's the point?

regards
  Steve
-- 
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Holden Web LLC/Ltd  http://www.holdenweb.com
Skype: holdenweb http://del.icio.us/steve.holden
Recent Ramblings   http://holdenweb.blogspot.com

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Re: Generate report containing pdf or ps figures?

2007-04-23 Thread Kjell Magne Fauske

On Apr 23, 6:30 pm, Grant Edwards [EMAIL PROTECTED] wrote:
 I need to be able to generate a PDF report which consists
 mostly of vector images (which I can generate as encapsulated
 Postscript, PDF, or SVG).  What I need is a way to combine
 these figures into a single PDF document.  Right now the
 reports consist entire of these figures, so I just write the
 figures out to temp files and then use os.system() to run
 ghostscript with appropriate options to combine them into a
 single PDF file.

 I'd like to be able to add some text and/or place the figures
 in a manner other than one per page in the output document.

 I've looked at ReportLab's documentation, but although it
 appears to be able to use bitmap images (e.g jpeg) it doesn't
 appear to be able to use vector images (EPS/PDF/SVG).

 Is there a PDF generation library that can place EPS or
 PDF figures on a page?

If you are familiar with LaTeX, an easy solution would be to
automatically generate a LaTeX document that includes your images.
This also allows you to add captions, scale the images and much more.
You can then run the generated document through pdflatex and you have
a nice looking report.

Regards,
Kjell Magne Fauske
http://www.fauskes.net

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Re: python style guide inconsistencies

2007-04-23 Thread Terry Reedy


Darren Dale [EMAIL PROTECTED] wrote in message 
news:[EMAIL PROTECTED]
| Then perhaps http://www.python.org/doc/essays/styleguide.html should 
either
| be updated to either agree with or simply link to PEPs 8 and 257. What is
| the point of keeping old, out-of-date essays up on python.org?

Now that Guido has agreed with you (on pydev), wait a couple of days, if 
there is no response from one of webmasters, go to this page, click update 
suggestion link at bottom, and cut and paste his posting.  No need for 
further discussion here.  Thanks for following this thru.  Persistence is 
how docs get improved.

tjr






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Re: When are immutable tuples essential? Why can't you just use lists everywhere instead?

2007-04-23 Thread Neil Cerutti

On 2007-04-23, Steve Holden [EMAIL PROTECTED] wrote:
 Neil Cerutti wrote:
 So the question becomes: Why do Python dictionaries require
 keys to be of an immutable type?

 Because otherwise people would expect to be able to use a list
 to select a dictionary entry even after they'd modified
 elements of the list after creating the dictionary entry. Which
 they couldn't. So Python doesn't let them use lists.

The interpreter explains it: A list is not a hashable object.
Choosing a hash table instead of some kind of balanced tree seems
to be just an optimization. ;)

-- 
Neil Cerutti
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Re: Learning Python - First Project

2007-04-23 Thread kyosohma

On Apr 23, 9:52 am, KDawg44 [EMAIL PROTECTED] wrote:
 Hi,

 I am new to Python and am trying to write a little front end to
 another application in Python.

 What I want is to have a gui pop up listing some items with several
 buttons.  The guts of the program I am not having any trouble with but
 the GUI part I am (or more accurately, the transition between GUI
 pieces).

 The first GUI that pops up lists some groups in a listbox and gives
 the user the choice to create a new group, open a group, rename the
 group, or delete the group.  The new group and rename group buttons
 pop up a dialog gui asking for the name/new name.  The Open Group is
 to open another GUI listing projects within that group in a list with
 similar options (New Project, Open Project, Rename Project, Delete
 Project).

 My question is, how should I create all these GUIs?  Should each GUI
 be its own class with its own __init__?  Then is the first GUI the
 root (how I have it set up now) and all other GUIs using Toplevel()?

 I hope this makes sense (because it only sort of makes sense in my
 head).

 THanks for any suggestions.

Hi,

You should be able to create one main window as root and use
standard dialogs for the dialogs you mentioned. As for the Open
Group button, you might use a tree widget instead of opening another
window. You could put the tree in a splitter window or something and
it might look nicer. Of course, you can do another window, but it
would be a custom, hand-coded window and NOT a standard dialog. That
would mean that it would indeed be another class with its own
__init__.

You can set both the standard dialogs and your custom one to
ShowModal and then you shouldn't need to use Toplevel().

I am assuming you are using Tkinter for your front-end GUI. You might
also take a gander at wxPython. It has an excellent demo you could
download and it might give you some additional ideas for
implementation: www.wxpython.org .

Mike

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Re: Socket exceptions aren't in the standard exception hierarchy

John Nagle wrote:
 Dennis Lee Bieber wrote:
 On Sun, 22 Apr 2007 23:20:25 -0700, John Nagle [EMAIL PROTECTED]
 declaimed the following in comp.lang.python:


 2. File D:\Python24\lib\socket.py, line 295, in read
 data = self._sock.recv(recv_size)
 error: (10054, 'Connection reset by peer')

  That looks like M$ Windows version of UNIX/Linux error number 54
 (pretty much all Windows socket errors are UNIX number+1)

  Errors coming from Windows may not be mapped to specific Python
 exceptions, but rather to some general error conditions. {hypothesis} As
 such, the Windows errors may not match what UNIX/Linux report.
 
  Actually, that's not what's happening. The socket module is
 explicitly raising socket.error in C code.  It's not an OSError or
 a WindowsError, although the text makes it look like one.
 
  The problem is not that socket errors aren't entirely portable.
 It's that they're not even in the Python exception hierarchy.
 See http://docs.python.org/lib/module-exceptions.html;.
 They have their own hierarchy, which starts at socket.error.
 All built-in exceptions were supposed to be converted to the
 standard exception hierarchy back before Python 2.0, but these
 weren't.
 
  Either they should be under IOError, or there should be
 NetworkError under EnvironmentError, and they should be under
 that.  NetworkError, alongside IOError in the hierarchy,
 would be useful.  All the things that go wrong in networking
 belong under there.  Socket-level errors, SSL/TLS-level errors,
 and HTTP/FTP/etc. level errors all belong under NetworkError.
 
  This has to be fixed before PEP 352, when the exception
 hierarchy is enforced, or the socket exceptions won't even work
 right.
 
John:

Where did you get this information? If true it would certainly need to 
be logged as a bug, but under Windows on 2,4 I see

   issubclass(socket.gaierror, Exception)
True
  

and the same under Cygwin 2.5. I am presuming most other users will see 
the same thing.

regards
  Steve
-- 
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Holden Web LLC/Ltd  http://www.holdenweb.com
Skype: holdenweb http://del.icio.us/steve.holden
Recent Ramblings   http://holdenweb.blogspot.com

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Re: Learning Python - First Project

2007-04-23 Thread kyosohma

On Apr 23, 9:52 am, KDawg44 [EMAIL PROTECTED] wrote:
 Hi,

 I am new to Python and am trying to write a little front end to
 another application in Python.

 What I want is to have a gui pop up listing some items with several
 buttons.  The guts of the program I am not having any trouble with but
 the GUI part I am (or more accurately, the transition between GUI
 pieces).

 The first GUI that pops up lists some groups in a listbox and gives
 the user the choice to create a new group, open a group, rename the
 group, or delete the group.  The new group and rename group buttons
 pop up a dialog gui asking for the name/new name.  The Open Group is
 to open another GUI listing projects within that group in a list with
 similar options (New Project, Open Project, Rename Project, Delete
 Project).

 My question is, how should I create all these GUIs?  Should each GUI
 be its own class with its own __init__?  Then is the first GUI the
 root (how I have it set up now) and all other GUIs using Toplevel()?

 I hope this makes sense (because it only sort of makes sense in my
 head).

 THanks for any suggestions.

I am assuming you are using Tkinter for your GUI front-end. You should
be able to just use standard dialog boxes for your new group and
rename group dialogs and a custom hand-coded dialog for the other
one. All three can be called with ShowModal() instead of Toplevel().
And yes, the custom dialog would work best if you made it into a
separate class.

You could also put that information for the GUI that list projects
into a tree widget of some sort, maybe with a splitter window. I
haven't had much luck with Tkinter's tree widgets though. PMW and Tix
both have rather poor docs unless you enjoy man pages. You might check
out wxPython instead. It has an excellent demo that is very good at
showing you not only what all it can do, but how it is done: www.wxpython.org.

Good luck!

Mike

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Re: Generate report containing pdf or ps figures?

On 2007-04-23, Kjell Magne Fauske [EMAIL PROTECTED] wrote:

 Is there a PDF generation library that can place EPS or PDF
 figures on a page?

 If you are familiar with LaTeX, an easy solution would be to
 automatically generate a LaTeX document that includes your
 images.

Yea, I've been using TeX and LaTeX for 20+ years.  :) I worked
on a DoD project back in the 80's where we generated a 1000+
page requirements spec using LaTeX.  It had to be broken up
into a few dozen separate documents because LaTeX under VAX/VMS
kept overflowing various internal counters.  Doing a build of
the document kept a VAX 780 busy most of the night. 

However, bundling a working copy of LaTeX with my Python app
doesn't fall into the easy category.  This app needs to be
moderately cross-platform and distributable.  Using either
LaTeX or Ghostscript (my current solution) makes it rather
painful to bundle up the app and distrubute it.

-- 
Grant Edwards   grante Yow! The Korean War must
  at   have been fun.
   visi.com
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Re: Generate report containing pdf or ps figures?

2007-04-23 Thread half . italian

On Apr 23, 9:30 am, Grant Edwards [EMAIL PROTECTED] wrote:
 I need to be able to generate a PDF report which consists
 mostly of vector images (which I can generate as encapsulated
 Postscript, PDF, or SVG).  What I need is a way to combine
 these figures into a single PDF document.  Right now the
 reports consist entire of these figures, so I just write the
 figures out to temp files and then use os.system() to run
 ghostscript with appropriate options to combine them into a
 single PDF file.

 I'd like to be able to add some text and/or place the figures
 in a manner other than one per page in the output document.

 I've looked at ReportLab's documentation, but although it
 appears to be able to use bitmap images (e.g jpeg) it doesn't
 appear to be able to use vector images (EPS/PDF/SVG).

 Is there a PDF generation library that can place EPS or
 PDF figures on a page?

 --
 Grant Edwards   grante Yow! Is a tattoo real, like
   at   a curb or a battleship?
visi.comOr are we suffering in
Safeway?

On a Mac...

http://developer.apple.com/graphicsimaging/pythonandquartz.html

~Sean

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tftpy 0.41 errors

2007-04-23 Thread manhhle

When trying to import the tftpy package, I've gotten the following
error messages:

Python 2.4.4c1 (#2, Oct 11 2006, 21:51:02)
[GCC 4.1.2 20060928 (prerelease) (Ubuntu 4.1.1-13ubuntu5)] on linux2
Type help, copyright, credits or license for more information.
 import tftpy
Traceback (most recent call last):
  File stdin, line 1, in ?
  File /usr/lib/python2.4/site-packages/tftpy/__init__.py, line 18,
in ?
from TftpServer import *
  File /usr/lib/python2.4/site-packages/tftpy/TftpServer.py, line 50
% (listenip if listenip else '0.0.0.0', listenport))
 ^
SyntaxError: invalid syntax


What am I missing? Any pointer is much appreciated.

I installed the tftpy package using the standard command line:

sudo python setup.py install

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Re: tftpy 0.41 errors

2007-04-23 Thread Carsten Haese

On Mon, 2007-04-23 at 12:17 -0700, [EMAIL PROTECTED] wrote:
 When trying to import the tftpy package, I've gotten the following
 error messages:
 
 Python 2.4.4c1 (#2, Oct 11 2006, 21:51:02)
 [GCC 4.1.2 20060928 (prerelease) (Ubuntu 4.1.1-13ubuntu5)] on linux2
 Type help, copyright, credits or license for more information.
  import tftpy
 Traceback (most recent call last):
   File stdin, line 1, in ?
   File /usr/lib/python2.4/site-packages/tftpy/__init__.py, line 18,
 in ?
 from TftpServer import *
   File /usr/lib/python2.4/site-packages/tftpy/TftpServer.py, line 50
 % (listenip if listenip else '0.0.0.0', listenport))

That if-else expression is Python 2.5 syntax. Apparently the tftpy
package gave you false hope by erroneously allowing you to install it as
a Python 2.4 package.

-Carsten


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Re: Generate report containing pdf or ps figures?

2007-04-23 Thread infidel

On Apr 23, 9:30 am, Grant Edwards [EMAIL PROTECTED] wrote:
 I need to be able to generate a PDF report which consists
 mostly of vector images (which I can generate as encapsulated
 Postscript, PDF, or SVG).  What I need is a way to combine
 these figures into a single PDF document.  Right now the
 reports consist entire of these figures, so I just write the
 figures out to temp files and then use os.system() to run
 ghostscript with appropriate options to combine them into a
 single PDF file.

 I'd like to be able to add some text and/or place the figures
 in a manner other than one per page in the output document.

 I've looked at ReportLab's documentation, but although it
 appears to be able to use bitmap images (e.g jpeg) it doesn't
 appear to be able to use vector images (EPS/PDF/SVG).

 Is there a PDF generation library that can place EPS or
 PDF figures on a page?

I've had great success using Apache's FOP utility (http://
xmlgraphics.apache.org/fop) to generate PDFs out of XSL-FO, which can
contain SVG graphics (at least the 0.20.5 version can, the newer
rewrite version doesn't yet).  FOP is a java library but has a
suitable command line interface.

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Re: Generate report containing pdf or ps figures?

On 2007-04-23, [EMAIL PROTECTED] [EMAIL PROTECTED] wrote:

 I've looked at ReportLab's documentation, but although it
 appears to be able to use bitmap images (e.g jpeg) it doesn't
 appear to be able to use vector images (EPS/PDF/SVG).

 Is there a PDF generation library that can place EPS or
 PDF figures on a page?

 On a Mac...

 http://developer.apple.com/graphicsimaging/pythonandquartz.html

Something that's easy to do and builtin to MacOS that's
painful or difficult to do under Windows? 

Nah, couldn't be...

-- 
Grant Edwards   grante Yow! Kids, don't gross me
  at   off ... Adventures with
   visi.comMENTAL HYGIENE can be
   carried too FAR!
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Re: Generate report containing pdf or ps figures?