Python in a desktop environment

[David Cramer]

If you had an application that you were about to begin development on
which you wanted to be cross platform (at least Mac and Windows),
would you suggest using c++ and Python?

I'm asking because we were originally thinking about doing c# but
after attending PyCon this year I'm reconsidering. We are already
using Python for the website and I figure a c++ backend w/ a Python
GUI may work really well, and would be pretty easy to port.

Any opinions?

[MonkeeSage]

On Mar 10, 9:23 pm, "David Cramer" <dcra...@gmail. comwrote:

If you had an application that you were about to begin development on
which you wanted to be cross platform (at least Mac and Windows),
would you suggest using c++ and Python?

Depending on what exactly you're trying to do, a pure python solution
may be sufficient, though obviously a C/C++ backend would be portable
as well. In terms of GUI; GTK or QT would probably be your best bet
(my personal preference is for pygtk), though Wxidgets may be a viable
option if the others are not (I'm not sure how advanced GTK/QT support
is on OSX). Your question is kind of vague, so this response is vague
as well. More info is needed to answer in a more specific way.

Regards,
Jordan

[sjdevnull]

David Cramer wrote:

If you had an application that you were about to begin development on
which you wanted to be cross platform (at least Mac and Windows),
would you suggest using c++ and Python?

I'd strongly consider a pure python solution (I'd choose wxpython),
but if I needed to code backend stuff in a lower level language I'd
use C rather than C++.

[David Cramer]

On Mar 10, 10:52 pm, "sjdevn...@yaho o.com" <sjdevn...@yaho o.com>
wrote:

David Cramer wrote:

If you had an application that you were about to begin development on
which you wanted to be cross platform (at least Mac and Windows),
would you suggest using c++ and Python?

I'd strongly consider a pure python solution (I'd choose wxpython),
but if I needed to code backend stuff in a lower level language I'd
use C rather than C++.

Well we want it to be very robust, and python isn't exactly the
fastest language, or one with the lowest overhead :)

[Mike Schinkel]

Hi,

I'm relatively new to Python but have lots of prior programming experience
as a developer, instructor, and author (ASP/VBScript/SQL Server and
Clipper.)

I'm trying to write an app that parses a text file containing an outline
useing essentially the same indentation rules as Python source code, i.e.
the first level has no indent, the second level has one indent, third level
has two indents, and so on. However, I can't know for sure that the
indentations are tabs or spaces, or even mixed tabs and spaces. What's
more, I can't know for sure what tab spacing the persons editor was using if
they saved as spaces, i.e. tab='N' spaces where N= (2,3,4,5,6,7,8, ...)

Clearly the source code for Python has to figure this out, but I wonder if
anyone knows how to do this in Python. Frankly I'm stumped on how to find an
elegant algorithm that does require multipass parsing and lots of code. Any
help would be appreciated.

--
-Mike Schinkel
http://www.mikeschinkel.com/blogs/
http://www.welldesignedurls.org
http://atlanta-web.org - http://t.oolicio.us

[Diez B. Roggisch]

David Cramer schrieb:

On Mar 10, 10:52 pm, "sjdevn...@yaho o.com" <sjdevn...@yaho o.com>
wrote:

>David Cramer wrote:

>>If you had an application that you were about to begin development on
which you wanted to be cross platform (at least Mac and Windows),
would you suggest using c++ and Python?

I'd strongly consider a pure python solution (I'd choose wxpython),
but if I needed to code backend stuff in a lower level language I'd
use C rather than C++.

Well we want it to be very robust, and python isn't exactly the
fastest language, or one with the lowest overhead :)

Erm, and what has _robustness_ with fast & less overhead to do? It's
exactly the other way round, a python program is much less likely to
crash that C/C++, and if so in manners that are much easier to manage
and fix.

I've done extensive GUI-development with PyQt, and can say that it's a
very productive and powerful combination. And GUI-code usually isn't
troublesome performance-wise.

Diez

[Duncan Booth]

"David Cramer" <dc*****@gmail. comwrote:

On Mar 10, 10:52 pm, "sjdevn...@yaho o.com" <sjdevn...@yaho o.com>
wrote:

>David Cramer wrote:

If you had an application that you were about to begin development on
which you wanted to be cross platform (at least Mac and Windows),
would you suggest using c++ and Python?

I'd strongly consider a pure python solution (I'd choose wxpython),
but if I needed to code backend stuff in a lower level language I'd
use C rather than C++.

Well we want it to be very robust, and python isn't exactly the
fastest language, or one with the lowest overhead :)

So if you want it to be robust it's a no brainer: Python and no C++ or C.

I'd advise you to start off doing it in pure Python, then when you get it
working see if it is fast enough, and if not profile it and find the
bottlenecks. Those bits which really do need speeding up you should then
rewrite using Pyrex, which won't take long at all since it is basically the
same syntax. Also see whether Psyco helps.

Python can be slow, but if you leverage the built in functionality
correctly you'll find it isn't much slower than C/C++ for many tasks, and
can even be faster than you would get from C/C++ without a spending a very
long time optimising it (that's because people have already spent a very
long time optimising Python's builtin functionality).

Even if you do eventually find you have to rewrite parts of the code in
C/C++ you should first have done what you can to optimise it in Python.
Usually the best way to speed up something which is too slow is to use a
different algorithm. That sort of change is comparatively easy to do in
Python but an expensive programming exercise in C/C++. When you come to
reimplement it then you'll be converting the already optimised code, which
in many cases will be much easier than writing it in C/C++ from scratch.

If you look at http://page.mi.fu-berlin.de/~prechel.../jccpprtTR.pdf
you'll see that, at least for that task, the relative runtimes for C/C++
and Python widely overlap. Yes, the C/C++ implementation included some very
fast ones, but they also included slows ones (and only Python of all the
languages tested had no unusable implementations ). OTOH, time to write the
programs does not overlap. Of course, since that paper was written Python
has changed a lot.

[Gabriel Genellina]

En Sun, 11 Mar 2007 06:34:03 -0300, Mike Schinkel <mi**********@g mail.com>
escribió:

I'm trying to write an app that parses a text file containing an outline
useing essentially the same indentation rules as Python source code, i.e.
the first level has no indent, the second level has one indent, third

You can get some ideas from tabnanny.py or reindent.py, but perhaps they
are too specific at parsing Python code.

I hope this informal description may help:

Start with IC = Previous IC = 0, and a stack with a single 0 element
For each line in the file:
compute the indentation column IC (that is, count the number of leading
whitespace characters; perhaps replacing tabs as 8 spaces)
compare IC with the Previous IC:
same: continue with next line
IC previous ("indent"): push IC onto indent stack
IC < previous ("dedent"):
discard top of stack
look at the new top of stack (but dont discard it); if not the same,
indentation error.
Previous IC = IC

Note: You can rewrite the above without using Previous IC, only the
stack... left to the reader :)
Note 2: At each stage, the "indentatio n level" is the current stack size.

--
Gabriel Genellina

[Hendrik van Rooyen]

"David Cramer" <dc...er@gmail. comwrote:

If you had an application that you were about to begin development on
which you wanted to be cross platform (at least Mac and Windows),
would you suggest using c++ and Python?

I'm asking because we were originally thinking about doing c# but
after attending PyCon this year I'm reconsidering. We are already
using Python for the website and I figure a c++ backend w/ a Python
GUI may work really well, and would be pretty easy to port.

Any opinions?

Why drag in the C++ ?
What do you intend to do in it that you can't do in python?
Seems unnecessarily complex to me.
And on a desktop, speed issues are kind of irrelevant - Python
is snappy enough on modern hardware for most things.

My style would be to have the gui connect via pipes to the
local backend as a separate process, with a third process if there
are any communications needed to off box dbs. But that is just
the way I think - YMMV

- Hendrik

[ce]

On Mar 11, 12:26 pm, "David Cramer" <dcra...@gmail. comwrote:

On Mar 10, 10:52 pm, "sjdevn...@yaho o.com" <sjdevn...@yaho o.com>
wrote:

David Cramer wrote:

If you had an application that you were about to begin development on
which you wanted to be cross platform (at least Mac and Windows),
would you suggest using c++ and Python?

I'd strongly consider a pure python solution (I'd choose wxpython),
but if I needed to code backend stuff in a lower level language I'd
use C rather than C++.

Well we want it to be very robust, and python isn't exactly the
fastest language, or one with the lowest overhead :)

only one word caught my attention "robust".. do u mean python is not
robust???
if this is your feeling, i don't recommend u to "reconsider " anymore,
turn back to ur previous programming language (what did'ya say it
was??? c# .. i remember one ad. about it's robustness .. a piece of
jelly!)

and by the way if u know something about C++, code the GUI with QT
(which would make it portable), and enjoy a high speed execution :P