Here are the steps I followed :

wget https://github.com/downloads/libevent/libevent/libevent-1.4.13-stable.tar.gz

tar xvzf libevent-1.4.13-stable.tar.gz

mkdir ~/externals

cd libevent-1.4.13-stable

./configure –prefix=$HOME/externals/

make

make install

pip install –install-option=”-I$HOME/externals/include” –install-option=”-L$HOME/externals/lib” gevent

Validating models…
0 errors found

Django version 1.2.1, using settings ‘xxx.settings’
Development server is running at http://127.0.0.1:8000/
Quit the server with CTRL-BREAK.

But when I visited the page http://127.0.0.1:8000/ (or http://127.0.0.1:8000/admin) I would get “Page Not Found :/” (or “Page Not Found :/admin” – depending on which page I tried to launch) Since I was trying this app for the first time, I suspected that this must be the problem with the app. I checked with other folks who worked on this project, but I couldn’t get any help.  While reading the Django documentation further – I came across an option to “runserver” command where one can start the server on non-default port. As part of troubleshooting, I just tried it, not hoping for much success, but it worked.

Now I am thinking why doesn’t the app work on default port, but works on non-default port. So I stopped the server (running on non-default port) and tried the URL again. I still got the “Page not found” error, and this made it clear that, some other server was listening on port 8000.  Eventually I was find out the process that was listening on port 8000 using the following command :

netstat -ao | findstr LISTENING

Option ‘0′ prints the process ID – I was able to find out the eecutable using ProcExp (which has replaced my Task Manager) On linux – use “grep” in place of “findstr” and “ps” can be used to find out the executable

What surprised me was even though some process is already listening on default port 8000, How did Django “runserver” did not give an error when it tries to bind to port 8000.  This can be reproduced easily by running two instances of same app (or two different apps) from two different terminals. Second instance should fail while binding to default port – and I expect it to show error – But it doesn’t. If it matters I was using Django 1.2.1 on Windows XP (Python 2.6)

All in all, It was very interesting to troubleshoot the problem.

This is in continuation with my previous blog post :

To get IronPython to use Standard Python Modules,  one needs to add the following two lines to C:\IronPython-2.0.1\Lib\site.py :

import sys
sys.path.append(r"C:\Python25\Lib")

While this works for most part, it doesn’t help if you are using Python extensions written in C. More about my specific problems in another post. But there is an open source project IronClad to deal specifically with this issue. In the meantime, you can check the differences between IronPython and CPython

Reading (and writing to) CSV file is critical part of my program, while in stadard python it was as easy as “import csv”, the same thing took some efforts to get it working in IronPython. I got the following error for my import statement

Error on line 7 in csv.py
from functools import reduce

I also tried using ActiveState Python 2.5.2.2 (which I already had from few months ago, didn’t feel like downloading the latest version till the problem was fixed) But that didn’t help either. With ActiveState, I got the same error on the same line, except this time it was for _csv.

To Quote from IronPython Cookbook :

For some reason the Python standard library csv module is written in C, which means that it isn’t available to IronPython.

The cookbook points to a third party library called A Fast Csv Reader . The cookbook has a nice example of how to use the said DLL with your IronPython Program.

It wasn’t clear to me as to why I had to register at Code Project to download this binary since it is provided under MIT Open Source License. But whom am I gonna complain to ? Beggars can’t be choosers

After working on initial prototype using pylons, on ubuntu, my employer needed a standalone application (on windows) So I was looking for ways to reuse my python code to avoid double work.  had only heard about iron python but beyond that I did not know anything more.

A bit of research later, I downloaded IronPython from here and IronPython Studio. I was quite thrilled to find out that Microsoft, has created this shell, which allows developers to integrate new languages with Visual Studio Shell.

Installing IronPython Studio

Installing IronPython was very straight forward. Considering it is one of the Python implementation itself, you don’t have to have standard python installed. (But I did, more on that later)

Setting up IronPython Studio wasn’t so straight forward.  I had to download standalone version of Visual Studio shell. But the problem, and it is well documented, is that installing the redistributable package in itself is not the complete step, as you would believe from the website. I confirmed that the package was installed, and stil IronPython Studio would complain, and refuse to proceed. It turns out that you need to install the Visual Studio environment, which is inside this directory structure you just created.

This is NOT enough

This is what IronPython Studio needs

Once I installed Visual Studio Shell, IronPython Studio installed easily.  Using IronPython has been nice experience in just a few hours I have been using it. The Code completion isn’t upto my liking yet, but it is helpful at times.

Using Standard Python Libraries

Since my original code was written on linux, it used only the standard python modules. In a manner of speaking, it was “pure” python code. Since IronPython is an implementation of the Python programming language running under .NET, it was obivious that my code may not work as is. But I’m glad that I did not have to make too many changes to get it working under IronPython.

As is well documented in IronPython Tutorial, it is not very difficult to use standard python libraries with IronPython (with a few exceptions – more about this a little later) To get IronPython to use Standard Python Modules,  one needs to add the following two lines to C:\IronPython-2.0.1\Lib\site.py :

import sys
sys.path.append(r"C:\Python25\Lib")

While this works for most part, it doesn’t help if you are using Python extensions written in C. More about my specific problems in another post. But there is an open source project IronClad to deal specifically with this issue. In the meantime, you can check the differences between IronPython and CPython

Related articles

• IronPython in Action (blogs.msdn.com)
• Why Python? (mehmetalierturk.com)

Here is the quick list of pdb commands

• n : Execute next line
• s : Step inside a module
• p : Print the value of a variable
• c : Continue
• l : List. Shows stack trace
• q : Quit (Most important command )

For details, check this site

But what if I can’t debug interactively ?

Typically, you come across this problem when you are running the script on a server. Even if the script worked OK in test environment, in live environment something goes wrong, because the script is executed by server, and you can not control the arguments that are being passed to the script. In this scenario, you need to resort to age-old logging technique

Here are few line of code you need to add to your script. Modify as per your needs (especially paths)
Earlier in your script (as early as possible) add following lines :

from time import strftime
f = open('D:/temp/log.txt', 'r+')
f.write("-- Begin Log at %s --n" % strftime("%Y-%m-%d %H:%M:%S"))


At the end of your script (as late as possible) add following lines :

f.write("-- End Log at %s --n" % strftime("%Y-%m-%d %H:%M:%S"))
f.close()


Your basic logging infrastructure is ready. Now you can add f.write() lines through out your code, as and where needed.

Note : I’m part of pythondev group on twitter.  Visit the website for details.