Our good friend Randall was talking about how he liked prototype inheritance such as that in JavaScript. He enjoyed how you can add, modify and remove methods from JavaScript classes and have them apply to all object instances.

Amazed as he was, he's now forcing me at gun point to write a post about it!

The first thing you have to understand about Python classes is that all they are is a collection of references to members. Methods are just function pointers that are referenced by the class, not embedded or copied into the class. This is why all methods require that the first parameter be self, the current instance. Instances themselves contain the real state and reference the class. When you invoke a method on the instance it looks up what function to call.

If you didn't read my previous post, you'll want to check that out first: The Purely Functional Python Brainfuck Challenge.

So, today was the first day I really invested some thought and time into the challenge. I decided that before just diving into code I'd spend some time reading up on functional programming in python, and learn a bit.

The first thing I read through was the official python functional programming page which you can find here. This had a bunch of useful information regarding functional programming tools in python, but didn't really have any examples of actual functional programs.

People are always wondering if Python has a ternary operator. The answer is yes but no.

There is no recognised ternary operator. However it is very simple to construct one out of logic operations.

Python short circuits conditional evaluations. This means that given a series of logic operations, if it can plainly see that a certain branch of that logic is unreachable or of no consequence it wont even attempt to execute it.

A question that is frequently asked by new Django programmers is: "How can I serve static content (css, images, javascript) with the Django development server?". This article is my attempt to answer that question by demonstrating the best practices way to do so.

Why Doesn't Django Serve Static Content Automatically?

Well, Django (and python in general) is built around the idea that it is better to be explicit than implicit. This concept means that you may need to write more code in order to do something, but that by doing it that way, you preserve code clarity and reduce complexity.

A little bit of code that loads network device statistics from any operating system that supports procfs.

Just a small snippet. Originally used in some network monitoring code that I wrote that graphed your network traffic.

I would include that here too but that's a little messy.

At work, I'm the lead developer of a rather large, complex web application which interacts with many different technologies (Asterisk, Freeswitch, Cisco routers, python, XML-RPC, JSON, Django--to name a few). A few days ago, while implementing a ban system, I bumped into an interesting problem that was not trivial to find a solution to. So, here it is :)

Background

The web application I'm developing is a private portal which allows users to manage teleconference lines real time. Since all of our telephony services are free of charge, we often get callers onto certain teleconference lines who want to abuse services (think of those trolls on the internet, except over the phone). As you can probably imagine, without strict regulation & technology in place, telephone trolls could cause huge problems for normal users.

While working on the new v2 release of pycall, I was doing some research on the internal limitations of Asterisk call files, and thought I'd share some interesting (technical) bits of information here.

All information below has been gathered from the latest Asterisk release (v1.6.2.7). If you don't do any programming, you may want to skip this article, as it is a bit geeky.

Recently I've been developing an API using python and Django for work, which uses XML responses to speak to clients. One of my goals for the client was to be able to easily parse the XML responses that the server sends, so that I could appropriately handle errors.

Fortunately, python has many tools for building and parsing XML. During my research, I tested several options, but found that the well supported library LXML was a perfect match for what I needed. Unfortunately, I had a hard time figuring this out, as examples to just parse XML content was lacking in the official tutorial, and there were no good resources online with code samples.

So let's take a quick peek at a sample XML document, then we'll analyze some simple LXML code to see how it works. Of course, before you can run any of these code samples, you'll need to download and install LXML (there are packages available on most linux systems already).

Here's a little C# program I made that gets the filename of the currently set desktop wallpaper and also can be used to set the desktop wallpaper.

Example usage: SetDesktopWallpaper.exe C:\MyNewWallpaper.jpg

Just something I made for my sister who has Windows 7 Starter edition and lacks the presentation controls. Add it to your 'Send To' folder and just select the file you want to set the wallpaper as and go.

This is a little piece of code I wrote to intercept and disregard a http or https request from urllib.urlopen if the Content-Type header on the response is not within a list of accepted content types.

I'm sure somebody might find a use for this.

This snippet creates a customer URLopener and then overrides the open_http and open_https methods, checks for MIME type and halts the request if the response is of a MIME type you do not accept.