IronPython in Action News

September 23-24th I'll be presenting a two day training session in Stockholm (the training is in English) with addskills. It is aimed at .NET developers looking to use IronPython for application development, scripting, embedding, testing or just as another useful tool. It will be a comprehensive training session for those with .NET experience who are interested in making practical use of IronPython. There will even be some IronRuby examples covered.

• Expertseminarium: IronPython and Dynamic Languages on the .NET Framework med Michael Foord

  This course is about how to make the most of dynamic languages like IronPython and IronRuby on the .NET framework; with a particular focus on IronPython. The dynamic language runtime, which is being incorporated into .NET 4.0 and is the basis of IronPython and IronRuby, enables a new class of language to run on the .NET framework. In the last few years dynamic languages have gained a reputation for increased developer productivity and being easy to learn. These new languages for the .NET framework have potential applications in everything from scripting tasks to application development to embedding in .NET programs as ready made scripting engines.

  Topics covered will include:

  • IronPython and the interactive environment (the REPL)
  • Why dynamic languages? (how Python and Ruby differ differ from statically typed languages)
  • The Python language
  • Multiple programming paradigms: object oriented, functional and metaprogramming
  • Working with the .NET framework
  • Development tools including IronPython in Visual Studio
  • Testing with IronPython
  • Dynamic Silverlight applications
  • Embedding the DLR (IronPython and IronRuby) in .NET applications
  • Interacting with dynamic objects and the dynamic keyword in C# 4.0
  • Practical tips, tricks, and participants' questions

It looks like attendees will also get a free copy of IronPython in Action.

Thanks to the wonder of Twitter I've heard about two different college courses that will be using IronPython in Action as course material next semester. One is Sargeant Reynolds College in America, with a course taught by Kevin Hazzard, and the other is Northtec in New Zealand with a course taught by Tony Meyer.

IronPython is an ideal language for learning programming, it has the great combination of an easy to learn general purpose programming language (Python) with a programming environment which is widely used in commercial development (the .NET framework). Not only these factors, but it is easy to teach good programming practise with Python; things like well structured code, testing, computer science theory including elements of functional programming and so on.

I exchanged emails with Tony who explained why he is using IronPython in Action:

The course is (unimaginatively) titled "Programming" (not my doing!). It's at NorthTec at the Whangarei campus (a couple of hours north of Auckland). It's the second programming course in their Bachelor of Applied Information Systems degree. We switched the first course from VB to Python a couple of years ago, but left this one as VB (because it's their introduction to Visual Studio and .NET).

Early last year I started work convincing people that IronPython would be a good choice, since they can continue with a language they (somewhat) know, but still get the intro to the Microsoft toolchain (plus, I hate VB, and dislike teaching in a language I never use in practice). I was expecting that I'd have to continue on without a textbook, until I saw that IronPython in Action was coming out.

BTW, while it's not like there is much choice in the way of books, yours is an excellent fit. The first section is a good Python refresher and .NET introduction. I introduce unit testing to them in the course, and the book handily has a chapter on that. They do a lot of sysadmin work later in their degree, so the chapter on using IronPython / PowerShell is great. They do ASP.NET stuff later on as well, so that'll be a good reference at that time (I don't expect I'll have time to cover that myself). I introduce them to databases and (since a couple of years ago) web services, and there's a chapter on that. Silverlight is an interesting example, and something I expect they'll be interested in given the later web development work, and there's an introduction to that.

Basically, you couldn't have done a lot better if I'd commissioned it! Thanks! - it certainly has made redoing the course material much simpler than if I was working completely from scratch.

As I mentioned in my tweet, I'll put my course material online at some point in the next couple of weeks (it's not quite finished) in case anyone else is interested in it.

Chapters three to six of IronPython in Action take you through building a simple example application called MultiDoc. MultiDoc is a multi-tabbed text editor using Windows Forms for the user interface. It is built with a few common design patterns (Model View Controller, command pattern, observer pattern and so on) to demonstrate structured programming with Python. In the process of building MultiDoc the reader will work with various .NET libraries and explore Python language features.

The source code for all the examples in the book can be downloaded from the Manning website or from the Sources page of this website.

The intention is that MultiDoc, along with as many examples from the book as possible, run on both Mono and the .NET framework; IronPython isn't just for Windows but can also be used on Linux and Mac OS X or anywhere that Mono will run.

Some readers have reported that MultiDoc crashes on exit when run with Mono. The root cause of this is the old version of IronPython 2 that ships with Mono. The full Mono distribution includes both IronPython 1 and 2, so after installing the full version of Mono you can run commands like:

ipy MultiDoc.py

ipy2 MultiDoc.py

The versions of IronPython included in Mono come from the FePy project; a community distribution of IronPython which can be compiled with Mono. The version of IronPython 2 is 2.0 Alpha 5 which is pretty old. Unfortunately Mono bugs or incompatibilities have stopped more recent versions being compiled with Mono. It isn't all bad news as IronPython 2.6 can be compiled with Mono which means we should have a FePy updated once this comes out. You can read more on the details in the FePy Status Update.

Some bug in either IronPython or Mono means that you will see the following crash on exiting MultiDoc when using IronPython 2a5 from Mono:

**
ERROR:generic-sharing.c:301:move_subclasses_not_in_image_foreach_func:
    assertion failed: (subclass->image == image)
Abort trap

This is reason enough to look at using a more recent version of IronPython 2. Even though IronPython can't be compiled with Mono you can still use the up to date Windows binaries (which is part of the point of Mono - binary compatibility). To use the latest version of IronPython (2.0.1) you'll need Mono 2.4 or more recent. For Mac OS X you can use the Mono Apple installer. For Linux you'll need to build Mono from source. This blog entry by Ali Afashar explains how to get IronPython 2 working with Ubuntu:

• How to install IronPython 2 on Ubuntu