Learning Ruby Meta-programming with MetaKoans 1

Posted by ryan Sun, 23 Sep 2007 03:29:00 GMT

As I mentioned previously, the MetaKoans Ruby Quiz (#67) is a great way to learn meta-programming. However, it had some shortcomings. I've used MetaKoans as a training tool, and something I hear a lot is that it's unclear why certain things make a koan, or set of koans, pass. One reason for this confusion is that, often times while puzzling through the solution, a student will do something that causes multiple koans to pass at once. Due to the way that the koans are structured, I wasn't able to find a way to make a single koan pass at a time.

I've addressed this shortcoming by restructuring the koans so that the problem can be solved incrementally, one koan at a time. While restructuring the koans, I wrote a solution to each in turn, and saved that solution to its own knowledge file. Each file is a small refactoring from the one before it, ultimately building up to the final solution.

For the purposes of future training sessions, I've also started adding documentation to each refactoring, explaining how it changed from the previous one, and why it changed the way it did. The documentation isn't complete yet, but it's a start.

The restructured MetaKoans, along with the individual refactorings of my solution, can be found at http://github.com/ryankinderman/metakoans_training. Feel free to check it out.

A little explanation

You'll notice that the knowledge files in my solution follow the pattern: knowledge_for_koan_XX_Y.rb. The XX number is the koan that the knowledge is a solution for. The Y number is the ordered refactoring index, with 1 being the first, most straight-forward solution, and subsequent indices being refinements of the original.

The reason for this structuring is that, often times, the straight-forward, brute-force solution to a koan isn't always the optimal solution. So, I'd make refactorings to show how the code could, IMHO, be improved.


Thanks go to ara.t.howard for coming up with the original MetaKoans quiz. It's been an extremely informative tool for myself and many others.