Saturday, November 11, 2006

Coding dojo

Last Saturday we conducted a coding dojo session for a software development company in Pune. A coding dojo is an exercise that brings the element of practice to programming. All sportspersons, musicians... practitioners of any craft, do a lot of practice, where they explore various aspects of their art, explore different techniques, tools, and solutions. But software developers never do that. The way they enhance their skills is by learning while working or traditional workshops.

Workshops are a good way to bring a group of people up the learning curve on a new technology, but they fall short when we use them to improve developer's programming skills. Programming skills are best improved by practice. Practicing alone is good, but practicing with a group and a mentor is even better. This is exactly what a dojo is. A group of software developers that gets together to practice programming, to explore solutions, learn and improve their programming skills in the process.

For this dojo, we decided to code Dave Thomas' Kata 4 - Data Munging. We were a group of six developers. After an explanation of the exercise, we started programming in pairs, but not all at the same time. What we actually did was projector programming. The first pair started coding and the rest watched as a participative audience. By participative I mean, they were not just watching, but also suggesting solutions, pointing typos, and generally participating in the solution. After 20 minutes, the first pair went in the audience and the next pair took over for the next 20 minutes... and so on.

Here's what we had after completing part 1 (Weather data) and part 2 (Soccer data).  

DataMunging.gif 

WeatherMain.java drove the weather data. Actual parsing of data was done by WeatherDataParser.java and WeatherData.java represented the data. Ditto for soccer data.

Part 3 of the coding kata is DRY fusion. We have to identify repititive code and refactor it so that it follows the DRY (Don't repeat yourself)  principle.

I would like to urge you to actually program the solution as explore how we can elliminate duplicate code. We can elliminate duplication with inheritance or with composition. I am inclined to use composition as the first choice because inheritance trees are more difficult to maintain, and also since polymorphism is not warranted here. Your views however might differ, and if they do, please write about them as a comment here or as a trackback to your own blog.

We will solve the DRY fusion problem this week, and will explain the solution here. 

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