Musical chairs and reproducibility drills

In a recent interview on the Hanselminutes podcast, Jeff Web said that if he were to teach a computer science class, he would have the class work on an assignment, then a week later make everyone move over one chair, i.e. have everyone take over the code their neighbor started. Aside from the difficulty of assigning individual grades in such a class, I think that’s a fantastic idea.

Suppose students did have to take over a new code base every week. People who write mysterious code would be chastised by their peers. Hopefully people who think they write transparent code would realize that they don’t. The students might even hold a meeting outside of class to set a strategy. I could imagine someone standing up to argue that they’re all going to do poorly in the class unless they agree on some standards. It would be fantastic if the students would discover a few principles of software engineering out of self-defense.

I had a small taste of this in college. My first assignment in one computer science class was to add functionality to a program the instructor had started. Then he asked us to add the same functionality to a program that a typical student had written the previous semester. As the instructor emphasized, he didn’t pick out the worst program turned in, only a typical one. As I recall, the student code wasn’t terrible, but it wasn’t exactly clear either. This was by far the most educational homework problem I had in a CS class. I realized that the principles we’d been taught about how to write good code were not just platitudes but survival skills. Later my experience as a professional programmer and as a project manager reinforced the same conclusion.

In some environments, it’s not practical to have people switch projects unless it is absolutely necessary. Maybe the code is high quality (and maybe it’s not!) but there is a large amount of domain knowledge necessary before someone could contribute to the code. But at least software developers ought to be able to build each other’s code, even if they couldn’t maintain it.

When I was managing a group of around 20 programmers, mostly working on one-person projects, I had what I called reproducibility drills. These were similar to Jeff Webb’s idea for teaching computer science. I had everyone try to build someone else’s project. These exercises turned out to be far more difficult than anyone anticipated, but they caused us to improve our development procedures.

We later added a policy that a build master would have to extract a project from version control and build it without help from the developer before the project could be deployed. The developer was allowed (required) to create written instructions for how to build the project, and these instructions were to be in a location dictated by convention. The build master position rotated so we wouldn’t become too dependent on one person’s implicit knowledge.

Having a rotating build master is great improvement, but it lacked some of the benefits of the reproducibility drills. The build master procedure only requires a project to be reproducible before it’s deployed. That is essential, but it could foster an attitude that it’s OK for a project to be in bad shape until the very end. Also, some projects never actually deploy, such as research projects, and so they never go to  the build master.

2 thoughts on “Musical chairs and reproducibility drills

  1. Pingback: Rotating programmers — The Endeavour

  2. Pingback: Do you really want to be indispensable? — The Endeavour

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