Question
My question is how can you teach the methods and importance of tidying-up and refactoring code?
Background
I was recently working on a code review for a colleague. They had made some modifications to a long-gone colleagues work. During the new changes, my colleague had tried to refactor items but gave up as soon as they hit a crash or some other problem (rather than chasing the rabbit down the hole to find the root of the issue) and so reimplemented the problem code and built more on top of that. This left the code in a tangle of workarounds and magic numbers, so I sat down with them to go through refactoring it.
I tried to explain how I was identifying the places we could refactor and how each refactoring can often highlight new areas. For example, there were two variables that stored the same information – why? I guessed it was a workaround for a bigger issue so I took out one variable and chased the rabbit down the hole, discovering other problems as we went. This eventually led to finding a problem where we were looping over the same things several times. This was due in no small part to the use of arrays of magic number sizes that obfuscated what was being done – fixing the initial ‘double-variable’ problem led to this discovery (and others).
As I went on this refactoring journey with my colleague, it was evident that she wasn’t always able to grasp why we made certain changes and how we could be sure the new functionality matched the original, so I took the time to explain and prove each change by comparing with earlier versions and stepping through the changes on paper. I also explained, through examples, how to tell if a refactoring choice was a bad idea, when to choose comments instead of code changes, and how to select good variable names.
I felt that the process of sitting together to do this was worthwhile for both myself (I got to learn a bit more about how best to explain things to others) and my colleague (they got to understand more of our code and our coding practices) but, the experience led me to wonder if there was a better way to teach the refactoring process.
…and finally…
I understand that what does or does not need refactoring, and how to refactor it are very subjective so I want to steer clear of that discussion, but I am interested to learn how others would tackle the challenge of teaching this important skill, and if others here have had similar experiences and what they learned from them (either as the teacher or the student).
Like most programming, refactoring skill comes with practice and experience. It would be nice to think it can be taught, but it has to be learned – and there is a significant difference in the amount of learning that can be accomplished in different environments.
To answer your question, you can teach refactoring methods and good design in a pedagogical fashion, and that’s fine. But, ultimately, you and I both know attaining a certain level is only through long hard experience.