The Pragmatic Programmer: From Journeyman to Master

"This is about the craft of software development, and thinking about how to produce good code. As the name suggests, it’s a very pragmatic and hands-on book. It really helped me on my journey as a software engineer, to be able to write quality code day in and day out, and be confident that it’s going to work correctly. It’s something that we never really talked about in my computer science education, and it’s certainly something that statisticians rarely think about. The goal is to turn an idea in your head into code that works, and that you can share with others. I think there are three main parts. First, for code to be good, it has to be correct and do what you think it does. Ideally, you want to verify that correctness somewhat formally, by writing unit tests . The idea of unit tests is the same as double-entry bookkeeping: if you record everything in two places, the chances of you making a mistake in both places on the same item are very low. So unit tests don’t guarantee that your code is correct, but they make it much more likely to be correct. But the requirements of your code will also change over time. So the second part, and maybe the bigger one, is to write code that will be correct in the future, i.e. easy to maintain. For example, it’s very important to write code that clearly communicates its intent; because you will come back to it six months later, having completely forgotten what you were trying to do. So the easier it is to read your code and understand what’s going on, the easier it will be to add new features in the future. “When writing code, you’re always collaborating with future-you; and past-you doesn’t respond to emails” The third part would be to make sure that it’s fast enough, so that it doesn’t become a bottleneck. It can be easy (and fun!) to get carried away with this, and obsess with writing code that’s exponentially faster. The important thing is to make sure that nothing is overly slowing down execution, to the point of interrupting the flow of your analysis, or meaning that your program has to run overnight. But it doesn’t matter how fast your code is, if it’s not correct and maintainable."