Conclusion

The end result of this program reads much better than it did at the start. It also works a bit better. I'm pretty pleased with the outcome. The program is much easier to understand and is therefore much easier to change. Also, the structure of the program has isolated its parts from one another. This also makes the program much easier to change.

You might be worried that extracting functions that are called only once might adversely affect performance. I think that the increased readability is worth a few extra nanoseconds in most cases. However, there may be deep inner loops where those few nanoseconds will be costly. My advice is to assume that the cost will be negligible and wait to be proved wrong.

Was this worth the time we invested in it? After all, the function worked when we started. I strongly recommend that you always practice such refactoring for every module you write and for every module you maintain. The time investment is very small compared to the effort you'll be saving yourself and others in the near future.

Refactoring is like cleaning up the kitchen after dinner. The first time you skip cleaning up, you are done with dinner sooner. But the lack of clean dishes and clear working space makes dinner take longer to prepare the next day. This makes you want to skip cleaning again. Indeed, you can always finish dinner faster today if you skip cleaning. But the mess builds and builds. Eventually, you are spending an inordinate amount of time hunting for the right cooking utensils, chiseling the encrusted dried food off the dishes, scrubbing them down so they are suitable to cook with, and so on. Dinner takes forever. Skipping the cleanup does not really make dinner go more quickly.

The goal of refactoring, as depicted in this chapter, is to clean your code every day, every hour, and every minute. We don't want the mess to build. We don't want to have to chisel and scrub the encrusted bits that accumulate over time. We want to be able to extend and modify our systems with a minimum of effort. The most important enabler of that ability is the cleanliness of the code.

I can't stress this enough. All the principles and patterns in this book come to naught if the code they are used within is a mess. Before investing in principles and patterns, invest in clean code.