Learn Web Development with Python

Reducing code duplication

Imagine that you are writing a piece of scientific software, and you need to calculate primes up to a limit, as we did in the previous chapter. You have a nice algorithm to calculate them, so you copy and paste it to wherever you need. One day, though, your friend, B. Riemann, gives you a better algorithm to calculate primes, which will save you a lot of time. At this point, you need to go over your whole code base and replace the old code with the new one.

This is actually a bad way to go about it. It's error-prone, you never know what lines you are chopping out or leaving in by mistake, when you cut and paste code into other code, and you may also risk missing one of the places where prime calculation is done, ...