Contemporary programmers are lucky: we live in a world where historical and influential program source code is available for us to review. However, most programmers only learn and study the programs they have worked on themselves. We rarely take the time to study historical works, and programming courses don’t typically spend any time on the subject.
We believe that software developers should review influential source code. This is similar to architects studying influential building designs (and critiques of those designs). Rather than repeating the same mistakes over-and-over, we should study the great works that preceded us and learn from and build upon their lessons.
Ideally, we would study great source code along with a commentary or critique which provides us information about the project’s context, successes, and failures. Such commentaries are rare, but here are a few excellent starting points:
You can also find a program you’ve used in the past and review the source code. It’s important to start with a program you are familiar with, so you can anchor the functional behavior to the source code. Here are resources you can use to find and browse historical source code: