Clean Code: A Handbook of Agile Software Craftsmanship, 2nd Edition

7

Clean Functions

In the earliest days of computing, programmers composed their systems of a sequence of routines that performed individual tasks. They quickly discovered that some of those routines were generally useful, and they wrote them in their notebooks and called them subroutines. When needed, they would transcribe those subroutines from their notebooks directly into the program they were creating. There were no calls—those subroutines were simply encoded inline within the program.

Later, in the early ’50s, instructions were added to the machines that would allow subroutines to be called. At first, programmers were reluctant to use ...