Don't Repeat Yourself (DRY)

The Don't Repeat Yourself (DRY) principle is a principle that you shouldn't repeat yourself in code. Code that isn't DRY is usually called "wet" or "diarrhea" code.

• The Pragmatic Programmer – your journey to mastery, 20th anniversary edition, chapter 9 "The Evils of Duplication" (freely available on the Internet)
• Refactoring.guru: Duplicate Code