Coding design attitudes

People like acronyms

DRY

Don't Repeat Yourself.

Functions are good to avoid repeating code.

OO classes are good to also avoid repeating state management. (if not as automatically good at encapsulation as we like to pretend they are, but that's practice to be a very real problem in, not nice abstracted acronyms)

YAGNI

You Aren't Gonna Need It basically says "don't add functionality until you actually need it"

Can apply to design as well as code.