Assuming imperative/object-oriented code: organize classes/structures around mutability patterns, and don't mix badly. Favor side-effect-free functions and immu

Assuming imperative/object-oriented code: organize classes/structures around mutability patterns, and don't mix badly. Favor side-effect-free functions and immutability without getting dogmatic, and be clear about member/struct variables that are mutable accumulators, registers, etc. Build abstractions at the right time. Base classes and common structs should hold completely common information, not be a bag of data that may or may not be there. Be tight with your reasoning about inheritance. Write tests, useful ones that exercise the logic. (Setters and getters aren't worth it usually.)