deciding-abstraction-level

Choose the right level of abstraction by evaluating coupling cost versus duplication cost and change patterns. Use when: (1) asked to evaluate whether similar code should be abstracted or kept separate, (2) an extraction is suggested without analysis of whether similar pieces change together or independently, (3) an abstraction is nameable only as "common parts" rather than a domain concept, (4) justification cites aesthetics or "might need" rather than maintenance costs and change patterns.