clean-code

Break a long method into small, focused methods using the Extract Method technique, keeping each at a single level of abstraction. Guard clauses can replace deeply nested conditionals, and methods over roughly 20 lines are a common signal to split.

Common code smells include long methods, long parameter lists, duplicated code, magic numbers, god classes, feature envy, and primitive obsession. Each maps to a refactoring such as Extract Method, Parameter Object, or introducing value objects.

Use camelCase nouns for variables, verb-plus-noun names for methods like calculateTotal, and is/has/can prefixes for booleans. Classes use PascalCase nouns, constants use UPPER_SNAKE_CASE, and vague names like Data, Manager, or Helper should be avoided.

Duplication is acceptable when similar-looking code serves different purposes and will evolve independently, such as shipping cost versus insurance cost calculations. Forcing premature abstraction for coincidental similarity creates worse coupling than the duplication itself.

Strict YAGNI means building only methods and interfaces currently needed, avoiding configurable options and abstract layers for hypothetical futures. The tradeoff is that genuinely anticipated requirements may require later refactoring, so judgment is needed for stable, well-understood domains.