Apply KISS Principle

Prefer the simplest implementation that correctly solves the problem. Complexity is a liability that must be justified, not a default.

Why This Is Best Practice

Adopted by: Google (code review guidelines explicitly value readability over cleverness), Amazon (Leadership Principle: "Simplify"), NASA (Kelly Johnson's original design mandate for Skunk Works aircraft), UNIX philosophy ("Write programs that do one thing well") — universal adoption across engineering cultures that prioritize long-term maintainability. Impact: McCabe (IEEE Transactions on Software Engineering, 1976) established that cyclomatic complexity >10 correlates with 2–5x higher defect density. Chidamber & Kemerer (1994) found complexity metrics are the strongest predictors of defect-prone classes across industrial Java systems. Code review throughput drops ~40% for functions over 50 lines vs under 20 lines (Google's internal review data, cited in "Software Engineering at Google", 2020). Why best: The alternative — optimizing for cleverness, generality, or premature abstraction — produces code that is hard to debug, hard to onboard, and brittle to change. YAGNI (You Aren't Gonna Need It) addresses feature scope; KISS addresses implementation complexity. Both are needed: YAGNI prevents unnecessary features, KISS prevents unnecessary complexity inside necessary features.

Sources: McCabe, "A Complexity Measure" (IEEE TSE, 1976); Chidamber & Kemerer, "A Metrics Suite for OO Design" (IEEE TSE, 1994); Winters, Manshreck & Wright, "Software Engineering at Google" (O'Reilly, 2020); Hunt & Thomas, "The Pragmatic Programmer" (Addison-Wesley, 1999)

Steps

1. Measure the complexity signal

Before simplifying, locate the complexity: