I recently spent a whole afternoon chasing a cryptic null‑reference through a class hierarchy that spanned seven files. The bug didn’t stem from a typo or a wrong assignment; the culprit was a tightly coupled component that pulled in state from the global context. Every time I added a feature, a “smart” method quietly mutated shared data, and my unit tests never caught it because the fault only surfaced when those hidden mutations happened consecutively in production.
The lesson? Prioritize clear, decoupled interfaces over clever shortcuts. Treat every public API as a contract: explicitly expose only what the calling code needs and keep internal state private. Add immutable data structures, dependency injection, and guards against accidental state changes. Even if the short‑term code is a little more verbose, you’ll save hours debugging, prevent cascading failures, and make the next migration a breeze. Also, remember to leave a comment that says, “Why is this here?”—if you can’t explain it, someone else (or future you) will struggle to maintain it.
