It didn't start off as a joke: https://www.martinfowler.com/bliki/TwoHardThings.html https://www.martinfowler.com/bliki/TwoHardThings.html If you're not caref

It didn't start off as a joke: https://www.martinfowler.com/bliki/TwoHardThings.html https://www.martinfowler.com/bliki/TwoHardThings.html If you're not careful with what you cache, you end up with bugs unless you invalidate the cache carefully. And doing that carefully is in itself surprisingly difficult and error-prone, unless you come up with a comprehensive scheme, at which point you probably no longer have a what we call a cache but more like a secondary index with performance/concurrency problems on it own. It doesn't seem hard until you've been there and given up. I think the same is true for naming. If you told someone new at programming that naming is the most difficult part, they'd laugh at you and continue using quickly thought up, confusing names that cause them to introduce bugs because they misunderstand themselves.