Leaver’s Law: “Everything the system does FOR you, the system also does TO you.”

I first heard this term coined by Don Leaver, one of the best “crusty C hackers” I’ve ever met. He got his start grinding out high-performance unix code, and these days he’s writing (if you can believe it) high-performance Windows code. (Seriously, the man is terrifying. His idea of a good time is making Windows completely surrender one of its CPUs and control of the USB bus so he can process signal data from a mission-critical device without fear of the operating system “taking the app out to lunch while my data puddles on the floor”.) As he modernized from simpler to more luxurious operating systems, this was his lament: that luxury is merely the upside of complexity, and when you gotta get crap done, complexity is the downside of luxury.

I have found that this law is not limited to operating systems, but can be applied to just about anything. I have quoted this law (usually with a curse) at everything from web frameworks to the automatic timer on my car’s headlights.

Leaver’s Law. Now you know.