Designated initializers. It's one of those things that a computer can do much better than a living person. I just have to tell it which element(s) I want initialized to what, and the layout is taken care of. Reduces errors, maintenance overhead, maintenance risk (if someone switches member order in a struct), increases readability A LOT, and no runtime overhead at all.
I don't know why these have been received with such lukewarm enthusiasm. I tell most people about them, and I get either a shoulder shrug, or a "hmm, that's nice." Whatever.
