Probably some combination of things that break principle of least surprise along with not needing to think about that thing very frequently. A good IDE and good coding standards can smooth things over.
I'm ok with regex too, but if you asked me to do something with look-behind I'd have to experiment a little to figure out how it works again.
I'm ok with regex too, but if you asked me to do something with look-behind I'd have to experiment a little to figure out how it works again.