[godshatter]

There's a difference between taking criticism of a section of code to be indicative of some kind of moral failing, and taking that criticism to mean that their understanding of that piece of code was not complete. The first is a direct hit to self worth, the second is a hit to one thing that is used to determine self worth along with lots of other things. The first way is taking it as some kind of attack, the second way is taking it as a learning experience and a chance to increase self-worth by becoming a better developer.

So I think what people mean when they suggest detaching their self worth from their code is that they shouldn't take criticism of their code as a personal attack but as a chance to learn and grow. Hence "you are not your code": the attack isn't a direct assault on you, it's a technical argument about the actual code itself.