[travisjungroth]

I love this. I think you could simplify it by generalizing. Something like immutability. These keys can’t be changed, only an object destroyed and another created. A case of that is a primary key (maybe that’s the only case).

You can always represent a change as a removal and an addition. It’s smart to actually consider when should you. “Never” and “whenever possible” don’t seem like the best answers.