I skimmed the DbC section. From what I can see they took pretty much the normal approach. I haven't seen any mention of getting the old value of variables/parameters (cf. Eiffel), but I am pretty sure this in there somewhere.|
I guess most of you are aware of the prblems with the classic DbC approahc (based on runtime checking of assertions expressed using the programming language's, restricted, boolean expressions).
Still, IMHO, DbC is useful.