From: David Whipp [mailto:[EMAIL PROTECTED]] > Peter Haworth [mailto:[EMAIL PROTECTED]] wrote: > > This is all very sensible, and I completely agree with it. > > However, don't we > > need some restrictions on what can go in PRE and POST blocks > > to ensure that they are still valid in inherited methods? > > There's another issue: sometimes we don't want to inherit PRE > conditions. DBC allows a derived method to strengthen (add) > post-conditions; but to weaken (remove) preconditions. I > haven't (yet) seen how this weakening would be accomplished.
In regard to Design-by-Contract, Larry did say more on that later. -Didn't he? In Class::Contract, pre-conditions are allowed to weaken by allowing either the satisfaction of the subclassed method's pre-conditions or by satisfying the pre-conditions of all classes from which it is derived.
