Lorenzo Caminiti skrev:
Hello everyone,
Allow me to reiterate my question:
On Sun, May 30, 2010 at 8:42 PM, Lorenzo Caminiti <lorcaminiti@gmail.com> wrote:
How should subcontracting work for non-public base classes? (See details in my previous email below.)
1) I have looked at N1962 (and its previous revisions) but I could not see how the proposal addresses non-public inheritance. I might be missing something (given that the N1962 is rather detailed)...
Well, since it has no special case for this, the same rules apply for all types of virtual functions.
2) What Eiffel does in this case does not help me much because there is not really something like protected inheritance in Eiffel...
You can override a private virtual function, so why should the rules be special for them?
3) I looked at an old Contract Programming proposal for C++ called "A++". This proposal addresses this issue as quoted below but this is a very old proposal from 1990 so I cannot consider it the "state of the art".
I had not seen this before. Thanks.
BTW, I am asking because I need to decide how to implement subcontracting for protected and private inheritance in Boost.Contract. One option could be (essentially following A++): a) Preconditions, postconditions, and invariants are all subcontracted for public inheritance. b) Only preconditions and postconditions (but no invariants) are subcontracted for protected inheritance. c) Nothing is subcontracted for private inheritance. This should still satisfy Liskov substitution principle.
I guess you can do whatever is the easiest. I'm not up to date with the rules, but is it not so that I can override a priviate virtual function of a private base class? If so, I see no reason to make special rules forbidding subcontracting although it is somewhat unclear what the point with a such a piece of code would be. -Thorsten