Hello all (and N1962 authors especially), How should subcontracting work for non-public base classes? I have listed a few examples below. Assume contracts were written for all these example classes (invariants) and their functions (pre/post conditions). My questions are: A) `c::p()` should subcontract; but what about any of the other member functions of `c`, should any of them subcontract also? B) Am I missing any other combination of member/inheritance access level significant for deciding when to subcontract? class bp { public: virtual void p(void) { std::cout << "bp called" << std::endl; } }; class bf { protected: virtual void f(void) { std::cout << "bg called" << std::endl; } }; class bg { public: virtual void g(void) { std::cout << "bg called" << std::endl; } }; class bh { public: virtual void h(void) { std::cout << "bh called" << std::endl; } }; class c: public bp, public bf, protected bg, private bh { public: // This should subcontract. virtual void p(void) { bp::p(); } // Should any of the following subcontract also? virtual void f(void) { bf::f(); } virtual void g(void) { bg::g(); } virtual void h(void) { bh::h(); } // Am I missing any other relevant combination? }; (I do not think multiple inheritance is relevant for my questions. I am using multiple inheritance in this example just so to have only one derived class `c` which exercises all the use cases.) My notes and questions: 1) All member functions of `c` are public so they will check their pre/post conditions as in `c` and `c` class invariants. 2) But shall any `c` member functions also check their base class invariants and/or base function pre/post conditions? 3) `c::p()` should subcontract `bp::p` pre/post and `bp` inv because it is a public function publicly inheriting from a base public function. ** 4) Maybe `c::f()` should subcontract `bf::f()` pre/post but not `bf` invariant... (because `bf::f` is protected thus it does not have to check `bf` invariant). ** ** 5) Should `c::g()` and `c::h()` subcontract given that their inheritance is not public? ** Thank you very much. -- Lorenzo