template<typename Tag>
struct result {
/* export it ... */
typedef typename Tag::type type;
static type ptr;
};
template<typename Tag>
typename result<Tag>::type result<Tag>::ptr;
template<typename Tag, typename Tag::type p>
struct rob : result<Tag> {
/* fill it ... */
struct filler {
filler() { result<Tag>::ptr = p; }
};
static filler filler_obj;
};
template<typename Tag, typename Tag::type p>
typename rob<Tag, p>::filler rob<Tag, p>::filler_obj;
struct A {
private:
void f() {
std::cout << "proof!" << std::endl;
}
};
struct Af { typedef void(A::*type)(); };
template class rob<Af, &A::f>;
int main() {
A a;
(a.*result<Af>::ptr)();
}