How to prevent a template class from being derived more than once?

Question

I have the following template class:

template
class T : public I
{
    // ...
};

This template class need to be derived once (an

Answer 1

I'm not a big fan of macros but if using macros is not a problem to you - you could use a simple and compact solution as follows:

#include 

template 
struct prohibit_double_inheritance { };

#define INHERIT(DERIVING, BASE) \
    template<> struct prohibit_double_inheritance { };\
    struct DERIVING: BASE


template
struct T: I
{
    // ...
    static void do_something() {
        std::cout << "hurray hurray!" << std::endl;
    }
};

struct U { };
struct V { };

INHERIT(A, T) {
};

//INHERIT(B, T) { // cause redetinition of the struct 
//};                 // prohibit_double_inheritance> 

int main() {
    A::do_something();
}

[live demo]