static if in plain c++?

Question

Problem in short:
How could one implement static if functionality, proposed in c++11, in plain c++ ?

History and original prob

Answer 1

std::string a("hello world");
// bool a = true;
if(std::is_same::value) {
    std::string &la = *(std::string*)&a;
    std::cout << "std::string " << la.c_str() << std::endl;
} else {
    bool &la = *(bool*)&a;
    std::cout << "other type" << std::endl;
}