C++/Tips/Technique/CompileTimePolymorphism/Code - lab.comp@wiki

#include <iostream>
 
struct point_tag {};
struct vector_tag {};
 
struct Point {
    typedef point_tag type;
};
 
struct Vector {
    typedef vector_tag type;
};
 
// Point用 print
void print_(const Point& target, point_tag) {
    std::cout << "Point\n";
}
 
// Vector用 print
void print_(const Vector& target, vector_tag) {
    std::cout << "Vector\n";
}
 
// Point/Vector用print
template <typename Arg>
void print( const Arg &x ) {
    print_( x, typename Arg::type() );  // Arg::type で上記のどっちかに振り分ける
}
 
int main() {
    Point p;
    Vector v;
    print(p);
    print(v);
}