#include <iostream>
 
void* my_crazy_function(int id) {
    static int a = 5;
    static double b = 7;
    if(id == 1) return &a;
    if(id == 2) return &b;
    return 0;
}
 
template<typename T, int def>
T vp_to_val(void *p) {
    return p ? *static_cast<T*>(p) : static_cast<T>(def);    
}
 
int main()
{
    std::cout << vp_to_val<int, 0>(my_crazy_function(1)) << std::endl;
    std::cout << vp_to_val<int, 0>(my_crazy_function(4)) << std::endl;
    std::cout << vp_to_val<double, 1>(my_crazy_function(2)) << std::endl;
    std::cout << vp_to_val<double, 1>(my_crazy_function(4)) << std::endl;
}

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