デジタルちんぶろぐ

#include <iostream> 

class base {
public:
    base() { std::cout << "base::base()" << std::endl; }
    base(int a) { std::cout << "base::base(" << a << ")" << std::endl; }
    virtual ~base() {}
}; 

class derived : virtual public base {
public:
    derived() { std::cout << "derived::derived()" << std::endl; }
    derived(int a) : base(a) { std::cout << "derived::derived(" << a << ")" << std::endl; }
}; 

class more_derived : virtual public derived {
public:
    more_derived() { std::cout << "more_derived::more_derived()" << std::endl; }
    more_derived(int a) : derived(a) { std::cout << "more_derived::more_derived(" << a << ")" << std::endl; }
}; 

template<typename T> void func(const T&) { std::cout << "func()" << std::endl; }
template<> void func<derived>(const derived&) { std::cout << "func<derived>()" << std::endl; } 

int main(int argc, const char* argv[])
{
    func(base(1));
    std::cout << "----------" << std::endl;
    func(derived(2));
    std::cout << "----------" << std::endl;
    func(more_derived(3)); 

    return 0;
}

base::base(1)
func()
----------
base::base(2)
derived::derived(2)
func()
----------
base::base()
derived::derived(3)
more_derived::more_derived(3)
func()