test.cpp

#include <iostream>
#include <vector>
#include <memory>

class A {
public:
    A() {}
    A(int i) {
        std::cout << i << std::endl;
    }

    virtual ~A() {
        std::cout << "A DIE" << std::endl;
    }
};

class B : public A {
public:
    B(const char *s) {
        std::cout << s << std::endl;
    }

    ~B() {
        std::cout << "B DIE" << std::endl;
    }
};

int main() {
    std::vector<std::unique_ptr<A>> av;
    av.push_back(std::move(std::unique_ptr<A>(new B("GOING INTO B"))));
    av.push_back(std::move(std::unique_ptr<A>(new A(5))));
    return 0;
}