Class NonCopyable

tests/test_virtual_functions.cpp:100–118

};

class NonCopyable {
public:
    NonCopyable(int a, int b) : value{new int(a * b)} { print_created(this, a, b); }
    NonCopyable(NonCopyable &&o) noexcept : value{std::move(o.value)} { print_move_created(this); }
    NonCopyable(const NonCopyable &) = delete;
    NonCopyable() = delete;
    void operator=(const NonCopyable &) = delete;
    void operator=(NonCopyable &&) = delete;
    std::string get_value() const {
        if (value) {
            return std::to_string(*value);
        }
        return "(null)";
    }
    ~NonCopyable() { print_destroyed(this); }

private:
    std::unique_ptr<int> value;
};

// This is like the above, but is both copy and movable.  In effect this means it should get moved
// when it is not referenced elsewhere, but copied if it is still referenced.