Moveable semantic fun

moveable_base_animal.cpp

#include <iostream>
#include <string>
#include <utility>
#include <boost/noncopyable.hpp>

struct animal : private boost::noncopyable
{
    animal() {}
    animal(char const* name) : name(name) {}

    animal(animal&& a) : name(a.name)
    {
        a.name.clear();
    }

    animal& operator=(animal&& a)
    {
        name = a.name;
        a.name.clear();
        return *this;
    }

    std::string name;
};

struct cat : public animal
{
    cat(char const* name) : animal(name) {}
};

struct dog : public animal
{
    dog(char const* name) : animal(name) {}
};

struct Cage
{
private:
    animal animal_;
public:
    void set_animal(animal&& a)
    {
        animal_ = std::move(a);
    }

    std::string who() const { return animal_.name; }
};

int main() 
{ 
    using std::cout;
    using std::endl;

    Cage cage;
    cage.set_animal(cat("Kitty"));
    std::cout << cage.who() << std::endl;

    cage.set_animal(dog("Bamboozle"));
    std::cout << cage.who() << std::endl;

    return 0;
}