Interfaces and covariance problem

Question

I have a particular class that stores a piece of data, which implements an interface:

template
class MyContainer : public Container

        

Answer 1

If the usage is supposed to be similar to stdlib, then the iterator needs to be a value object, because it normally gets copied by value a lot. (Also, otherwise what would the begin and end method return a reference to?)

template 
class Iterator
{
    shared_ptr it;
public:
    Iterator(shared_ptr);
    T& operator*() { it->deref(); }
    T* operator->() { return &it->deref(); }
    Iterator& operator++() { it->inc(); return *this; }
    etc.
};