A C++ iterator adapter which wraps and hides an inner iterator and converts the iterated type

Question

Having toyed with this I suspect it isn\'t remotely possible, but I thought I\'d ask the experts. I have the following C++ code:

class IInterface
{
    virtual vo         


        

Answer 1

Create an abstract IteratorImplementation class:

template
class IteratorImplementation
{
    public:
        virtual ~IteratorImplementation() = 0;

        virtual T &operator*() = 0;
        virtual const T &operator*() const = 0;

        virtual Iterator &operator++() = 0;
        virtual Iterator &operator--() = 0;
};

And an Iterator class to wrap around it:

template
class Iterator
{
    public:
        Iterator(IteratorImplementation * = 0);
        ~Iterator();

        T &operator*();
        const T &operator*() const;

        Iterator &operator++();
        Iterator &operator--();

    private:
        IteratorImplementation *i;
}

Iterator::Iterator(IteratorImplementation *impl) :
    i(impl)
{
}

Iterator::~Iterator()
{
    delete i;
}

T &Iterator::operator*()
{
    if(!impl)
    {
        // Throw exception if you please.
        return;
    }

    return (*impl)();
}

// etc.

(You can make IteratorImplementation a class "inside" of Iterator to keep things tidy.)

In your Container class, return an instance of Iterator with a custom subclass of IteratorImplementation in the ctor:

class ObjectContainer
{
    public:
        void insert(Object *o);
        // ...

        Iterator