Hi, I'd like a const iterator that acts as a proxy by giving access to elements of type A as if they were elements of unrelated type B. In that case I guess the dereference() member function should return a temporary value, right?
Would that be a correct implementation of the idea? Here I just want to access an array of SourceVertexType as if it were an array of VertexType.

        template<class VertexType>
        class ConstVerticesIterator : public boost::iterator_adaptor< ConstVerticesIterator<VertexType>, const SourceVertexType*, const VertexType >
        {
            private:

            friend class boost::iterator_core_access;

            VertexType dereference() const
            {
                const SourceVertexType& source_vertex( *base() );
                return VertexType( source_vertex.x, source_vertex.y );
            }

            public:

            explicit ConstVerticesIterator( const SourceVertexType* vertices )
                :
                boost::iterator_adaptor< ConstVerticesIterator<VertexType>, const SourceVertexType*, const VertexType >( vertices )
            {}
        };