Question

I have a class like this:

template <class T>
    class bag
    {
    private:    
        typedef struct{T item; unsigned int count;} body;
        typedef struct _node{_node* prev; body _body; _node* next;}* node;  
        struct iterator{
            enum exception{NOTDEFINED, OUTOFLIST};
            body operator*();

            explicit iterator();
            explicit iterator(const iterator&);
            iterator& operator=(const iterator&);
            iterator& operator++(int);
            iterator& operator--(int);
            bool operator==(const iterator&) const;
            bool operator!() const;     
        private:
            node current;

            friend class bag;
        };
        node head;
        node foot;

        iterator _begin;
        iterator _end;

        /* ... */

    public: /* ... */
        bag();
        const iterator& begin;
        const iterator& end;        
    };

In the bag() I have to set the reference begin to _begin, and end to _end.

begin = _begin;
end = _end;

But I think this line

begin = _begin;

invokes bag::iterator::operator=() function.

How can i avoid that?

Answer 1

References can’t be assigned, only initialised. So you will need to initialise them in the constructor’s initialisation list:

bag() : begin(_begin), end(_end) {}

However, it’s more conventional (and also reduces the class size) to get these using accessor functions rather than public references:

const iterator& begin() {return _begin;}
const iterator& end() {return _end;}