PPT Slide
class emptyBox : public box {public: // constructors emptyBox () : box() , aField() { } emptyBox (const emptyBox & right) : box(right), aField(right.aField) { }
~emptyBox() // destructor { // implicit deletion of aField // implicit call on parent class destructor } const emptyBox & operator = (const emptyBox & right) {// operators aField = right.aField; box::operator = (right); return *this; } emptyBox * operator & () { return * this; } template <class T> const T & operator , (const T & right) { return right; }private: box aField;};