Virtual constructor & virtual copy constructor

virtual constructor :  virtual constructor is function that creates different type of object of objects depending on the input it is given.

Example: Factory design pattern is the example of virtual constructor.

virtual copy constructor : virtual copy constructor returns a pointer to a new copy of the the object invoking the function. Because of this behaviour, virtual copy constructor is also known as 'copyself', 'cloneself' or just 'clone'.

class base {
    public:
        virtual base* clone() = 0;
};

class Text : public base
{
    public:
        virtual Text* clone()
        {
            return new Text(*this);
        }
};

class Image : public base
{
    public:
        virtual Image* clone()
        {
            return new Image(*this);
        }
};

If real copy constructor perform swallow copy, then virtual copy constructor also perform swallow copy. If real copy constructor perform deep copy then virtual copy constructor perform deep copy.

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