Could you explain this copy member function to me?

[ruwan2]

Hi,

I am still new to C++. When I read a post on-line, I do not understand one line:



Fred(const Fred& f) : p_(new Wilma(*f.p_)) { }

  class Wilma { };
class Fred {
public:
  Fred()                : p_(new Wilma())      { }
  Fred(const Fred& f)   : p_(new Wilma(*f.p_)) { }
 ~Fred()                { delete p_; }
  Fred& operator= (const Fred& f)
    {
      // Bad code: Doesn't handle self-assignment!
      delete p_;                // Line #1
      p_ = new Wilma(*f.p_);    // Line #2
      return *this;
    }
private:
  Wilma* p_;
};

I know that f is a reference to a Fred object. *f.p_ is the pointer of object f. My question is about

Wilma(*f.p_)

or

new Wilma(*f.p_)


is class Wilma incomplete?
Please explain it to me if you can.


Thanks,

[liuyang]

new Wilma(*f.p_)
This line creates a new Wilma instance. It calls the copy constructor of Wilma.

Wilma::Wilma(const Wilma &rhs)

As we know that the default constructor and copy constructor are automatically generated, so we can't say Wilma incomplete.