Returning pointer to derived form a base class function

[oseri]

Is that posibble with covariant return types ? Namely that code :

class Derived;
class Base
{
public:
	virtual Derived* clone() const
	{
		return new Derived;
	}
};

class Derived : public Base{
public:
	Derived() {};
	virtual Derived* clone() const
	{
		return new Derived(*this);
	}
};

#include <iostream>

int main()
{
	Base ob;
	Derived od;
        return 0;
}

fails to compile and complains that no relevant Derived() constructor exist

[Peter87]

It fails because the Derived class is not defined when you try to create the object. You need to define Base::clone() after the Derived class has been defined.

[oseri]

Thanks, it works now. Sometimes it seems that I lack such basic knowledge, eh..