C++: Copying protected members of base class to derived class

[Edan]

I have a base class with protected members (`Base`). The function `MakeBase()` is a member function of another class, that returns a `Base` object initialized with private members of this class.
Now the thing is, I want to extend the functionality of `Base` class. I do that by inheriting `Base` class by `Derived`, but then I can't use `MakeBase()` function. It all makes sense to me, but I don't seem to find an appropriate solution.
Since I don't want to give any access to the private / protected members of these classes, I don't see how I can implement copy constructors
So I'm basically asking for suggestions. Maybe this is just bad design and I need to think differently (the `MakeBase()` thing).

This code gives the basic idea:

#include <iostream>
using namespace std;
 
 
class Base
{
  protected:
    int i;
    int n;
 
  public:
    Base(int _i, int _n)
    {
      i = _i;
      n = _n;
    }
    void Print()
    {
      cout << "i = " << i << endl;
      cout << "n = " << n << endl;
    }
};
 
 
Base MakeBase()
{
  /* This is originally a member function of a class,
     and the values are protected members of this class */
  return Base(1,2);
}
 
 
class Derived : public Base
{
  public:
    /* ... or any other function that adds
       functionality to the base class */
    void Increase()
    {
      i++;
      n++;
    }
};
 
 
int main()
{
 
  cout << "Base class:\n========" << endl;
  Base base_class = MakeBase();
  base_class.Print();
 
  cout << "----" << endl;
 
  cout << "Derived class:\n========" << endl;
  Derived derived_class = MakeBase(); /* This obviously isn't valid, but it illustrates what I want */
  derived_class.Print();
 
  return 0;
}
 

[Banfa]

Create an operator= in the base class that takes a type of Base &

Create an operator= in the derived class that takes a type of Base &, with-in this operator call the Base class operator= using the passed parameter.

[weaknessforcats]

You are trying to implement the Factory design pattern. In this case, an Abstract Factory.

You might want to Google on this or get a design patterns book.

[Edan]

I see. I've changed a couple of things to get a solution, and it's fine, but I will read about design patterns anyway.

Thanks,
Edan