C++ inheritance pattern

Question

I am after your opinion on how best to implement an inheritance pattern in C++. I have two base classes, say

class fooBase{
protected:
    barBase* b;
};

class barBase{};

where fooBase has a barBase. I intend to put these classes in a library, so that wherever I have a fooBase it can use its barBase member.

I now intend to create a specialisation of these in a specific program

class fooSpec : public fooBase{};
class barSpec : public barBase{};

Now I want fooSpec::b to point to a barSpec instead of a barBase. I know that I can just initialise b with a new barSpec, but this would require me to cast the pointer to a barSpec whenever I wanted to use specific functions in the specialisation wouldn't it?

Is there another way that this is often acheived?

Cheers.

Answer 1

Create a method in your specclass to cast the b into the special version. That way instead of casting it all the time, it looks like a getter.

On the other hand OO is about programming towards interfaces and not objects. So what you are doing here looks like programming towards objects. But the is difficult to see as this example is purely theoretical.