gistfile1.hpp

class Base{
public:
    Base(){}
    void Doit(){
        stage1();
        stage2();
        stage3();
    }
private;
    void stage1(){ .. }
    void stage3(){ ... }
protected:
    virtual void stage2() = 0;
};

class Derived : public Base
{
    Derived(){}
protected:
    void stage2(){ /* ny implementasjon */ }
};

int main()
{
    Base* b = new Derived();
    b->Doit();
}