class base
{
    public:
        void virtual something() = 0;        
};

template <class T>
class derived : public base
{
    public:
        void something(){}
        T* member;        
};

int main()
{
    base* test = new derived();
    
    // now i want to have test accessing member
    // ... test->member ...
    // how?
    return 0;
}