Question

Let’s say I have this :

class A 
{
    virtual int Method2(){/*...*/}
};

template<typename T>
class B<T> : public A
{
public :
    virtual int Method1(){/*...*/}
    virtual int Method2(){/*...*/}
};

Is it possible to do something similar to this (this does not work of course…) ?

A* a = ...;

B* b = dynamic_cast<B*>(a);

b->Method1();

Thanks

Answer 1

What people normally do is have an intermediary class.

class A { virtual ~A() {} };
class B : public A { virtual void method(); }
template<typename T> class C : public B {
    void method() { ... }
};

A* a = new C<int>();
if(B* b = dynamic_cast<B>(a)) {
    b->method();
}

This is known as type erasure. However, in this system, A doesn’t really serve much purpose.