The following code example is taken from the book
C++ Templates - The Complete Guide, 2nd Edition
by David Vandevoorde, Nicolai M. Josuttis, and Douglas Gregor,
Addison-Wesley, 2017
© Copyright David Vandevoorde, Nicolai M. Josuttis, Douglas Gregor 2017
#include <iostream>
class NotVirtual {
};
class Virtual {
public:
virtual void foo() {
}
};
template<typename... Mixins>
class Base : public Mixins... {
public:
// the virtuality of foo() depends on its declaration
// (if any) in the base classes Mixins...
void foo() {
std::cout << "Base::foo()" << '\n';
}
};
template<typename... Mixins>
class Derived : public Base<Mixins...> {
public:
void foo() {
std::cout << "Derived::foo()" << '\n';
}
};
int main()
{
Base<NotVirtual>* p1 = new Derived<NotVirtual>;
p1->foo(); // calls Base::foo()
Base<Virtual>* p2 = new Derived<Virtual>;
p2->foo(); // calls Derived::foo()
}