Mega Code Archive
Virtual template
<![CDATA[
/* The following code example is taken from the book
* "C++ Templates - The Complete Guide"
* by David Vandevoorde and Nicolai M. Josuttis, Addison-Wesley, 2002
*
* (C) Copyright David Vandevoorde and Nicolai M. Josuttis 2002.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
#include <iostream>
class NotVirtual {
};
class Virtual {
public:
virtual void foo() {
}
};
template <typename VBase>
class Base : private VBase {
public:
// the virtuality of foo() depends on its declaration
// (if any) in the base class VBase
void foo() {
std::cout << "Base::foo()" << '\n';
}
};
template <typename V>
class Derived : public Base<V> {
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()
}
Base::foo()
Derived::foo()
]]>