// This program demos the use of a template metaprogram
// to construct fibonacci numbers.
// Template metaprograms were introduced by Todd Veldhuizen,
// in C++ Report, Vol. 7, No. 4.

// Note that template instantiation requires the equivalent
// of a pattern-matching based interpreter to be included
// in the compiler, making template implementation tricky!

#include <iostream>

template< unsigned long N >
class Fib {
public:
   enum { value = Fib<N-1>::value + Fib<N-2>::value };
};

// Explicit specialization of first fibonacci number:
class Fib<1> {
public:
   enum { value = 1 };
};

// Explicit specialization of second fibonacci number:
class Fib<2> {
public:
   enum { value = 1 };
};

main() {
   Fib<5> five;
   Fib<6> six;
   std::cout << five.value << std::endl;
   std::cout << six.value << std::endl;

   std::cout << Fib<1000>::value << std::endl;
}