Re: operator+ on nested type within template class

Hello,

I have this code:

#include <iostream>

template<unsigned int modulus> class modRing {
     public:
         class element {
             public:
                 element(unsigned int valIn):
                     val(valIn)
                 {}
                 unsigned int val;
         };
};

template<unsigned int modulus>
typename modRing<modulus>::element
operator+(typename modRing<modulus>::element const &a, typename
modRing<modulus>::element const &b) {
     return typename modRing<modulus>::element((a.val + b.val) % modulus);
}

int main() {
     typedef modRing<5> R;
     R::element a(3);
     R::element b(4);
     std::cout << (a + b).val;
}

Compilation with g++ 4.1.2 results in:

In function ???int main()???:
24: error: no match for ???operator+??? in ???a + b???

So the compiler does not recognize that it can specialize the operator+
function to the situation in line 24. My questions are:
Why?

How can I fix this problem?