Operator+ for a subtype of a template classe.
- by baol
I have a template class that defines a subtype. I'm trying to define the binary operator+ as a template function, but the compiler cannot resolve the template version of the operator+.
#include <iostream>
template<typename other_type>
struct c {
c(other_type v) : cs(v) {}
struct subtype { subtype(other_type v) : val(v) {} other_type val; } cs;
};
template<typename other_type>
typename c<other_type>::subtype operator+(const typename c<other_type>::subtype& left,
const typename c<other_type>::subtype& right)
{ return typename c<other_type>::subtype(left.val + right.val); }
// This one works
// c<a>::subtype operator+(const c<a>::subtype& left,
// const c<a>::subtype& right)
// { return c<a>::subtype(left.val + right.val); }
int main()
{
c<int> c1 = 1;
c<int> c2 = 2;
c<int>::subtype cs3 = c1.cs + c2.cs;
std::cerr << cs3.val << std::endl;
}
I think the reason is because the compiler (g++4.3) cannot guess the template type so it's searching for operator+<int> instead of operator+.
What's the reason for that? What elegant solution can you suggest?
