How do I define friends in global namespace within another C++ namespace?

Question

I\'d like to define a binary operator on in the global namespace. The operator works on a class that is defined in another namespace and the operator should get access to th

Answer 1

It is possible - you can enclose the declarator in parentheses: friend A (::operator * (double lhs, const A& rhs));

You also need to forward-declare both the class and the function.

namespace NAME {class A;}
NAME::A operator *(double lhs, const NAME::A& rhs);

// ...

namespace NAME
{
    class A {
        public:
            friend A (::operator * (double lhs, const A& rhs));
        private:
            int private_var;
    };
}

NAME::A operator *(double lhs, const NAME::A& rhs) {
  //...
}

But I agree with Andreas that it would be better to define both in the same namespace if possible.