If the operations return "type&&" instead of "type", they can potentially be more efficient, but I'm a little cautious to do that without giving it some thought because the choice implies subtle differences. I'm sure Daniel has already taken this all into consideration.
Return by value please. Otherwise:
type const& x = type() + type(); std::cout << x; // BOOM; x is dangling
Won't the following fail too, making it completely useless?
void foo(type const& x) { ... }
foo(type() + type());
No, because the temporary created by "type() + type()" is guaranteed to live until after foo returns.
I meant in the case where operator+ returns a type&&. Then the object in question is a local variable inside operator+, which will not live past the point when operator+ returns. Of course the case when operator+ returns a type is fine. Regards, Nate