Question

Is something like this possible?

// We can even assume T and U are native C++ types
template<typename T, typename U>
magically_deduce_return_type_of(T * U) my_mul() { return T * U; }

Or would somebody have to hack up a return_type struct and specialize it for every pair of native types?

Answer 1

Heard of decltype?

In C++0x you can do

template<class T, class U>
auto mul(T x, U y) -> decltype(x*y)
{
    return x*y;
}