C++ Template problem adding two data types

Question

I have a template class with an overloaded + operator. This is working fine when I am adding two ints or two doubles. How do I get it to add and int and a double and return th

Answer 1

Here be dragons. You're getting into parts of c++ that will probably result in a lot of questions posted to StackOverflow :) Think long and hard about if you really want to do this.

Start with the easy part, you want to allow operator+ to add types that are not always the same as T. Start with this:

template 
TemplateTest operator+(const TemplateTest& rhs) {
  return TemplateTest(this->x + rhs.x);
}

Note that this is templated on T2 as well as T. When adding doubleTt1 + intTt2, T will be doubleTt1 and T2 will be intTt2.

But here's the big problem with this whole approach.

Now, when you add a double and an int, what do you expect? 4 + 2.3 = 6.3? or 4 + 2.3 = 6? Who would expect 6? Your users should, because you're casting the double back to an int, thus losing the fractional part. Sometimes. Depending on which operand is first. If the user wrote 2.3 + 4, they would get (as expected?) 6.3. Confusing libraries make for sad users. How best to deal with that? I dunno...