That was practically a poster example to sell C++. Look, you can overload operators and get arrays with bounds checking, integers that trap overflows and so on.

Twenty years ago, C++ was still hot and there was a lot of interest in all sorts of techniques. Books, seminars, papers, blogs, you name it.

There is a way to use C++ template partial specialization to mimic the built-in conversion rules, like "int op long" promoting the left operan to "int". You can mirror the language in itself and bend the rules.