strong_typedef_example.cc

#include <iostream>
#include <boost/serialization/strong_typedef.hpp>

BOOST_STRONG_TYPEDEF(double, Time)
BOOST_STRONG_TYPEDEF(double, Distance)
BOOST_STRONG_TYPEDEF(double, Velocity)

Velocity calculateVelocity(Distance d, Time t) {
  return Velocity{static_cast<double>(d) / static_cast<double>(t)};
}

int main() {
  // auto v = calculateVelocity(10.0, 5.0);  // What is this? What is 10? What is 5? -> Compiler Error!
  auto v = calculateVelocity(Distance{10.0}, Time{5.0});

  std::cout << static_cast<double>(v) << '\n';
}

The overhead of casting is (theoretically) only on library side. For the user, it is fully transparent. They only use code as written in main. What could be of use is a general overload for streaming operators or even calculations…

I could think of something like

#define STRONG_TYPEDEF_WITH_OSTREAM(T, ALIAS)             \
    BOOST_STRONG_TYPEDEF(T, ALIAS)                        \
    std::ostream& operator<<(std::ostream& os, ALIAS a) { \
      os << static_cast<T>(a);                            \
      return os;                                          \
    }

(not tested)