Generic concatenation

test.cpp

#include <iostream>
#include <sstream>

struct Tester {

  static void print(std::ostream& out) {}

  template <typename Head, typename... Tail>
  static void print(std::ostream& out, const Head& head, const Tail&... tail) {
    out << head;
    print(out, tail...);
  }

};

int main() {
  std::ostringstream ss;
  
  Tester::print(ss, "abc", 1, 2, 3);
  ss << std::endl;
  Tester::print(ss, "xyz");
  ss << std::endl;
  Tester::print(ss, 4);
  ss << std::endl;
  
  std::cout << ss.str();

  return 0;
}