format_tuple.cpp

#include <iostream>
#include <sstream>
#include <tuple>

using namespace std;

template <size_t Pos, typename Tpl, typename Head>
void _format_tuple(ostream& os, const Tpl& tpl) {
	os << get<Pos>(tpl);
}

template <size_t Pos, typename Tpl, typename Head, typename Snd, typename... Tail>
void _format_tuple(ostream& os, const Tpl& tpl) {
	os << get<Pos>(tpl) << ", ";
	_format_tuple<Pos+1, Tpl, Snd, Tail...>(os, tpl);
}

string format_tuple(const tuple<>& tpl) {
	return "()";
}

template <typename... Args>
string format_tuple(const tuple<Args...>& tpl) {
	ostringstream os;
	os << "(";
	_format_tuple<0, tuple<Args...>, Args...>(os, tpl);
	os << ")";
	return os.str();
}

int main(int argc, char* argv[]) {
	cout << format_tuple(make_tuple()) << endl;
	cout << format_tuple(make_tuple(1)) << endl;
	cout << format_tuple(make_tuple(1, "foo")) << endl;
	cout << format_tuple(make_tuple(1, "foo", "bar")) << endl;
}