#include <iostream>
 
struct csv_t { };
csv_t csv;
 
struct chain
{
	bool first, alive;
	std::ostream* stream;
 
	chain(std::ostream* stream) : first(true), alive(true), stream(stream) { }
 
	chain(chain&& src) : first(false), alive(src.alive), stream(src.stream)
	{ src.alive = false; }
 
	~chain() { if(alive) *stream << "\n"; }
};
 
chain operator<<(std::ostream& str, csv_t& csv)
{
	return chain(&str);
}
 
template<typename T>
chain operator<<(chain c, T const& arg)
{
	if(c.first) c.first = false;
	else *c.stream << ",";
	*c.stream << arg;
	return c;
}
 
int main() {
	std::cout << csv << 1 << "abc" << 3.14f;
}

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