Leitura de configuração em C++

config.h

struct my_value {
	std::string sval;
	using const_iterator = std::string::const_iterator;
};
//...
auto cfg = configuration::load<std::string, my_value>(fname, 
	[](auto &config, iter_type b, iter_type m, iter_type e) {
		std::string k(b, m);
		my_value mv;
		mv.sval = std::string(m+1, e);
		config.add_item( k, mv );
	});