#include "tclap/CmdLine.h"
#include <iterator>

using namespace TCLAP;

// Define a simple 3D vector type
struct Vect3D {
    double v[3];

    // operator= will be used to assign to the vector
    Vect3D& operator=(const std::string &str)
    {
	std::istringstream iss(str);
	if (!(iss >> v[0] >> v[1] >> v[2]))
	    throw TCLAP::ArgParseException(str + " is not a 3D vector");

	return *this;
    }

    std::ostream& print(std::ostream &os) const
    {
	std::copy(v, v + 3, std::ostream_iterator<double>(os, " "));
	return os;
    }
};

// Create an ArgTraits for the 3D vector type that declares it to be
// of string like type
namespace TCLAP {
template<>
struct ArgTraits<Vect3D> {
    using ValueCategory = StringLike;
};
}

int main(int argc, char *argv[])
{
    CmdLine cmd("Command description message", ' ', "0.9");
    ValueArg<Vect3D> vec("v", "vect", "vector", 
			 true, Vect3D(), "3D vector", cmd);
    
    try {
	cmd.parse(argc, argv);
    } catch(std::exception &e) {
	std::cout << e.what() << std::endl;
	return EXIT_FAILURE;
    }

    vec.getValue().print(std::cout);
    std::cout << std::endl;
}

