Use a command line style that does not think '-3' is an option. Multitoken
options are BAD, exactly because of these ambiguities.

- Volodya

Usually what I'm trying to do is input a 3d coordinate. I have tried to do this:

vgl_point_3d<double> Point;
desc.add_options()
("point,p", po::value<vgl_point_3d<double> >(&Point)->default_value(vgl_point_3d<double>(0.0, 0.0, 0.0)), "set point")

But when I run the program with:
./Test --point 1 2 3

I get:
what(): in option 'point': invalid option value '1'

(the input operator is properly defined, ie
vgl_point_3d<double> P;
std::cin >> P;

works as expected).

This is why I resorted to a multitoken option. The other option I can think of is --x 1 --y 2 --z 3, is that what you are recommending?

Thanks,

Dave