[Boost-users] [program options] storing values into a set instead of vector?

Hello all! I would like to allow only unique parameters to be stored: param = X param = Y param = X should result in a collection of {X, Y} Therefore I want my params to be stored in a set instead of vector? Is there any chance to implement/specify it without putting the params into the vector of strings and re-inserting them into a set? Doing it the way: value<string_set>() result in an error. Some other question? As I see "program options" works only with basic_strings<charT>, where it is assumed that the traits class is default. What if I wish to specify my traits class for the basic_string will it work? Many thanks! Ovanes