include <set>;
include <map>;
include <vector>;
include <string>;

// We can place the options classes into namespaces which mapped to C++
// namespaces.
//
namespace features
{
  class options
  {
    // We can have several aliases for the same option. The first one is used
    // to derive the accessor name.
    //
    std::string --out-dir | -o;

    // We can use both assignment and constructor notations to provide the
    // default option value.
    //
    std::string --first-name = "John";
    std::string --last-name ("Mr John Doe", 8, 3);

    // We can use containers to to collect option value. If we have a command
    // line like this: -v 1 -v 2 -v 1 -s 1 -s 2 -s 1 then the vector returned
    // by the vector() accessor will contain three elements: 1, 2, and 1 while
    // the set returned by the set() accessor will contain two elements: 1 and
    // 2.
    //
    std::vector<int> --vector | -v;
    std::set<int> --set | -s;

    // We can also use maps. In this case the option value is expected to have
    // two parts: the key and the value, separated by '='. For example: -m a=A
    // -m =B -m c= -m d (same as -m d=).
    //
    std::map<std::string, std::string> --map | -m;
  };
}