preferences_dialog.cpp

std::vector<double> accl_speeds_;

const auto accl_load = [this]()->int {
  return std::find(accl_speeds_.begin(), accl_speeds_.end(), turbo_speed()) -
    accl_speeds_.begin() + 1;
};

const auto accl_save = [this](int i) {
  set_turbo_speed(accl_speeds_[i - 1]);
};

register_integer("turbo_slider", true, accl_load, accl_save);

std::vector<std::string> accl_speed_labels;
accl_speed_labels.resize(accl_speeds_.size());
std::transform(accl_speeds_.begin(), accl_speeds_.end(), accl_speed_labels.begin(),
               [] (double speed) { return lexical_cast<std::string>(speed); });

find_widget<tslider>(&window, "turbo_slider", false).set_value_labels(accl_speed_labels);