- boost::function<boost::optional<std::string> ()> get_username,
- boost::function<void (std::string)> set_username,
- boost::function<void ()> unset_username,
- boost::function<boost::optional<std::string> ()> get_password,
- boost::function<void (std::string)> set_password,
- boost::function<void ()> unset_password
+ std::function<boost::optional<std::string> ()> get_username,
+ std::function<void (std::string)> set_username,
+ std::function<void ()> unset_username,
+ std::function<boost::optional<std::string> ()> get_password,
+ std::function<void (std::string)> set_password,
+ std::function<void ()> unset_password