/** @file list3501.cpp */
/** Listing 35-1. Defining a Derived Class */
class work
{
public:
  work() : id_(), title_() {}
  work(std::string const& id, std::string const& title) : id_(id), title_(title) {}
  std::string const& id()    const { return id_; }
  std::string const& title() const { return title_; }
private:
  std::string id_;
  std::string title_;
};

class book : public work
{
public:
  book() : author_(), pubyear_(0) {}
  book(std::string const& id, std::string const& title, std::string const& author,

       int pubyear)
  : work(id, title), author_(author), pubyear_(pubyear)
  {}
  std::string const& author() const { return author_; }
  int pubyear()               const { return pubyear_; }
private:
  std::string author_;
  int pubyear_; ///< year of publication
};

class periodical : public work
{
public:
  periodical() : volume_(0), number_(0), date_() {}
  periodical(std::string const& id, std::string const& title, int volume,
             int number,
 std::string const& date)
  : work(id, title), volume_(volume), number_(number), date_(date)
  {}
  int volume()              const { return volume_; }
  int number()              const { return number_; }
  std::string const& date() const { return date_; }
private:
  int volume_;       ///< volume number
  int number_;       ///< issue number
  std::string date_; ///< publication date
};