Class Sentinel

include/chaiscript/dispatchkit/boxed_value.hpp:249–276

      auto pointer_sentinel(std::shared_ptr<T> &ptr) const
      {
        struct Sentinel {
          Sentinel(std::shared_ptr<T> &t_ptr, Data &data)
            : m_ptr(t_ptr), m_data(data)
          {
          }

          ~Sentinel()
          {
            // save new pointer data
            const auto ptr_ = m_ptr.get().get();
            m_data.get().m_data_ptr = ptr_;
            m_data.get().m_const_data_ptr = ptr_;
          }

          Sentinel& operator=(Sentinel&&s) = default;
          Sentinel(Sentinel &&s) = default;

          operator std::shared_ptr<T>&() const
          {
            return m_ptr.get();
          }

          Sentinel &operator=(const Sentinel &) = delete;
          Sentinel(Sentinel&) = delete;

          std::reference_wrapper<std::shared_ptr<T>> m_ptr;
          std::reference_wrapper<Data> m_data;
        };

        return Sentinel(ptr, *(m_data.get()));
      }