CRTPてこんなの

   template<class derived_t>
   class TLogPolicy {
   public:
      void log() { log_ += (static_cast<derived_t*>(this))->data_ + "\n"; };
   protected:
      TLogPolicy() {};
   private:
      std::string log_;
   };
   class TManager : public TLogPolicy<TManager> {
   public:
      void test() { log(); };
   private:
      std::string data_;
      friend TLogPolicy<TManager>;
   };

けっこう有名なテクニックだとおもうけど？