A simple variable would be a scoped resource, unique_ptr can be transferred.

    {
       RAII file = ....;
       // do stuff
    } // file is no longer open

vs

    unique_ptr<RAII> outer_ptr;
    {
       unique_ptr<RAII> file = make_unique(...);
       // do stuff
       outer_ptr = file;
    } // resource still open