- Spanner*sp = dynamic_cast<Spanner*> (s);
-
- SCM s1 = sp->get_bound (LEFT) ? sp->get_bound (LEFT)->self_scm () : SCM_EOL;
- SCM s2 = sp->get_bound (RIGHT) ? sp->get_bound (RIGHT)->self_scm () : SCM_EOL;
-
- SCM pair = gh_cons (s1,s2);
- extend_spanner_over_elements (sp->mutable_property_alist_, pair);
-
- Grob *p1 = unsmob_grob (gh_car (pair));
- Grob* p2 = unsmob_grob (gh_cdr (pair));
- sp->set_bound (LEFT,p1);
- sp->set_bound (RIGHT, p2);