struct bar*
create_event(foo_sv)
  SV* foo_sv
  struct type_foo* foo = NULL;
  CODE:
    if ( SvROK(foo_sv)) {
      SV *tmp = (SV*) SvRV(foo_sv);
      if ( SvOK (tmp)) {
        foo = (struct type_foo*) SvIV(tmp);
      }
    } else {
      warn( "Foo::create_bar() -- foo is not an SV reference" );
      XSRETURN_UNDEF;
    }

    RETVAL = my_c_create_bar(foo);
  OUTPUT:
    RETVAL