INPUT
T_PTROBJ
    if (sv_derived_from($arg, \"${ntype}\")) {
        IV tmp = SvIV((SV*)SvRV($arg));
        $var = INT2PTR($type,tmp);
    }
    else
        croak(\"$var is not of type ${ntype}\")

OUTPUT
T_PTROBJ
    sv_setref_pv($arg, \"${ntype}\", (void*)$var);