# typedef struct bar*      Bar;
# typedef struct type_foo* Foo;

TYPEMAP
#######

Bar	T_NULLABLE_PTROBJ
Foo	T_NULLABLE_PTROBJ


INPUT
#####

T_NULLABLE_PTROBJ
	if ( !SvOK( $arg ) ) {  /* if not defined */
		$var = NULL;
	}
	else if ( sv_derived_from( $arg, \"${ntype}\" ) ) {
		IV tmp = SvIV( (SV*)SvRV( $arg ) );
		$var = INT2PTR( $type, tmp );
	}
	else {
		Perl_croak( aTHX_ \"$var is not of type ${ntype}\" )
	}


OUTPUT
######

T_NULLABLE_PTROBJ
	if ( $var )  /* if defined */
		sv_setref_pv( $arg, \"${ntype}\", (void*)$var );
	else
		$arg = &PL_sv_undef;