Use new server method definition

router/handler.go

@@ -60,20 +60,20 @@ func getEndpoint(m reflect.Method) *endpoint {
 		return nil
 	}
 
-	// Functions must have inputs like (c context.Context, d *data.Data), plus one input for the receiver
-	if m.Type.NumIn() != 3 {
+	// Functions must have inputs like (c context.Context, req *data.Request, resp *data.Response), plus one input for the receiver
+	if m.Type.NumIn() != 4 {
 		return nil
 	}
 
-	// Functions must return either 1 or 2 values
-	if m.Type.NumOut() == 0 || m.Type.NumOut() > 2 {
+	// Functions must return an error value
+	if m.Type.NumOut() != 1 {
 		return nil
 	}
 
 	return &endpoint{
 		Name:        m.Name,
 		HandlerFunc: m.Func,
 		In:          m.Type.In(2),
-		Out:         m.Type.Out(0),
+		Out:         m.Type.In(3),
 	}
 }

router/router.go

@@ -73,26 +73,24 @@ func (s *router) Handle(path string, data []byte) ([]byte, error) {
 		return nil, fmt.Errorf("decode request: %w", err)
 	}
 
+	respValue := reflect.New(method.Out)
+
 	ret := method.HandlerFunc.Call([]reflect.Value{
 		reflect.ValueOf(handler.Instance),
 		reflect.ValueOf(context.Background()),
 		*in,
+		respValue,
 	})
 
-	if len(ret) == 2 && !ret[1].IsNil() {
+	if !ret[0].IsNil() {
 		return nil, &HandlerError{
 			endpoint: method,
 			handler:  handler,
-			err:      ret[1].Interface().(error),
+			err:      ret[0].Interface().(error),
 		}
 	}
 
-	retval := ret[0]
-	if len(ret) == 2 {
-		retval = ret[1]
-	}
-
-	outdata, err := s.codec.Marshal(retval.Interface())
+	outdata, err := s.codec.Marshal(respValue.Interface())
 	if err != nil {
 		return nil, fmt.Errorf("encode response: %w", err)
 	}