diff --git a/iguana/ylt/reflection/member_count.hpp b/iguana/ylt/reflection/member_count.hpp
index e323c7ee..04d12a42 100644
--- a/iguana/ylt/reflection/member_count.hpp
+++ b/iguana/ylt/reflection/member_count.hpp
@@ -11,7 +11,10 @@
 #endif
 
 #include "user_reflect_macro.hpp"
-
+namespace struct_pack {
+template <typename T, uint64_t version>
+struct compatible;
+}
 namespace ylt::reflection {
 template <typename T>
 using remove_cvref_t = std::remove_cv_t<std::remove_reference_t<T>>;
@@ -47,7 +50,7 @@ constexpr bool expected = expected_impl<T>::value;
 
 #if __cpp_concepts >= 201907L
 template <typename Type>
-concept optional = requires(Type optional) {
+concept optional = !expected<Type> && requires(Type optional) {
   optional.value();
   optional.has_value();
   optional.operator*();
@@ -87,14 +90,12 @@ template <typename T>
 constexpr bool tuple_size = tuple_size_impl<T>::value;
 #endif
 
-template <typename T, uint64_t version = 0>
-struct compatible;
-
 template <typename Type>
 constexpr inline bool is_compatible_v = false;
 
 template <typename Type, uint64_t version>
-constexpr inline bool is_compatible_v<compatible<Type, version>> = true;
+constexpr inline bool is_compatible_v<struct_pack::compatible<Type, version>> =
+    true;
 
 struct UniversalVectorType {
   template <typename T>
diff --git a/iguana/ylt/reflection/member_names.hpp b/iguana/ylt/reflection/member_names.hpp
index 72c94168..e4a8c7bb 100644
--- a/iguana/ylt/reflection/member_names.hpp
+++ b/iguana/ylt/reflection/member_names.hpp
@@ -7,9 +7,6 @@
 
 namespace ylt::reflection {
 
-template <typename T>
-struct ylt_alias_struct;
-
 template <typename T>
 inline constexpr auto get_alias_field_names();
 
@@ -64,32 +61,54 @@ struct member_tratis<T Owner::*> {
 };
 
 template <typename T, typename = void>
-struct has_alias_field_names_t : std::false_type {};
+struct has_alias_struct_name_t : std::false_type {};
 
 template <typename T>
-struct has_alias_field_names_t<
-    T, std::void_t<decltype(ylt_alias_struct<T>::get_alias_field_names())>>
+struct has_alias_struct_name_t<
+    T, std::void_t<decltype(get_alias_struct_name((T*)nullptr))>>
+    : std::true_type {};
+
+template <typename T, typename = void>
+struct has_inner_alias_struct_name_t : std::false_type {};
+
+template <typename T>
+struct has_inner_alias_struct_name_t<
+    T, std::void_t<decltype(T::get_alias_struct_name((T*)nullptr))>>
     : std::true_type {};
 
 template <typename T>
-inline constexpr bool has_alias_field_names_v =
-    has_alias_field_names_t<T>::value;
+constexpr bool has_alias_struct_name_v = has_alias_struct_name_t<T>::value;
+
+template <typename T>
+constexpr bool has_inner_alias_struct_name_v =
+    has_inner_alias_struct_name_t<T>::value;
 
 template <typename T, typename = void>
-struct has_alias_struct_names_t : std::false_type {};
+struct has_alias_field_names_t : std::false_type {};
 
 template <typename T>
-struct has_alias_struct_names_t<
-    T, std::void_t<decltype(ylt_alias_struct<T>::get_alias_struct_name())>>
+struct has_alias_field_names_t<
+    T, std::void_t<decltype(get_alias_field_names((T*)nullptr))>>
+    : std::true_type {};
+
+template <typename T, typename = void>
+struct has_inner_alias_field_names_t : std::false_type {};
+
+template <typename T>
+struct has_inner_alias_field_names_t<
+    T, std::void_t<decltype(T::get_alias_field_names((T*)nullptr))>>
     : std::true_type {};
 
 template <typename T>
-inline constexpr bool has_alias_struct_name_v =
-    has_alias_struct_names_t<T>::value;
+constexpr bool has_alias_field_names_v = has_alias_field_names_t<T>::value;
+
+template <typename T>
+constexpr bool has_inner_alias_field_names_v =
+    has_inner_alias_field_names_t<T>::value;
 
 template <typename T, typename U, size_t... Is>
-inline constexpr void init_arr_with_tuple(const T& tp, U& arr,
-                                          std::index_sequence<Is...>) {
+inline constexpr void init_arr_with_tuple(U& arr, std::index_sequence<Is...>) {
+  constexpr auto tp = struct_to_tuple<T>();
   ((arr[Is] = internal::get_member_name<internal::wrap(std::get<Is>(tp))>()),
    ...);
 }
@@ -106,10 +125,9 @@ get_member_names() {
     return type::refl_member_names(ylt::reflection::identity<type>{});
   }
   else {
-    constexpr auto tp = struct_to_tuple<T>();
-
     std::array<std::string_view, Count> arr;
 #if __cplusplus >= 202002L
+    constexpr auto tp = struct_to_tuple<T>();
     [&]<size_t... Is>(std::index_sequence<Is...>) mutable {
       ((arr[Is] =
             internal::get_member_name<internal::wrap(std::get<Is>(tp))>()),
@@ -117,7 +135,7 @@ get_member_names() {
     }
     (std::make_index_sequence<Count>{});
 #else
-    init_arr_with_tuple(tp, arr, std::make_index_sequence<Count>{});
+    init_arr_with_tuple<T>(arr, std::make_index_sequence<Count>{});
 #endif
     return arr;
   }
@@ -210,26 +228,18 @@ inline constexpr size_t index_of() {
   return names.size();
 }
 
-template <size_t Idx>
 struct field_alias_t {
   std::string_view alias_name;
-  inline static constexpr auto index = Idx;
+  size_t index;
 };
 
-template <typename Tuple, size_t... Is>
-inline constexpr auto get_alias_field_names_impl(Tuple& tp,
-                                                 std::index_sequence<Is...>) {
-  return std::array<std::pair<size_t, std::string_view>, sizeof...(Is)>{
-      std::make_pair(std::tuple_element_t<Is, std::decay_t<Tuple>>::index,
-                     std::get<Is>(tp).alias_name)...};
-}
-
 template <typename T>
 inline constexpr auto get_alias_field_names() {
   if constexpr (internal::has_alias_field_names_v<T>) {
-    constexpr auto tp = ylt_alias_struct<T>::get_alias_field_names();
-    return get_alias_field_names_impl(
-        tp, std::make_index_sequence<std::tuple_size_v<decltype(tp)>>{});
+    return get_alias_field_names((T*)nullptr);
+  }
+  else if constexpr (internal::has_inner_alias_field_names_v<T>) {
+    return T::get_alias_field_names((T*)nullptr);
   }
   else {
     return std::array<std::string_view, 0>{};
@@ -239,7 +249,10 @@ inline constexpr auto get_alias_field_names() {
 template <typename T>
 constexpr std::string_view get_struct_name() {
   if constexpr (internal::has_alias_struct_name_v<T>) {
-    return ylt_alias_struct<T>::get_alias_struct_name();
+    return get_alias_struct_name((T*)nullptr);
+  }
+  else if constexpr (internal::has_inner_alias_struct_name_v<T>) {
+    return T::get_alias_struct_name((T*)nullptr);
   }
   else {
     return type_string<T>();
@@ -251,10 +264,11 @@ inline constexpr std::array<std::string_view, members_count_v<T>>
 get_member_names() {
   auto arr = internal::get_member_names<T>();
   using U = ylt::reflection::remove_cvref_t<T>;
-  if constexpr (internal::has_alias_field_names_v<U>) {
+  if constexpr (internal::has_alias_field_names_v<U> ||
+                internal::has_inner_alias_field_names_v<U>) {
     constexpr auto alias_arr = get_alias_field_names<U>();
     for (size_t i = 0; i < alias_arr.size(); i++) {
-      arr[alias_arr[i].first] = alias_arr[i].second;
+      arr[alias_arr[i].index] = alias_arr[i].alias_name;
     }
   }
   return arr;
diff --git a/iguana/ylt/reflection/member_ptr.hpp b/iguana/ylt/reflection/member_ptr.hpp
index fec004ec..1fa090e9 100644
--- a/iguana/ylt/reflection/member_ptr.hpp
+++ b/iguana/ylt/reflection/member_ptr.hpp
@@ -3,7 +3,7 @@
 
 // modified based on:
 // https://github.com/getml/reflect-cpp/blob/main/include/rfl/internal/bind_fake_object_to_tuple.hpp
-// thanks for alxn4's greate idea!
+// thanks for alxn4's great idea!
 namespace ylt::reflection {
 namespace internal {
 
diff --git a/test/test_cpp20.cpp b/test/test_cpp20.cpp
index 1d915371..0e8e2e58 100644
--- a/test/test_cpp20.cpp
+++ b/test/test_cpp20.cpp
@@ -15,17 +15,16 @@ YLT_REFL(point_t, x, y);
 struct point_t1 {
   int x;
   int y;
-};
-YLT_REFL(point_t1, x, y);
-
-template <>
-struct ylt::reflection::ylt_alias_struct<point_t1> {
-  static constexpr std::string_view get_alias_struct_name() { return "point"; }
 
-  static constexpr auto get_alias_field_names() {
-    return std::make_tuple(field_alias_t<0>{"X"}, field_alias_t<1>{"Y"});
+  static constexpr auto get_alias_field_names(point_t1*) {
+    return std::array{field_alias_t{"X", 0}, field_alias_t{"Y", 1}};
+  }
+  static constexpr std::string_view get_alias_struct_name(point_t1*) {
+    return "point";
   }
 };
+YLT_REFL(point_t1, x, y);
+
 struct test_variant {
   test_variant() = default;
   test_variant(int a, std::variant<double, std::string, int> b, double c)
@@ -253,8 +252,8 @@ TEST_CASE("test xml") {
   constexpr auto names = ylt::reflection::get_member_names<point_t1>();
   constexpr auto st_name = ylt::reflection::get_struct_name<point_t1>();
   CHECK(names == std::array<std::string_view, 2>{"X", "Y"});
-  CHECK(alias_names[0].second == "X");
-  CHECK(alias_names[1].second == "Y");
+  CHECK(alias_names[0].alias_name == "X");
+  CHECK(alias_names[1].alias_name == "Y");
   CHECK(st_name == "point");
 
   constexpr auto name1 = ylt::reflection::get_struct_name<int>();
diff --git a/test/test_xml.cpp b/test/test_xml.cpp
index cdc63833..25be2322 100644
--- a/test/test_xml.cpp
+++ b/test/test_xml.cpp
@@ -734,14 +734,14 @@ struct next_obj_t {
 };
 YLT_REFL(next_obj_t, x, y);
 
-template <>
-struct ylt::reflection::ylt_alias_struct<next_obj_t> {
-  static constexpr std::string_view get_alias_struct_name() { return "next"; }
+inline constexpr std::string_view get_alias_struct_name(next_obj_t *) {
+  return "next";
+}
 
-  static constexpr auto get_alias_field_names() {
-    return std::make_tuple(field_alias_t<0>{"w"}, field_alias_t<1>{"h"});
-  }
-};
+inline constexpr auto get_alias_field_names(next_obj_t *) {
+  return std::array{ylt::reflection::field_alias_t{"w", 0},
+                    ylt::reflection::field_alias_t{"h", 1}};
+}
 
 struct out_object {
   std::unique_ptr<int> id;
@@ -750,14 +750,14 @@ struct out_object {
   YLT_REFL(out_object, id, name, obj);
 };
 
-template <>
-struct ylt::reflection::ylt_alias_struct<out_object> {
-  static constexpr std::string_view get_alias_struct_name() { return "qi"; }
+inline constexpr std::string_view get_alias_struct_name(out_object *) {
+  return "qi";
+}
 
-  static constexpr auto get_alias_field_names() {
-    return std::make_tuple(field_alias_t<0>{"w"}, field_alias_t<1>{"h"});
-  }
-};
+inline constexpr auto get_alias_field_names(out_object *) {
+  return std::array{ylt::reflection::field_alias_t{"w", 0},
+                    ylt::reflection::field_alias_t{"h", 1}};
+}
 
 TEST_CASE("test alias") {
   out_object m{std::make_unique<int>(20), "tom", {21, 42}};