diff --git a/include/xo/reflect/function/FunctionTdx.hpp b/include/xo/reflect/function/FunctionTdx.hpp
index 116f372..5d2f57c 100644
--- a/include/xo/reflect/function/FunctionTdx.hpp
+++ b/include/xo/reflect/function/FunctionTdx.hpp
@@ -24,6 +24,10 @@ namespace xo {
             static std::unique_ptr<FunctionTdx> make_function(TypeDescr retval_td,
                                                               std::vector<TypeDescr> arg_td_v,
                                                               bool is_noexcept);
+            /** create instance from FunctionTdxInfo
+             *  @param fn_info.   function ingredients -- return type, arg types, noexcept
+             **/
+            static std::unique_ptr<FunctionTdx> make_function(const FunctionTdxInfo & fn_info);
 
             // ----- Inherited from TypeDescrExtra -----
 
@@ -39,9 +43,7 @@ namespace xo {
             virtual bool fn_is_noexcept() const override { return info_.is_noexcept_; }
 
         private:
-            FunctionTdx(TypeDescr retval_td,
-                        bool is_noexcept,
-                        std::vector<TypeDescr> arg_td_v);
+            FunctionTdx(const FunctionTdxInfo & fn_info);
 
         private:
             /** ingredients in complete function type description **/
diff --git a/src/reflect/function/FunctionTdx.cpp b/src/reflect/function/FunctionTdx.cpp
index c81041a..27c0f8f 100644
--- a/src/reflect/function/FunctionTdx.cpp
+++ b/src/reflect/function/FunctionTdx.cpp
@@ -11,17 +11,21 @@ namespace xo {
                                    std::vector<TypeDescr> arg_td_v,
                                    bool is_noexcept)
         {
-            return std::unique_ptr<FunctionTdx>(new FunctionTdx(retval_td,
-                                                                is_noexcept,
-                                                                std::move(arg_td_v)));
+            return make_function(FunctionTdxInfo(retval_td,
+                                                 std::move(arg_td_v),
+                                                 is_noexcept));
         }
 
-        FunctionTdx::FunctionTdx(TypeDescr retval_td,
-                                 bool is_noexcept,
-                                 std::vector<TypeDescr> arg_td_v)
-            : info_{retval_td, std::move(arg_td_v), is_noexcept}
+        std::unique_ptr<FunctionTdx>
+        FunctionTdx::make_function(const FunctionTdxInfo & fn_info)
         {
-            if (!retval_td) {
+            return std::unique_ptr<FunctionTdx>(new FunctionTdx(fn_info));
+        }
+
+        FunctionTdx::FunctionTdx(const FunctionTdxInfo & fn_info)
+            : info_{fn_info}
+        {
+            if (!info_.retval_td_) {
                 throw std::runtime_error("FunctionTdx::ctor: null return type?");
             }
         }