From d6e2d808c4c2387f65f9d0de3431cb574d72da70 Mon Sep 17 00:00:00 2001
From: "Claudius \"keldu\" Holeksa" <mail@keldu.de>
Date: Tue, 6 May 2025 14:04:39 +0200
Subject: Confused about the descriptors

---
 c++/write_vtk.hpp   | 12 ++++++------
 tests/vtk_write.cpp | 10 +++++++++-
 2 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/c++/write_vtk.hpp b/c++/write_vtk.hpp
index 3e417f8..fec4ea5 100644
--- a/c++/write_vtk.hpp
+++ b/c++/write_vtk.hpp
@@ -19,7 +19,7 @@ struct lbm_vtk_writer {
 template<typename... MemberTypes, saw::string_literal... MemberNames>
 struct lbm_vtk_writer<sch::Struct<sch::Member<MemberTypes,MemberNames>...>> {
 
-	saw::error_or<void> apply(){
+	static saw::error_or<void> apply(){
 		return saw::make_void();
 	}
 };
@@ -34,14 +34,14 @@ struct lbm_vtk_writer<sch::FixedArray<T,D>> {
 template<typename Desc, typename... StructT, saw::string_literal... StructN>
 struct lbm_vtk_writer<sch::CellField<Desc,sch::Struct<sch::Member<StructT,StructN>...>>> {
 	template<uint64_t i, uint64_t Dep>
-	saw::error_or<void> write_i_iterate_d(std::ostream& vtk_file, const saw::data<sch::CellField<Desc,sch::Struct<sch::Member<StructT,StructN>...>>>& field, saw::data<sch::FixedArray<sch::UInt64,Desc::D>>& index){
+	static saw::error_or<void> write_i_iterate_d(std::ostream& vtk_file, const saw::data<sch::CellField<Desc,sch::Struct<sch::Member<StructT,StructN>...>>>& field, saw::data<sch::FixedArray<sch::UInt64,Desc::D>>& index){
 		if constexpr (Dep == Desc::D){
 
 		}
 	}
 
 	template<uint64_t i>
-	saw::error_or<void> write_i(std::ostream& vtk_file, const saw::data<sch::CellField<Desc,sch::Struct<sch::Member<StructT,StructN>...>>>& field){
+	static saw::error_or<void> write_i(std::ostream& vtk_file, const saw::data<sch::CellField<Desc,sch::Struct<sch::Member<StructT,StructN>...>>>& field){
 
 		auto meta = field.meta();
 		saw::data<sch::FixedArray<sch::UInt64,Desc::D>> index;
@@ -59,7 +59,7 @@ struct lbm_vtk_writer<sch::CellField<Desc,sch::Struct<sch::Member<StructT,Struct
 	}
 
 	template<uint64_t i>
-	saw::error_or<void> iterate_i(std::ostream& vtk_file, const saw::data<sch::CellField<Desc,sch::Struct<sch::Member<StructT,StructN>...>>>& field){
+	static saw::error_or<void> iterate_i(std::ostream& vtk_file, const saw::data<sch::CellField<Desc,sch::Struct<sch::Member<StructT,StructN>...>>>& field){
 		{
 			auto eov = write_i<i>(vtk_file, field);
 			if(eov.is_error()){
@@ -72,7 +72,7 @@ struct lbm_vtk_writer<sch::CellField<Desc,sch::Struct<sch::Member<StructT,Struct
 		return saw::make_void();
 	}
 
-	saw::error_or<void> apply(std::ostream& vtk_file,
+	static saw::error_or<void> apply(std::ostream& vtk_file,
 		const saw::data<sch::CellField<Desc,sch::Struct<sch::Member<StructT,StructN>...>>>& field){
 
 		vtk_file
@@ -120,7 +120,7 @@ struct lbm_vtk_writer<sch::CellField<Desc,sch::Struct<sch::Member<StructT,Struct
 }
 
 template<typename Struct>
-saw::error_or<void> write_vtk(const std::string_view file_name, const saw::data<Struct>& field){
+saw::error_or<void> write_vtk_file(const std::string_view file_name, const saw::data<Struct>& field){
 
 	std::string vtk_file_name{file_name};
 	std::ofstream vtk_file{vtk_file_name};
diff --git a/tests/vtk_write.cpp b/tests/vtk_write.cpp
index e12c33e..0fcc169 100644
--- a/tests/vtk_write.cpp
+++ b/tests/vtk_write.cpp
@@ -3,6 +3,7 @@
 #include <iostream>
 #include "../c++/write_vtk.hpp"
 
+#include <sstream>
 
 namespace {
 namespace sch {
@@ -33,7 +34,14 @@ using CellStruct = Struct<
 SAW_TEST("VTK Write test example"){
 	using namespace kel;
 
-	write_vtk();
+	// write_vtk();
+
+	std::stringstream sstream;
+
+	saw::data<sch::CellField<sch::D2Q5,sch::CellStruct<sch::D2Q5>>> cells;
+
+	auto eov = lbm::impl::lbm_vtk_writer<sch::CellField<sch::D2Q5,sch::CellStruct<sch::D2Q5>>>::apply(sstream, cells);
+	SAW_EXPECT(eov.is_value(), "vtk writer failed to write");
 
 	// using Type = typename parameter_pack_type<i,T...>::type;
 }
-- 
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