8 files changed, 71 insertions, 53 deletions
diff --git a/core/src/Model/Project.hpp b/core/src/Model/Project.hpp
index bce58c2..1eca09d 100644
--- a/core/src/Model/Project.hpp
+++ b/core/src/Model/Project.hpp
@@ -59,7 +59,7 @@ public:
 
 	const tsl::array_map<char, TemplateInfo>& GetTemplates() const;
 	std::unique_ptr<Template> LoadTemplate(std::string_view name);
-	bool InsertTemplate(std::string_view name, TemplateInfo info);
+	TemplateInfo* InsertTemplate(std::string_view name, TemplateInfo info);
 	bool RemoveTemplate(std::string_view name);
 	bool RenameTemplate(std::string_view oldName, std::string_view newName);
 
diff --git a/core/src/Model/Template/TableTemplate.cpp b/core/src/Model/Template/TableTemplate.cpp
index 0ad1cca..b8444b7 100644
--- a/core/src/Model/Template/TableTemplate.cpp
+++ b/core/src/Model/Template/TableTemplate.cpp
@@ -1,6 +1,7 @@
 #include "TableTemplate.hpp"
 
 #include <xlsxwriter.h>
+#include <iostream>
 #include <map>
 
 bool TableCell::IsDataHoldingCell() const
@@ -189,14 +190,14 @@ TableTemplate::BreakCellsResult TableTemplate::BreakCells(Vec2i topLeft)
 	return BCR_Success;
 }
 
-lxw_workbook* TableTemplate::InstanciateToExcelWorkbook(const TableInstanciationParameters& params) const
+lxw_workbook* TableTemplate::InstantiateToExcelWorkbook(const TableInstanciationParameters& params) const
 {
 	auto workbook = workbook_new("Table.xlsx");
-	InstanciateToExcelWorksheet(workbook, params);
+	InstantiateToExcelWorksheet(workbook, params);
 	return workbook;
 }
 
-lxw_worksheet* TableTemplate::InstanciateToExcelWorksheet(lxw_workbook* workbook, const TableInstanciationParameters& params) const
+lxw_worksheet* TableTemplate::InstantiateToExcelWorksheet(lxw_workbook* workbook, const TableInstanciationParameters& params) const
 {
 	auto worksheet = workbook_add_worksheet(workbook, "CpltExport.xlsx");
 
@@ -301,3 +302,13 @@ lxw_worksheet* TableTemplate::InstanciateToExcelWorksheet(lxw_workbook* workbook
 
 	return worksheet;
 }
+Template::ReadResult TableTemplate::ReadFrom(std::istream& stream)
+{
+	// TODO
+	return ReadResult::RR_Success;
+}
+
+void TableTemplate::WriteTo(std::ostream& stream) const
+{
+	// TODO
+}
diff --git a/core/src/Model/Template/TableTemplate.hpp b/core/src/Model/Template/TableTemplate.hpp
index 688192a..f7a79e9 100644
--- a/core/src/Model/Template/TableTemplate.hpp
+++ b/core/src/Model/Template/TableTemplate.hpp
@@ -34,12 +34,12 @@ public:
 	Vec2i Location;
 	/// Location of the primary (top left) cell, if this cell is a part of a merged group.
 	/// Otherwise, either component of this field shall be -1.
-	Vec2i PrimaryCellLocation;
-	int SpanX;
-	int SpanY;
-	TextAlignment HorizontalAlignment = AlignAxisMin;
-	TextAlignment VerticalAlignment = AlignAxisMin;
-	CellType Type;
+	Vec2i PrimaryCellLocation{ -1, -1 };
+	int SpanX = 0;
+	int SpanY = 0;
+	TextAlignment HorizontalAlignment = AlignCenter;
+	TextAlignment VerticalAlignment = AlignCenter;
+	CellType Type = ConstantCell;
 	/// The id of the group description object, if this cell isn't a constant or singluar parameter cell. Otherwise, this value is -1.
 	int DataId = -1;
 
@@ -56,7 +56,7 @@ public:
 // TODO support horizontal filling order
 /// Parameter group information for a grouped array of cells. When instanciated, an array of 0 or more
 /// elements shall be provided by the user, which will replace the group of templated cells with a list
-/// of rows, each instanciated with the n-th element in the provided array.
+/// of rows, each instantiated with the n-th element in the provided array.
 /// \code
 ///	[["foo", "bar", "foobar"],
 ///  ["a", "b", c"],
@@ -124,7 +124,7 @@ public:
 	const TableTemplate& GetTable() const;
 };
 
-/// A table template, where individual cells can be filled by workflows instanciating this template. Merged cells,
+/// A table template, where individual cells can be filled by workflows instantiating this template. Merged cells,
 /// parametric rows/columns, and grids are also supported.
 ///
 /// This current supports exporting to xlsx files.
@@ -163,6 +163,9 @@ public:
 	};
 	BreakCellsResult BreakCells(Vec2i topLeft);
 
-	lxw_workbook* InstanciateToExcelWorkbook(const TableInstanciationParameters& params) const;
-	lxw_worksheet* InstanciateToExcelWorksheet(lxw_workbook* workbook, const TableInstanciationParameters& params) const;
+	lxw_workbook* InstantiateToExcelWorkbook(const TableInstanciationParameters& params) const;
+	lxw_worksheet* InstantiateToExcelWorksheet(lxw_workbook* workbook, const TableInstanciationParameters& params) const;
+
+	virtual ReadResult ReadFrom(std::istream& stream) override;
+	virtual void WriteTo(std::ostream& stream) const override;
 };
diff --git a/core/src/Model/Template/Template.hpp b/core/src/Model/Template/Template.hpp
index 0901a1b..f7dd898 100644
--- a/core/src/Model/Template/Template.hpp
+++ b/core/src/Model/Template/Template.hpp
@@ -29,8 +29,8 @@ public:
 		RR_Success,
 		RR_InvalidFormat,
 	};
-	ReadResult ReadFrom(std::istream& stream) = 0;
-	void WriteTo(std::ostream& stream) const = 0;
+	virtual ReadResult ReadFrom(std::istream& stream) = 0;
+	virtual void WriteTo(std::ostream& stream) const = 0;
 };
 
 class TemplateInfo
diff --git a/core/src/Model/Template/Template_Main.cpp b/core/src/Model/Template/Template_Main.cpp
index eeb6871..08437b7 100644
--- a/core/src/Model/Template/Template_Main.cpp
+++ b/core/src/Model/Template/Template_Main.cpp
@@ -2,4 +2,6 @@
 
 std::unique_ptr<Template> TemplateInfo::LoadFromDisk() const
 {
+	// TODO
+	return nullptr;
 }
diff --git a/core/src/Model/Workflow/Values/BasicValues.cpp b/core/src/Model/Workflow/Values/BasicValues.cpp
index a7cf635..748c652 100644
--- a/core/src/Model/Workflow/Values/BasicValues.cpp
+++ b/core/src/Model/Workflow/Values/BasicValues.cpp
@@ -14,14 +14,13 @@ NumericValue::NumericValue()
 {
 }
 
-template <class T>
+template <class T, int kMaxSize>
 static std::string NumberToString(T value)
 {
-	constexpr auto kSize = std::numeric_limits<T>::max_digits10;
-	char buf[kSize];
+	char buf[kMaxSize];
 
 #if PLATFORM_WIN32
-	auto res = std::to_chars(buf, buf + kSize, value);
+	auto res = std::to_chars(buf, buf + kMaxSize, value);
 	if (res.ec == std::errc()) {
 		return std::string(buf, res.ptr);
 	} else {
@@ -35,17 +34,20 @@ static std::string NumberToString(T value)
 
 std::string NumericValue::GetTruncatedString() const
 {
-	return ::NumberToString((int64_t)mValue);
+	constexpr auto kMaxSize = std::numeric_limits<int64_t>::digits10;
+	return ::NumberToString<int64_t, kMaxSize>((int64_t)mValue);
 }
 
 std::string NumericValue::GetRoundedString() const
 {
-	return ::NumberToString((int64_t)std::round(mValue));
+	constexpr auto kMaxSize = std::numeric_limits<int64_t>::digits10;
+	return ::NumberToString<int64_t, kMaxSize>((int64_t)std::round(mValue));
 }
 
 std::string NumericValue::GetString() const
 {
-	return ::NumberToString(mValue);
+	constexpr auto kMaxSize = std::numeric_limits<double>::max_digits10;
+	return ::NumberToString<double, kMaxSize>(mValue);
 }
 
 int64_t NumericValue::GetInt() const
diff --git a/core/src/Model/Workflow/Workflow.hpp b/core/src/Model/Workflow/Workflow.hpp
index ded9bfb..161400e 100644
--- a/core/src/Model/Workflow/Workflow.hpp
+++ b/core/src/Model/Workflow/Workflow.hpp
@@ -5,6 +5,7 @@
 #include "cplt_fwd.hpp"
 
 #include <imgui_node_editor.h>
+#include <any>
 #include <cstddef>
 #include <cstdint>
 #include <filesystem>
@@ -240,34 +241,27 @@ public:
 
 	/* Graph rebuild */
 
-	struct GraphUpdateResult
+	enum GraphUpdateResult
 	{
-		struct Success
-		{
-		};
-
-		struct NoWorkToDo
-		{
-		};
-
-		struct UnsatisfiedDependencies
-		{
-			std::vector<uint32_t> UnsatisfiedNodes;
-		};
-
-		struct UnreachableNodes
-		{
-			std::vector<uint32_t> UnreachableNodes;
-		};
-
-		using T = std::variant<
-			Success,
-			NoWorkToDo,
-			UnsatisfiedDependencies,
-			UnreachableNodes>;
+		/// Successfully rebuilt graph dependent data.
+		/// Details: nothing is written.
+		GUR_Success,
+		/// Nothing has changed since last time UpdateGraph() was called.
+		/// Details: nothing is written.
+		GUR_NoWorkToDo,
+		/// Details: list of nodes is written.
+		GUR_UnsatisfiedDependencies,
+		/// Details: list of nodes is written.
+		GUR_UnreachableNodes,
 	};
 
-	GraphUpdateResult::T UpdateGraph();
+	using GraphUpdateDetails = std::variant<
+		// Case: nothing
+		std::monostate,
+		// Case: list of nodes (ids)
+		std::vector<uint32_t>>;
+
+	GraphUpdateResult UpdateGraph(GraphUpdateDetails* details = nullptr);
 
 	/* Serialization */
 
diff --git a/core/src/Model/Workflow/Workflow_Main.cpp b/core/src/Model/Workflow/Workflow_Main.cpp
index bfe007c..61cd510 100644
--- a/core/src/Model/Workflow/Workflow_Main.cpp
+++ b/core/src/Model/Workflow/Workflow_Main.cpp
@@ -524,10 +524,10 @@ bool Workflow::DisconnectByDestination(WorkflowNode& destinationNode, uint32_t d
 	return true;
 }
 
-Workflow::GraphUpdateResult::T Workflow::UpdateGraph()
+Workflow::GraphUpdateResult Workflow::UpdateGraph(GraphUpdateDetails* details)
 {
 	if (!mDepthsDirty) {
-		return GraphUpdateResult::NoWorkToDo{};
+		return GUR_NoWorkToDo;
 	}
 
 	// Terminology:
@@ -577,7 +577,10 @@ Workflow::GraphUpdateResult::T Workflow::UpdateGraph()
 		}
 
 		if (!unsatisfiedNodes.empty()) {
-			return GraphUpdateResult::UnsatisfiedDependencies{ std::move(unsatisfiedNodes) };
+			if (details) {
+				details->emplace<decltype(unsatisfiedNodes)>(std::move(unsatisfiedNodes));
+			}
+			return GUR_UnsatisfiedDependencies;
 		}
 	}
 
@@ -624,10 +627,13 @@ Workflow::GraphUpdateResult::T Workflow::UpdateGraph()
 			unreachableNodes.push_back(i);
 		}
 
-		return GraphUpdateResult::UnreachableNodes{ std::move(unreachableNodes) };
+		if (details) {
+			details->emplace<decltype(unreachableNodes)>(std::move(unreachableNodes));
+		}
+		return GUR_UnreachableNodes;
 	}
 
-	return GraphUpdateResult::Success{};
+	return GUR_Success;
 }
 
 Workflow::ReadResult Workflow::ReadFrom(std::istream& stream)