From 8cc7ef8b72e408cd7d0b7f347cd508137d471208 Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Thu, 29 Apr 2021 17:42:05 +0100
Subject: Automatic type registration

---
 lib/persistance.h         | 32 ++++++++++++++++++++++++++++++--
 test/test-persistance.cpp | 16 +++++-----------
 2 files changed, 35 insertions(+), 13 deletions(-)

diff --git a/lib/persistance.h b/lib/persistance.h
index 04da744..f797157 100644
--- a/lib/persistance.h
+++ b/lib/persistance.h
@@ -75,7 +75,8 @@ namespace Persistanace {
 	};
 
 	struct PersistanceStore {
-		// virtual bool persistType(const std::type_info &) = 0;
+		template<typename T> inline bool persistType() const;
+
 		template<typename T>
 		inline bool
 		persistValue(const std::string_view key, T & value)
@@ -144,10 +145,37 @@ namespace Persistanace {
 
 		virtual bool persist(PersistanceStore & store) = 0;
 
+		template<typename T>
+		constexpr static auto
+		typeName()
+		{
+			constexpr std::string_view name {__PRETTY_FUNCTION__};
+			constexpr auto s {name.find("T = ") + 4}, e {name.rfind(']')};
+			return name.substr(s, e - s);
+		}
+
+		template<typename T> static void addFactory() __attribute__((constructor));
 		static void addFactory(const std::string_view, std::function<std::unique_ptr<Persistable>()>);
 		static std::unique_ptr<Persistable> callFactory(const std::string_view);
 	};
 
+	template<typename T>
+	void
+	Persistable::addFactory()
+	{
+		addFactory(typeName<T>(), std::make_unique<T>);
+	}
+
+	template<typename T>
+	inline bool
+	PersistanceStore::persistType() const
+	{
+		if constexpr (!std::is_abstract_v<T>) {
+			[[maybe_unused]] constexpr auto f = &Persistable::addFactory<T>;
+		}
+		return true;
+	}
+
 	template<typename T> struct SelectionT<std::unique_ptr<T>> : public SelectionV<std::unique_ptr<T>> {
 		using Ptr = std::unique_ptr<T>;
 		struct SelectionObj : public SelectionV<Ptr> {
@@ -230,7 +258,7 @@ namespace Persistanace {
 	};
 }
 
-#define STORE_TYPE store.persistType(typeid(*this))
+#define STORE_TYPE store.persistType<std::decay_t<decltype(*this)>>()
 #define STORE_MEMBER(mbr) store.persistValue(#mbr, mbr)
 
 #endif
diff --git a/test/test-persistance.cpp b/test/test-persistance.cpp
index ffc8a3c..a4fda31 100644
--- a/test/test-persistance.cpp
+++ b/test/test-persistance.cpp
@@ -16,7 +16,7 @@ struct AbsObject : public Persistanace::Persistable {
 	bool
 	persist(Persistanace::PersistanceStore & store) override
 	{
-		return STORE_MEMBER(base);
+		return STORE_TYPE && STORE_MEMBER(base);
 	}
 
 	virtual void dummy() const = 0;
@@ -28,7 +28,7 @@ struct SubObject : public AbsObject {
 	bool
 	persist(Persistanace::PersistanceStore & store) override
 	{
-		return AbsObject::persist(store) && STORE_MEMBER(sub);
+		return AbsObject::persist(store) && STORE_TYPE && STORE_MEMBER(sub);
 	}
 
 	void
@@ -54,18 +54,12 @@ struct TestObject : public Persistanace::Persistable {
 	bool
 	persist(Persistanace::PersistanceStore & store) override
 	{
-		return STORE_MEMBER(flt) && STORE_MEMBER(str) && STORE_MEMBER(bl) && STORE_MEMBER(pos) && STORE_MEMBER(flts)
-				&& STORE_MEMBER(poss) && STORE_MEMBER(nest) && STORE_MEMBER(ptr) && STORE_MEMBER(aptr)
-				&& STORE_MEMBER(vptr);
+		return STORE_TYPE && STORE_MEMBER(flt) && STORE_MEMBER(str) && STORE_MEMBER(bl) && STORE_MEMBER(pos)
+				&& STORE_MEMBER(flts) && STORE_MEMBER(poss) && STORE_MEMBER(nest) && STORE_MEMBER(ptr)
+				&& STORE_MEMBER(aptr) && STORE_MEMBER(vptr);
 	}
 };
 
-BOOST_AUTO_TEST_CASE(setup)
-{
-	Persistanace::Persistable::addFactory("TestObject", std::make_unique<TestObject>);
-	Persistanace::Persistable::addFactory("SubObject", std::make_unique<SubObject>);
-}
-
 struct JPP : public Persistanace::JsonParsePersistance {
 	template<typename T>
 	T
-- 
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