StaticValue helper.

Incorporated into `Testing`, for now.  Semi-threadsafe statics,
initialize them before going multithreaded.

Testing/test.h

@@ -15,6 +15,8 @@ static_assert( __cplusplus > 201700, "C++17 Required" );
 
 #include <Alepha/console.h>
 #include <Alepha/types.h>
+#include <Alepha/Utility/evaluation.h>
+#include <Alepha/Utility/StaticValue.h>
 
 namespace Alepha::Hydrogen::Testing
 {
@@ -34,6 +36,8 @@ namespace Alepha::Hydrogen::Testing
 		}
 
 		using namespace std::literals::string_literals;
+		using namespace Utility::exports::evaluation;
+		using namespace Utility::exports::static_value;
 
 		struct TestName
 		{
@@ -65,12 +69,8 @@ namespace Alepha::Hydrogen::Testing
 			}
 		}
 
-		inline auto &
-		registry()
-		{
-			static std::vector< std::tuple< std::string, bool, std::function< void() > > > registry;
-			return registry;
-		}
+		StaticValue< std::vector< std::tuple< std::string, bool, std::function< void() > > > > registry;
+		auto initRegistry= enroll <=registry;
 
 		// It is okay to discard this, if making tests in an enroll block.
 		inline auto

Utility/StaticValue.h

@@ -0,0 +1,47 @@
+static_assert( __cplusplus > 201700, "C++17 Required" );
+
+#pragma once
+
+namespace Alepha::Hydrogen::Utility
+{
+	inline namespace exports { inline namespace static_value {} }
+
+	namespace detail::static_value
+	{
+		inline namespace exports {}
+
+		template< typename T >
+		struct default_init
+		{
+			T *operator()() const { return new T{}; }
+		};
+
+		namespace exports
+		{
+			template< typename T, typename Init= default_init< T > >
+			struct StaticValue;
+		}
+
+		template< typename T, typename Init >
+		struct exports::StaticValue
+		{
+			private:
+				T *storage= nullptr;
+
+			public:
+				decltype( auto )
+				get()
+				{
+					if( not storage ) storage= Init{}();
+					return *storage;
+				}
+
+				decltype( auto ) operator ()() { return get(); }
+		};
+	}
+
+	namespace exports::static_value
+	{
+		using namespace detail::static_value::exports;
+	}
+}