reload: encapsulate each engine generation more

src/core/generation.hpp

@@ -0,0 +1,23 @@
+#pragma once
+
+#include <qobject.h>
+#include <qtclasshelpermacros.h>
+
+#include "shell.hpp"
+#include "singleton.hpp"
+
+class EngineGeneration {
+public:
+	explicit EngineGeneration();
+	~EngineGeneration();
+	Q_DISABLE_COPY_MOVE(EngineGeneration);
+
+	// assumes root has been initialized, consumes old generation
+	void onReload(EngineGeneration* old);
+
+	static EngineGeneration* findObjectGeneration(QObject* object);
+
+	QQmlEngine engine;
+	ShellRoot* root = nullptr;
+	SingletonRegistry singletonRegistry;
+};