1 files changed, 16 insertions, 1 deletions
diff --git a/src/factory.h b/src/factory.h
index 495db5474..ca90a6e9a 100644
--- a/src/factory.h
+++ b/src/factory.h
@@ -1,9 +1,21 @@
-#pragma once
+#ifndef FACTORY_H_SEEN
+#define FACTORY_H_SEEN
 
 #include <exception>
 #include <map>
 #include <string>
 
+/**
+ * A simple singleton implementation.
+ */
+template<class T>
+struct Singleton {
+	static T& instance() {
+		static T inst;
+		return inst;
+	}
+};
+
 namespace FactoryExceptions {
 	class TypeNotRegistered : public std::exception {
 	public:
@@ -78,3 +90,6 @@ struct NodeTraits {
 		return name;
 	}
 };
+
+#endif
+