Add Plugin class

SDLWrapper/__Plugin.h

@@ -0,0 +1,36 @@
+#pragma once
+#include "begin_code.h"
+namespace _internal
+{
+
+/// This is just an empty class.
+/// Most wrapper class regard this class as a friend class.
+/// You can get/set raw pointers through this class.
+class Plugin
+{
+public:
+    template<typename T>
+    decltype(auto) get(const T& obj)
+    {
+        return obj._get();
+    }
+    template<typename T,typename U>
+    void set(T& obj,U&& value)
+    {
+        obj._set(value);
+    }
+    template<typename T>
+    void clear(T& obj)
+    {
+        obj._clear();
+    }
+
+    template<typename T,typename U>
+    void set_no_delete(T& obj,U&& value)
+    {
+        obj._set_no_delete(value);
+    }
+};
+
+}
+#include "end_code.h"