bugfix: clear cached sub node

lualib/sharedata/corelib.lua

@@ -31,14 +31,14 @@ end
 local function update(root, cobj, gcobj)
 	root.__obj = cobj
 	root.__gcobj = gcobj
-	-- don't use pairs
-	for k,v in next, root do
-		if type(v)=="table" and k~="__parent" then
+	local children = root.__cache
+	if children then
+		for k,v in pairs(children) do
 			local pointer = index(cobj, k)
 			if type(pointer) == "userdata" then
 				update(v, pointer, gcobj)
 			else
-				root[k] = nil
+				children[k] = nil
 			end
 		end
 	end
@@ -74,13 +74,22 @@ function meta:__index(key)
 	local obj = getcobj(self)
 	local v = index(obj, key)
 	if type(v) == "userdata" then
-		local r = setmetatable({
+		local children = self.__cache
+		if children == nil then
+			children = {}
+			self.__cache = children
+		end
+		local r = children[key]
+		if r then
+			return r
+		end
+		r = setmetatable({
 			__obj = v,
 			__gcobj = self.__gcobj,
 			__parent = self,
 			__key = key,
 		}, meta)
-		self[key] = r
+		children[key] = r
 		return r
 	else
 		return v