private void unload_script_file()
 {
     if (_script != null)
     {
         _lua.L_Unref(LuaDef.LUA_REGISTRYINDEX, _selfTableIndex);
         if (_script.Release() == 0)
         {
             if (LuaVM.useScriptCache && _cachedScripts.ContainsKey(_luaScriptFile))
             {
                 _cachedScripts.Remove(_luaScriptFile);
             }
         }
     }
 }