     /// list of names of setting file name (without extension)
     override var settingNames: [String] {
         
-        return self.settings.keys.sorted { $0.localizedCaseInsensitiveCompare($1) == .orderedAscending }
+        return self._settingNames
     }
     
     

            
            settings[name] = try? self.loadSetting(at: url)
        }
    }
    
    

    
    // MARK: Private Properties
    
    private var _settingNames: [String] = []
    private var settings: [String: Setting] = [:]
    
    
    
