Hi all, joined Zoo package is a attempt to translate in code what we discussed here before about preference refactoring. The framework is made of 3 classes: PreferenceCollector, PreferenceDefinition and PreferenceValue. In Zoo there are also 2 classes for testing: PrefProvider and PrefChangeListener. PrefProvider class declares some preferences and PrefChangeListener is here to test preference change notification. PrefChangeListener>>initialize super initialize. PreferenceCollector whenChanged: #gradientButtonLook inClass: PrefProvider notify: self using: #gradientButtonLookIsNow: . PreferenceCollector whenChanged: #gradientButtonLook inClass: PrefProvider notify: self using: #gradientLook: PrefChangeListener class>>test "self test" PrefChangeListener new inspect. PrefProvider gradientButtonLook: PrefProvider gradientButtonLook value not. PrefProvider gradientButtonLook: PrefProvider gradientButtonLook value not. PrefProvider gradientButtonLook: PrefProvider gradientButtonLook value not. From PreferenceCollector comment: -------------------------------------- A PreferenceCollector automatically collects all preferences. A preference is represented by a PreferenceDefinition. All PreferenceDefinition are stored in the preferences instance variable. Instance Variables preferences: OrderedCollection of PreferenceDefinition preferences - contains all PreferenceDefinition which are automatically built from pragma found in preference getters ADDING A PREFERENCE PreferenceCollector makes use of the SystemChangeNotifier in order to automate the adding, the removing and the updating of preferences. See #PreferenceCollector>>event: to see how preferences update is implemented. Editing a new method with a preference pragma or inserting a preference pragma in an existing method are the two ways for preference definition adding. The only way to remove a preference definition is to remove the corresponding method. Example of a "blackAndWhite" preference. Methods below are defined by the preference provider APreferencePrivider class. Note that the value stored in BlackAndWhite class variable is an instance of PreferenceValue. In this example, the default value is directly given with the pragma: ------------- APreferencePrivider class>>blackAndWhite <preference: 'Use black and white' type: #Boolean set: #blackAndWhite: defaultValue: false description: 'Use black and white'> ^ BlackAndWhite ifNil: [BlackAndWhite := PreferenceValue value: false location: self selector: #blackAndWhite] APreferencePrivider class>>blackAndWhite: aBoolean self blackAndWhite value: aBoolean ------------- If a default value can't be specified in the pragma, another way consists in using a selector which represents the message to send to the class in order to get the default value: ------------- APreferencePrivider class>>standardFont <preference: 'The default system font' type: #LogicalFont set: #standardFont: default: #defaultStandardFont description: 'The default system font'> ^ StandardFont ifNil: [StandardFont := PreferenceValue value: self defaultStandardFont location: self selector: #standardFont] APreferencePrivider class>>standardFont: aFont self standardFont value: aFont APreferencePrivider class>>defaultStandardFont ^ LogicalFont familyName: 'Arial' fallbackFamilyNames: nil pointSize: 12 stretchValue: 5 weightValue: 400 slantValue: 0 ------------- LISTENING TO A PREFERENCE VALUE CHANGE Any object can register itself as a preference value change listener. See #PreferenceCollector class>>whenChanged: inClass:notify:using:. Each time a preference value is changed, #preference: inClass:changedWith: is sent to the PreferenceCollector class. Example of code a listener can implement in order to be notified each time a gradientButtonLook preference defined by a PrefProvider class is changed. In this example, the listener ask to be notified by a send of #gradientButtonLookIsNow: message. The argument given to gradientButtonLookIsNow: is the new preference value. ------------- .... PreferenceCollector whenChanged: #gradientButtonLook inClass: PrefProvider notify: self using: #gradientButtonLookIsNow:. .... ------------- What do you think ? cheers Alain