Looks good. Is there really a need for a PreferenceValue class though? I'm concerned that the getter returns a different kind of object to that expected by the setter... For any preference tool the presence of the pragma is sufficient to get/set the native value and, assuming always class-side, support event triggering for changes.
Regards, Gary ----- Original Message ----- From: "Alain Plantec" <[email protected]> To: <[email protected]> Sent: Monday, March 02, 2009 8:41 AM Subject: Re: [Pharo-project] Preference refactoring again Geert a écrit : > Hi Alain, this sounds very interesting. thanks > I have never been a big fan of the > current "Preference Browser". The main problem with current preference system is that it makes uses of globals (declared in the class side of Preferences) and that a lot of packages depend on it. The main goal of the refactoring is to make preferences local to the packages in which they are declared. Current preference browser is not that bad and could be reused. > I am now trying to grasp (still learning > here) how this new "Pharo Preference Mechanism" works.It would be great if > the mechanism could be explained in detail in something like the new Pharo > By Example manual :) > Each preference is stored by a PreferenceValue instance and each time a PreferenceValue is updated (with a #value: message sent) an event is sent to the class which defines the preference. The event sending is standard: PreferenceValue>>value: anObject realValue ~= anObject ifTrue: [realValue := anObject. location triggerEvent: selector with: anObject] realValue is the instance variable wich stores current preference value. location is the class which declares the preference selector is the selector of the preference (i.e. #gradientButtonLook) So my proposition is to declare a preference locally. Let's take the example of freetype monitorTypeLCD preference. If we implement it the way it is now, as a boolean, it could be: --------------- FreeTypeSettings class>>monitorTypeLCD <preference: 'LCD monitor type' type: #Boolean set: #monitorTypeLCD: defaultValue: false description: 'Use of a LCD...'> ^ MonitorTypeLCD ifNil: [MonitorTypeLCD := PreferenceValue value: false location: self selector: #monitorTypeLCD] FreeTypeSettings class>>monitorTypeLCD: aBoolean self monitorTypeLCD value: hintingFull FreeTypeSettings class>>initialize FreeTypeSettings when: #monitorTypeLCD send: #monitorTypeLCDPreferenceChanged: to: self. FreeTypeSettings class>>monitorTypeLCDPreferenceChanged: aBoolean self current monitorTypeLCDPreferenceChanged: aBoolean ------------- The pragma you see in FreeTypeSettings class>>monitorTypeLCD in only here for UI tools such as PreferenceBrowser. If a client object needs monitorTypeLCD value, it asks directly to its provider which is FreeTypeSettings class: ... useLCD := FreeTypeSettings monitorTypeLCD value. ... but note that such a preference should be set as a choice between two values #LCD or #CRT... hope things are a little bit clearer now. alain > > Alain Plantec wrote: > >> I've joined 4 packages : >> - PrefCore contains PreferenceValue which is now the only mandatory >> class. >> >> 2 packages for testing: >> - PrefProvider contains PrefProvider class which declares some >> preferences >> - PrefUser contains PrefChangeListener (try PrefChangeListener test). >> >> 1 package for UI: >> - PrefTool contains PreferenceCollector and PreferenceDefinition. They >> are optional. >> >> > > _______________________________________________ Pharo-project mailing list [email protected] http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project _______________________________________________ Pharo-project mailing list [email protected] http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project
