MVVM light imo it's a great framework to start with mvvm and even for complex scenarios, it helps alot having templates to start your projects.
regards Rui Rui Marinho Software Developer _____________________________________________________ M: T: +351 914408168 +351 912358027 Hospital São João Alameda Professor Hernâni Monteiro 4200-319 Porto De: [email protected] [mailto:[email protected]] Em nome de Adrian Hara Enviada: terça-feira, 16 de Março de 2010 15:59 Para: ozWPF Assunto: RE: MicroModels question Hi Paul, Thanks for the reply. Its too bad that you dont intend on improving the MicroModels framework, I find its really cool. What MVVM Framework do you use or recommend in your daily work? Adrian From: [email protected] [mailto:[email protected]] On Behalf Of Paul Stovell Sent: Tuesday, March 16, 2010 11:49 AM To: ozWPF Subject: RE: MicroModels question Hi Adrian, The implementation should probably do that as it does allow some things to work. Personally I never really liked that event I find it very half-baked and crying out as a performance bottleneck so its never front-of-mind when writing custom delegates. What I would have liked to have done would be to use expression dependencies to trigger the CanExecuteChanged event. So something like this would work: Command("Save", ()=>DoSave(), () => HasChanges) The commands CanExecuteChanged event would be raised whenever HasChanges property changed event is raised. I should add - as it wasnt clear on my initial blog post that MicroModels was a throw it out and see if it sticks project. The code isnt very mature and I dont have any plans to improve on it, it was purely a fun thing (unlike Magellan which I am using and do maintain). If its working for you then thats good but expect to make a few changes as you have done J Paul From: [email protected] [mailto:[email protected]] On Behalf Of Adrian Hara Sent: Tuesday, 16 March 2010 5:04 PM To: ozWPF Subject: RE: MicroModels question Hi Paul, Thanks for the answer, this is exactly what I did, I was just wondering if there was a more MicroModelsy solution J In the meantime Ive another question: why doesnt the MicroModels implementation of DelegateCommand use CommandManager.RequerySuggested for its implementation of the CanExecuteChanged event? I found that using the current implementation doesnt requery the CanExecute delegate when the UI state changes (i.e. its only queried once, when the command is bound, then never again). I changed the implementation of the CanExecuteChanged event to look like so: public event EventHandler CanExecuteChanged { add { CommandManager.RequerySuggested += value; } remove { CommandManager.RequerySuggested -= value; } } and now the CanExecute delegate is requeried whenever the UI state changes (e.g. user presses a button). What do you think about this, is this ok? Thanks, Adrian From: [email protected] [mailto:[email protected]] On Behalf Of Paul Stovell Sent: Tuesday, March 16, 2010 1:35 AM To: ozWPF Subject: RE: MicroModels question Hi Adrian, I havent tried, but something like this might work: private Foo _foo; public Foo Foo { get { return _foo; } set { _foo = value; NotifyChanged("Foo"); } } public FooViewModel(Foo foo, Baz baz) { Foo = foo; Property(() => Foo.Bar); baz.SomeEvent += () => Foo = new Foo(); } By doing this, the MicroModels expression walker should also subscribe to the Foo property change event and re-evaluate when it changes. Paul From: [email protected] [mailto:[email protected]] On Behalf Of Adrian Hara Sent: Monday, 15 March 2010 7:16 PM To: [email protected] Subject: MicroModels question Hi, Im playing with the very-cool MicroModels framework from Paul Stovell, but I have a question. Suppose I have this view model Class FooViewModel : MicroModel { Public FooViewModel(Foo foo, Baz baz) { Property(() => foo.Bar); baz.SomeEvent += () => foo = new Foo(); } } So the idea is that the underlying domain object upon which the view model is based (in this case the instance of Foo) can change (e.g. in response to some event). In this case the micro-model properties are lost, i.e. they are still subscribed to the old instance of Foo and not to the new one. What would be a good solution in this case so the properties get re-wired to use the new instance of Foo? Thanks, Adrian
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