Nihkil wrote sometime ago about ‘actions’, which was a concept he created that attach some behavior to elements. Think of the action of pressing the ‘enter’ key in a textbutton and executing some logic (sparing the user a click on the button next to the textbutton).
He has clearly been thinking more about his framework and now posts about the MVC concept of the ViewModel, extending it with his actions here. Good write-up. Go read it.
Basically, he explains what a ViewModel is and shows how to execute ‘command’-like behavior on them. As you might know, Silverlight does not support the concepts of commands, like WPF does. His syntax is like this:
1 <vm:View xmlns="..." xmlns:x="..."
2 xmlns:vm="clr-namespace:Silverlight.FX.ViewModel;assembly=Silverlight.FX"
3 xmlns:app="clr-namespace:AmazonSearch.Views">
4 <vm:View.Model>
5 <app:SearchViewModel />
6 </vm:View.Model>
7
8 <Grid>
9 <TextBox x:Name="searchTextBox" />
10 <Button Content="Search" IsEnabled="{Binding CanSearch}">
11 <vm:ButtonEvents.Click>
12 <vm:InvokeMethod MethodName="Search">
13 <vm:ElementParameter ElementName="searchTextBox" ElementProperty="Text" />
14 </vm:InvokeMethod>
15 </vm:ButtonEvents.Click>
16 </Button>
17
18 <ItemsControl ItemsSource="{Binding Products}">
19 <ItemsControl.ItemTemplate>
20 <DataTemplate><app:ProductView /></DataTemplate>
21 </ItemsControl.ItemTemplate>
22 </ItemsControl>
23 </Grid>
24 </vm:View>
25
The thing to note is in lines 10 to 15. There he invokes a method straight on the ViewModel.
The concept is quite the same as the Caliburn project from Rob and the idea is very powerful!
It enables you to have no code-behind and go straight to the viewmodel. Very nice!
Thinking about this a bit though, does make me wonder if the added Xaml is worth the ability to go straight to the viewmodel. Wouldn't it be just as simple to define a Search method on the codebehind and invoke the correct method in the viewmodel?
My point being: is it worth to incorporate such a framework (albeit very small and succinct). What do you think?