A great MVVM view model base class for SL4

Brian Genisio blogged about a MVVM ViewModel base class with lots of fantastic features to save you from writing too much plumbing code. You can read about it in his blog:

My view model base
My view model base - Silverlight support

To me, this base class contains of two basic ideas.

1. The first idea is that you do not need to write all those ICommand-type properties yourself but let them generate dynamically from methods that are named by the convention Execute_< commandname > / CanExecute_< commandname >. The properties are stored within a dictionary within the base class.
2. The second idea is not to write all these OnPropertyChanged notification code all the time you publish a property in your view model, but let the base class do it. For this reason the base classes dictionary (the same on in which the ICommand-properties are stored) acts as a value storage for all your property values. Within your view model you only call a base class method to get and set the value. Therby all get /set code runs thorugh a central point that handles the OnPropertyChanged-stuff.

Up to Silverlight 3 there was a problem with data binding of these "dynamic" properties, because in contrast to WPF Silverlight was not able to bind against dictionaries. The workaround was to use a value converter to do the magic.

With Silverlight 4 it is possible to bind against indexers using the following syntax:

< button type="submit" command="{Binding" content="Click me" />

Note the square brackets around the command name - they indicate that the name inside the brackets is to be interpreted as the key of the indexer and yields to

MyViewModelInstance["ButtonClick"]

With this new feature in place, the value converter is no longer needed, which makes the code more readable.

Brian hosted all the sourcecode on codplex.

Thanks for sharing!