Validation of your data is a requirement for almost every application. By using validation, you make sure that no invalid data is (eventually) persisted in your datastore. When you don't implement validation, there's a risk that a user will input wrongly formatted or plain incorrect data on the screen and even persist this data in your datastore. This is something you should definitely avoid.
In Silverlight 4, a new way of validating your data is possible by using
INotifyDataErrorInfo. This allows us to invalidate the properties without throwing exceptions and the validation code doesn't have to reside in the set accessor of the property. It can be called whenever it's ...