Programming Microsoft® Composite UI Application Block and Smart Client Software Factory

D. More Complex Example: Passing and Modifying Parameters

1. It is reasonable and likely that an action method would like some sort of input parameter to help it do its job. You can pass this as the last parameter to the Execute method. It can be an object of any type. In the hospital example, you might expect that this would be the new patient ID. Counterintuitively, we don't do that. The reason is that we want the currently selected patient ID to come from one and only one place, that being the clinical context service. That way, it can never get out of sync.

   You can also use the object parameter as a means to get output from the action method and even the action conditions. The parameter is passed by reference, so the action conditions can modify ...