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ICommand vs RoutedCommand

Let's have a button Command property bound to a custom command.

When should I implement ICommand and when derive from RoutedCommand? I see that RoutedCommand implements ICommand.

In which case could I need to implement an ICommand? What about MVVM model? Which one suits better for this purpose?

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theSpyCry Avatar asked Jul 16 '09 07:07

theSpyCry


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1 Answers

As you have noticed the RoutedCommand class is an implementation of the ICommand interface, its main distinction if that its function is similar to that of a RoutedEvent:

The Execute and CanExecute methods on a RoutedCommand do not contain the application logic for the command as is the case with a typical ICommand, but rather, these methods raise events that traverse the element tree looking for an object with a CommandBinding. The event handlers attached to the CommandBinding contain the command logic.

The Execute method raises the PreviewExecuted and Executed events. The CanExecute method raises the PreviewCanExecute and CanExecute events.

In a case when you don't want the behavior of the RoutedCommand you'll be looking at your own implementation of ICommand. As for the MVVM pattern I can't say that one solution, it seems that everyone has their own methodology. However, here are a few approaches to this problem that I've come across:

  • Using RoutedCommands with a ViewModel in WPF
  • Relaying Command Logic
  • Simple Command (almost identical to Relay Command but worth reading)
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Richard McGuire Avatar answered Oct 01 '22 02:10

Richard McGuire