The Shuriken library provides the base class ObservableObject (which implements the INotifyPropertyChanged interface).
In order to provide public observable properties (e.g. for binding) use the following guidelines to define properties:
| Case | Guideline | Behavior when annotated with the [Observable] attribute |
|---|---|---|
| Regular properties | Always annotate the property with the [Observable] attribute. |
The property values are tracked automatically. |
| Immutable properties | Never annotate the property with the [Observable] attribute. It's not needed to track the property values as they never change. |
The property values are tracked, however, as property values never change it just consumes valuable resources. |
| Indexer | Never annotate the property with the [Observable] attribute. An indexer cannot be tracked automatically. Use the NotifyIndexerChange method to send notifications. |
The indexer values are not tracked. |
Command properties* |
Consider annotating the property with the [Observable] attribute. Even if the property is immutable (never changes) the CanExecute can change. However, if the CanExecute never changes the property should not be annotated with the [Observable] attribute. |
The property values (the Command objects) as well as the CanExecute are tracked automatically.Note: the CanExecute always returns false while the command is being executed. |
AsyncCommand properties* |
Always annotate the property with the [Observable] attribute. Even if the property is immutable (never changes) the CanExecute can change. |
The property values (the AsyncCommand objects) as well as the CanExecute are tracked automatically.Note: the CanExecute always returns false while the command is being executed. |
Command<T> properties* |
Consider not annotating the property with the [Observable] attribute. Changes of CanExecute(T) cannot be tracked automatically. Use the NotifyCanExecuteChanged method to send notifications. Only if the property is not immutable it should be annotated with the [Observable] attribute. |
The property values (the Command<T> objects) are tracked, but the CanExecute(T) are not tracked.Note: the CanExecute(T) always returns false while the command is being executed. |
AsyncCommand<T> properties* |
Always annotate the property with the [Observable] attribute. Even if the property is immutable (never changes) and the CanExecute(T) cannot be tracked automatically the method will always return false while the command is being executed. |
The property values (the AsyncCommand<T> objects) are tracked, but the CanExecute(T) are not tracked.Note: the CanExecute(T) always returns false while the command is being executed. |
ICommand properties* |
Consider not annotating the property with the [Observable] attribute. Changes of CanExecute(object) cannot be tracked automatically. Only if the property is not immutable it should be annotated with the [Observable] attribute. |
The property values (the ICommand objects) are tracked, but the CanExecute(object) are not tracked. |
* declared property types
Note: the [Observable] annotation does nothing if the class doesn't derive from the ObservableObject