Command and selection classes

TCommand is the base class from which data commands are derived.

TDocumentComponentCommandBinding is the base class that defines the interface for commands that are bound to a selection. All document commands must be bound to a selection (to permit collaboration, recovery, and undo). It provides the necessary mechanisms for managing and executing commands on model or presenter selections.

The following three classes all provide analogous interfaces. The data that commands operate on can be model data, presenter data, or both at the
same time:

• TModelSelection is the base class and defines the interface for commands that want to select a model in the component hierarchy.
• TPresenterStateSelection is the base class and defines the interface for commands that want to select a presenter state in the component hierarchy.
• TDocumentComponentSelection defines the interface for commands that want to select a component in a component hierarchy. It should not be subclassed.