Observer Pattern

Handles the relation between a Publisher and his subscribers (or Subject/observers or Observable/observers).

How

• The Observer-interface: All observers must implement this interface: So they all have a Notify-method.
• The observable base-class: Keeps track of all the observer-objects (reference to their Observer-interface)
• Your observable class will inherit from the observable baseclass. This class will thus inherit the behaviour that manages and notifies the observers. When needed, you just call NotifyObservers().
• Your observers will implement the Observer-interface, so their Notify-method can be called by the Observable class.

To pass the new data between the observable and the observers:

1. Pass an object with all the data via the Notify-methods
2. The observer gets the data via the properties of the observable-object

Observable calls Notify() on an interface => Loosely coupled.