The observer design pattern

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Data Access and Operations - slide 42 : 45

The observer design pattern

The Observer is often used to ensure a loose coupling between an application and its user interface

In general, Observer can be used whenever a set of observer objects need to be informed about state changes in a subject object

Design patterns

Templates of the Subject class and the SubjectState class.

A templates of the Observer class.

Application of the Subject and Observer classes.