Observasjonsmønster

Observasjonsmønster, also known as the Observer pattern, is a behavioral design pattern in software engineering. It defines a one-to-many dependency between objects so that when one object changes state, all of its dependents are notified and updated automatically. The object that is being observed is called the "subject" or "observable," and the objects that observe it are called "observers."

The primary purpose of the observasjonsmønster is to decouple the subject from its observers. The subject does not need to know the concrete classes of its observers; it only needs to know that they implement a common observer interface. This makes it easy to add or remove observers dynamically without modifying the subject.

When the subject's state changes, it notifies all registered observers by calling a specific method on each observer, typically passing the new state information. Each observer then decides how to react to the notification. This pattern is widely used in event-driven systems, graphical user interfaces, and any situation where multiple objects need to be kept in sync with changes in a central object. Common implementations include the use of callbacks, event handlers, or message queues. The observasjonsmønster promotes loose coupling and makes systems more flexible and maintainable.