Observerpattern

The Observer pattern is a behavioral design pattern that defines a one-to-many dependency between objects. It ensures that when one object, known as the subject, changes its state, all its dependents, called observers, are automatically notified and updated. This pattern decouples the subject from its observers, allowing them to exist independently.

The subject maintains a list of its observers and provides methods to attach and detach them. When the subject's state changes, it iterates through its list of observers and calls an update method on each one. The observers, in turn, can query the subject to retrieve the new state. This mechanism allows for dynamic relationships between objects, where observers can be added or removed at runtime.

Common use cases for the Observer pattern include graphical user interfaces, where UI elements (observers) update when underlying data (subject) changes, and event handling systems, where multiple listeners (observers) are notified of an event (subject state change). It promotes loose coupling, making systems more flexible and easier to maintain and extend. The key benefit is that the subject does not need to know the concrete classes of its observers, only that they implement a common observer interface.