Observer Pattern

Observer - behavioral design pattern.

Uses a one-to-many relationship. In this regard, there is one suspicious object and many observers. And when an allergy to an object occurs, an alert to all observers automatically occurs.

C# already has a built-in implementation of the pattern using interfaces:IObservable<T> & IObserver<T>

1. Сlass that implements an interface IObservable<T> is called a provider or subject.
2. Сlass that implements the interface IObserver<T> is called an observer that receives notifications from the provider.
3. IObserver<T>.OnNext method that provides the observer with new or current information

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Example:

Press LMB key to press button and call everyone observers to move to the center.

1. All observers move to their points :

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2. The button is pressed, all observers received a notification and came to the center:

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