© Vaskaran Sarcar 2020
V. SarcarDesign Patterns in C#https://doi.org/10.1007/978-1-4842-6062-3_14

14. Observer Pattern

Vaskaran Sarcar1 
(1)
Garia, Kolkata, West Bengal, India
 

This chapter covers the Observer pattern.

GoF Definition

Define a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically.

Concept

In this pattern, there are many observers (objects) that are observing a particular subject (also an object). Observers want to be notified when there is a change made inside the subject. So, they register for that subject. When they lose interest in the subject, they simply unregister from the subject. Sometimes this model is called a Publisher-Subscriber (Pub-Sub) model ...

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