December 2015
Beginner to intermediate
195 pages
2h 52m
English
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CHAPTER 2
Observer Patterns
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) which are observing a particular subject (object). Observers are basically interested and want to be notified when there is a change made inside that subject. So, they register themselves to that subject. When they lose interest in the subject they simply unregister from the subject. Sometimes this model is also referred to as the Publisher-Subscriber model.
Real-Life Example
We can think about a celebrity ...
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.