SOFTWARE DESIGN
DESIGN PATTERNS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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concept of a finite state machine
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subscription to a chain of events
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extract traversal behavior from a collection to an object
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put a new behavior in a separate class called visitor
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Detailed explanation-1: -The Observer pattern suggests that you add a subscription mechanism to the publisher class so individual objects can subscribe to or unsubscribe from a stream of events coming from that publisher.
Detailed explanation-2: -According to GoF definition, observer pattern defines a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically. It is also referred to as the publish-subscribe pattern.
Detailed explanation-3: -An Observer Pattern says that “just define a one-to-one dependency so that when one object changes state, all its dependents are notified and updated automatically". The observer pattern is also known as Dependents or Publish-Subscribe.