Mid From PDF GoF Patterns Gang of Four Patterns

Subject (NewsPublisher):?

Q: Subject (NewsPublisher):?

Short answer: The NewsPublisher class acts as the subject in the Observer Pattern. It maintains a list of IObserver instances (subscribers) and provides methods to add (Subscribe), remove (Unsubscribe), and notify them (Notify). Real-world example (ShopNest) When order status changes, observers update email, SMS, and analytics without the Order class knowing each one. Say this in the interview Define — one clear sentence (the short answer above). Example — relate it to a project like ShopNest or your real work. Trade-off — when you would not use it.

Short answer: The NewsPublisher class acts as the subject in the Observer Pattern. It maintains a list of IObserver instances (subscribers) and provides methods to add (Subscribe), remove (Unsubscribe), and notify them (Notify).

Real-world example (ShopNest)

When order status changes, observers update email, SMS, and analytics without the Order class knowing each one.

Say this in the interview

Define — one clear sentence (the short answer above).
Example — relate it to a project like ShopNest or your real work.
Trade-off — when you would not use it.

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60–90 second framework

Define — one crisp sentence
Example — project or course app
Trade-off — what you gain vs sacrifice
Guardrail — test, monitor, or prevent failure

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Say your answer aloud, then check against the written answer above.

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