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Observer: Notifications Keeping Systems in Sync

Writer: The MainesThe Maines

Introduction

The Observer pattern establishes a one-to-many relationship, where an object (the subject) notifies multiple dependents (observers) when a state changes.


Real-Life Example

A social media platform: When a user posts an update, all followers get notified instantly without the user needing to manually notify each one.


Pros

  • Encourages loose coupling between objects.

  • Efficiently updates multiple dependencies simultaneously.

  • Supports event-driven programming.


Cons

  • Managing too many observers can introduce performance concerns.

  • Difficult to debug when dependencies grow complex.


When to Use It

  • When multiple objects need to react to changes in another object.

  • When implementing publish-subscribe systems (e.g., UI event handling, stock market updates).


Conclusion

Observer simplifies event-driven architectures but must be handled with care to avoid unintended complexity.


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