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Observer

Observer in PHP

Observer is a behavioral design pattern that allows some objects to notify other objects about changes in their state.

The Observer pattern provides a way to subscribe and unsubscribe to and from these events for any object that implements a subscriber interface.

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Usage examples: PHP has several built-in interfaces (SplSubject, SplObserver) that can be used to make your implementations of the Observer pattern compatible with the rest of the PHP code.

Identification: The pattern can be recognized by subscription methods, that store objects in a list and by calls to the update method issued to objects in that list.

Observer in Other Languages

Observer in C# Observer in C++ Observer in Go Observer in Java Observer in Python Observer in Ruby Observer in Rust Observer in Swift Observer in TypeScript