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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.

Usage of the pattern in PHP

Complexity:

Popularity:

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

Design Patterns: Observer in Java Design Patterns: Observer in C# Design Patterns: Observer in C++ Design Patterns: Observer in Python Design Patterns: Observer in Ruby Design Patterns: Observer in Swift Design Patterns: Observer in TypeScript