Observer Pattern In PHP 8+. One of the most used design patterns in the PHP world is the Observer. PHP has built-in interfaces that help us to implement the Observer Design Pattern. To implement the Observable object we can use the SplSubject interface, and for the Observers, we can use the SplObserver Interface.
The easiest guide to implementing the observer pattern in PHP 8+
One of the most used design patterns in the PHP world is the Observer, it’s very useful when we have several objects which are dependent on another object and are required to perform an action when the state of that object changes, or an object needs to notify others without knowing who they are or how many there are.
The Observer Design Pattern is a behavioral design pattern that lets an object notify other objects when an event occurs, like a state change or a method execution.
This pattern is composed of an object called Observable (or Subject/Publisher, in some sources) and many other objects called Observers (or Subscribers). The Observable holds a list o Observers as property and notifies them automatically of any state changes, generally calling one of the observer’s methods.
The observer pattern is generally used for implementing event handlers in an application without creating a dependency between the main class and the event listeners' objects.
In our example, we’ll create a simple system that can create users and store their data in memory. And then we’ll implement a notification every time that a user is created
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