Chain of Responsibility in PHP
Chain of Responsibility is behavioral design pattern that allows passing request along the chain of potential handlers until one of them handles request.
The pattern allows multiple objects to handle the request without coupling sender class to the concrete classes of the receivers. The chain can be composed dynamically at runtime with any handler that follows a standard handler interface.
Usage examples: The Chain of Responsibility is pretty common in various PHP frameworks. Arguably, one of the most famous examples of using this pattern in PHP is HTTP Request Middleware described in PSR-15.
Identification: The pattern is recognizable by behavioral methods of one group of objects that indirectly call the same methods in other objects, while all the objects follow the common interface.