Mastering PHP Design Patterns

Chain of Responsibility

Suppose we have a group of objects that together are meant to solve a problem. When one object can't solve a problem, we want the object to send the task to a different object in a given chain. This is what the Chain of Responsibility design pattern is used for.

In order to get this to work, we need a handler, which will be our Chain interface. The various objects in the chain will all implement this Chain interface.

Let's start with a simple example; an associate can purchase an asset for less than $100, a manager can purchase something for less than $500.

Our abstraction for the Purchaser interface looks like this:

<?php interface Purchaser { public function setNextPurchaser(Purchaser $nextPurchaser): bool; public function ...