The chain-of-responsibility pattern

Computer software is for processing information, and there are different ways of structuring and processing that information. We already know that when we talk about object-oriented programming, we should assign a single responsibility to each class in order to make our design easy to extend and maintain.

Consider a scenario where multiple types of operations can be performed on a set of data that comes with a client request. Instead of adding information about all the operations in a single class, we can maintain different classes responsible for the different types of operations. This helps us keep our code loosely coupled and clean.

These classes are called handlers. The first handler will receive the request and take a call if it needs to perform an action, or pass it on to the second handler. Similarly, the second handler checks and can pass on the request to the next handler in the chain.