Design Patterns in Modern C++20: Reusable Approaches for Object-Oriented Software Design

© Dmitri Nesteruk 2022

D. NesterukDesign Patterns in Modern C++20https://doi.org/10.1007/978-1-4842-7295-4_19

19. Null Object

Dmitri Nesteruk¹  

(1)

St. Petersburg, Russia

 

We don’t always choose the interfaces we work with. For example, I’d rather have my car drive me to my destination by itself, without me having to give 100% of my attention to the road and the dangerous lunatics driving next to me. And it’s the same with software: sometimes you don’t really want a piece of functionality, but it’s built in as part of interface requirements. This means you have to provide some value even if you don’t need this particular piece of functionality.

So what do you do? You make a Null Object.

Scenario

Suppose you inherited a library that uses the following ...