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

© Dmitri Nesteruk 2018

Dmitri NesterukDesign Patterns in Modern C++https://doi.org/10.1007/978-1-4842-3603-1_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 into the interface. So what do you do? You make a Null Object.

Scenario

Suppose you inherited a library that uses the following interface :

1   struct Logger

2   {

3     virtual ~Logger() = default;

4     virtual void info(const string& s) = 0;

5      ...