layout: pattern
title: Subclass Sandbox
folder: subclass-sandbox
permalink: /patterns/subclass-sandbox/
categories: Behavioral

– Game programming


The subclass sandbox pattern describes a basic idea, while not having a lot of detailed mechanics. You will need the pattern when you have several similar subclasses. If you have to make a tiny change, then change the base class, while all subclasses shouldn’t have to be touched. So the base class has to be able to provide all of the operations a derived class needs to perform.

Class diagram

alt text


The Subclass Sandbox pattern is a very simple, common pattern lurking in lots of codebases, even outside of games. If you have a non-virtual protected method laying around, you’re probably already using something like this. Subclass Sandbox is a good fit when:

  • You have a base class with a number of derived classes.
  • The base class is able to provide all of the operations that a derived class may need to perform.
  • There is behavioral overlap in the subclasses and you want to make it easier to share code between them.
  • You want to minimize coupling between those derived classes and the rest of the program.