What is a Singleton?

The Singleton pattern in a nutshell is where you have a class that you can access anywhere within your project, due to the fact that only one object (instance) of that class is created (instantiated). The pattern provides a way for programmers to give access to a class's information globally by creating a single instance of an object in your game.

Whereas there are quite a few issues with using global variables, you can think of a Singleton as an improved global variable due to the fact that you cannot create more than one. With this in mind, the Singleton pattern is an attractive choice for classes that only have a unique instance in your game project, such as your graphics pipeline and input libraries, as having more than one of these in your projects doesn't make sense.

This single object uses a static variable and static functions to be able to access the object without having to pass it through all of our code.

In the Mach5 engine, Singletons are used for the application...