BREW Up a Better Way to Synch Data Between Apps Using a Singleton

s a BREW developer, you're probably intimately familiar with the process of writing applications, but perhaps not as familiar with the process of writing extensions. In BREW, an application is a class that can only have one instance. This means that a BREW application is a singleton, an example of a class which ensures that only one instance of the class can be created (for an in-depth examination of the singleton design pattern, see Design Patterns, by Gamma, et al.).

Occasionally, however, you may need to create a BREW extension, often to manage shared resources or a shared interface: a good place in which to use a singleton. For example, say you have a private extension between two applications that controls access to data in /brew/shared on the file system. In a case like this, you want to ensure that the extension accurately represents the state of the file system; if both applications are running (say one in background and one in foreground mode), a singleton can greatly simplify synchronization.