Brew Extensions: How They Work and When to Use Them

xtensions are tricky objects. They behave similarly to C++ classes except they're ruthlessly complicated to implement. They give Brew developers, usually limited to C code, a chance to stretch their legs into the wonderful world of objects and obfuscation. Extensions, when mastered, give nearly all the benefits of C++ style with a few drawbacks. In this article, I hope to do three things:

1. I will bore you, at length, with an explanation of Brew's extension architecture.
2. I will demonstrate how to create, use and destroy a custom Brew extension.
3. I will explain how to take advantage of C++ code from within a C only extension.

I've written a very simple object that reverses strings for the purpose of demonstration. It's not a particularly useful or complicated object, but it should serve to demonstrate the topic at hand. Hopefully, you'll finish with a strong understanding of Brew's extensions and the experience to put that architecture to work in your own projects.

Extensions in Context
Before diving into the nuts and bolts, let's quickly discuss how Brew extensions function from a somewhat academic standpoint. If you're reading this article for more practical purposes, feel free to skip down to the next section.