In a new post to the test.icial.ly blog today Christian looks at interfaces in PHP and why they seem to be ignored in a lot of the development work being done.

Every once in a while I stumble upon interfaces or somebody mentions them to me. Whenever this happens I realise that the use of Interfaces as an OOP key feature in PHP is next to none at all. But why is that?

They note that, while interfaces are used all over projects in other languages, it seems like PHP development has steered away from their use. They define normal interfaces and abstract interfaces for those that don't know and talk about the differences between them. He also includes a brief code sample with description of its use and a bit about interfaces and frameworks.