I'm watching cosmos on hulu on this all hallows eve. Earlier I took the dog for a walk. She does not like children in costumes.

First we are going to do a quick introduction to the interfaces we will be using. After that we will jump right into code and examples. Please keep in mind that the collection class we are going to build is more about demonstrating the capabilities of these particular SPL interfaces then actual practical use, although you could easily turn this into a useful class.

Good clear tutorial about implementing SPL interfaces.