Although I have a good knowledge of the PHP API and object oriented programming concepts, I learned something very interesting about interfaces in PHP. You probably know that an interface can extend another interface like a class does with another class. But, did you know that an interface can extend multiple interfaces in a row unlike classes? I didn’t until today. I just discovered thanks to one of the best contributors of the Symfony2 framework: Bernhard Schussek aka WebMozart (love his nickname by the way :) ).