Michael Girouard has pointed out that things in the PHP world are one step closer to being able to create an abstract Singleton object via a simple script he's shared.

The singleton is an incredibly useful pattern in PHP for many reasons. I tend to find myself using them when I know I should be using static classes, but can’t because of PHP's lack of proper class name discovery in extended static classes.

[...] And that works like a charm every time. The problem is, in one application there may be several classes that need to be singletons. In which case my first thought was to build an abstract singleton.

Unfortunately, it didn't quite work like he'd thought it would. He did, however, come up with something that did work - creating an interface and making an abstract implementation of it (code example for this included).