Creating the Singleton design pattern in PHP5

Question

How would one create a Singleton class using PHP5 classes?

Answer 1

All this complexity ("late static binding" ... harumph) is, to me, simply a sign of PHP's broken object/class model. If class objects were first-class objects (see Python), then "$_instance" would be a class instance variable -- a member of the class object, as opposed to a member/property of its instances, and also as opposed to shared by its descendants. In the Smalltalk world, this is the difference between a "class variable" and a "class instance variable".

In PHP, it looks to me as though we need to take to heart the guidance that patterns are a guide towards writing code -- we might perhaps think about a Singleton template, but trying to write code that inherits from an actual "Singleton" class looks misguided for PHP (though I supposed some enterprising soul could create a suitable SVN keyword).

I will continue to just code each singleton separately, using a shared template.

Notice that I'm absolutely staying OUT of the singletons-are-evil discussion, life is too short.