This is clearly a Factory pattern. The class is dynamically choosing between different objects based on input, which is the essence of the Factory design—creating different instances on demand. The Strategy pattern, on the other hand, is about varying behavior, not creating objects. So, no doubt, this is Factory all the way.

But wait a second. Maybe it is a Strategy pattern, just a slightly twisted one. What if those objects—singletonA and singletonB—represent different strategies for handling some sort of operation? If the input is deciding which algorithm (or strategy) to use based on context, maybe this is the Strategy pattern, albeit through a bizarre object instantiation lens.

I have no idea