I think you could replace all of that with "Don't use Singletons. Ever. Seriously. Like, use a Monostate or something else. Dude, I'm not kidding. It's just an 'object-oriented' global."

The thing is, they push singletons in university CS "software engineering" classes. I've had arguments of several minutes with my professors about whether or not it's appropriate to use a singleton, myself arguing that it perverts proper application flow and hampers readability (as well as breaking flexibility) and them arguing that they're lazy.

Academics...

Nice one for collecting all those links together. Shall have to remember this link for the inevitable future discussion [smile]

I find that design pattern usage is in one of two extremes - over use or under use, never "just right." People religiously sticking to a pattern are just an example of those with tunnel vision that over-use something and try desperately hard to distort the world to fit that one tool...

My sarcasm detector might not be working, but I disagree that a monostate is any better than a singleton. Both are globals in disguise (though monostates are very well disguised... which might even be a problem of it's own).

Global mutable state is the major issue I think, since it introduces implicit dependencies between modules that use the state. You may call it a singleton, a monostate or a static variable, but they all suffer from the same problem. The solution is simple: avoid it as much as possible.