What do you call a class not intended to be instantiated

[Matimus]

On Sep 21, 3:39 pm, Steven D'Aprano <st... at REMOVE-THIS-
cybersource.com.au> wrote:
> I have a class which is not intended to be instantiated. Instead of using
> the class to creating an instance and then operate on it, I use the class
> directly, with classmethods. Essentially, the class is used as a function
> that keeps state from one call to the next.
>
> The problem is that I don't know what to call such a thing! "Abstract
> class" isn't right, because that implies that you should subclass the
> class and then instantiate the subclasses.
>
> What do you call such a class?
>
> --
> Steven

It actually sounds like you are doing something similar to the
monostate pattern. In Java the monostate pattern is usually
implemented by creating a class that only has static functions and
variables. You _can_ instantiate it, but every instance will share the
same state. In that way it is very similar to the Singleton pattern
(http://en.wikipedia.org/wiki/Singleton_pattern).

In Python I haven't found a need for monostate, since you can override
__new__ and return exactly the same instance. However, you you wanted
to be able to inherit a monostate object and share some of the state
between the class and subclass it might still be useful.

Perhaps if you post some example code?

Matt