Can a non-object exist in Python?

Question

As everyone knows, everything is an object in Python. What I'm wondering about is whether it's possible to create an "object" x such that isinstance(x, object) returns False. I suspect it's possible with sufficient abuse of the CPython API, though achieving this with pure Python would be even more interesting.

Initially I thought that old-style classes would return False since the object hierarchy might not fully apply, but it seems like isinstance(x, object) is indeed True for instances of old-style classes.

While this is mostly of theoretical interest, it might be interesting (or dangerous) if Python allows the creation of a new object hierarchy disconnected from the base object type.

Answer 1

Of course you can do everything via the C API (in particular via the awesome forbiddenfruit module)

>>> from forbiddenfruit import curse
>>> class C: pass
... 
>>> curse(type, "__instancecheck__", lambda cls, obj: type(obj) != C)
>>> isinstance(C(), object)
False
>>> isinstance(C(), C)
True

Answer 2

From the docs, chapter 3 (Data Model): "All data in a Python program is represented by objects." Seems clear enough. You say the alternative "might be interesting" but there are already lots of interesting things that aren't Python.