Can't set attributes on instance of “object” class

Question

So, I was playing around with Python while answering this question, and I discovered that this is not valid:

o = object()
o.attr = \'hello\'

<

Answer 1

It is simply due to optimization.

Dicts are relatively large.

>>> import sys
>>> sys.getsizeof((lambda:1).__dict__)
140

Most (maybe all) classes that are defined in C do not have a dict for optimization.

If you look at the source code you will see that there are many checks to see if the object has a dict or not.