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\'

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Answer 1

It's because object is a "type", not a class. In general, all classes that are defined in C extensions (like all the built in datatypes, and stuff like numpy arrays) do not allow addition of arbitrary attributes.