Question

If I create a class A as follows:

class A:     def __init__(self):         self.name = 'A' 

Inspecting the __dict__ member looks like {'name': 'A'}

If however I create a class B:

class B:     name = 'B' 

__dict__ is empty.

What is the difference between the two, and why doesn’t name show up in B‘s __dict__?

Answer 1

B.name is a class attribute, not an instance attribute. It shows up in B.__dict__, but not in b = B(); b.__dict__.

The distinction is obscured somewhat because when you access an attribute on an instance, the class dict is a fallback. So in the above example, b.name will give you the value of B.name.