What happens when accessing an attribute from a Class vs an instance in python? -

i trying understand access of attributes class vs object. experiment this:

>>> class test():         x = 1         y = 2         def __init__(self, a, b):             self.x =             self.y = b >>> test.x, test.y (1, 2) >>> t = test(3, 4) >>> (t.x, t.y) (3, 4)  # looks class attributes , instance attributes completed unrelated, ... >>> del t.x >>> del t.y >>> t.x, t.y (1, 2)  # looks instance attributes shadows class attributes,  # accessed when instance attrs not present, ... >>> t.x = 5 # expected class attributes changed, ... >>> test.x 1 # class attribute not changed >>> t.x 5 

what happens when try access attribute (read/write/delete)?

and why python designed way?

you're correct instance attributes shadow class attributes. in __init__ method , in t.x = 5, you're adding attributes instance. way create instance attributes.