classvariables.py

# So, consider:

>>> class SomeClass:
...    var = 'foo'
...
>>> x = SomeClass()
>>> x.var
'foo'
>>> SomeClass.var
'foo'

# So far so good. But *who* does `var` belong to? Well, as the name class-variable implies, it belongs to *the class*. This is obvious if we check the class namespace vs the instance namespace:

>>> x.__dict__
{}
>>> SomeClass.__dict__
mappingproxy({'__module__': '__main__', 'var': 'foo', '__dict__': <attribute '__dict__' of 'SomeClass' objects>, '__weakref__': <attribute '__weakref__' of 'SomeClass' objects>, '__doc__': None})

# Now, what happens if we change `x.var`? Does `SomeClass.var` see that change?

>>> x.var = 'bar'
>>> SomeClass.var
'foo'
>>> x.var
'bar'

# And one final look at the namespaces makes it clear, 

>>> x.__dict__
{'var': 'bar'}
>>> SomeClass.__dict__
mappingproxy({'__module__': '__main__', 'var': 'foo', '__dict__': <attribute '__dict__' of 'SomeClass' objects>, '__weakref__': <attribute '__weakref__' of 'SomeClass' objects>, '__doc__': None})
>>>