Why I can't refer to class variable from nested class?

February 22, 2022

In simple case I can call teacher in loh function:

class Student:
   teacher = 'Mrs. Jones'

   def __init__(self, name):
       self.name = name
    
def loh():
  print(Student.teacher)

loh()

### Mrs. Jones

But, If I try to do that next way, I got mistake "not defined". Why?

class Student:
  class UnderStudent:
    teacher = 'Mrs. Jones'
  def f():
    print(UnderStudent.teacher)
  f()

>Solution :

f tries to lookup UnderStudent in the global scope, but the name isn’t defined there; it’s only defined in the namespace of the class statement, which turns the name into a class attribute.

class Student:
    class UnderStudent:
        teacher = 'Mrs.Jones'
    def f(self):
        print(self.UnderStudent.teacher)
        # or print(Student.UnderStudent.teacher)

Nested classes are rare in Python, as there is no restriction on having multiple top-level classes in the same file as in some other languages.