Jupyter & Python: Why can't a child's call to a parent method recognize the parent's import?

Question

In my current working directory I have the files active.ipynb which contains class B, subclass of A, and I have A.py where A is defined.

When I'm defining everything within the notebook (i.e. class A and B are both defined within a cell in the notebook), everything works fine which is what I expect. When class A is moved into it's own file, I get problems. Importing math in class B does not help, and I also tested this in a separate notebook from my real project to make sure I'm not doing something detrimental somewhere.

Consider

A.py contents:

#edited to reflect this issue occurring regardless of import location

import math    

class A:

    def method(self):
        #parent related code...
        self.parentmethod()

    def parentmethod(self):
        print(math.pi)

In my current cell I have:

import A


class B(A.A):
    def method(self):
        #child related overridden code...
        self.parentmethod()

b = B()

b.method()

and I get the following error:

NameError                                 Traceback (most recent call last)
<ipython-input-84-42c1e6969f03> in <module>
      9 b = B()
     10 
---> 11 b.method()

<ipython-input-84-42c1e6969f03> in method(self)
      5     def method(self):
      6         #child related code...
----> 7         self.parentmethod()
      8 
      9 b = B()

~\Documents\Projects\FunctionNetwork\A.py in parentmethod(self)
      7 
      8     def parentmethod(self):
----> 9         print(math.pi)

NameError: name 'math' is not defined

What's going on?

Answer 1

I figured it out by accidentally repeating the error moments ago, and now I can replicate it at will.

I copied class A from JN, and accidentally missed the math import at the module level. I then imported class A into a fresh cell and called it's method which lead to a name error referencing the math module. This is expected because I didn't import math anywhere.

I added the math import to A.py, saved it, then reran the cell assuming it would reimport A.py with the new information. This is not the case. When I cleared the notebook, only then did it recognize that I updated A.py.

Apparently, being consistent can be a boon even if you're consistently sloppy.