AttributeError with extended class in Python-CodePudding

I'm trying to create a new method for a class from a different file (not the file where the class was defined). My code is:

from derivations import derivation

class Derivation(derivation.Derivation):
    
    def autoderive(self, index):
        ...

deriv = derivation.Derivation()

But if I try to run this method from the terminal, it doesn't work:

>>> deriv.autoderive()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'Derivation' object has no attribute 'autoderive'

I don't have problems with the "native" methods. And I'm working with a fork of this: https://github.com/alexwarstadt/minimalism

Thank you very much.

CodePudding user response：

I do not know much about the derivation module, but you are not creating an instance of your Derivation class, where you have defined the autoderive method, by doing this:

deriv = derivation.Derivation()

To create an instance of your custom class Derivation, that derives from derivation.Derivation():

deriv = Derivation()