[Tutor] OOD - Another class question

[Alan Gauld]

"James Reynolds" <eire1130 at gmail.com> wrote

> parent class and two child classes. Some stuff is done to the object that 
> is
> passed to the function in one of the child classes and this then calls a
> function from the global class passing local variables (from the child
> class).

You really need to tighten up on the terminology because the
imprecision is part of your problems understanding the concepts.

You pass an object to a method of a child class which calls
a method in the parent class. You pass instance variables
of the child class as arguments to the parent class method..

> When I do this, I am told: AttributeError: 'HillBuilder' object has no
> attribute 'MountainBuilder'

> The question is, what am I doing wrong?

Confusing inheritance with composition.
 Your child class does not have an attribute MountainBuilder,
it *is* a MountainBuilder. self within the method referes to your
subclass of MountainBuilder so you only need self.

> class MountainBuilder(object):
>      def pinetree_func(self, knoll)
>            do stuff to knoll
>            return knoll
>      def mountain_func(self, hill)
>            knoll = hill * 2
>            pinetree = pintree_func(knoll)
>            return hill
>
> class HillBuilder(MountainBuilder):
> def __init__(self, mountain):
>              OptionLoad.__init__(self, mountain)
>              self.MountainBuilder.mountain_func

This should be
                self.mountain_func(mountain)

>      def hill_func(self)
>            hill= do stuff to self.mountain
>            grassyknoll = MountainBuilder.mountain_func(hill)

And this should be
              grassyknoll = self.mountain_func(hill)

mountain func as a method of MountainBuilder is also
a method of HillBuilder (thats what inheritance means)
so you access it through self.


Take a look at the BankAccount example in the OOP
topic of my tutor for more examples of subclasses
calling superclass methods

HTH,

-- 
Alan Gauld
Author of the Learn to Program web site
http://www.alan-g.me.uk/