How to access a variable initialised in Parent Class using a Child object?

Question

I have the following code:

class aa(object):
    def __init__(self):
        self.height = 12

class bb(aa):
    def __init__(self):
        self.weight = 13

AA = aa()
BB = bb()

I am trying to access the variable initialized in the Parent class (aa), using the Child object as below. Please suggest the correct way to do it as I am getting errors doing this way:

(If someone can point me to a good documentation on subclassing in Python, it would be great.)

print AA.height # 12
print BB.height # Error

you can find a good example here: tutorialspoint.com/python/python_classes_objects.htm — user3522371
– user3522371, Commented Oct 26, 2014 at 10:59

user1804599 · Accepted Answer · 2014-10-26 10:54:43Z

3

You must call __init__ from the superclass. It will not be called implicitly.

class bb(aa):
    def __init__(self):
        super(bb, self).__init__()
        self.weight = 13

answered Oct 26, 2014 at 10:54

user1804599

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Comments

anon582847382 · Accepted Answer · 2014-10-26 11:00:00Z

2

You need to explicitly initialize the superclass. Edit your __init__ method of bb such that it looks like this:

class bb(aa):
    def __init__(self):
        super(bb, self).__init__()  # Call the __init__ method of the superclass.
        self.weight = 13

It should then work:

print AA.height  # 12
print BB.height  # 12

As for the documentation on using superclasses, refer to the super function in the documentation.

edited Oct 26, 2014 at 11:00

answered Oct 26, 2014 at 10:54

anon582847382

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