newb __init__ inheritance

hyperboogie hyperboogie at gmail.com
Thu Mar 8 16:25:06 CET 2012


Hello everyone.

This is my first post in this group.
I started learning python a week ago from the "dive into python" e-
book and thus far all was clear.
However today while reading chapter 5 about objects and object
orientation I ran into something that confused me.
it says here:
http://www.diveintopython.net/object_oriented_framework/defining_classes.html#fileinfo.class.example

"__init__ methods are optional, but when you define one, you must
remember to explicitly call the ancestor's __init__ method (if it
defines one). This is more generally true: whenever a descendant wants
to extend the behavior of the ancestor, the descendant method must
explicitly call the ancestor method at the proper time, with the
proper arguments. "

However later on in the chapter:
http://www.diveintopython.net/object_oriented_framework/userdict.html

it says:
"Methods are defined solely by their name, and there can be only one
method per class with a given name. So if a descendant class has an
__init__ method, it always overrides the ancestor __init__ method,
even if the descendant defines it with a different argument list. And
the same rule applies to any other method. "

My question is if __init__ in the descendant class overrides __init__
in the parent class how can I call the parent's __init__ from the
descendant class - I just overrode it didn't I?

Am I missing something more fundamental here?
Thanks



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