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Date: Thu, 18 Jun 2015 21:43:28 +1000
Subject: Re: Classic OOP in Python
From: Chris Angelico <rosuav@gmail.com>
Cc: "python-list@python.org" <python-list@python.org>
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Xref: csiph.com comp.lang.python:92822

On Thu, Jun 18, 2015 at 9:03 PM, Fabien <fabien.maussion@gmail.com> wrote:
> Would you consider the following kind of program "unpythonic"?
>
> class MovingObject(object):
>     """Great doc about what a moving object is"""
>
>     def move(self):
>         """Great doc about move"""
>         raise NotImplementedError()
>
> class Dog(MovingObject):
>     def move(self):
>         print "Dog is moving"
>
> class Car(MovingObject):
>     def move(self):
>         print "Car is moving"
>
> (Disclaimer: I learned OOP with Java)

Now try extending the concept to two, three, or four such interfaces.
Files can be moved, opened, copied, and unlinked. Should they share
any sort of interface with dogs, boxes, handwriting, and railway
carriages? It's much better to simply define the attributes of each
object separately; most non-trivial cases don't involve simple methods
with no additional arguments, and the chances of an incompatibility
(or worse, a forced compatibility) go up.

ChrisA