[Tutor] design of Point class
matt.gregory at oregonstate.edu
Fri Aug 20 17:45:18 CEST 2010
I often struggle with object design and inheritance. I'd like opinions on how best to design a Point class to be used in multiple circumstances.
I typically deal with geographic (either 2D or 3D) data, yet there are occasions when I need n-dimensional points as well. My thought was to create a superclass which was an n-dimensional point and then subclass that to 2- and 3-dimensional cases. The rub to this is that in the n-dimensional case, it probably makes most sense to store the actual coordinates as a list whereas with the 2- and 3-D cases, I would want 'named' variables, such as x, y, z.
Here's a (very rough) first cut at the constructor and a generic distance function for the n-dimensional case:
def __init__(self, a_list):
self.a_list = a_list[:]
def distance(self, right):
assert(len(self.coord) == len(right))
squared_diffs = [(i-j)*(i-j) for (i,j) in zip(self.coord, right)]
But how can I subclass this in such a way to be able to:
1) Have named variables in the 2- and 3-D cases
2) Be able to initialize with separate passed values, e.g. 'p = Point2D(3.0, 5.0)'
rather than passing in a list
Or am I totally off on thinking this is a good place for inheritance?
Thanks for any help,
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