What is the best solution to solve the following problem in Python 3.3?
import math >>> class Point: ... def __init__(self, x=0, y=0): ... self.x = x ... self.y = y ... def __sub__(self, other): ... return Point(self.x - other.x, self.y - other.y) ... def distance(self, point=Point()): ... """Return the distance from `point`.""" ... return math.sqrt((self - point).x ** 2 + (self - point).y ** 2) ... Traceback (most recent call last): File "<stdin>", line 1, in <module> File "<stdin>", line 5, in Point NameError: name 'Point' is not defined I propose three solutions. The first one: >>> class Point: ... def __init__(self, x=0, y=0): ... self.x = x ... self.y = y ... def __sub__(self, other): ... return Point(self.x - other.x, self.y - other.y) ... def distance(self, point=None): ... p = point if point else Point() ... return math.sqrt((self - p).x ** 2 + (self - p).y ** 2) ... >>> p = Point() >>> p.distance() 0.0 >>> p.distance(Point(3, 4)) 5.0 The second one: >>> class Point: ... def __init__(self, x=0, y=0): ... self.x = x ... self.y = y ... def __sub__(self, other): ... return Point(self.x - other.x, self.y - other.y) ... >>> def distance(self, point=Point()): ... return math.sqrt((self - point).x ** 2 + (self - point).y ** 2) ... >>> Point.distance = distance >>> p = Point() >>> p.distance(Point(3, 4)) 5.0 The last one: >>> class Point: ... def __init__(self, x=0, y=0): ... self.x = x ... self.y = y ... Point.distance = distance ... def __sub__(self, other): ... return Point(self.x - other.x, self.y - other.y) ... >>> def distance(self, point=Point()): ... return math.sqrt((self - point).x ** 2 + (self - point).y ** 2) ... >>> p = Point() >>> p.distance(Point(3, 4)) 5.0 Is there a better solution? -- Jennie -- http://mail.python.org/mailman/listinfo/python-list
