On 11/10/2012 03:51 PM, Jennie wrote: > On 11/10/2012 09:29 PM, Terry Reedy wrote: > >> On 11/10/2012 2:33 PM, Jennie wrote: >>> >>> 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) > >> What I do not like about this one is that it creates a new 0 point each >> time one is needed. Two solutions: >> >> change Point() to point0 in the distance function and create >> point0 = Point() >> after the class. >> >> -or- >> instead of p = line, >> px,py = point.x, point.y if point else 0.0, 0.0 > > Thanks, I like the second one :) > I like the first, once you fix the minor inefficiency in it; add the qualifier "is None"
... def distance(self, point=None): ... p = point if point is None else Point() ... return math.sqrt((self - p).x ** 2 + (self - p).y ** 2) The advantage it then has over the second one is that the whole class is defined inside the class. -- DaveA -- http://mail.python.org/mailman/listinfo/python-list
