Steve D'Aprano wrote:
Circle didn't use any setters, but I could have let you set the
diameter, which in
turn would set the radius:
circle.radius = 2
assert circle.diameter == 4
circle.diameter == 2 # requires a setter
assert circle.radius == 1
Getting that to work is left as an exercise :-)
It WAS a good exercise!! I was concerned about "infinite recursion"
between my two property setters.. Thanks! Next? :)
Bill
import math
class Circle(object):
""" Define a circle class with radius and diameter""" def __init__(self,
radius):
self.radius = radius
self.diameter =2*radius
@property def radius(self):
return self._radius
@radius.setter def radius(self, value):
self._radius = value
self._diameter=2*value
@property def diameter(self):
return self._diameter
@diameter.setter def diameter(self, value):
self._diameter = value
self._radius = value /2 @property def area(self):
return math.pi *self.radius **2 @property def circumference(self):
return 2 * math.pi *self.radius
## Start here ## circle = Circle(1 / math.pi)
print("Area = {:.2f}".format(circle.area))
print("Circumference = {:.2f}".format(circle.circumference))
circle.radius =2 assert circle.diameter ==4 print("Area =
{:.2f}".format(circle.area))
print("Circumference = {:.2f}".format(circle.circumference))
circle.diameter =2 # requires a setter assert circle.radius ==1 print("Area =
{:.2f}".format(circle.area))
print("Circumference = {:.2f}".format(circle.circumference))
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