Lecture Notes on 23 Jan 2013

import math

class Point (object):
  # constructor
  def __init__ (self, x = 0, y = 0):
    self.x = x
    self.y = y

  # get distance
  def dist (self, p):
    return math.hypot (self.x - p.x, self.y - p.y)

  # string representation
  def __str__ (self):
    return '(' + str(self.x) + ', ' + str(self.y) + ')'

class Circle (object):
  # constructor
  def __init__ (self, radius = 0.0):
    self.radius = radius     # public radius

  # compute circumference
  def circumference (self):
    return 2.0 * math.pi * self.radius

  # compute area
  def area (self):
    return math.pi * self.radius * self.radius

  # string representation
  def __str__(self):
    return 'Radius = ' + str(self.radius)

  # test for equality
  def __eq__ (self, c):
    return (abs(self.radius - c.radius) < 1.0e-16)
  
def main():
  # create an object
  circleA = Circle ()
  circleB = Circle (2.3)

  # change radius
  circleA.radius = 1.2

  # get radius
  print (circleA.radius)

  # compute area
  print (circleB.area())

  # print Cirlce
  print (circleB)

  # test if two circles are equal
  print (circleA == circleB)

main()