python如何让类支持比较运算

#!/usr/bin/python3
 
from math import pi
 
 
class Circle(object):
  def __init__(self, radius):
    self.radius = radius
 
  def get_area(self):
    return round(pow(self.radius, 2) * pi, 2)
 
  # 重定义小于比较
  def __lt__(self, other):
    return self.get_area() < other.get_area()
 
  # 重定义等于比较
  def __eq__(self, other):
    return self.get_area() == other.get_area()
 
if __name__ == '__main__':
  c1 = Circle(3.0)
  c2 = Circle(5.0)
 
  print(c1 < c2)   # c1.__le__(c2)
  print(c1 == c2)   # c1.__eq__(c2)　　

#!/usr/bin/python3
 
from math import pi
 
 
class Circle(object):
  def __init__(self, radius):
    self.radius = radius
 
  def get_area(self):
    return round(pow(self.radius, 2) * pi, 2)
 
  # 重定义小于比较
  def __lt__(self, other):
    return self.get_area() < other.get_area()
 
  # 重定义等于比较
  def __eq__(self, other):
    return self.get_area() == other.get_area()
 
if __name__ == '__main__':
  c1 = Circle(3.0)
  c2 = Circle(5.0)
 
  print(c1 < c2)   # c1.__le__(c2)
  print(c1 == c2)   # c1.__eq__(c2)
 
 
# !/usr/bin/python3
 
from math import pi
 
 
class Circle(object):
  def __init__(self, radius):
    self.radius = radius
 
  def get_area(self):
    return round(pow(self.radius, 2) * pi, 2)
 
  # 重定义小于比较
  def __lt__(self, other):
    return self.get_area() < other.get_area()
 
  # 重定义等于比较
  def __eq__(self, other):
    return self.get_area() == other.get_area()
 
 
class Rectangle(object):
  def __init__(self, width, height):
    self.width = width
    self.height = height
 
  def get_area(self):
    return self.width * self.height
 
  # 重定义小于比较
  def __lt__(self, other):
    return self.get_area() < other.get_area()
 
  # 重定义等于比较
  def __eq__(self, other):
    return self.get_area() == other.get_area()
 
 
if __name__ == '__main__':
  c1 = Circle(5.0)
  R1 = Rectangle(4.0, 5.0)
 
  print(c1 > R1) # c1.__le__(c2)
  print(c1 == R1) # c1.__eq__(c2)　

# !/usr/bin/python3
 
from math import pi
from abc import abstractmethod
from functools import total_ordering
 
 
@total_ordering
class Shape(object):
  """
  定义一个抽象类，重定义比较运算，再定义抽象方法，然后子类通过这个方法进行比较,
  其他子类比较类都需要重构抽象方法，实现比较运算
  """
   
  # 标记比较方法，抽象方法
  @abstractmethod
  def get_area(self):
    pass
   
  # 重定义小于比较
  def __lt__(self, other):
    return self.get_area() < other.get_area()
   
  # 重定义等于比较
  def __eq__(self, other):
    return self.get_area() == other.get_area()
 
 
class Circle(Shape):
  def __init__(self, radius):
    self.radius = radius
   
  def get_area(self):
    return round(pow(self.radius, 2) * pi, 2)
   
 
class Rectangle(Shape):
  def __init__(self, width, height):
    self.width = width
    self.height = height
   
  def get_area(self):
    return self.width * self.height
 
 
if __name__ == '__main__':
  c1 = Circle(5.0)
  R1 = Rectangle(4.0, 5.0)
   
  print(c1 > R1) # c1.__le__(c2)
  print(c1 == R1) # c1.__eq__(c2)