让类支持比较操作

方法1：比较运算符重载，需要实现以下方法：小于，小于等于，大于，大于等于，等于，不等于。

from functools import total_ordering
from abc import ABCMeta,abstractmethod

@total_ordering  #装饰类
class Shape(object):   #父类
    @abstractmethod
    def area(self):
        pass
    # 小于
    def __lt__(self, other):
        print('in_lt_')
        if not isinstance(other, Shape):
            raise TypeError('other is not Shape')
        return self.area() < other.area()

    def __eq__(self, other):
        print('in_eq_')
        if not isinstance(other, Shape):
            raise TypeError('other is not Shape')
        return self.area() == other.area()

class Rectangle(Shape):           #继承
    def __init__(self, w, h):
        self.w = w
        self.h = h
    def area(self):
        return self.w * self.h

class Circle(Shape):
    def __init__(self, r):
        self.r = r
    def area(self):
        return self.r ** 2 * 3.14
r1 = Rectangle(5, 3)
r2 = Rectangle(4, 4)
c1 = Circle(3)

print(c1 <= r1)
print(r1 > c1)