python 类与对象深度2

比较两个类的两种方法：圆的面积 矩形和圆面积作比较 ：

第一种： 通过装饰器来比较两个类：将共同代码抽出， 强制子类 实现area方法

import abc
from functools import total_ordering
import math
@total_ordering
class Shap(metaclass= abc.ABCMeta):
    @abc.abstractmethod
    def area_res(self):
        pass
    def __gt__(self, other):
        return self.area() > other.area()
    def __ge__(self, other):
        return self.area() >= other.area()
class Rect(Shap):
    def __init__(self,w, h):
        self.w = w
        self.h = h
    def area(self):
        return self.w * self.h
class Circle(Shap):
    def __init__(self,r):
        self.r = r
    def area(self):
        return self.r ** 2 *math.pi
c = Circle(4)
r = Rect(1,2)
print(c == r)

第二种方法：

# 求矩形面积
from functools import total_ordering
@total_ordering
class Rect(object):
    #
    def __init__(self,w, h):
        self.w = w
        self.h = h
    def area(self):
        return self.w * self.h
    def __str__(self):
        # 字符串格式化
        # f"" 3.6版本以上支持
        return f"({self.w},{self.h})"
    def __gt__(self, other):
        return self.area() > other.area()
    def __ge__(self, other):
        return self.area() >= other.area()
# r1 = Rect(1,2)
# r2 = Rect(3,4)
# print(r1)
# print(r2)
# print(r1>r2)  # TypeError: '>' not supported between instances of 'Rect' and 'Rect'
# print(r1>r2)  # 类与类之间比较 直接报错  添加 __gt__方法 可以比较
# print(r1 >= r2)
# print(r1 <= r2)
"""
圆的面积  矩形和圆面积作比较
"""
import math
class Circle(object):
    def __init__(self,r):
        self.r = r
    def area(self):
        return self.r ** 2 *math.pi
    # def __gt__(self, other):
    #     return self.area() > other.area()
    #
    # def __ge__(self, other):
    #     return self.area() >= other.area()
c = Circle(2)
r = Rect(2,2)
print("比较：",c == r)