特殊方法使用《python语言程序设计》2018版--第8章18题第4部分（最后总结）

__cmp__ __lt__ 小于<__le__ 小于等于<=__eq__ 等于==__ne__ 不等于!=__gt__ 大于>__ge__ 大于等于>=

如何实现

__cmp__在 Python 2.x 中是核心比较方法，可一站式定义所有比较逻辑；
Python 3.x 中被__eq__/__lt__/__gt__等取代

方法和返回值列表

我们直接利用两个圆的半径对比来将这些重载和特殊方法一一展示。

defmain_method():circle1=Circle(0,0,150)#圆1circle2=Circle(0,0,200)#圆2r1=circle1.get_radius()r2=circle2.get_radius()#重载相等print("__eq__测试圆1半径{r1}和圆2半径{r2}相等",r1.__eq__(r2))#重载不相等print("__ne__测试圆1半径{r1}和圆2半径{r2}不相等",r1.__ne__(r2))#重载圆1小于圆2print("__lt__测试圆1半径{r1}小于圆2半径{r2}",r1.__lt__(r2))#重载圆1大于圆2print("__gt__测试圆1半径{r1}小于圆2半径{r2}",r1.__gt__(r2))#重载圆1小于等于圆2print("__le__测试圆1半径{r1}小于圆2半径{r2}",r1.__le__(r2))#重载圆1大于等于圆2print("__ge__测试圆1半径{r1}小于圆2半径{r2}",r1.__ge__(r2))main_method()

最终完整代码

classCircle:# 建立圆形的类def__init__(self,x=0,y=0,radius=0):# 初始化self.__x=x# x私有域self.__y=y# y私有域self.__radius=radius# radius私有域# set x,y,radius域defset_x(self,x):self.__x=xdefset_y(self,y):self.__y=ydefset_radius(self,radius):ifradius<0:print("圆的半径不能为负数")self.__radius=radius# get x,y,radius域defget_x(self):returnself.__xdefget_y(self):returnself.__ydefget_radius(self):returnself.__radius# 返回圆的面积defget_area(self):return3.1415926*pow(self.__radius,2)defget_perimeter(self):return2*3.1415926*self.__radiusdef__str__(self):returnf"Circle(半径={self.__radius},周长={self.get_perimeter():.2f},面积={self.get_area():.2f})"definit_set(self):returnf"圆 x:{self.__x}, y:{self.__y}, radius:{self.__radius}."# 2025.12.14 增加测量两个圆的x,y的距离defcontains_point(self,other_x,other_y):x1=self.__x y1=self.__y x2=other_x y2=other_y countDis=int((pow((x2-x1),2)+pow((y2-y1),2))**0.5)ifcountDis<self.__radius:print(f"坐标x:{other_x},y:{other_y},点2在园1内")returnTrueelse:print(f"坐标x:{other_x},y:{other_y},点2不在园1内")returnFalse# 2025.12.14 对比圆2是否在圆1内# 2025.12.15 if条件为两点距离+圆2半径小于圆1，这样完全覆盖圆defcontains(self,circle_2D):x1=self.__x y1=self.__y x2=circle_2D.get_x()y2=circle_2D.get_y()r1=self.__radius r2=circle_2D.get_radius()countDis=(pow((x2-x1),2)+pow((y2-y1),2))**0.5ifcountDis+r2<r1:# 修改后可以完全包含print(f"坐标x:{x2},y:{y2},半径{r2},点2在园1内")returnTrueelse:print(f"坐标x:{x2},y:{y2},半径{r2},点2不在园1内")returnFalse# 2025.12.15 将昨天的圆2在圆1中的函数直接拷贝的defoverlaps(self,circle_2D):x1=self.__x y1=self.__y x2=circle_2D.get_x()y2=circle_2D.get_y()r1=self.__radius r2=circle_2D.get_radius()countDis=(pow((x2-x1),2)+pow((y2-y1),2))**0.5ifcountDis<r1andr2<r1:# 但我这个还是有瑕疵print(f"坐标x:{x2},y:{y2},半径{r2},点2在园1内")returnTrueelse:print(f"坐标x:{x2},y:{y2},半径{r2},点2不在园1内")returnFalsedef__contains__(self,other):x1=self.__x y1=self.__y x2=other.get_x()y2=other.get_y()r1=self.__radius r2=other.get_radius()countDis=(pow((x2-x1),2)+pow((y2-y1),2))**0.5ifcountDis+r2<r1:# 修改后可以完全包含print(f"坐标x:{x2},y:{y2},半径{r2},点2在园1内")returnTrueelse:print(f"坐标x:{x2},y:{y2},半径{r2},点2不在园1内")returnFalsedefmain_base():print("main_base函数。。。。。。。。。。。。。。。")a=Circle()print("默认圆函数",a.init_set())# 打印类默认的x,y,radiusx=100y=100radius=50b=Circle(x,y,radius)print("圆构造好的内容",b.init_set())defmain_add():print("main_add函数。。。。。。。。。。。。。。。")# x:1 y:2 radius:5c1=Circle(1,2,5)# 因为有__str__的帮助可以直接打印输出print(c1)print(f"周长（高纬度）：{c1.get_perimeter():.6f}")# x:1 y:2 radius:10c1=Circle(1,2,10)# 因为有__str__的帮助可以直接打印输出print(f"周长（高纬度）：{c1.get_perimeter():.6f}")defmain_contains_point():other_X2=120other_y2=120c1=Circle(100,200,150)c1.contains_point(other_X2,other_y2)defmain_contain_cicle():circle1=Circle(100,200,150)circle2=Circle(100,200,50)circle1.contains(circle2)#12.14用正常方法circle1.__contains__(circle2)#12.15利用修改魔法方法defmain_method():circle1=Circle(0,0,150)#圆1circle2=Circle(0,0,200)#圆2r1=circle1.get_radius()r2=circle2.get_radius()#重载相等print("__eq__测试圆1半径{r1}和圆2半径{r2}相等",r1.__eq__(r2))#重载不相等print("__ne__测试圆1半径{r1}和圆2半径{r2}不相等",r1.__ne__(r2))#重载圆1小于圆2print("__lt__测试圆1半径{r1}小于圆2半径{r2}",r1.__lt__(r2))#重载圆1大于圆2print("__gt__测试圆1半径{r1}小于圆2半径{r2}",r1.__gt__(r2))#重载圆1小于等于圆2print("__le__测试圆1半径{r1}小于圆2半径{r2}",r1.__le__(r2))#重载圆1大于等于圆2print("__ge__测试圆1半径{r1}小于圆2半径{r2}",r1.__ge__(r2))main_base()main_add()main_contains_point()main_contain_cicle()#12.14 重载测试圆2是否在圆1里main_method()#12.15重载方法测试

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