由于AttributeError，加法无效：“Circle”对象没有属性“x”

Question

我有以下代码，有两个类-一个点和一个圆：

import math
class Point:
    """Two-Dimensional Point(x, y)"""
    def __init__(self, x=0, y=0):
        # Initialize the Point instance
        self.x = x
        self.y = y

    def __iter__(self):
         yield self.x
         yield self.y

    def __iadd__(self, other):
         self.x = self.x + other.x
         self.y = self.y + other.y
         return self

    def __add__(self, other):
         return Point(self.x + other.x, self.y + other.y)

    def __mul__(self, other):
        mulx = self.x * other
        muly = self.y * other
        return Point(mulx, muly)

    def __rmul__(self, other):
        mulx = self.x * other
        muly = self.y * other
        return Point(mulx, muly)

    @classmethod
    def from_tuple(cls, tup):
        x, y = tup
        return cls(x, y)

    def loc_from_tuple(self, tup):
  #       self.x=t[0]
  #       self.y=t[1]
        self.x, self.y = tup

    @property
    def magnitude(self):
        # """Return the magnitude of vector from (0,0) to self."""
        return math.sqrt(self.x ** 2 + self.y ** 2)

    def distance(self, self2):
         return math.sqrt((self2.x - self.x) ** 2 + (self2.y - self.y) ** 2)

    def __str__(self):
        return 'Point at ({}, {})'.format(self.x, self.y)

    def __repr__(self):
        return "Point(x={},y={})".format(self.x, self.y)
class Circle(Point):
    """Circle(center, radius) where center is a Point instance"""
    def __init__(self, center= Point(0,0), radius=1):
 #       Point.__init__(self,center)
        self.center = 1 * center
        self.radius = radius
 #       if not isinstance(center,Point):
 #           raise TypeError("The center must be a Point!")

    @property
    def center(self):
        return self._center

    @center.setter
    def center(self, _center):
        self._center = _center
        if (isinstance(self._center, Point) is False):
            raise TypeError("The center must be a Point!")

    def __getitem__(self,item):
        return self.center[item]

    def __add__(self,other):
        return Circle(
        Point(self.center.x + other.center.x, self.center.y+other.center.y),
        self.radius + other.radius)

    @classmethod
    def from_tuple(cls, center,radius):
        return cls(center, radius)

    @property
    def radius(self):
        return self._radius

    @radius.setter
    def radius(self, radius):
         if radius < 0:
             raise ValueError('The radius cannot be negative')
         self._radius = radius

    @property
    def area(self):
        """Calculate and return the area of the Circle"""
        return math.pi * self.radius ** 2

    @property
    def diameter(self):
        """Calculate and return the diameter of the Circle"""
        return self.radius * 2

    def __str__(self):
        return "Circle with center at ({0}, {1}) and radius {2}".format(self.center.x, self.center.y, self.radius)

    def __repr__(self):
        return "Circle(center=Point({0}, {1}), radius={2})".format(self.center[0],self.center[1],self.radius)

正常加法按预期工作，但+=不能。以下是预期输出。在

^{pr2}$

当我尝试运行此程序时，出现以下错误：

Traceback (most recent call last): File "/Users/ayushgaur/Downloads/HW8_files (1)/shapes.py", line 206, in circle1 += circle2 File "/Users/ayushgaur/Downloads/HW8_files (1)/shapes.py", line 18, in iadd self.x = self.x + other.x AttributeError: 'Circle' object has no attribute 'x

有人知道为什么会这样吗？在

Answer 1

class Circle(Point):表示类Circle是从类Point继承而来的，因此Point的函数{}。我不明白您为什么要从Point继承Circle。

我建议删除继承，即简单地使用class Circle:并为circle定义一个函数__iadd__，这个函数定义了circle1 += circle2的功能。

Answer 2

Circle继承了Point的__iadd__()方法，在调用+=时使用。

您可能希望重写__iadd__()方法：

def __iadd__(self, other):
    return self.add(self, other)