在定义的类中使用方法答案

【问题标题】：Using Methods in a Defined Class在定义的类中使用方法
【发布时间】：2015-04-01 21:03:58
【问题描述】：

我正在尝试制作一个脚本，我应该在其中制作一个 Dot 类，它采用 X 位置、Y 位置和颜色。我已经制作了课程和所有的方法。我遇到的问题是如何应用该方法。这是我所做的：

class Dot:
    '''A class that stores information about a dot on a flat grid
       attributes: X (int) Y (int), C (str)'''

    def __init__(self, xposition, yposition, color):
        '''xposition represents the x cooridinate, yposition represents
           y coordinate and color represent the color of the dot'''
        self.X = xposition
        self.Y = yposition
        self.C = color


    def __str__(self):
        "Creates a string for appropiate display to represent a point"
        return str(self.X) + " " + str(self.Y) + " " + str(self.C)

    def move_up(self,number):
        '''Takes an integer and modifies the point by adding the given
           number to the x-coordinate
           attributes: number (int)'''

        self.Y = number + self.Y

    def move_right(self,number):
        '''Takes an integer and modifies the Point by adding the given number to the y-coordinate
           attributes: number (int)'''

        self.X = number + self.X

    def distance_to(point2):
        '''Takes another Dot and returns the distance to that second Dot
           attributes: X (int) Y (int)'''

        distance = ((self.X - point2.X )**2) + ((self.Y - point2.Y)**2)
        real_distance = distance.sqrt(2)

        return real_distance



point1 = (2,3,"red")
print("Creates a" + " " + str(point1[2]) + " " + "dot with coordinates (" + str(point1[0]) + "," + str(point1[1]) + ")")
point2 = (1,2,"blue")
print("Creates a" + " " + str(point2[2]) + " " + "dot with coordinates (" + str(point2[0]) + "," + str(point2[1]) + ")")
new_point = point1.move_up(3)
print("Moves point up three on the y axis")

这是返回的内容：

AttributeError: 'tuple' object has no attribute 'move_up'

【问题讨论】：

我想我们在同一个班级，我遇到了和你一样的问题……他们的答案解决了问题吗？因为他们没有修好我的
@JaredBanton 那你为什么不问你自己的问题呢？

标签： python class methods

【解决方案1】：

您永远不会实例化 Dot 对象，您会创建一个包含 3 个元素的元组。将其更改为：

point1 = Dot(2,3,"red")
point2 = Dot(1,2,"blue")

而不是

print("Creates a" + " " + str(point1[2]) + " " + "dot with coordinates (" + str(point1[0]) + "," + str(point1[1]) + ")")

使用

print "Creates a" + " " + point1.C + " " + "dot with coordinates (" + str(point1.X) + "," + str(point1.Y) + ")"

顺便说一句，.format() 的语法更清晰：

print "Creates a {0} dot with coordinates ({1}, {2})".format(point1.C, point1.X, point1.Y)

【讨论】：

当我将脚本更改为您的脚本时，我收到一个类型错误“点”对象不支持索引。知道为什么会这样吗？

【解决方案2】：

您的代码：

point1 = (2,3,"red")

不创建 Dot 类的实例 - 它只是创建一个 tuple。

要创建一个点，你必须调用它的构造函数（__init__），即：

point1 = Dot(2,3,"red")

【讨论】：