为什么它说我的实例没有属性 x？

Question

我在 python 中定义了以下类：

class ArcherDown:
    def draw(self, x, y, direction):
        self.x = x
        self.y = y
    def move(self, newx, newy, direction):
        self.x+=newx
        self.y+=newy
        self.draw(self.x, self.y, direction)
    def shoot(self, x, y):
        print 'Shot!'

    def remove(self, x, y):
        pass

class Archer:
    def draw(self, x, y, direction):
        self.x = x
        self.y = y

    def move(self, newx, newy, direction):
        self.x+=newx
        self.y+=newy
        self.draw(self.x, self.y, direction)

    def shoot(self, x, y):
        print 'Shot!'

    def remove(self, x, y):
        pass

我这样称呼它们：

myarcher = Archer()
if pygame.mouse.get_pos()[1] > myarcher.y:
    myarcher = ArcherDown()
else:
    myarcher = Archer()

myarcher.draw(myarcher.x, myarcher.y, 'right')

但是，这会引发错误：

Traceback (most recent call last):
  File "game.py", line 7, in <module>
    myarcher.draw(myarcher.x, myarcher.y, direction)
AttributeError: ArcherDown instance has no attribute 'x'

这只会为ArcherDown() 提供错误，而不是Archer()。知道为什么吗？

另外，当我添加__init__ 如下：

class ArcherDown:
    def __init__(self):
        self.x = 100
        self.y = 100
    def draw(self, x, y, direction):
        self.x = x
        self.y = y
    def move(self, newx, newy, direction):
        self.x+=newx
        self.y+=newy
        self.draw(self.x, self.y, direction)
    def shoot(self, x, y):
        print 'Shot!'

    def remove(self, x, y):
        pass

class Archer:
    def draw(self, x, y, direction):
        self.x = x
        self.y = y

    def move(self, newx, newy, direction):
        self.x+=newx
        self.y+=newy
        self.draw(self.x, self.y, direction)

    def shoot(self, x, y):
        print 'Shot!'

    def remove(self, x, y):
        pass

self.x 始终是100，这是我不想要的。

我知道x 没有在ArcherDown() 中定义，但为什么它在Archer() 中工作？

Answer 1

这是因为您从未在ArcherDown 或Archer 中为x 和y 设置初始值。您可以通过添加诸如

之类的方法来解决此问题

def __init__(self, x, y):
  self.x = x
  self.y = y

每个班级。