设置属性时Python AttributeError

发布于 2025-01-20 15:50:32 字数 1057 浏览 0 评论 0原文

我正在使用Pygame创建一个蛇克隆，并且遇到了一个奇怪的问题。我有一个名为snake_tile的类，它从pygame矩形类继承，带有一个附加属性，瓷砖正在移动的方向：

import pygame

class snake_tile(pygame.Rect):
    def __init__(self, left, top, width, height, direction):
        super().__init__(left, top, width, height)
        self.direction = direction

我在初始化snake_tile对象时将元组作为方向传递为方向：

snake_head = snake_tile(snake_tile_x, snake_tile_y, 10, 10, (0,0))

当我移动瓷砖时，它将用作偏移量稍后，随着pygame.rect.move（）函数的x和y偏移量：

snake_head = snake_head.move(snake_head.direction[0], snake_head.direction[1])

但是，当我尝试像上面一样移动瓷砖时，我会遇到此错误：

AttributeError: 'snake_tile' object has no attribute 'direction'

但是当我尝试这样的事情时：

print(snake_head.direction)
snake_head = snake_head.move(snake_head.direction[0], snake_head.direction[1])

我得到输出：

(0, 0)
AttributeError: 'snake_tile' object has no attribute 'direction'

因此，似乎正确设置了方向属性，但是当我尝试访问时，再次移动蛇头时，我会得到属性错误。

有什么想法吗？

原文

I am creating a snake clone using pygame and I am running into a strange problem. I have a class called snake_tile that inherits from the pygame rectangle class with one additional attribute, the direction the tile is moving:

import pygame

class snake_tile(pygame.Rect):
    def __init__(self, left, top, width, height, direction):
        super().__init__(left, top, width, height)
        self.direction = direction

I pass in a tuple as the direction when initializing the snake_tile object:

snake_head = snake_tile(snake_tile_x, snake_tile_y, 10, 10, (0,0))

Which will serve as the offset when I move the tile later on, as the pygame.Rect.move() function takes in an x and y offset:

snake_head = snake_head.move(snake_head.direction[0], snake_head.direction[1])

However, when I attempt to move the tile like above I get this error:

AttributeError: 'snake_tile' object has no attribute 'direction'

But when I try something like this:

print(snake_head.direction)
snake_head = snake_head.move(snake_head.direction[0], snake_head.direction[1])

I get the output:

(0, 0)
AttributeError: 'snake_tile' object has no attribute 'direction'

So it seems as though the direction attribute is correctly being set, but when I try to access is again to move the snake head I get an attribute error.

Any ideas?

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眼泪也成诗 2025-01-27 15:50:32

pygame.Rect.move不更改到位的矩形对象：它创建一个新对象并返回该新实例。

尽管它具有继承功能：IE返回任何子类的新实例，而不是普通的rect，但它不会在其上设置.Direction属性。

您的工作就像在子类中设置方向属性一样简单。

class snake_tile(pygame.Rect):
    def __init__(self, left, top, width, height, direction):
        super().__init__(left, top, width, height)
        self.direction = direction

    def move(self, *args, **kw):
        new_instance = super().move(*args, **kw) # we don't care which arguments are passed
        new_instance.direction = self.direction
        return new_instance

pygame.Rect.move does not change the rectangle object in place: it creates a new object and returns that new instance.

Although it plays well with inheritance: i.e. it returns a new instance of any subclass, and not a plain Rect, it won't set the .direction attribute on it.

Your work around is as simple as setting the direction attribute in your subclass' .move method:

class snake_tile(pygame.Rect):
    def __init__(self, left, top, width, height, direction):
        super().__init__(left, top, width, height)
        self.direction = direction

    def move(self, *args, **kw):
        new_instance = super().move(*args, **kw) # we don't care which arguments are passed
        new_instance.direction = self.direction
        return new_instance

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