如何访问类中的全局对象?

时间:2015-06-14 21:38:16

标签: python pygame livewires

我需要访问类中的全局对象来更改它的图像。这是代码:

import pygame
from livewires import games
from livewires import color
import time
import random

games.init(screen_width = 640, screen_height = 480, fps = 50)

class Cursor(games.Sprite):
    """The pokemon based cursor!"""

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



    def update(self):


        self.x = games.mouse.x
        self.y = games.mouse.y   
        self.check_collide()

    def check_collide(self):
        for sprite in self.overlapping_sprites:
            sprite.handle_collide()



class Play_Button(games.Sprite):
    """The 'Play' button on the menu."""

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

    def handle_collide(self):
        global play_obj

        play_image2 = games.load_image("playbtn2.png", transparent = True)
        play_obj.value = play_image2
        print("COME ON!")


class P1C_Button(games.Sprite):

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

class Logo(games.Sprite):

    def handle_collide(self):
        print("Collision ignored.")



play_image = games.load_image("playbtn.png", transparent = True)
play_obj = Play_Button(image = play_image,
                x = games.screen.width/2,
                y = games.screen.height/2)
games.screen.add(play_obj)


logo_image = games.load_image("FamilyMon.png", transparent = True)
logo_obj = Logo(image = logo_image,
                x = games.screen.width/2,
                y = 75)
games.screen.add(logo_obj)

white_image = games.load_image("white.png", transparent = False)
games.screen.background = white_image

cursor_image = games.load_image("cursor.png", transparent = True)
cursor_obj = Cursor(image = cursor_image,
                    x = games.mouse.x,
                    y = games.mouse.y)
games.screen.add(cursor_obj)
games.mouse.is_visible = False
games.screen.event_grab = True

games.screen.mainloop()

其中重要的部分是'Play_Button'的handle_collide方法。它试图访问创建的对象'play_obj',但代码似乎什么都不做。当鼠标设置的Play_Button的handle_collide什么都没有。我已经尽力了,所以如果这看起来像是一个愚蠢的问题而不是抱歉,因为我是新人。

2 个答案:

答案 0 :(得分:2)

我试图理解为什么以下列方式做这件事并不能让你满意

def handle_collide(self):
    play_image2 = games.load_image("playbtn2.png", transparent = True)
    self.value = play_image2
    print("COME ON!")

...

从我看到的情况来看,只有一个Play_Button实例,您希望在collide发生时更改其图像。

那么,为什么不使用self.value

答案 1 :(得分:2)

你不应该首先使用全局变量。

您只创建一个Play_Button对象,因此全局play_obj 始终 is self。您可以让该对象设置自己的字段:

self.value = play_image2