从超类通过子类的Python调用方法不能按预期工作

时间:2013-04-20 00:24:33

标签: python inheritance polymorphism pygame duck-typing

我已将pygame.Rect类扩展为Ball。当我使用nstanceOfBall.colliderect()(第66行)时,不会抛出任何错误,但它永远不会返回true。任何洞察colliderect为什么不适用于我的Ball实例?

    import sys, pygame
    import os
    import ball
    import random
    import math
    #from ball import Ball

    ###############################################################################################

    class Ball(pygame.Rect):
        def __init__(self, x, y, width, height, screenWidth, screenHeight):
            super(pygame.Rect,self).__init__(x, y, width, height)
            self.floatX=x
            self.floatY=x
            self.screenWidth=screenWidth
            self.screenHeight=screenHeight
            self.speed=[random.random()*5-2.5, random.random()*5-2.5]

        def runLogic(self):
            self.floatX+=self.speed[0]
            self.floatY+=self.speed[1]

            if self.floatX+16<0: self.floatX=self.screenWidth
            if self.floatX>self.screenWidth: self.floatX=-16
            if self.floatY+16<0: self.floatY=self.screenHeight
            if self.floatY>self.screenHeight: self.floatY=-16

            self.x=self.floatX
            self.y=self.floatY

    ###############################################################################################

    os.environ['SDL_VIDEO_WINDOW_POS'] = "%d,%d" % (700, 200)#1680,1440)

    pygame.init()

    size = width, height = 320, 240
    white = 255, 255, 255
    blue=0,0,255

    screen = pygame.display.set_mode(size)

    image = pygame.image.load("ball.png")
    ballRect=image.get_rect()
    balls = []

    for x in range(0, 100):
        balls.append(Ball(random.random()*width, random.random()*height, ballRect.width, ballRect.height, width, height))

    lastFrameStartTime=pygame.time.get_ticks()

    while 1:
        for event in pygame.event.get():
            if event.type == pygame.QUIT: 
                sys.exit()

            if event.type == pygame.KEYDOWN:
                if event.key == pygame.K_ESCAPE:
                    sys.exit()

        for ball in balls:
            ball.runLogic()

            for ball2 in balls:
                if ball != ball2:                
                    if ball.colliderect(ball2):
                        print("collision detected!")
                        balls.pop(balls.index(ball))
                        balls.pop(balls.index(ball2))
                        #balls.remove(ball2)

        screen.fill(blue)
        for ball in balls:
            screen.blit(image, ball)
        pygame.display.flip()

        pygame.time.wait(33-(pygame.time.get_ticks()-lastFrameStartTime))
        lastFrameStartTime=pygame.time.get_ticks()

在Ball.init中使用super(Ball,self)而不是super(pygame.Rect,self)就可以了。

谢谢。

1 个答案:

答案 0 :(得分:1)

super的第一个标记必须是当前的类,即Ball而不是pygame.Rect

class Ball(pygame.Rect):
    def __init__(self, x, y, width, height, screenWidth, screenHeight):
        super(Ball, self).__init__(x, y, width, height)
        ...

documentation on super中有一个例子。

super的要点是,它允许您在继承顺序中调用下一个方法,而无需显式引用父类。这在使用多重继承时很方便,参见例如super confusing python multiple inheritance super()