How to get value of variable from inside of class in Python?

Question

So, im writing some simple code in python pygame, just to learn. I encountered problem, when i want to check collisions of ball whether it is the same as y possition of my pallete. The main problem is that the value of variable of my pallete is updating by the user, and it sits inside class pallete, in function move. How can i get it out and put it outside class, into function holding ball?

import pygame
from pygame.constants import DROPTEXT
pygame.init()
#window
w_width = 1000
w_height = 600
screen = pygame.display.set_mode((w_width, w_height))
clock = pygame.time.Clock()
open = True
#player
x,y = 100,250
#define player action variables
speed = 5
speed_x,speed_y = 5,4
moving_down = False
moving_up = False
#define ball action variables
x_ball,y_ball = 500,250
radius = 30
class palette(pygame.sprite.Sprite):
    global x,y

    def __init__(self, x, y, speed):
        self.speed = speed
        pygame.sprite.Sprite.__init__(self)
        self.player_rect = pygame.Rect(x,y,30,100)

    def draw(self):
        pygame.draw.rect(screen, 'White', self.player_rect)

    def move(self, moving_up, moving_down):
        #reset movement variables
        global dy
        dy = 0

        #assing movement variables if moving up or down
        if moving_up:
            dy = -self.speed
        if moving_down:
            dy = self.speed

        #update pallete possition
        self.player_rect.y += dy
        
def ball():
    global speed_x,speed_y,x_ball,y_ball
    #update pos of bal
    x_ball += speed_x
    y_ball += speed_y
    #basic colision with screen
    if x_ball>=w_width-(0.5*radius) or x_ball <=0+(0.5*radius):
        speed_x*=-1
    if y_ball>=w_height-(0.5*radius) or y_ball <=0+(0.5*radius):
        speed_y*=-1
    #collision with pallettes

    pygame.draw.circle(screen, (255,255,255), (x_ball,y_ball), radius, 5)

#build players and enemies
player = palette(x,y, speed)
enemy = palette(x*9,y, speed)
#game
while open:
    for event in pygame.event.get():
        #quit game
        if event.type == pygame.QUIT:
            open = False
        #keyboard presses
        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_w:
                moving_up = True
            if event.key == pygame.K_s:
                moving_down = True
            if event.key == pygame.K_ESCAPE:
                open = False
        #keyboard button released
        if event.type == pygame.KEYUP:
            if event.key == pygame.K_w:
                moving_up = False
            if event.key == pygame.K_s:
                moving_down = False
    
    screen.fill((0,0,0))
    clock.tick(60)
    pygame.display.flip


    #keys


    #init players
    player.draw()
    enemy.draw()
    enemy.move(moving_up, moving_down)
    player.move(moving_up, moving_down)
    ball()

    pygame.display.update()

Rabbid76 · Accepted Answer · 2021-12-13 20:12:24Z

Read about Classes and Instance Objects. The "variables" in a class are called "attributes". You can access the instance attributes through the instance object. In your case player and enemy are instances of the class palette. The palette class has a player_rect attribute which is a pygame.Rect object. Therefore:

y = player.pylyer_rect.y

However read the documentation. pygame.sprite.Group.draw() and pygame.sprite.Group.update() are methods which are provided by pygame.sprite.Group.

The latter delegates to the update method of the contained pygame.sprite.Sprites — you have to implement the method. See pygame.sprite.Group.update():

Calls the update() method on all Sprites in the Group. [...]

The former uses the image and rect attributes of the contained pygame.sprite.Sprites to draw the objects — you have to ensure that the pygame.sprite.Sprites have the required attributes. See pygame.sprite.Group.draw():

Draws the contained Sprites to the Surface argument. This uses the Sprite.image attribute for the source surface, and Sprite.rect. [...]

So you should rename player_rect to rect. Class Names should normally use the CapWords convention. So rename palette in Palette:

class Palette(pygame.sprite.Sprite):
    def __init__(self, x, y, speed):
        self.speed = speed
        pygame.sprite.Sprite.__init__(self)
        self.rect = pygame.Rect(x,y,30,100)

    # [...]

player = Palette(x, y, speed)
enemy = Palette(x*9, y, speed)

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