Why does it throw an error File "obrazew.py", line 41, in update if not (jump): UnboundLocalError: local variable 'jump' referenced before assignment?

Question

Python

import pygame

WIDTH = 1280
HEIGHT = 700
FPS = 60
jump = False
jumpcount = 10
# Задаем цвета
WHITE = (255, 255, 255)
BLACK = (0, 0, 0)
RED = (255, 0, 0)
GREEN = (0, 255, 0)
BLUE = (0, 0, 255)
YELLOW = (255, 255, 0)

# Создаем игру и окно
pygame.init()
pygame.mixer.init()
screen = pygame.display.set_mode((WIDTH, HEIGHT))
pygame.display.set_caption("Game!")
clock = pygame.time.Clock()

class Player(pygame.sprite.Sprite):
    def __init__(self):
        pygame.sprite.Sprite.__init__(self)
        self.image = pygame.Surface((50, 40))
        self.image.fill(GREEN)
        self.rect = self.image.get_rect()
        self.rect.centerx = WIDTH / 2
        self.rect.bottom = HEIGHT - 10
        self.speedx = 0

    def update(self):
        self.speedx = 0
        keystate = pygame.key.get_pressed()
        if keystate[pygame.K_LEFT]:
            self.speedx = -5
        if keystate[pygame.K_RIGHT]:
            self.speedx = 5
        if not (jump):
            if keystate[pygame.K_SPACE]:
                jump = True
        else:
            if jumpcount>= -10:
                if jumpcount < 0:
                    y+= (jumpcount ** 2) / 2
                else:
                    y-= (jumpcount ** 2) / 2
                jumpcount -= 1
            else:
                jump = False
                jumpcount = 10

        self.rect.x += self.speedx
        if self.rect.right > WIDTH:
            self.rect.right = WIDTH
        if self.rect.left < 0:
            self.rect.left = 0

all_sprites = pygame.sprite.Group() 
player = Player()
all_sprites.add(player)

# Цикл игры
running = True
while running:
    # Держим цикл на правильной скорости
    clock.tick(FPS)
    # Ввод процесса (события)
    for event in pygame.event.get():
        # проверка для закрытия окна
        if event.type == pygame.QUIT:
            running = False

    # Обновление
    all_sprites.update()
    
    # Рендеринг
    screen.fill(BLACK)
    all_sprites.draw(screen)
    # После отрисовки всего, переворачиваем экран
    pygame.display.flip()

pygame.quit()

gives the following error:
File "obrazew.py", line 41, in update
if not (jump):
UnboundLocalError: local variable 'jump' referenced before assignment

Explain why?

Answer 1

Because you don’t need to use global variables like that, why do you need them when you have an object where you can store all states.