《python编程从入门到实践》十二章12.6

#game_functions.py
import sys
import pygame

def check_events(ship):
for event in pygame.event.get():
if event.type == pygame.QUIT:
sys.exit()

elif event.type == pygame.KEYDOWN:
if event.key == pygame.K_LEFT:
ship.moving_left = True
elif event.key == pygame.K_RIGHT:
ship.moving_right = True

elif event.type == pygame.KEYUP:
if event.key == pygame.K_LEFT:
ship.moving_left = False
elif event.key == pygame.K_RIGHT:
ship.moving_right = False

def update_screen(screen, ai_settings, ship):
screen.fill(ai_settings.bg_color)
ship.update()
ship.blitme()
pygame.display.flip()

#settings.py
import pygame

class Settings():
def __init__(self):
self.screen_width = 1200
self.screen_height = 800
self.bg_color = (230,230,230)

#ship.py
import pygame

class Ship():
"""创建ship类"""
def __init__(self, screen):
self.screen = screen
self.image = pygame.image.load("images/ship.bmp")
self.rect = self.image.get_rect()
self.screen_rect = self.screen.get_rect()

#设置飞船的位置
self.rect.centerx = self.screen_rect.centerx
self.rect.bottom = self.screen_rect.bottom

#左右移动标志量
self.moving_left = False
self.moving_right = False

def update(self):
if self.moving_left:
self.rect.centerx -= 1
if self.moving_right:
self.rect.centerx += 1

def blitme(self):
self.screen.blit(self.image, self.rect)

#主程序
import sys

import pygame

from settings import Settings
from ship import Ship

import game_functions as gf

def run_game():
pygame.init()
ai_settings = Settings()
screen = pygame.display.set_mode(
(ai_settings.screen_width,ai_settings.screen_height))
pygame.display.set_caption("Alien Invasion")

ship = Ship(screen)

while True:
gf.check_events(ship)
gf.update_screen(screen, ai_settings, ship)
run_game()

今天敲了《python编程从入门到实践》的第十二章外星人入侵，只敲到12.6，但是有一个疑问，为什么代码片game_functions.py中的check_events函数判断时候用的是，if-elif，按照自己的理解这里应该是两个if呀，但是按照书中的方法实现的又没有错。很迷惑。

def check_events(ship):
for event in pygame.event.get():
if event.type == pygame.QUIT:
sys.exit()

elif event.type == pygame.KEYDOWN:
if event.key == pygame.K_LEFT:
ship.moving_left = True
elif event.key == pygame.K_RIGHT:
ship.moving_right = True

elif event.type == pygame.KEYUP:
if event.key == pygame.K_LEFT:
ship.moving_left = False
elif event.key == pygame.K_RIGHT:
ship.moving_right = False

敲了三天这些代码，发现多敲果然非常有好处，前面看到这些代码是懵逼的，但是现在看到它们感到非常的熟悉，以后一定要多敲代码！！！！