python編程從入門到實踐p221頁，浮點報錯的問題

ship.py的__init()__寫變量少了。改爲

def __init__(self,ai_settings,screen):

以下爲截止到python編程從入門到實踐p221頁，浮點移動的程序

ship.py

import pygame
class Ship():
	def __init__(self,ai_settings,screen):
		self.screen = screen
		self.ai_settings = ai_settings
		#加載飛船圖像
		self.image = pygame.image.load("images/ship.bmp")
		#獲取飛船的屬性rect
		self.rect = self.image.get_rect()
		self.screen_rect = screen.get_rect()
		#讓遊戲元素居中，設置相應rect對象的center,centerx,centery.
		self.rect.centerx = self.screen_rect.centerx
		#讓遊戲元素與邊緣對齊，top,bottom,left,right.
		self.rect.bottom = self.screen_rect.bottom
		self.center = float(self.rect.centerx)
		#移動標誌
		self.moving_right = False
		self.moving_left = False

	def update(self):
		"""根據移動標誌調整飛船的位置，可以連續移動"""
		if self.moving_right:
			#讓遊戲元素居中，設置相應rect對象的center,centerx,centery.
			self.center += self.ai_settings.ship_speed_factor

		if self.moving_left:
			self.center -= self.ai_settings.ship_speed_factor
		
		self.rect.centerx = self.center

	def blitme(self):
		#將飛船的圖像繪製到屏幕上
		self.screen.blit(self.image,self.rect)

settings.py，在這裏有個self.ship_speed_factor = 1.5

class Settings():
	"""存儲設置的類"""
	def __init__(self):
		"""初始化遊戲設置"""
		#屏幕的設置
		self.screen_width = 800
		self.screen_height = 600
		self.bg_color = (230,230,230)

		#飛船的設置
		self.ship_speed_factor = 1.5
		

game_functions.py

import sys
import pygame
def check_events(ship):
	"""響應鼠標事件"""
	#監聽鍵盤鼠標事件
	for event in pygame.event.get():#鍵盤鼠標事件
		if event.type == pygame.QUIT:#注意 == 兩個等號
			sys.exit()

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

			if event.key == pygame.K_LEFT:
				ship.moving_left = True

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

			if event.key == pygame.K_LEFT:
				ship.moving_left = False
				
def update_screen(ai_settings,screen,ship):
	"""更新圖像"""
	#用背景色填充屏幕
	screen.fill(ai_settings.bg_color)	
	#將飛船的圖像繪製到屏幕上
	ship.blitme()
	#在while裏面一直刷新屏幕,這一條程序放到最下面
	pygame.display.flip()

alien_invasion.py

import sys
import pygame
from settings import Settings
from ship import Ship
import game_functions as gf #as是別名
def run_game():
	#初始化遊戲
	pygame.init()#這個是pygame的初始化
	pygame.display.set_caption("飛機大戰")
	ai_settings = Settings()
	#創建屏幕對象
	screen = pygame.display.set_mode([ai_settings.screen_width,ai_settings.screen_height])
	#創建一艘飛船
	ship = Ship(ai_settings,screen)
	#遊戲的主循環
	while True:#注意True首字母大寫
		#監聽鍵盤鼠標事件
		gf.check_events(ship)
		ship.update()

		gf.update_screen(ai_settings,screen,ship)

run_game()

將settings.py中的 self.ship_speed_factor = 5.5，速度就很明顯了！