python中出现TypeError: object of type 'Ship' has no len()

Question

#alien_invasion.py
import sys
import pygame
from settings import Settings
from ship import Ship
import game_functions as gf
from pygame.sprite import Group

def run_game():
    #初始化pygame。设置和屏幕对象
    pygame.init()
    ai_settings = Settings()
    screen = pygame.display.set_mode(
        (ai_settings.screen_width,ai_settings.screen_height))
    pygame.display.set_caption("Alien Invasion")


    #创建一艘飞船
    ship = Ship(ai_settings,screen)
    #创建一个用于存储子弹的编组
    bullets = Group()

    #开始游戏主循环
    while True:
        gf.check_events(ai_settings,screen,ship,bullets)
        ship.update()
        gf.update_bullets(bullets)
        #print(len(bullets))

        gf.update_screen(ai_settings,screen,ship,bullets)


run_game()

#bullet.py
import pygame
from pygame.sprite import Sprite

class Bullet(Sprite):
    """一个对飞船发射的子弹进行管理的类"""
    def __int__(self,ai_settings,screen,ship):
        """在飞船所处的位置创建一个子弹对象"""
        super().__int__()
        self.screen = screen

        #在（0，0）处创建一个表示子弹的矩形，在设置正确的位置
        self.rect = pygame.Rect(0,0,ai_settings.bullet_width,ai_settings.bullet_height)
        self.rect.centerx = ship.rect.centerx
        self.rect.top = ship.rect.top

        #存储小鼠表示的子弹位置
        self.y = float(self.rect.y)

        self.color = ai_settings.bullet_color
        self.speed_factor = ai_settings.bullet_speed_factor

    def update(self):
        """向上移动子弹"""
        #更新表示子弹位置的小数值
        self.y -= self.speed_factor
        #更新表示子弹的rect的位置
        self.rect.y = self.y

    def draw_bullet(self):
        """在屏幕上绘制子弹"""
        pygame.draw.rect(self.screen,self.color,self.rect)
        

#game_functions.py
import sys
import pygame
from bullet import Bullet

def check_keydown_events(event,ship,ai_settings,screen,bullets):
    """响应按键"""
    if event.key == pygame.K_RIGHT:
        ship.moving_right = True
    elif event.key == pygame.K_LEFT:
        ship.moving_left =True
    elif event.key == pygame.K_SPACE:
        #创建一颗新子弹，并将其加入编组bullets
        if  len(bullets) < ai_settings.bullets.bullets_allowed:
            
            new_bullet = Bullet(ai_settings,screen,ship)
            bullets.add(new_bullet)
        
def fire_bullet(ai_settings,screen,ship,bullets):
    
    if len(bullets) < ai_settings.bullets_allowed:
        new_bullet = Bullet(ai_settings,screen,ship)
        bullets.add(new_bullet)

def check_keyup_events(event,ship):
    """响应松开"""
    if event.key == pygame.K_RIGHT:
        ship.moving_right = False
    elif event.key == pygame.K_LEFT:
        ship.moving_left =False

def check_events(ship,ai_settings,bullets,screen):
    """响应按键和鼠标事件"""
    for event in pygame.event.get():
        if event.type ==pygame.QUIT:
            sys.exit()

        elif event.type ==pygame.KEYDOWN:
            check_keydown_events(event,ship,ai_settings,screen,bullets)
        elif event.type == pygame.KEYUP:
            check_keyup_events(event,ship)

def update_screen(ai_settings,screen,ship,bullets):
    """更新屏幕上的图像，并切换到新屏幕"""
    #每次循环都会重绘屏幕
    screen.fill(ai_settings.bg_color)
    #在飞船和外星人后面重绘所有子弹
    for bullet in bullets.sprites():
        bullet.draw_bullet()
    ship.blitme()
    #让最近绘制屏幕可见
    pygame.display.flip()
def update_bullets(bullets):
    """更新子弹位置，并删除已消失的子弹"""
    #更新子弹位置
    bullets.update()

        #删除消失的子弹
    for bullet in bullets.copy():
        if bullet.rect.bottom <= 0:
            bullets.remove(bullet)

#ship.py
import pygame
class Ship():
    
    def __init__(self,ai_settings,screen):
        """初始化飞船，并设置初始位置"""
        self.screen = screen
        self.ai_settings = ai_settings

        #加载飞船图像并获取外接矩形
        self.image = pygame.image.load('images/ship.bmp')
        self.rect = self.image.get_rect()
        self.screen_rect = screen.get_rect()

        #将每艘飞船放在屏幕底部
        self.rect.centerx = self.screen_rect.centerx
        self.rect.bottom = self.screen_rect.bottom

        #在飞船的属性center中存储小数值
        self.center = float(self.rect.centerx)

        #移动标志
        self.moving_right = False
        self.moving_left = False

    def update(self):
        """根据移动标志调整飞船位置"""
        #更新飞船的center值，而不是rect
        if self.moving_right and self.rect.right < self.screen_rect.right:
            self.center += self.ai_settings.ship_speed_factor

        if self.moving_left and self.rect.left > 0:
            self.center -= self.ai_settings.ship_speed_factor

        #根据self。center更新rect对象
        self.rect.centerx = self.center

    def blitme(self):
        """在指定位置绘制飞船"""
        self.screen.blit(self.image,self.rect)
        

#settings.py
class Settings():
    """docstring for settings"""
    def __init__(self):
        """初始化游戏设置"""
        #屏幕设置
        self.screen_width = 1200
        self.screen_height = 700
        self.bg_color = (230,230,230)    

        #飞船的设置
        self.ship_speed_factor = 1.5    

        #子弹设置
        self.bullet_speed_factor = 1
        self.bullet_width = 3
        self.bullet_height =15
        self.bullet_color = (60,60,60)
        self.bullets_allowed = 3

Answer 1

参数没对齐，函数定义的时候是这样定义的：

def check_events(ship,ai_settings,bullets,screen):

但调用的时候是这样调用的：

gf.check_events(ai_settings,screen,ship,bullets)

Answer 2

这种一般是Ship返回了None值，而None是没有len（）方法的。你应该检查Ship是否正确返回了