导入自定义类后调用函数触发AttributeError：str对象无make_turn属性

尝试从另一个文件导入类和方法运行自定义函数，但无论修改前置文件，PyCharm始终返回相同错误。

代码片段 #

randomwalk.py #

import random
class Coin:
    def __init__(self):
        pass
    def flip(self):
        return random.choice(['heads', 'tails'])

class Dice:
    def __init__(self):
        pass
    def roll(self):
        return random.randint(1, 6)

class Player:
    def __init__(self):
        self.position = 0
    def update_position(self, delta):
        self.position += delta
    def make_turn(self, coin, dice):
        coin_toss = coin.flip()
        dice_roll = dice.roll()
        if coin_toss == 'heads':
            movement = 1
        else:
            movement = -1
        self.update_position(movement * dice_roll)

class Game:
    def __init__(self, player, coin, dice):
        self.player = player
        self.coin = coin
        self.dice = dice
        pass
    def play(self):
        for i in range(20):
            self.player.make_turn(self.coin, self.dice)
            return self.player.position

simulation.py #

from randomwalk import Game


def startSimulation():
    num_games = 100
    position = 0
    for i in range(num_games):
        games = Game('Alex', 'heads', 3)
        end_position = games.play()
        position += end_position

    average_position = position/num_games
    print('Average position after'+ str(num_games)+ 'games(20 moves per game) is' + str(average_position))

startSimulation()

错误信息 #

D:\Python\pythonProject\venv\Scripts\python.exe D:\Python\pythonProject\simulation.py 
Traceback (most recent call last):
  File "D:\Python\pythonProject\simulation.py", line 15, in <module>
    startSimulation()
  File "D:\Python\pythonProject\simulation.py", line 9, in startSimulation
    end_position = games.play()
                   ^^^^^^^^^^^^
  File "D:\Python\pythonProject\randomwalk.py", line 36, in play
    self.player.make_turn(self.coin, self.dice)
    ^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'str' 对象没有属性 'make_turn'

进程已结束，退出代码 1

解决方法 #

1. 错误根源
   Game类的__init__方法要求传入Player、Coin、Dice的实例对象，但你传入的是字符串'Alex'、'heads'和数字3，导致self.player被赋值为字符串，调用make_turn方法时自然会触发AttributeError——字符串没有这个方法。

2. 修正步骤

   • 首先在simulation.py中导入所有需要的类：

     from randomwalk import Game, Player, Coin, Dice
     

   • 创建对应类的实例，再传入Game的构造函数：

     player = Player()
     coin = Coin()
     dice = Dice()
     game = Game(player, coin, dice)
     

   • 另外，Game类的play方法存在逻辑错误：for循环的第一次迭代就执行了return，导致只运行1次回合而非预期的20次，需要把return移到循环外面：

     def play(self):
         for i in range(20):
             self.player.make_turn(self.coin, self.dice)
         return self.player.position
     

3. 修正后的完整代码

   修正后的simulation.py #

   from randomwalk import Game, Player, Coin, Dice
   
   
   def startSimulation():
       num_games = 100
       total_position = 0
       for i in range(num_games):
           player = Player()
           coin = Coin()
           dice = Dice()
           game = Game(player, coin, dice)
           end_position = game.play()
           total_position += end_position
   
       average_position = total_position / num_games
       print(f'Average position after {num_games} games (20 moves per game) is {average_position}')
   
   startSimulation()
   

   修正后的randomwalk.py中Game类的play方法 #

   class Game:
       def __init__(self, player, coin, dice):
           self.player = player
           self.coin = coin
           self.dice = dice
   
       def play(self):
           for i in range(20):
               self.player.make_turn(self.coin, self.dice)
           return self.player.position
   

内容的提问来源于stack exchange，提问作者Arbab Qaisar