Python OOP：初始化BasketballPlayer对象为何需传入player_name参数？

我是一名学生开发者，正在为即将到来的测试备考。做继承与多态练习题时代码实现了预期效果，但搞不懂为什么初始化BasketballPlayer对象时必须传player_name参数，去掉就会抛出TypeError: Player.__init__() missing 1 required positional argument: 'player_name'。

Player.py 代码 #

class Player:
    def __init__(self, player_name):
        self.player_name = player_name

    def get_player_name(self):
        return self.player_name

    def set_player_name(self, player_name):
        self.player_name = player_name


class BasketballPlayer(Player):

    positions = ['Guard', 'Forward', 'Center']

    def __init__(self, player_name):
        super().__init__(player_name)
        self.player_position = None

    def get_player_position(self):
        return self.player_position

    def set_player_position(self, player_position):
        self.player_position = player_position
        if self.player_position not in BasketballPlayer.positions:
            print("Invalid position for basketball player.")
            self.player_position = ""

    def __str__(self):
        return f"{self.get_player_name()} playing as a {self.player_position}"

测试程序代码 #

from Player import *                                                                                              

List_of_players = []                                                                               
team_name = str(input("Please enter the basketball team name: "))                                 

for i in range(5):                                                                                
    player_name = str(input("Please enter player name: "))                                        
    player_position = str(input("Please enter the basketball player's position: "))                

    BasketBallPlayer_obj = BasketballPlayer(player_name)                                          

    BasketBallPlayer_obj.set_player_position(player_position)                                     
    BasketBallPlayer_obj.set_player_name(player_name)                                             

    List_of_players.append(BasketBallPlayer_obj)                                                  

print(f"Team {team_name} consists of the following players: ")                                    
for i in range(len(List_of_players)):                                                               
    print(List_of_players[i])                                                                      

原因解析 #

1. 父类构造函数的参数要求 #

父类Player的__init__方法必须接收player_name参数，用来初始化实例属性self.player_name。子类BasketballPlayer的__init__方法里通过super().__init__(player_name)主动调用了父类的构造函数，这就要求必须提供player_name参数给父类使用，否则父类的构造函数会因为缺少必要参数报错。

2. 子类构造函数的参数定义 #

你编写的BasketballPlayer类的__init__方法签名是def __init__(self, player_name):，这明确规定了创建该类对象时，必须传入player_name参数（self是Python自动传入的实例引用，不需要手动传）。如果去掉这个参数，子类的__init__就没有player_name值可以传递给父类的构造函数，必然触发参数缺失的错误。

额外优化提示 #

测试代码中，创建BasketBallPlayer_obj后调用set_player_name(player_name)是冗余操作——因为初始化对象时已经将player_name传给父类，完成了self.player_name的赋值，完全可以删掉这一行代码。

内容的提问来源于stack exchange，提问作者Joshua Long