為什么它一直顯示 Python 3 代碼錯誤類未定義但已定義？

Question

我收到以下錯誤消息：

Traceback (most recent call last):
  File "main.py", line 13, in <module>
    class Archer(User):
  File "main.py", line 22, in Archer
    archer1 = Archer('Joie', 100)
NameError: name 'Archer' is not defined

從這個代碼：

class User():
      def sign_in(self):
        print('logged in')
    
    class Wizard(User):
      def __init__(self, name, power):
        self.name = name 
        self.power = power
    
      def attack(self):
        print(f'attacking with power of {self.power}')
    
    class Archer(User):
      def __init__(self, name, num_arrows):
        self.name = name 
        self.num_arrows = num_arrows
    
      def attack(self):
        print(f'attacking with arrows: arrows left- {self.num_arrows}')
    
      wizard1 = Wizard('John', 50)
      archer1 = Archer('Joie', 100)
      wizard1.attack()
      archer1.attack()

為什么此時 Archer 類“未定義”？

Answer 1

與其縮進最后四行，不如讓它們像這樣：

class Archer(User):
  def __init__(self, name, num_arrows):
    self.name = name 
    self.num_arrows = num_arrows

  def attack(self):
    print(f'attacking with arrows: arrows left- {self.num_arrows}')


wizard1 = Wizard('John', 50)
archer1 = Archer('Joie', 100)
wizard1.attack()
archer1.attack()