局部变量可能在赋值之前被引用-Python

Question

我一直在尝试做一个加密和解密系统，但我遇到了一个小错误。这是我的代码：

    import sys
    import pyperclip


    def copy(data):
        question = input("Copy to clipboard? ")

        if question.lower() == 'yes' or question.lower() == 'y':
            pyperclip.copy(data)
            print("Encrypted message copied to clipboard.")
            rerun()

        elif question.lower() == 'no' or question.lower() == 'n':
            rerun()

        else:
            print("You did not enter a valid input.")
            copy(data)


    def rerun():
        ask = input("\nWould you like to run this program again? ")

        if ask.lower() == "yes" or ask.lower() == "y":
            print(" ")
            run()

        elif ask.lower() == 'no' or ask.lower() == 'n':
            sys.exit("\nThank you!")

        else:
            print("You did not enter a valid input.")
            rerun()


    def encrypt(key, msg):
        encrypted_message = []
        for i, c in enumerate(msg):
            key_c = ord(key[i % len(key)])
            msg_c = ord(c)
            encrypted_message.append(chr((msg_c + key_c) % 127))
        return ''.join(encrypted_message)


    def decrypt(key, encrypted):
        msg = []
        for i, c in enumerate(encrypted):
            key_c = ord(key[i % len(key)])
            enc_c = ord(c)
            msg.append(chr((enc_c - key_c) % 127))
        return ''.join(msg)


    def run():
        function_type = input("Would you like to encrypt or decrypt a message? ")

        if function_type.lower() == "encrypt" or function_type.lower() == "e":
            key = input("\nKey: ")
            msg = input("Message: ")
            data = encrypt(key, msg)
            enc_message = "\nYour encrypted message is: " + data
            print(enc_message)
            copy(data)

        elif function_type.lower() == "decrypt" or function_type.lower() == "d":
            key = input("\nKey: ")

            question = input("Paste encrypted message from clipboard? ")

            if question.lower() == 'yes' or question.lower() == 'y':
                encrypted = pyperclip.paste()
                print("Message: " + encrypted)

            elif question.lower() == 'no' or question.lower() == 'n':
                encrypted = input("Message: ")

            else:
                print("You did not enter a valid input.")
                run()

            decrypted = decrypt(key, encrypted)
            decrypted_message = "\nYour decrypted message is: " + decrypted
            print(decrypted_message)
            copy(decrypted)

        else:
            print("\nYou did not enter a valid input.\n")
            run()

    run()

它说局部变量“encrypted”可能在赋值之前被引用并突出显示

    decrypted = decrypt(key, encrypted)

在run（）函数下。

是因为我在其他函数中使用了“encrypted”变量吗？如果是这样，我该如何解决这个问题，并仍然保持我的程序的功能？

我对python比较陌生，所以如果您能解释一下您的答案，我将不胜感激。

Answer 1

在run()之前添加encrypted = None

Answer 2

如果执行else分支，则不定义encrypted。IDE不知道您再次调用run()。

请记住，这可能会导致无限递归，因此您应该使用另一个控制流机制（尝试使用while循环，该循环在输入有效时中断）

Answer 3

local variable 'encrypted' might be referenced before assignment

是由绒布生成的警告。

这是因为linter看到encrypted在两个if条件内被赋值

 if question.lower() == 'yes' or question.lower() == 'y':

以及

elif question.lower() == 'no' or question.lower() == 'n':

但是，如果这两个条件是互补的，那么棉绒就不能知道这两个条件是互补的。因此，考虑到没有一个条件为真的情况，变量encrypted将最终未初始化。

若要消除此警告，只需在使用None值的任何if条件之前初始化变量