Python类属性访问报错AttributeError，如何跨方法访问类属性？

我是Python新手，尝试访问bank_Customer类的acnt_amount属性时触发AttributeError错误。请问如何在类的getDetails方法与withdraw方法之间访问属性？我犯了什么错误？恳请帮助，谢谢！

代码：

class bank_Customer:

    def getDetails(self, cname, acnt_no, acnt_type, acnt_amount):
        self.cname = cname
        self.acnt_no = acnt_no
        self.acnt_type = acnt_type
        self.acnt_amount = acnt_amount
        row = self.cname + "," + str(self.acnt_no) + "," + self.acnt_type + "," + str(self.acnt_amount) + "\n"
        file = open('cust_details.csv','a')
        file.write(str(row))
        file.close()
        print('*'*40)
        print("Account has been added successfully!")
        return self.acnt_amount

    def withdraw(self):
        cash = int(input("Please enter the amount to be withdrawn: "))
        self.acnt_amount = self.acnt_amount - cash
        f"balance amount is {balance}"
        return balance

base = bank_Customer()
base.withdraw()

错误信息：

Traceback (most recent call last):
  File "C:\Users\kisha\IdeaProjects\Git projects in python\ATM application.py", line 96, in <module>
    base.withdraw()
  File "C:\Users\kisha\IdeaProjects\Git projects in python\ATM application.py", line 66, in withdraw
    self.acnt_amount = self.acnt_amount - cash
AttributeError: 'bank_Customer' object has no attribute 'acnt_amount'

问题原因 #

1. 属性未初始化就访问：你创建bank_Customer对象后直接调用withdraw()，但acnt_amount属性仅在getDetails()方法中赋值，此时对象还未拥有该属性，必然触发AttributeError。
2. withdraw方法变量未定义：方法内使用的balance变量没有声明，应该用self.acnt_amount替代。

修复方案 #

方案一：先初始化属性再调用取款方法

修改主代码逻辑，先调用getDetails()完成属性初始化：

base = bank_Customer()
# 先传入客户信息初始化所有属性
base.getDetails("张三", 123456, "储蓄卡", 10000)
# 再执行取款操作
base.withdraw()

方案二：用构造方法规范初始化（更推荐）

Python类推荐用__init__构造方法初始化属性，替代自定义的getDetails，代码更符合规范：

class BankCustomer:  # 类名改用大驼峰，符合PEP8规范
    def __init__(self, cname, acnt_no, acnt_type, acnt_amount):
        self.cname = cname
        self.acnt_no = acnt_no
        self.acnt_type = acnt_type
        self.acnt_amount = acnt_amount
        self._save_to_file()
        print('*'*40)
        print("Account has been added successfully!")

    # 把文件写入逻辑抽成私有方法，职责更清晰
    def _save_to_file(self):
        row = f"{self.cname},{self.acnt_no},{self.acnt_type},{self.acnt_amount}\n"
        # 用with语句自动关闭文件，避免资源泄漏
        with open('cust_details.csv','a') as file:
            file.write(row)

    def withdraw(self):
        cash = int(input("请输入取款金额："))
        # 增加余额校验，避免出现负数
        if cash > self.acnt_amount:
            print("余额不足，无法完成取款")
            return self.acnt_amount
        self.acnt_amount -= cash
        balance = self.acnt_amount
        print(f"当前余额为：{balance}")
        return balance

# 创建对象时直接传入初始化信息
base = BankCustomer("张三", 123456, "储蓄卡", 10000)
base.withdraw()

额外提示 #

• 类名遵循PEP8规范，用大驼峰命名（如BankCustomer而非bank_Customer）。
• 文件操作优先使用with语句，自动处理文件关闭，更安全可靠。
• 取款逻辑建议增加余额校验，避免出现不合理的负数余额。

内容的提问来源于stack exchange，提问作者Kishan