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python - Python 中的 OOP。我如何做类方法？

问题描述

我正在尝试做一个程序（针对家庭作业问题），它可以创建不同的帐户并允许您从中存款/取款。当使用 Account.totalAllBalance 提示时，我还应该显示所有帐户的余额。一切都很顺利，但我想弄清楚如何将起始余额添加到我的 totalAllBalance 总数中。我不断收到这个错误，我不知道为什么。我对编程很陌生，我应该使用我们在课堂上做的非常基本的编程。我的问题是为什么我会收到这个错误，我该如何解决？

错误在第 20 行，它说

在init Account.totalAllBalance = Account.totalAllBalance + num TypeError: +: 'method' 和 'int' 不支持的操作数类型

这是我迄今为止的尝试：

class Account:
    totalAllBalance = 0
    totalAccounts = 0

    def __init__(self, name, startBalance):
        self.name = name
        self.startBalance = startBalance
        num = startBalance
        if self.startBalance < .01:
            print("You may not start an account with that balance.")
        else :
            self.deposits = 0
            self.withdraws = 0
            Account.totalAccounts += 1
            if Account.totalAccounts is 1:
                Account.totalBalance = 0
            else:
               Account.totalAllBalance = Account.totalAllBalance + num

    def deposit(self, num):
        self.deposits += num
        print(self.name, "has deposited", num, "dollars.")
        Account.totalAllBalance = Account.totalAllBalance + num
        return(self.totalBalance())


    def withdraw(self, num):
        self.withdraws += num 
        if num > self.startBalance + -1*(self.withdraws-num) + self.deposits:
            print("You may not withdraw more than your balance.")
            self.withdraws -= num
        else:  
            num2= -1 * num
            print(self.name, "has withdrawn", num,"dollars.")
            return(self.totalBalance())
        Account.totalAllBalance = Account.totalAllBalance + num2

    def totalBalance(self):
        if self.withdraws is None:
            W = 0
        if self.deposits is None:
            D = 0
        S = self.startBalance 
        W = self.withdraws * -1 
        D = self.deposits
        num = S + W + D
        print(self.name,"has", S + W + D , "dollars in their account.")

    @classmethod
    def totalAllBalance(cls):
        print(cls.totalAllBalance)

    @classmethod
    def amtAccounts(cls):
        print("There is", cls.totalAccounts, "account(s).")

标签： pythonoop

解决方案

原因是因为您totalAllBalance同时拥有类方法和类属性。除此之外，您访问的方式Account.totalAllBalance使编译器解释为方法而不是属性。我建议改为使用self.totalAllBalance并为您的类方法使用不同的名称（例如printTotalAllBalance）

def deposit(self, num):
    self.deposits += num
    print(self.name, "has deposited", num, "dollars.")
    self.totalAllBalance = self.totalAllBalance + num
    return(self.totalBalance())

@classmethod
def printTotalAllBalance(cls):
    print(cls.totalAllBalance)

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