class BankAccount:
    def __init__(self, balance):
        self._balance = balance  # 受保護(hù)屬性
        self.__secret_code = 1234  # 私有屬性

account = BankAccount(1000)
print(account.__secret_code)  # 報(bào)錯(cuò)：AttributeError
print(account._BankAccount__secret_code)  # 可以訪問，但不推薦

class Temperature:
    def __init__(self, celsius):
        self._celsius = celsius
    @property
    def celsius(self):
        """獲取攝氏溫度"""
        return self._celsius
    @celsius.setter
    def celsius(self, value):
        """設(shè)置攝氏溫度，確保不低于絕對(duì)零度"""
        if value < -273.15:
            raise ValueError("溫度不能低于絕對(duì)零度(-273.15℃)")
        self._celsius = value
    @property
    def fahrenheit(self):
        """計(jì)算并返回華氏溫度"""
        return (self._celsius * 9/5) + 32

temp = Temperature(25)
print(temp.celsius)  # 25
print(temp.fahrenheit)  # 77.0
temp.celsius = -300  # ValueError: 溫度不能低于絕對(duì)零度(-273.15℃)

class BankAccount:
    def __init__(self, account_holder, initial_balance=0):
        self.account_holder = account_holder
        self._balance = initial_balance
        self.__transaction_history = []
    @property
    def balance(self):
        """獲取當(dāng)前余額"""
        return self._balance
    def deposit(self, amount):
        """存款"""
        if amount <= 0:
            raise ValueError("存款金額必須為正數(shù)")
        self._balance += amount
        self.__record_transaction(f"存款: +{amount}")
    def withdraw(self, amount):
        """取款"""
        if amount <= 0:
            raise ValueError("取款金額必須為正數(shù)")
        if amount > self._balance:
            raise ValueError("余額不足")
        self._balance -= amount
        self.__record_transaction(f"取款: -{amount}")
    def __record_transaction(self, description):
        """私有方法：記錄交易"""
        self.__transaction_history.append(
            f"{datetime.now().isoformat()}: {description}, 余額: {self._balance}"
        )
    def get_statement(self):
        """獲取交易記錄"""
        return "\n".join(self.__transaction_history)

account = BankAccount("張三", 1000)
account.deposit(500)
account.withdraw(200)
print(account.balance)  # 1300
print(account.get_statement())