如何在类内部自定义并使用装饰器？

问题描述：

想在类内部自定义装饰器log_transaction用来记录用户交易详情，但无法用@staticmethod和@classmethod修饰它，也不能让其作为普通方法，再作为装饰器调用

请问如何正确地在类内部自定义装饰器？

以下代码为何报错？

相关代码：

1.不用@staticmethod和@classmethod

class FundingManagement(object):
    def __init__(self, initial_funding):
        self.__funding = initial_funding

    def log_transaction(self, func):
        def inner(*args, **kwargs):
            t = Transaction()
            t.balance = func(*args, **kwargs)
            t.date = datetime.datetime.now().strftime('%Y-%m-%d')
            if func.__name__ == 'deposit':
                t.kind = '存款'
            elif func.__name__ == 'withdrawal':
                t.kind = '取款'
            elif func.__name__ == 'transfer':
                t.kind = '网转'
            t.value = args[1]
            t.currency = '人民币'
            t.print_transaction_details()
            return

        return inner

    @log_transaction
    def deposit(self, value):
        self.__funding += value
        return self.__funding

    @log_transaction
    def withdrawal(self, value):
        self.__funding -= value
        return self.__funding

    @log_transaction
    def transfer(self, value):
        self.__funding += value
        return self.__funding

相关截图：

相关代码：

2.使用@classmethod

class FundingManagement(object):
    def __init__(self, initial_funding):
        self.__funding = initial_funding

    @classmethod
    def log_transaction(cls, func):
        def inner(*args, **kwargs):
            t = Transaction()
            t.balance = func(*args, **kwargs)
            t.date = datetime.datetime.now().strftime('%Y-%m-%d')
            if func.__name__ == 'deposit':
                t.kind = '存款'
            elif func.__name__ == 'withdrawal':
                t.kind = '取款'
            elif func.__name__ == 'transfer':
                t.kind = '网转'
            t.value = args[1]
            t.currency = '人民币'
            t.print_transaction_details()
            return

        return inner

    @log_transaction
    def deposit(self, value):
        self.__funding += value
        return self.__funding

    @log_transaction
    def withdrawal(self, value):
        self.__funding -= value
        return self.__funding

    @log_transaction
    def transfer(self, value):
        self.__funding += value
        return self.__funding

相关截图：

相关代码：

2.使用@staticmethod

class FundingManagement(object):
    def __init__(self, initial_funding):
        self.__funding = initial_funding

    @staticmethod
    def log_transaction(func):
        def inner(*args, **kwargs):
            t = Transaction()
            t.balance = func(*args, **kwargs)
            t.date = datetime.datetime.now().strftime('%Y-%m-%d')
            if func.__name__ == 'deposit':
                t.kind = '存款'
            elif func.__name__ == 'withdrawal':
                t.kind = '取款'
            elif func.__name__ == 'transfer':
                t.kind = '网转'
            t.value = args[1]
            t.currency = '人民币'
            t.print_transaction_details()
            return

        return inner

    @log_transaction
    def deposit(self, value):
        self.__funding += value
        return self.__funding

    @log_transaction
    def withdrawal(self, value):
        self.__funding -= value
        return self.__funding

    @log_transaction
    def transfer(self, value):
        self.__funding += value
        return self.__funding

相关截图：

尝试过的解决方式：

在FundingManagerment类外创建了Log类，将log_transaction作为Log类的静态函数

在FundingManagerment类中使用@Log.log_transaction修饰那几个方法

这样虽然行得通，但是我认为这样破坏了封装性，自定义log_transaction的初衷就是只用来修饰FundingManagerment其他几个方法的，并不是一个通用的装饰器

相关代码：

class Log(object):

    @staticmethod
    def log_transaction(func):
        def inner(*args, **kwargs):
            t = Transaction()
            t.balance = func(*args, **kwargs)
            t.date = datetime.datetime.now().strftime('%Y-%m-%d')
            if func.__name__ == 'deposit':
                t.kind = '存款'
            elif func.__name__ == 'withdrawal':
                t.kind = '取款'
            elif func.__name__ == 'transfer':
                t.kind = '网转'
            t.value = args[1]
            t.currency = '人民币'
            t.print_transaction_details()
            return

        return inner