Python3.Descriptor.Class

Question

你好，我有个简单的任务，但我又卡住了：

如何将变量从类使用为描述符？

我有来自父类的commission变量，在调用set：self.amount = int(amount) * int(commission)时，我需要将它用作描述符

我该怎么做？

谢谢!

完整代码如下：

class Value():
    def __init__(self):

        return

    def __get__(self, obj, obj_type):
        return self.amount

    def __set__(self, obj, amount, commission):
        self.amount = int(amount) * int(commission)


class Account:

    def __init__(self, commission):
        self.commission = commission

    amount = Value(self.commission)

new_account = Account(0.1)
new_account.amount = 100

print(new_account.amount)

Answer 1

正确的代码如下：

class Value():
    def __init__(self):
        return

    def __get__(self, obj, obj_type):
        return self.value

    def __set__(self, obj, value):
        self.value = value * (1 - obj.commission)


class Account:
    amount = Value()

    def __init__(self, commission):
        self.commission = commission


new_account = Account(0.1)
new_account.amount = 100

print(new_account.amount)

诀窍是，当您在描述符上调用__set__时，在里面传递obj，并且可以像往常一样调用任何变量或方法( obj.xxx )，这是基本的，但我确实是OOP的新手。