Python - 可以将相同的属性逻辑应用于多个属性吗？

Question

有没有办法将相同的属性逻辑应用于类中的一组属性？例如，我想申请相同的@attr1.setter装饰器attr2，attr3以及attr4不必定义每个属性的属性。

class Sample:

    def __init__(self):

        self.attr1 = None

        self.attr2 = None

        self.attr3 = None

        self.attr4 = None

    @property

    def attr1(self):

        return self.__attr1

    @attr1.setter

    def attr1(self, val):

        if val < 0:

            self.__attr1 = 0

        else:

            self.__attr1 = val

Answer 1

只需为此创建您自己的描述符：class MyDescriptor:&nbsp; &nbsp; def __set_name__(self, owner, name):&nbsp; &nbsp; &nbsp; &nbsp; self.name = f'_{name}'&nbsp; &nbsp; def __get__(self, instance, owner):&nbsp; &nbsp; &nbsp; &nbsp; return getattr(instance, self.name)&nbsp; &nbsp; def __set__(self, instance, val):&nbsp; &nbsp; &nbsp; &nbsp; if val is None:&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; setattr(instance, self.name, None)&nbsp; &nbsp; &nbsp; &nbsp; elif val < 0:&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; setattr(instance, self.name, 0)&nbsp; &nbsp; &nbsp; &nbsp; else:&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; setattr(instance, self.name, val)class Sample:&nbsp; &nbsp; attr1 = MyDescriptor()&nbsp; &nbsp; attr2 = MyDescriptor()&nbsp; &nbsp; attr3 = MyDescriptor()&nbsp; &nbsp; attr4 = MyDescriptor()&nbsp; &nbsp; def __init__(self):&nbsp; &nbsp; &nbsp; &nbsp; self.attr1 = None&nbsp; &nbsp; &nbsp; &nbsp; self.attr2 = None&nbsp; &nbsp; &nbsp; &nbsp; self.attr3 = None&nbsp; &nbsp; &nbsp; &nbsp; self.attr4 = None现在，在行动：In [3]: s = Sample()In [4]: s.attr1 = -99In [5]: s.attr1Out[5]: 0In [6]: s.attr2In [7]: s.attr2 = 10In [8]: s.attr2Out[8]: 10In [9]: s.attr2 = -1In [10]: s.attr2Out[10]: 0请参阅描述符 HOWTO和一些更相关的文档请注意，我None在您的 setter 逻辑中加入了可能性（您的代码会TypeError在实例初始化时引发 a ，因为 setter 检查 if None < 0）。另请注意，您可能不想使用双下划线名称修饰（这并不意味着 private），因此我使用传统的单下划线来表示不属于公共 api 的变量。使用双下划线名称修改会使这里的事情复杂化。

Answer 2

您可以覆盖__getattr__和__setattr__以按照您希望的方式行事。这样你就不需要定义任何私有变量，也不需要初始化任何成员变量。class Sample:&nbsp; &nbsp; def __getattr__(self, attr):&nbsp; &nbsp; &nbsp; &nbsp; return self.__dict__.get(attr)&nbsp; &nbsp; def __setattr__(self, attr, val):&nbsp; &nbsp; &nbsp; &nbsp; if val is not None and val < 0:&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; self.__dict__[attr] = 0&nbsp; &nbsp; &nbsp; &nbsp; else:&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; self.__dict__[attr] = vals = Sample()print(s.attr1) # Nones.attr1 = 10print(s.attr1) # 10s.attr1 = -10print(s.attr1) # 0s.attr1 = Noneprint(s.attr1) # None