"对象没有__dict__,因此您无法将任意属性分配给对象类的实例."

Question

来自https://docs.python.org/3.3/library/functions.html#object

object没有__dict__,所以你不能将任意属性分配给object类的实例.

为什么" object没有__dict__"？这个对我有用

>>> object.__dict__
mappingproxy({'__repr__': <slot wrapper '__repr__' of 'object' objects>, '__hash__': <slot wrapper '__hash__' of 'object' objects>, '__subclasshook__': <method '__subclasshook__' of 'object' objects>, '__ne__': <slot wrapper '__ne__' of 'object' objects>, '__format__': <method '__format__' of 'object' objects>, '__new__': <built-in method __new__ of type object at 0xa3dc20>, '__doc__': 'The most base type', '__class__': <attribute '__class__' of 'object' objects>, '__dir__': <method '__dir__' of 'object' objects>, '__delattr__': <slot wrapper '__delattr__' of 'object' objects>, '__getattribute__': <slot wrapper '__getattribute__' of 'object' objects>, '__le__': <slot wrapper '__le__' of 'object' objects>, '__init__': <slot wrapper '__init__' of 'object' objects>, '__gt__': <slot wrapper '__gt__' of 'object' objects>, '__ge__': <slot wrapper '__ge__' of 'object' objects>, '__eq__': <slot wrapper '__eq__' of 'object' objects>, '__reduce__': <method '__reduce__' of 'object' objects>, '__lt__': <slot wrapper '__lt__' of 'object' objects>, '__str__': <slot wrapper '__str__' of 'object' objects>, '__reduce_ex__': <method '__reduce_ex__' of 'object' objects>, '__sizeof__': <method '__sizeof__' of 'object' objects>, '__setattr__': <slot wrapper '__setattr__' of 'object' objects>})

为什么"你不能将任意属性分配给object类的实例"？

Answer 1

您__dict__将类型与实例上的属性混淆.object() 实例没有__dict__属性:

 >>> object().__dict__
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'object' object has no attribute '__dict__'

请注意,__dict__自定义Python类实例的属性是描述符 ; 实例本身没有属性,它是提供它的类(因此type(instance).__dict__['__dict__'].__get__(instance)返回).object.__dict__可能存在,但object.__dict__['__dict__']不存在.

object()不支持实例属性,因为它是所有自定义Python类的基础,它们必须支持__dict__在定义槽时不具有属性.