Yes, but A objects have no slots, no dict, do not accept attribute assignment, but are mutable.

>>> a = A()

>>> a

[]

>>> a.__slots__

()

>>> a.__dict__

Traceback (most recent call last):

File "<stdin>", line 1, in <module>

AttributeError: 'A' object has no attribute '__dict__'

>>> a.append(1)

>>> a.append(2)

>>> a

[1, 2]

2017-07-28 20:23 GMT+02:00 Mike Miller <python-ideas@mgmiller.net>:

That's a subclass. Also:

>>> class A(list): __slots__ = ()
...
>>>
>>> a = A()
>>> a.foo = 'bar'
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: 'A' object has no attribute 'foo'

-Mike

On 2017-07-28 01:06, Antoine Rozo wrote:

> If an object has no slots or dict and does not accept attribute assignment, is it not effectively immutable?

No, not necessarily.

class A(list): __slots__ = ()

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Antoine Rozo