How do I create an object that has no class in Python?

Question

I am using the object function (object()) to make an object without a class in Python but it does not have any attributes or arguments, so I am trying to customise it by creating a variable like thing = object() and then using setattr(thing, 'name', 'Marco') but it won't let me because it throws an error saying:

>>> thing = object()
>>> setattr(thing, 'name', 'nothing')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'object' object has no attribute 'name'

How do I get past this? I don't get why it does this when object can't have attributes but the object function can (object()) and then it throws AttributeError when I try to set an attribute for the object that is assigned to the variable when the whole point of using setattr() is to set attributes lol

Does this answer your question? Can't set attributes on instance of "object" class — AlexK
– AlexK, Commented Apr 14, 2021 at 0:22
Every Python object has a class. What problem are you trying to solve by creating an object without a class? — user2357112
– user2357112, Commented Apr 14, 2021 at 0:24
Why don't you create a class with the attributes you require? — Nicholas Hunter
– Nicholas Hunter, Commented Apr 14, 2021 at 0:35

ShadowRanger · Accepted Answer · 2021-04-14 00:24:28Z

4

To be clear, object() has a class (the class is object); it's impossible to have an instance without a class in Python.

That said, plain object doesn't have storage for arbitrary attributes. If you want a minimalist object that lets you make arbitrary attributes, use types.SimpleNamespace, e.g.:

import types  # At top of file

thing = types.SimpleNamespace()
setattr(thing, 'name', 'nothing')

Of course, setattr isn't necessary here since you're using known attribute names. Just use normal attribute assignment instead:

thing.name = 'nothing'

If you're really using dynamic attribute names via setattr, you're probably better off skipping attributes entirely, and just using a dict with dict lookup syntax:

thing = {}
thing['name'] = 'nothing'

answered Apr 14, 2021 at 0:24

ShadowRanger

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3 Comments

ddejohn Over a year ago

I'd never heard of SimpleNamespace before today, neat! What are the differences between a SimpleNamespace and a dataclass? Seems like they do roughly the same thing. EDIT: never mind, I found this SO post: stackoverflow.com/questions/51082418/…

Marco El-Korashy Over a year ago

@ShadowRanger Your "solution" literally involves using classes

ShadowRanger Over a year ago

@MarcoEl-Korashy: Because it's literally impossible to avoid using classes. Everything in Python is an object, and all objects are instances of a class. The answer does explain that difficulty, and it does offer solutions that uses a minimalist built-in class to avoid defining new user-defined classes (which I suspect was the OP's goal).

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