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Comment by notpushkin | Hacker News Reader

> something you (or your very clever coworker) can circumvent by using object.__setattr__()

This fits pretty well with a lot of other stuff in Python (e.g. there’s no real private members in classes). There’s a bunch of escape hatches that you should avoid (but that can still be useful sometimes), and those usually are pretty obvious (e.g. if you see code using object.__setattr__, something is definitely not right).

Can’t tell whether this is good design or not, but personally I like it.

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Counterpoint: I've used `object.__setattr__` pretty often when setting values in the `__post_init__` of frozen dataclasses

I'd argue, that's about the only correct usage of this stuff.

Is there a difference between global setattr(object, v) and object.__setattr__(v)? I've seen setattr() in the wild all over but I've never encountered the dunder one.

Note that `object` here is not a placeholder variable but actually refers to the global object type (basically a superclass of pretty much every other type in Python). It allows you to bypass the classes’ __setattr__ and set the value regardless (the setattr() function can’t do that):

  In [1]: from dataclasses import dataclass

  In [2]: @dataclass(frozen=True)
     ...: class Foo:
     ...:     a: int
     ...:

  In [3]: foo = Foo(5)

  In [4]: foo.a = 10
  FrozenInstanceError: cannot assign to field 'a'

  In [5]: setattr(foo, "a", 10)
  FrozenInstanceError: cannot assign to field 'a'

  In [6]: object.__setattr__(foo, "a", 10)

  In [7]: foo.a
  Out[7]: 10

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