[eyegor]

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.

[notpushkin]

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