dataclasses are not cooperative

[a-recknagel]

dataclasses are not cooperative:

>>> class SayFoo:
...     def __init__(self, *args, **kwargs):
...         print('Foo')
...         super().__init__(*args, **kwargs)
... 
>>> @dataclass
... class DC(SayFoo):
...     var: int
...     
>>> DC(1)
DC(var=1)  # doesn't say 'Foo'

This makes writing useful mixins for dataclasses quite hard. Is there a reason why they were written this way?

[ericvsmith]

Because I don't know the signature of the base class's __init__. You may call it yourself in __post_init__.

I'm closing this because this repo is only for the backport of dataclasses to Python 3.6. If you want to discuss this further, I recommend using the python-dev mailing list, or bugs.python.org.

[a-recknagel]

Thanks for the answer, sorry for using the wrong channel.