New submission from Joseph Perez : Class definition can have kwargs which are used by `__init_subclass__` (and `__prepare__`). However, passing these kwargs using `type` builtin function instead of class definition syntax is not documented; kwargs are not mentioned in the function signature. https://docs.python.org/3/library/functions.html#type However, passing kwargs to `type` works: ```python class Foo: def __init_subclass__(cls, **kwargs): print(kwargs) Bar = type("Bar", (Foo,), {}, bar=None) # mypy and Pycharm complain #> {'bar': None} ``` By the way, the possibility to pass kwargs in `type` call is not documented in https://docs.python.org/3/reference/datamodel.html#customizing-class-creatio... too. ---------- assignee: docs@python components: Documentation messages: 375936 nosy: docs@python, joperez priority: normal severity: normal status: open title: builtin type kwargs versions: Python 3.10, Python 3.6, Python 3.7, Python 3.8, Python 3.9 _______________________________________ Python tracker https://bugs.python.org/issue41644 _______________________________________