| from __future__ import annotations | |
| from typing import NoReturn, TypeVar | |
| from attrs import define as _define, frozen as _frozen | |
| _T = TypeVar("_T") | |
| def define(cls: type[_T]) -> type[_T]: # pragma: no cover | |
| cls.__init_subclass__ = _do_not_subclass | |
| return _define(cls) | |
| def frozen(cls: type[_T]) -> type[_T]: | |
| cls.__init_subclass__ = _do_not_subclass | |
| return _frozen(cls) | |
| class UnsupportedSubclassing(Exception): | |
| def __str__(self): | |
| return ( | |
| "Subclassing is not part of referencing's public API. " | |
| "If no other suitable API exists for what you're trying to do, " | |
| "feel free to file an issue asking for one." | |
| ) | |
| def _do_not_subclass() -> NoReturn: # pragma: no cover | |
| raise UnsupportedSubclassing() | |