New submission from Gregory Beauregard <g...@greg.red>:
In https://bugs.python.org/issue46491 the typing runtime behavior was changed so that `Annotated[Classvar[...]]` is now valid at runtime in order to alleviate tension between typing and non-typing annotation space uses. dataclasses.py should likely follow suit in its runtime use of `ClassVar` and `InitVar`. Reviewing the code I see two areas that would need addressed: 1) `InitVar` needs changed so `Annotated[InitVar[...]]` is no longer a runtime error. This is currently a runtime error completely by accident: typing.py expects special type forms to be `callable()`, usually by implementing a `__call__` that throws an error, but `InitVar` does not implement this. Adding an implementation like in typing.py would fix the runtime error: https://github.com/python/cpython/blob/b1a3446f077b7d56b89f55d98dadb8018986a3e5/Lib/typing.py#L391-L392 2) The dataclasses-specific typehint introspection implementation needs modified to accommodate being wrapped by an `Annotated` annotation. I see in the comments the code is performance sensitive so I'm not sure what you want to do; f.ex. the regex needs modified, but it's not clean. What are your thoughts? ---------- components: Library (Lib) messages: 411567 nosy: GBeauregard, Jelle Zijlstra, eric.smith priority: normal severity: normal status: open title: dataclasses: Allow typing.Annotated to wrap dataclasses-specific annotations type: behavior versions: Python 3.10, Python 3.11, Python 3.9 _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue46511> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
