Submission for SC consideration: PEP 681 -- Data Class Transforms #117

Please consider PEP 681 for inclusion in Python 3.11.

This is a typing PEP that provides a way to describe the behavior of dataclass-like libraries to static type checkers.

The PEP has been discussed at length in several typing-sig threads:

• The primary PEP discussion thread: Dataclass Transform draft PEP
• Early pre-PEP discussions:
  • Supporting dataclass-like semantics
  • Dataclass Transform
• Threads on specific aspects of the design:
  • PEP 681: Descriptor fields with dataclass_transform
  • Clarification about PEP 681 statement
  • dataclass_transform support for converter field descriptor parameter

We also posted an RFC notification on discuss.python.org pointing to the canonical thread on typing-sig.

There is a reference implementation of the type checking part in Pyright, and an implementation of the dataclass_transform decorator in typing_extensions.py.

CC: @JelleZijlstra @erictraut

https://www.python.org/dev/peps/pep-0681/