https://github.com/python/cpython/commit/e13c3d643e508f201a5bcd2e522d4acf6c93f4fe commit: e13c3d643e508f201a5bcd2e522d4acf6c93f4fe branch: main author: Sanghun Lee <[email protected]> committer: hugovk <[email protected]> date: 2026-08-17T03:51:28Z summary:
gh-149083: Document that dataclasses.MISSING and KW_ONLY are sentinels (#155919) Co-authored-by: Claude Opus 5 (1M context) <[email protected]> files: M Doc/library/dataclasses.rst diff --git a/Doc/library/dataclasses.rst b/Doc/library/dataclasses.rst index ce59d89843e761d..9f4871a55bc8af3 100644 --- a/Doc/library/dataclasses.rst +++ b/Doc/library/dataclasses.rst @@ -262,8 +262,8 @@ Module contents c = C() c.mylist += [1, 2, 3] - As shown above, the :const:`MISSING` value is a sentinel object used to - detect if some parameters are provided by the user. This sentinel is + As shown above, the :const:`MISSING` value is a :class:`sentinel` object + used to detect if some parameters are provided by the user. This sentinel is used because ``None`` is a valid value for some parameters with a distinct meaning. No code should directly use the :const:`MISSING` value. @@ -528,11 +528,14 @@ Module contents .. data:: MISSING - A sentinel value signifying a missing default or default_factory. + A :class:`sentinel` object signifying a missing default or *default_factory*. + + .. versionchanged:: 3.15 + :const:`!MISSING` is now a :class:`sentinel` object. .. data:: KW_ONLY - A sentinel value used as a type annotation. Any fields after a + A :class:`sentinel` object used as a type annotation. Any fields after a pseudo-field with the type of :const:`!KW_ONLY` are marked as keyword-only fields. Note that a pseudo-field of type :const:`!KW_ONLY` is otherwise completely ignored. This includes the @@ -557,6 +560,9 @@ Module contents .. versionadded:: 3.10 + .. versionchanged:: 3.15 + :const:`!KW_ONLY` is now a :class:`sentinel` object. + .. exception:: FrozenInstanceError Raised when an implicitly defined :meth:`~object.__setattr__` or _______________________________________________ Python-checkins mailing list -- [email protected] To unsubscribe send an email to [email protected] https://mail.python.org/mailman3//lists/python-checkins.python.org Member address: [email protected]
