v25.4.0

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Backwards-incompatible Changes

• Class-levelkw_only=True behavior is now consistent withdataclasses.

  Previously, a class that setskw_only=True makes all attributes keyword-only, including those from base classes.
  If an attribute setskw_only=False, that setting is ignored, and it is still made keyword-only.

  Now, only the attributes defined in that class that doesn't explicitly setkw_only=False are made keyword-only.

  This shouldn't be a problem for most users, unless you have a pattern like this:

  @​attrs.define(kw_only=True)classBase:a:intb:int=attrs.field(default=1,kw_only=False)@​attrs.defineclassSubclass(Base):c:int

  Here, we have akw_only=Trueattrs class (Base) with an attribute that setskw_only=False and has a default (Base.b), and then create a subclass (Subclass) with required arguments (Subclass.c).
  Previously this would work, since it would makeBase.b keyword-only, but now this fails sinceBase.b is positional, and we have a required positional argument (Subclass.c) following another argument with defaults.
  #​1457

Changes

• Values passed to the__init__() method ofattrs classes are now correctly passed to__attrs_pre_init__() instead of their default values (in cases wherekw_only was not specified).
  #​1427

• Added support for Python 3.14 andPEP 749.
  #​1446,
  #​1451

• attrs.validators.deep_mapping() now allows to leave out eitherkey_validator xorvalue_validator.
  #​1448

• attrs.validators.deep_iterator() andattrs.validators.deep_mapping() now accept lists and tuples for all validators and wrap them into aattrs.validators.and_().
  #​1449

• Added a newexperimental way to inspect classes:

  attrs.inspect(cls) returns theeffective class-wide parameters that were used byattrs to construct the class.

  The returned class is the same data structure thatattrs uses internally to decide how to construct the final class.
  #​1454

• Fixed annotations forattrs.field(converter=...).
  Previously, atuple of converters was only accepted if it had exactly one element.
  #​1461

• The performance ofattrs.asdict() has been improved by 45–260%.
  #​1463

• The performance ofattrs.astuple() has been improved by 49–270%.
  #​1469

• The type annotation forattrs.validators.or_() now allows for different types of validators.

  This was only an issue on Pyright.
  #​1474

v2025.10.5

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v2.25.2

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Bug Fixes

• Deprecate credentials_file argument (#​841) (324eb74)
• Fix async tests and round-off error in test expectations (#​837) (14a5978)