pypi / attrs
attrs
What changed in attrs 26, from its official release notes, upgrade guides and advisories. Sources checked 2026-10-17.
3 new APIs and options1 behavior and defaults2 fixes and other
See which of these apply to your code, ranked, in your agent:
npx @unstale/cli initattrs 266 changes
New APIs and options 3
Adds a flag indicating whether an attribute alias was auto-generated or explicitly set by the user.
attrs.fields() now accepts attrs instances as well as attrs classes.
Frozen classes can now use attrs.setters.NO_OP for on_setattr in addition to None.
Behavior and default changes 1
The disabled validator context manager can now be nested.
Fixes and other changes 2
Type annotations no longer reject tuples containing more than one validator.
Field aliases are resolved before field_transformer runs, so transformers receive fully populated Attribute objects with usable alias values.