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attrs v19.1.0 Release Notes

Release Date: 2019-03-03 // about 5 years ago

  • Backward-incompatible Changes

    • 🛠 Fixed a bug where deserialized objects with cache_hash=True could have incorrect hash code values. This change breaks classes with cache_hash=True when a custom __setstate__ is present. An exception will be thrown when applying the attrs annotation to such a class. This limitation is tracked in issue #494 <https://github.com/python-attrs/attrs/issues/494>. #482 <https://github.com/python-attrs/attrs/issues/482>

    🔄 Changes ^

    • Add is_callable, deep_iterable, and deep_mapping validators.

      • is_callable: validates that a value is callable
      • deep_iterable: Allows recursion down into an iterable, applying another validator to every member in the iterable as well as applying an optional validator to the iterable itself.
      • deep_mapping: Allows recursion down into the items in a mapping object, applying a key validator and a value validator to the key and value in every item. Also applies an optional validator to the mapping object itself.

    You can find them in the attr.validators package. #425 <https://github.com/python-attrs/attrs/issues/425>_

    • Fixed stub files to prevent errors raised by mypy's disallow_any_generics = True option. #443 <https://github.com/python-attrs/attrs/issues/443>_
    • Attributes with init=False now can follow after kw_only=True attributes. #450 <https://github.com/python-attrs/attrs/issues/450>_
    • 👻 attrs now has first class support for defining exception classes.

    If you define a class using @attr.s(auto_exc=True) and subclass an exception, the class will behave like a well-behaved exception class including an appropriate __str__ method, and all attributes additionally available in an args attribute. #500 <https://github.com/python-attrs/attrs/issues/500>_

    • 📚 Clarified documentation for hashing to warn that hashable objects should be deeply immutable (in their usage, even if this is not enforced). #503 <https://github.com/python-attrs/attrs/issues/503>_