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attrs v21.3.0 Release Notes

Release Date: 2021-12-28 // over 2 years ago

  • Backward-incompatible Changes

    • 0️⃣ When using @define, converters are now run by default when setting an attribute on an instance -- additionally to validators. I.e. the new default is on_setattr=[attrs.setters.convert, attrs.setters.validate].

    This is unfortunately a breaking change, but it was an oversight, impossible to raise a DeprecationWarning about, and it's better to fix it now while the APIs are very fresh with few users. #835 <https://github.com/python-attrs/attrs/issues/835>, #886 <https://github.com/python-attrs/attrs/issues/886>

    • import attrs has finally landed! As of this release, you can finally import attrs using its proper name.

    Not all names from the attr namespace have been transferred; most notably attr.s and attr.ib are missing. See attrs.define and attrs.field if you haven't seen our next-generation APIs yet. A more elaborate explanation can be found On The Core API Names <https://www.attrs.org/en/latest/names.html>_

    This feature is at least for one release provisional. We don't plan on changing anything, but such a big change is unlikely to go perfectly on the first strike.

    The API docs have been mostly updated, but it will be an ongoing effort to change everything to the new APIs. Please note that we have not moved -- or even removed -- anything from attr!

    Please do report any bugs or documentation inconsistencies! #887 <https://github.com/python-attrs/attrs/issues/887>_

    🔄 Changes ^

    • attr.asdict(retain_collection_types=False) (default) dumps collection-esque keys as tuples. #646 <https://github.com/python-attrs/attrs/issues/646>, #888 <https://github.com/python-attrs/attrs/issues/888>
    • __match_args__ are now generated to support Python 3.10's Structural Pattern Matching <https://docs.python.org/3.10/whatsnew/3.10.html#pep-634-structural-pattern-matching>. This can be controlled by the match_args argument to the class decorators on Python 3.10 and later. On older versions, it is never added and the argument is ignored. #815 <https://github.com/python-attrs/attrs/issues/815>
    • If the class-level on_setattr is set to attrs.setters.validate (default in @define and @mutable) but no field defines a validator, pretend that it's not set. #817 <https://github.com/python-attrs/attrs/issues/817>_
    • The generated __repr__ is significantly faster on Pythons with f-strings. #819 <https://github.com/python-attrs/attrs/issues/819>_
    • Attributes transformed via field_transformer are wrapped with AttrsClass again. #824 <https://github.com/python-attrs/attrs/issues/824>_
    • Generated source code is now cached more efficiently for identical classes. #828 <https://github.com/python-attrs/attrs/issues/828>_
    • ➕ Added attrs.converters.to_bool(). #830 <https://github.com/python-attrs/attrs/issues/830>_
    • attrs.resolve_types() now resolves types of subclasses after the parents are resolved. #842 <https://github.com/python-attrs/attrs/issues/842>_ #843 <https://github.com/python-attrs/attrs/issues/843>_
    • ➕ Added new validators: lt(val) (< val), le(va) (≤ val), ge(val) (≥ val), gt(val) (> val), and maxlen(n). #845 <https://github.com/python-attrs/attrs/issues/845>_
    • attrs classes are now fully compatible with cloudpickle <https://github.com/cloudpipe/cloudpickle>_ (no need to disable repr anymore). #857 <https://github.com/python-attrs/attrs/issues/857>_
    • ➕ Added new context manager attrs.validators.disabled() and functions attrs.validators.(set|get)_disabled(). They deprecate attrs.(set|get)_run_validators(). All functions are interoperable and modify the same internal state. They are not – and never were – thread-safe, though. #859 <https://github.com/python-attrs/attrs/issues/859>_
    • attrs.validators.matches_re() now accepts pre-compiled regular expressions in addition to pattern strings. #877 <https://github.com/python-attrs/attrs/issues/877>_