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attrs v17.3.0 Release Notes

Release Date: 2017-11-08 // over 6 years ago

  • Backward-incompatible Changes

    • Attributes are no longer defined on the class body.

    This means that if you define a class C with an attribute x, the class will not have an attribute x for introspection. Instead of C.x, use attr.fields(C).x or look at C.__attrs_attrs__. The old behavior has been deprecated since version 16.1. (#253 <https://github.com/python-attrs/attrs/issues/253>_)

    🔄 Changes ^

    • super() and __class__ now work with slotted classes on Python 3. (#102 <https://github.com/python-attrs/attrs/issues/102>, #226 <https://github.com/python-attrs/attrs/issues/226>, #269 <https://github.com/python-attrs/attrs/issues/269>, #270 <https://github.com/python-attrs/attrs/issues/270>, #272 <https://github.com/python-attrs/attrs/issues/272>_)
    • Added type argument to attr.ib() and corresponding type attribute to attr.Attribute.

    This change paves the way for automatic type checking and serialization (though as of this release attrs does not make use of it). In Python 3.6 or higher, the value of attr.Attribute.type can alternately be set using variable type annotations (see PEP 526 <https://www.python.org/dev/peps/pep-0526/>). (#151 <https://github.com/python-attrs/attrs/issues/151>, #214 <https://github.com/python-attrs/attrs/issues/214>, #215 <https://github.com/python-attrs/attrs/issues/215>, #239 <https://github.com/python-attrs/attrs/issues/239>_)

    • The combination of str=True and slots=True now works on Python 2. (#198 <https://github.com/python-attrs/attrs/issues/198>_)
    • attr.Factory is hashable again. (#204 <https://github.com/python-attrs/attrs/issues/204>_)
    • Subclasses now can overwrite attribute definitions of their base classes.

    That means that you can -- for example -- change the default value for an attribute by redefining it. (#221 <https://github.com/python-attrs/attrs/issues/221>, #229 <https://github.com/python-attrs/attrs/issues/229>)

    • Added new option auto_attribs to @attr.s that allows to collect annotated fields without setting them to attr.ib().

    Setting a field to an attr.ib() is still possible to supply options like validators. Setting it to any other value is treated like it was passed as attr.ib(default=value) -- passing an instance of attr.Factory also works as expected. (#262 <https://github.com/python-attrs/attrs/issues/262>, #277 <https://github.com/python-attrs/attrs/issues/277>)

    • Instances of classes created using attr.make_class() can now be pickled. (#282 <https://github.com/python-attrs/attrs/issues/282>_)