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Page 1

  • v21.4.0 Changes

    December 29, 2021

    ๐Ÿ”„ Changes ^

    • ๐Ÿ›  Fixed the test suite on PyPy3.8 where cloudpickle does not work. #892 <>_
    • ๐Ÿ›  Fixed coverage report for projects that use attrs and don't set a --source. #895 <>, #896 <>

  • v21.3.0 Changes

    December 28, 2021

    Backward-incompatible Changes

    • 0๏ธโƒฃ 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 <>, #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 <>_

    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 <>_

    ๐Ÿ”„ Changes ^

    • attr.asdict(retain_collection_types=False) (default) dumps collection-esque keys as tuples. #646 <>, #888 <>
    • __match_args__ are now generated to support Python 3.10's 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 <>
    • 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 <>_
    • The generated __repr__ is significantly faster on Pythons with f-strings. #819 <>_
    • Attributes transformed via field_transformer are wrapped with AttrsClass again. #824 <>_
    • Generated source code is now cached more efficiently for identical classes. #828 <>_
    • โž• Added attrs.converters.to_bool(). #830 <>_
    • attrs.resolve_types() now resolves types of subclasses after the parents are resolved. #842 <>_ #843 <>_
    • โž• Added new validators: lt(val) (< val), le(va) (โ‰ค val), ge(val) (โ‰ฅ val), gt(val) (> val), and maxlen(n). #845 <>_
    • attrs classes are now fully compatible with cloudpickle <>_ (no need to disable repr anymore). #857 <>_
    • โž• 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 โ€“ and never were โ€“ thread-safe, though. #859 <>_
    • attrs.validators.matches_re() now accepts pre-compiled regular expressions in addition to pattern strings. #877 <>_

  • v21.2.0 Changes

    May 07, 2021

    Backward-incompatible Changes

    • โช We had to revert the recursive feature for attr.evolve() because it broke some use-cases -- sorry! #806 <>_
    • ๐Ÿ“‡ Python 3.4 is now blocked using packaging metadata because attrs can't be imported on it anymore. To ensure that 3.4 users can keep installing attrs easily, we will yank <>_ 21.1.0 from PyPI. This has no consequences if you pin attrs to 21.1.0. #807 <>_

  • v21.1.0 Changes

    May 06, 2021

    ๐Ÿ—„ Deprecations ^

    • The long-awaited, much-talked-about, little-delivered import attrs is finally upon us!

    Since the NG APIs have now been proclaimed stable, the next release of attrs will allow you to actually import attrs. We're taking this opportunity to replace some defaults in our APIs that made sense in 2015, but don't in 2021.

    So please, if you have any pet peeves about defaults in attrs's APIs, now is the time to air your grievances in #487! We're not gonna get such a chance for a second time, without breaking our backward-compatibility guarantees, or long deprecation cycles. Therefore, speak now or forever hold you peace! #487 <>_

    • The cmp argument to attr.s() and attr.ib() has been undeprecated It will continue to be supported as syntactic sugar to set eq and order in one go.

    I'm terribly sorry for the hassle around this argument! The reason we're bringing it back is it's usefulness regarding customization of equality/ordering.

    The cmp attribute and argument on attr.Attribute remains deprecated and will be removed later this year. #773 <>_

    ๐Ÿ”„ Changes ^

    • It's now possible to customize the behavior of eq and order by passing in a callable. #435 <>, #627 <>
    • The instant favorite next-generation APIs <>_ are not provisional anymore!

    They are also officially supported by Mypy as of their 0.800 release <>_.

    We hope the next release will already contain an (additional) importable package called attrs. #668 <>, #786 <>

    • If an attribute defines a converter, the type of its parameter is used as type annotation for its corresponding __init__ parameter.

    If an attr.converters.pipe is used, the first one's is used. #710 <>_

    • ๐Ÿ›  Fixed the creation of an extra slot for an attr.ib when the parent class already has a slot with the same name. #718 <>_
    • __attrs__init__() will now be injected if init=False, or if auto_detect=True and a user-defined __init__() exists.

    This enables users to do "pre-init" work in their __init__() (such as super().__init__()).

    __init__() can then delegate constructor argument processing to self.__attrs_init__(*args, **kwargs). #731 <>_

    • bool(attr.NOTHING) is now False. #732 <>_
    • It's now possible to use super() inside of properties of slotted classes. #747 <>_
    • Allow for a __attrs_pre_init__() method that -- if defined -- will get called at the beginning of the attrs-generated __init__() method. #750 <>_
    • โž• Added forgotten attr.Attribute.evolve() to type stubs. #752 <>_
    • attrs.evolve() now works recursively with nested attrs classes. #759 <>_
    • ๐Ÿ‘ Python 3.10 is now officially supported. #763 <>_
    • attr.resolve_types() now takes an optional attrib argument to work inside a field_transformer. #774 <>_
    • ClassVar\ s are now also detected if they come from typing-extensions <>. #782 <>
    • To make it easier to customize attribute comparison (#435), we have added the attr.cmp_with() helper.

    See the new docs on comparison <>_ for more details. #787 <>_

    • Added provisional support for static typing in pyright via the dataclass_transforms specification <>_. Both the pyright specification and attrs implementation may change in future versions of both projects.

    Your constructive feedback is welcome in both attrs#795 <>_ and pyright#1782 <>. #796 <>

  • v20.3.0 Changes

    November 05, 2020

    Backward-incompatible Changes

    • attr.define(), attr.frozen(), attr.mutable(), and attr.field() remain provisional.

    This release does not change change anything about them and they are already used widely in production though.

    If you wish to use them together with mypy, you can simply drop this plugin <>_ into your project.

    Feel free to provide feedback to them in the linked issue #668.

    We will release the attrs namespace once we have the feeling that the APIs have properly settled. #668 <>_

    ๐Ÿ”„ Changes ^

    • attr.s() now has a field_transformer hook that is called for all Attribute\ s and returns a (modified or updated) list of Attribute instances. attr.asdict() has a value_serializer hook that can change the way values are converted. Both hooks are meant to help with data (de-)serialization workflows. #653 <>_
    • kw_only=True now works on Python 2. #700 <>_
    • raise from now works on frozen classes on PyPy. #703 <>, #712 <>
    • attr.asdict() and attr.astuple() now treat frozenset\ s like set\ s with regards to the retain_collection_types argument. #704 <>_
    • The type stubs for attr.s() and attr.make_class() are not missing the collect_by_mro argument anymore. #711 <>_

  • v20.2.0 Changes

    September 05, 2020

    Backward-incompatible Changes

    • attr.define(), attr.frozen(), attr.mutable(), and attr.field() remain provisional.

    This release fixes a bunch of bugs and ergonomics but they remain mostly unchanged.

    If you wish to use them together with mypy, you can simply drop this plugin <>_ into your project.

    Feel free to provide feedback to them in the linked issue #668.

    We will release the attrs namespace once we have the feeling that the APIs have properly settled. #668 <>_

    ๐Ÿ”„ Changes ^

    • attr.define() et al now correct detect __eq__ and __ne__. #671 <>_
    • attr.define() et al's hybrid behavior now also works correctly when arguments are passed. #675 <>_
    • It's possible to define custom __setattr__ methods on slotted classes again. #681 <>_
    • In 20.1.0 we introduced the inherited attribute on the attr.Attribute class to differentiate attributes that have been inherited and those that have been defined directly on the class.

    It has shown to be problematic to involve that attribute when comparing instances of attr.Attribute though, because when sub-classing, attributes from base classes are suddenly not equal to themselves in a super class.

    Therefore the inherited attribute will now be ignored when hashing and comparing instances of attr.Attribute. #684 <>_

    • โœ… zope.interface is now a "soft dependency" when running the test suite; if zope.interface is not installed when running the test suite, the interface-related tests will be automatically skipped. #685 <>_
    • The ergonomics of creating frozen classes using @define(frozen=True) and sub-classing frozen classes has been improved: you don't have to set on_setattr=None anymore. #687 <>_

  • v20.1.0 Changes

    August 20, 2020

    Backward-incompatible Changes

    • ๐Ÿ‘ Python 3.4 is not supported anymore. It has been unsupported by the Python core team for a while now, its PyPI downloads are negligible, and our CI provider removed it as a supported option.

    It's very unlikely that attrs will break under 3.4 anytime soon, which is why we do not block its installation on Python 3.4. But we don't test it anymore and will block it once someone reports breakage. #608 <>_

    ๐Ÿ—„ Deprecations ^

    • ๐Ÿš€ Less of a deprecation and more of a heads up: the next release of attrs will introduce an attrs namespace. That means that you'll finally be able to run import attrs with new functions that aren't cute abbreviations and that will carry better defaults.

    This should not break any of your code, because project-local packages have priority before installed ones. If this is a problem for you for some reason, please report it to our bug tracker and we'll figure something out.

    The old attr namespace isn't going anywhere and its defaults are not changing โ€“ this is a purely additive measure. Please check out the linked issue for more details.

    These new APIs have been added provisionally as part of #666 so you can try them out today and provide feedback. Learn more in the API docs <>. #408 <>

    ๐Ÿ”„ Changes ^

    • โž• Added attr.resolve_types(). It ensures that all forward-references and types in string form are resolved into concrete types.

    You need this only if you need concrete types at runtime. That means that if you only use types for static type checking, you do not need this function. #288 <>, #302 <>

    • Added @attr.s(collect_by_mro=False) argument that if set to True fixes the collection of attributes from base classes.

    It's only necessary for certain cases of multiple-inheritance but is kept off for now for backward-compatibility reasons. It will be turned on by default in the future.

    As a side-effect, attr.Attribute now always has an inherited attribute indicating whether an attribute on a class was directly defined or inherited. #428 <>, #635 <>

    • ๐Ÿ“„ On Python 3, all generated methods now have a docstring explaining that they have been created by attrs. #506 <>_
    • It is now possible to prevent attrs from auto-generating the __setstate__ and __getstate__ methods that are required for pickling of slotted classes.

    Either pass @attr.s(getstate_setstate=False) or pass @attr.s(auto_detect=True) and implement them yourself: if attrs finds either of the two methods directly on the decorated class, it assumes implicitly getstate_setstate=False (and implements neither).

    This option works with dict classes but should never be necessary. #512 <>, #513 <>, #642 <>_

    • ๐Ÿ›  Fixed a ValueError: Cell is empty bug that could happen in some rare edge cases. #590 <>_
    • attrs can now automatically detect your own implementations and infer init=False, repr=False, eq=False, order=False, and hash=False if you set @attr.s(auto_detect=True). attrs will ignore inherited methods. If the argument implies more than one method (e.g. eq=True creates both __eq__ and __ne__), it's enough for one of them to exist and attrs will create neither.

    This feature requires Python 3. #607 <>_

    • โž• Added attr.converters.pipe(). The feature allows combining multiple conversion callbacks into one by piping the value through all of them, and retuning the last result.

    As part of this feature, we had to relax the type information for converter callables. #618 <>_

    • ๐Ÿ›  Fixed serialization behavior of non-slots classes with cache_hash=True. The hash cache will be cleared on operations which make "deep copies" of instances of classes with hash caching, though the cache will not be cleared with shallow copies like those made by copy.copy().

    Previously, copy.deepcopy() or serialization and deserialization with pickle would result in an un-initialized object.

    This change also allows the creation of cache_hash=True classes with a custom __setstate__, which was previously forbidden (#494 <>). #620 <>

    • It is now possible to specify hooks that are called whenever an attribute is set after a class has been instantiated.

    You can pass on_setattr both to @attr.s() to set the default for all attributes on a class, and to @attr.ib() to overwrite it for individual attributes.

    attrs also comes with a new module attr.setters that brings helpers that run validators, converters, or allow to freeze a subset of attributes. #645 <>, #660 <>

    • Provisional APIs called attr.define(), attr.mutable(), and attr.frozen() have been added.

    They are only available on Python 3.6 and later, and call attr.s() with different default values.

    If nothing comes up, they will become the official way for creating classes in 20.2.0 (see above).

    Please note that it may take some time until mypy โ€“ and other tools that have dedicated support for attrs โ€“ recognize these new APIs. Please do not open issues on our bug tracker, there is nothing we can do about it. #666 <>_

    • We have also provisionally added attr.field() that supplants attr.ib(). It also requires at least Python 3.6 and is keyword-only. Other than that, it only dropped a few arguments, but changed no defaults.

    As with attr.s(): attr.ib() is not going anywhere. #669 <>_

  • v19.3.0 Changes

    October 15, 2019

    ๐Ÿ”„ Changes ^

    • ๐Ÿ›  Fixed auto_attribs usage when default values cannot be compared directly with ==, such as numpy arrays. #585 <>_

  • v19.2.0 Changes

    October 01, 2019

    Backward-incompatible Changes

    • โœ‚ Removed deprecated Attribute attribute convert per scheduled removal on 2019/1. This planned deprecation is tracked in issue #307 <>. #504 <>
    • __lt__, __le__, __gt__, and __ge__ do not consider subclasses comparable anymore.

    This has been deprecated since 18.2.0 and was raising a DeprecationWarning for over a year. #570 <>_

    ๐Ÿ—„ Deprecations ^

    • ๐Ÿ—„ The cmp argument to attr.s() and attr.ib() is now deprecated.

    Please use eq to add equality methods (__eq__ and __ne__) and order to add ordering methods (__lt__, __le__, __gt__, and __ge__) instead โ€“ just like with dataclasses <>_.

    Both are effectively True by default but it's enough to set eq=False to disable both at once. Passing eq=False, order=True explicitly will raise a ValueError though.

    Since this is arguably a deeper backward-compatibility break, it will have an extended deprecation period until 2021-06-01. After that day, the cmp argument will be removed.

    attr.Attribute also isn't orderable anymore. #574 <>_

    ๐Ÿ”„ Changes ^

    • Updated attr.validators.__all__ to include new validators added in #425. #517 <>
    • Slotted classes now use a pure Python mechanism to rewrite the __class__ cell when rebuilding the class, so super() works even on environments where ctypes is not installed. #522 <>_
    • 0๏ธโƒฃ When collecting attributes using @attr.s(auto_attribs=True), attributes with a default of None are now deleted too. #523 <>, #556 <>
    • Fixed attr.validators.deep_iterable() and attr.validators.deep_mapping() type stubs. #533 <>_
    • ๐Ÿ‘ป attr.validators.is_callable() validator now raises an exception attr.exceptions.NotCallableError, a subclass of TypeError, informing the received value. #536 <>_
    • ๐Ÿ“š @attr.s(auto_exc=True) now generates classes that are hashable by ID, as the documentation always claimed it would. #543 <>, #563 <>
    • โž• Added attr.validators.matches_re() that checks string attributes whether they match a regular expression. #552 <>_
    • Keyword-only attributes (kw_only=True) and attributes that are excluded from the attrs's __init__ (init=False) now can appear before mandatory attributes. #559 <>_
    • The fake filename for generated methods is now more stable. It won't change when you restart the process. #560 <>_
    • The value passed to @attr.ib(repr=โ€ฆ) can now be either a boolean (as before) or a callable. That callable must return a string and is then used for formatting the attribute by the generated __repr__() method. #568 <>_
    • ๐Ÿ”– Added attr.__version_info__ that can be used to reliably check the version of attrs and write forward- and backward-compatible code. Please check out the section on deprecated APIs <>_ on how to use it. #580 <>_

    .. _#425:

  • v19.1.0 Changes

    March 03, 2019

    Backward-incompatible Changes

    • ๐Ÿ›  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 <>. #482 <>

    ๐Ÿ”„ 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 <>_

    • Fixed stub files to prevent errors raised by mypy's disallow_any_generics = True option. #443 <>_
    • Attributes with init=False now can follow after kw_only=True attributes. #450 <>_
    • ๐Ÿ‘ป 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 <>_

    • ๐Ÿ“š Clarified documentation for hashing to warn that hashable objects should be deeply immutable (in their usage, even if this is not enforced). #503 <>_