Changelog¶
Versions follow Calendar Versioning with a strict backwards-compatibility policy.
The first number of the version is the year. The second number is incremented with each release, starting at 1 for each year. The third number is when we need to start branches for older releases (only for emergencies).
You can find our backwards-compatibility policy here.
Changes for the Upcoming Release¶
Warning
These changes reflect the current development progress and have not been part of a PyPI release yet.
No significant changes.
24.1.0 - 2024-08-03¶
Backwards-incompatible Changes¶
attrs.evolve()
doesn’t accept the inst argument as a keyword argument anymore. Pass it as the first positional argument instead. #1264attrs.validators.provides()
has been removed. The removed code is available as a gist for convenient copy and pasting. #1265All packaging metadata except from
__version__
and__version_info__
has been removed from theattr
andattrs
modules (for example,attrs.__url__
).Please use
importlib.metadata
or importlib_metadata instead. #1268Speed up the generated
__eq__
methods significantly by generating a chain of attribute comparisons instead of constructing and comparing tuples. This change arguably makes the behavior more correct, but changes it if an attribute compares equal by identity but not value, likefloat('nan')
. #1310
Deprecations¶
Changes¶
Allow original slotted
functools.cached_property
classes to be cleaned by garbage collection. Allowsuper()
calls in slotted cached properties. #1221Our type stubs now use modern type notation and are organized such that VS Code’s quick-fix prefers the
attrs
namespace. #1234Preserve
AttributeError
raised by properties of slotted classes withfunctools.cached_properties
. #1253It is now possible to wrap a converter into an
attrs.Converter
and get the current instance and/or the current field definition passed into the converter callable.Note that this is not supported by any type checker, yet. #1267
attrs.make_class()
now populates the__annotations__
dict of the generated class, so thatattrs.resolve_types()
can resolve them. #1285Added the
attrs.validators.or_()
validator. #1303The combination of a
__attrs_pre_init__
that takes arguments, a kw-only field, and a default on that field does not crash anymore. #1319attrs.validators.in_()
now transforms certain unhashable options to tuples to keep the field hashable.This allows fields that use this validator to be used with, for example,
attrs.filters.include()
. #1320If a class has an inherited method called
__attrs_init_subclass__
, it is now called once the class is done assembling.This is a replacement for Python’s
__init_subclass__
and useful for registering classes, and similar. #1321
23.2.0 - 2023-12-31¶
Changes¶
The type annotation for
attrs.resolve_types()
is now correct. #1141Type stubs now use
typing.dataclass_transform
to decorate dataclass-like decorators, instead of the non-standard__dataclass_transform__
special form, which is only supported by Pyright. #1158Fixed serialization of namedtuple fields using
attrs.asdict/astuple()
withretain_collection_types=True
. #1165attrs.AttrsInstance
is now atyping.Protocol
in both type hints and code. This allows you to subclass it along with anotherProtocol
. #1172If attrs detects that
__attrs_pre_init__
accepts more than justself
, it will call it with the same arguments as__init__
was called. This allows you to, for example, pass arguments tosuper().__init__()
. #1187Slotted classes now transform
functools.cached_property
decorated methods to support equivalent semantics. #1200Added class_body argument to
attrs.make_class()
to provide additional attributes for newly created classes. It is, for example, now possible to attach methods. #1203
23.1.0 - 2023-04-16¶
Backwards-incompatible Changes¶
Deprecations¶
The support for zope-interface via the
attrs.validators.provides
validator is now deprecated and will be removed in, or after, April 2024.The presence of a C-based package in our development dependencies has caused headaches and we’re not under the impression it’s used a lot.
Let us know if you’re using it and we might publish it as a separate package. #1120
Changes¶
attrs.filters.exclude()
andattrs.filters.include()
now support the passing of attribute names as strings. #1068attrs.has()
andattrs.fields()
now handle generic classes correctly. #1079Fix frozen exception classes when raised within, for example,
contextlib.contextmanager
, which mutates their__traceback__
attributes. #1081@frozen
now works with type checkers that implement PEP-681 (ex. pyright). #1084Restored ability to unpickle instances pickled before 22.2.0. #1085
attrs.asdict()
’s andattrs.astuple()
’s type stubs now accept theattrs.AttrsInstance
protocol. #1090Fix slots class cellvar updating closure in CPython 3.8+ even when
__code__
introspection is unavailable. #1092attrs.resolve_types()
can now passinclude_extras
totyping.get_type_hints()
on Python 3.9+, and does so by default. #1099Added instructions for pull request workflow to
CONTRIBUTING.md
. #1105Added type parameter to
attrs.field()
function for use withattrs.make_class()
.Please note that type checkers ignore type metadata passed into
make_class()
, but it can be useful if you’re wrapping attrs. #1107It is now possible for
attrs.evolve()
(andattr.evolve()
) to change fields namedinst
if the instance is passed as a positional argument.Passing the instance using the
inst
keyword argument is now deprecated and will be removed in, or after, April 2024. #1117attrs.validators.optional()
now also accepts a tuple of validators (in addition to lists of validators). #1122
22.2.0 - 2022-12-21¶
Backwards-incompatible Changes¶
Python 3.5 is not supported anymore. #988
Deprecations¶
Python 3.6 is now deprecated and support will be removed in the next release. #1017
Changes¶
attrs.field()
now supports an alias option for explicit__init__
argument names.Get
__init__
signatures matching any taste, peculiar or plain! The PEP 681 compatible alias option can be use to override private attribute name mangling, or add other arbitrary field argument name overrides. #950attrs.NOTHING
is now an enum value, making it possible to use with, for example,typing.Literal
. #983Added missing re-import of
attr.AttrsInstance
to theattrs
namespace. #987Fix slight performance regression in classes with custom
__setattr__
and speedup even more. #991Class-creation performance improvements by switching performance-sensitive templating operations to f-strings.
You can expect an improvement of about 5% – even for very simple classes. #995
attrs.has()
is now aTypeGuard
forAttrsInstance
. That means that type checkers know a class is an instance of anattrs
class if you check it usingattrs.has()
(orattr.has()
) first. #997Made
attrs.AttrsInstance
stub available at runtime and fixed type errors related to the usage ofattrs.AttrsInstance
in Pyright. #999On Python 3.10 and later, call
abc.update_abstractmethods()
on dict classes after creation. This improves the detection of abstractness. #1001attrs’s pickling methods now use dicts instead of tuples. That is safer and more robust across different versions of a class. #1009
Added
attrs.validators.not_(wrapped_validator)
to logically invert wrapped_validator by accepting only values where wrapped_validator rejects the value with aValueError
orTypeError
(by default, exception types configurable). #1010The type stubs for
attrs.cmp_using()
now have default values. #1027To conform with PEP 681,
attr.s()
andattrs.define()
now accept unsafe_hash in addition to hash. #1065
22.1.0 - 2022-07-28¶
Backwards-incompatible Changes¶
Python 2.7 is not supported anymore.
Dealing with Python 2.7 tooling has become too difficult for a volunteer-run project.
We have supported Python 2 more than 2 years after it was officially discontinued and feel that we have paid our dues. All version up to 21.4.0 from December 2021 remain fully functional, of course. #936
The deprecated
cmp
attribute ofattrs.Attribute
has been removed. This does not affect the cmp argument toattr.s
that can be used as a shortcut to set eq and order at the same time. #939
Changes¶
Instantiation of frozen slotted classes is now faster. #898
If an
eq
key is defined, it is also used before hashing the attribute. #909Added
attrs.validators.min_len()
. #916attrs.validators.deep_iterable()
’s member_validator argument now also accepts a list of validators and wraps them in anattrs.validators.and_()
. #925Added missing type stub re-imports for
attrs.converters
andattrs.filters
. #931Added missing stub for
attr(s).cmp_using()
. #949attrs.validators._in()
’sValueError
is not missing the attribute, expected options, and the value it got anymore. #951Python 3.11 is now officially supported. #969
21.4.0 - 2021-12-29¶
Changes¶
21.3.0 - 2021-12-28¶
Backward-incompatible Changes¶
When using
@define
, converters are now run by default when setting an attribute on an instance – additionally to validators. Meaning: the new default ison_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, #886import attrs
has finally landed! As of this release, you can finally importattrs
using its proper name.Not all names from the
attr
namespace have been transferred; most notablyattr.s
andattr.ib
are missing. Seeattrs.define
andattrs.field
if you haven’t seen our next-generation APIs yet. A more elaborate explanation can be found On The Core API NamesThis 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
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 thematch_args
argument to the class decorators on Python 3.10 and later. On older versions, it is never added and the argument is ignored. #815If 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. #817The generated
__repr__
is significantly faster on Pythons with f-strings. #819Attributes transformed via
field_transformer
are wrapped withAttrsClass
again. #824Generated source code is now cached more efficiently for identical classes. #828
Added
attrs.converters.to_bool()
. #830attrs.resolve_types()
now resolves types of subclasses after the parents are resolved. #842 #843Added new validators:
lt(val)
(< val),le(va)
(≤ val),ge(val)
(≥ val),gt(val)
(> val), andmaxlen(n)
. #845attrs
classes are now fully compatible with cloudpickle (no need to disablerepr
anymore). #857Added new context manager
attrs.validators.disabled()
and functionsattrs.validators.(set|get)_disabled()
. They deprecateattrs.(set|get)_run_validators()
. All functions are interoperable and modify the same internal state. They are not – and never were – thread-safe, though. #859attrs.validators.matches_re()
now accepts pre-compiled regular expressions in addition to pattern strings. #877
21.2.0 - 2021-05-07¶
Backward-incompatible Changes¶
We had to revert the recursive feature for
attr.evolve()
because it broke some use-cases – sorry! #806Python 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 installingattrs
easily, we will yank 21.1.0 from PyPI. This has no consequences if you pinattrs
to 21.1.0. #807
21.1.0 - 2021-05-06¶
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 actuallyimport 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! #487The cmp argument to
attr.s()
andattr.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 onattr.Attribute
remains deprecated and will be removed later this year. #773
Changes¶
It’s now possible to customize the behavior of
eq
andorder
by passing in a callable. #435, #627The 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, #786If 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. #710Fixed 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 ifinit=False
, or ifauto_detect=True
and a user-defined__init__()
exists.This enables users to do “pre-init” work in their
__init__()
(such assuper().__init__()
).__init__()
can then delegate constructor argument processing toself.__attrs_init__(*args, **kwargs)
. #731bool(attr.NOTHING)
is nowFalse
. #732It’s now possible to use
super()
inside of properties of slotted classes. #747Allow for a
__attrs_pre_init__()
method that – if defined – will get called at the beginning of theattrs
-generated__init__()
method. #750Added forgotten
attr.Attribute.evolve()
to type stubs. #752attrs.evolve()
now works recursively with nestedattrs
classes. #759Python 3.10 is now officially supported. #763
attr.resolve_types()
now takes an optional attrib argument to work inside afield_transformer
. #774ClassVar
s are now also detected if they come from typing-extensions. #782To 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 PEP 681. Both thepyright
specification andattrs
implementation may change in future versions of both projects.Your constructive feedback is welcome in both attrs#795 and pyright#1782. #796
20.3.0 - 2020-11-05¶
Backward-incompatible Changes¶
attr.define()
,attr.frozen()
,attr.mutable()
, andattr.field()
remain provisional.This release does not 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
Changes¶
attr.s()
now has a field_transformer hook that is called for allAttribute
s and returns a (modified or updated) list ofAttribute
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. #653kw_only=True
now works on Python 2. #700attr.asdict()
andattr.astuple()
now treatfrozenset
s likeset
s with regards to the retain_collection_types argument. #704The type stubs for
attr.s()
andattr.make_class()
are not missing the collect_by_mro argument anymore. #711
20.2.0 - 2020-09-05¶
Backward-incompatible Changes¶
attr.define()
,attr.frozen()
,attr.mutable()
, andattr.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
Changes¶
attr.define()
et al now correctly detect__eq__
and__ne__
. #671attr.define()
et al’s hybrid behavior now also works correctly when arguments are passed. #675It’s possible to define custom
__setattr__
methods on slotted classes again. #681In 20.1.0 we introduced the
inherited
attribute on theattr.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 ofattr.Attribute
. #684zope.interface
is now a “soft dependency” when running the test suite; ifzope.interface
is not installed when running the test suite, the interface-related tests will be automatically skipped. #685The ergonomics of creating frozen classes using
@define(frozen=True)
and sub-classing frozen classes has been improved: you don’t have to seton_setattr=None
anymore. #687
20.1.0 - 2020-08-20¶
Backward-incompatible Changes¶
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
Deprecations¶
Less of a deprecation and more of a heads up: the next release of
attrs
will introduce anattrs
namespace. That means that you’ll finally be able to runimport 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 – 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
Changes¶
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 toTrue
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 aninherited
attribute indicating whether an attribute on a class was directly defined or inherited. #428, #635On Python 3, all generated methods now have a docstring explaining that they have been created by
attrs
. #506It 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: ifattrs
finds either of the two methods directly on the decorated class, it assumes implicitlygetstate_setstate=False
(and implements neither).This option works with dict classes but should never be necessary. #512, #513, #642
Fixed a
ValueError: Cell is empty
bug that could happen in some rare edge cases. #590attrs
can now automatically detect your own implementations and inferinit=False
,repr=False
,eq=False
,order=False
, andhash=False
if you set@attr.s(auto_detect=True)
.attrs
will ignore inherited methods. If the argument implies more than one method (for example,eq=True
creates both__eq__
and__ne__
), it’s enough for one of them to exist andattrs
will create neither.This feature requires Python 3. #607
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
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 bycopy.copy()
.Previously,
copy.deepcopy()
or serialization and deserialization withpickle
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). #620It 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 moduleattr.setters
that brings helpers that run validators, converters, or allow to freeze a subset of attributes. #645, #660Provisional APIs called
attr.define()
,attr.mutable()
, andattr.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 – and other tools that have dedicated support for
attrs
– recognize these new APIs. Please do not open issues on our bug tracker, there is nothing we can do about it. #666We have also provisionally added
attr.field()
that supplantsattr.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
19.3.0 - 2019-10-15¶
Changes¶
Fixed
auto_attribs
usage when default values cannot be compared directly with==
, such asnumpy
arrays. #585
19.2.0 - 2019-10-01¶
Backward-incompatible Changes¶
Removed deprecated
Attribute
attributeconvert
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
Deprecations¶
The
cmp
argument toattr.s()
andattr.ib()
is now deprecated.Please use
eq
to add equality methods (__eq__
and__ne__
) andorder
to add ordering methods (__lt__
,__le__
,__gt__
, and__ge__
) instead – just like with dataclasses.Both are effectively
True
by default but it’s enough to seteq=False
to disable both at once. Passingeq=False, order=True
explicitly will raise aValueError
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
Changes¶
Updated
attr.validators.__all__
to include new validators added in #425. #517Slotted classes now use a pure Python mechanism to rewrite the
__class__
cell when rebuilding the class, sosuper()
works even on environments wherectypes
is not installed. #522When collecting attributes using
@attr.s(auto_attribs=True)
, attributes with a default ofNone
are now deleted too. #523, #556Fixed
attr.validators.deep_iterable()
andattr.validators.deep_mapping()
type stubs. #533attr.validators.is_callable()
validator now raises an exceptionattr.exceptions.NotCallableError
, a subclass ofTypeError
, informing the received value. #536@attr.s(auto_exc=True)
now generates classes that are hashable by ID, as the documentation always claimed it would. #543, #563Added
attr.validators.matches_re()
that checks string attributes whether they match a regular expression. #552Keyword-only attributes (
kw_only=True
) and attributes that are excluded from theattrs
’s__init__
(init=False
) now can appear before mandatory attributes. #559The 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=…)
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. #568Added
attr.__version_info__
that can be used to reliably check the version ofattrs
and write forward- and backward-compatible code. Please check out the section on deprecated APIs on how to use it. #580
19.1.0 - 2019-03-03¶
Backward-incompatible Changes¶
Fixed a bug where deserialized objects with
cache_hash=True
could have incorrect hash code values. This change breaks classes withcache_hash=True
when a custom__setstate__
is present. An exception will be thrown when applying theattrs
annotation to such a class. This limitation is tracked in issue #494. #482
Changes¶
Add
is_callable
,deep_iterable
, anddeep_mapping
validators.is_callable
: validates that a value is callabledeep_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. #425Fixed stub files to prevent errors raised by mypy’s
disallow_any_generics = True
option. #443Attributes with
init=False
now can follow afterkw_only=True
attributes. #450attrs
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 anargs
attribute. #500Clarified documentation for hashing to warn that hashable objects should be deeply immutable (in their usage, even if this is not enforced). #503
18.2.0 - 2018-09-01¶
Deprecations¶
Comparing subclasses using
<
,>
,<=
, and>=
is now deprecated. The docs always claimed that instances are only compared if the types are identical, so this is a first step to conform to the docs.Equality operators (
==
and!=
) were always strict in this regard. #394
Changes¶
attrs
now ships its own PEP 484 type hints. Together with mypy’sattrs
plugin, you’ve got all you need for writing statically typed code in both Python 2 and 3!At that occasion, we’ve also added narrative docs about type annotations in
attrs
. #238Added kw_only arguments to
attr.ib
andattr.s
, and a corresponding kw_only attribute toattr.Attribute
. This change makes it possible to have a generated__init__
with keyword-only arguments on Python 3, relaxing the required ordering of default and non-default valued attributes. #281, #411The test suite now runs with
hypothesis.HealthCheck.too_slow
disabled to prevent CI breakage on slower computers. #364, #396attr.validators.in_()
now raises aValueError
with a useful message even if the options are a string and the value is not a string. #383attr.asdict()
now properly handles deeply nested lists and dictionaries. #395Added
attr.converters.default_if_none()
that allows to replaceNone
values in attributes. For exampleattr.ib(converter=default_if_none(""))
replacesNone
by empty strings. #400, #414Fixed a reference leak where the original class would remain live after being replaced when
slots=True
is set. #407Slotted classes can now be made weakly referenceable by passing
@attr.s(weakref_slot=True)
. #420Added cache_hash option to
@attr.s
which causes the hash code to be computed once and stored on the object. #426Attributes can be named
property
anditemgetter
now. #430It is now possible to override a base class’ class variable using only class annotations. #431
18.1.0 - 2018-05-03¶
Changes¶
x=X(); x.cycle = x; repr(x)
will no longer raise aRecursionError
, and will instead show asX(x=...)
.attr.ib(factory=f)
is now syntactic sugar for the common case ofattr.ib(default=attr.Factory(f))
.Added
attr.field_dict()
to return an ordered dictionary ofattrs
attributes for a class, whose keys are the attribute names.The order of attributes that are passed into
attr.make_class()
or the these argument of@attr.s()
is now retained if the dictionary is ordered (in other words:dict
on Python 3.6 and later,collections.OrderedDict
otherwise).Before, the order was always determined by the order in which the attributes have been defined which may not be desirable when creating classes programmatically.
In slotted classes,
__getstate__
and__setstate__
now ignore the__weakref__
attribute.Setting the cell type is now completely best effort. This fixes
attrs
on Jython.We cannot make any guarantees regarding Jython though, because our test suite cannot run due to dependency incompatibilities.
If
attr.s
is passed a these argument, it will no longer attempt to remove attributes with the same name from the class body.The hash of
attr.NOTHING
is now vegan and faster on 32bit Python builds.The overhead of instantiating frozen dict classes is virtually eliminated. #336
Generated
__init__
methods now have an__annotations__
attribute derived from the types of the fields.We have restructured the documentation a bit to account for
attrs
’ growth in scope. Instead of putting everything into the examples page, we have started to extract narrative chapters.So far, we’ve added chapters on initialization and hashing.
Expect more to come!
17.4.0 - 2017-12-30¶
Backward-incompatible Changes¶
The traversal of MROs when using multiple inheritance was backward: If you defined a class
C
that subclassesA
andB
likeC(A, B)
,attrs
would have collected the attributes fromB
before those ofA
.This is now fixed and means that in classes that employ multiple inheritance, the output of
__repr__
and the order of positional arguments in__init__
changes. Because of the nature of this bug, a proper deprecation cycle was unfortunately impossible.Generally speaking, it’s advisable to prefer
kwargs
-based initialization anyways – especially if you employ multiple inheritance and diamond-shaped hierarchies.The
__repr__
set byattrs
no longer produces anAttributeError
when the instance is missing some of the specified attributes (either through deleting or after usinginit=False
on some attributes).This can break code that relied on
repr(attr_cls_instance)
raisingAttributeError
to check if anyattrs
-specified members were unset.If you were using this, you can implement a custom method for checking this:
def has_unset_members(self): for field in attr.fields(type(self)): try: getattr(self, field.name) except AttributeError: return True return False
Deprecations¶
The
attr.ib(convert=callable)
option is now deprecated in favor ofattr.ib(converter=callable)
.This is done to achieve consistency with other noun-based arguments like validator.
convert will keep working until at least January 2019 while raising a
DeprecationWarning
.
Changes¶
Generated
__hash__
methods now hash the class type along with the attribute values. Until now the hashes of two classes with the same values were identical which was a bug.The generated method is also much faster now.
attr.ib
’s metadata argument now defaults to a unique emptydict
instance instead of sharing a common emptydict
for all. The singleton emptydict
is still enforced.ctypes
is optional now however if it’s missing, a baresuper()
will not work in slotted classes. This should only happen in special environments like Google App Engine.The attribute redefinition feature introduced in 17.3.0 now takes into account if an attribute is redefined via multiple inheritance. In that case, the definition that is closer to the base of the class hierarchy wins.
Subclasses of
auto_attribs=True
can be empty now.Equality tests are much faster now.
All generated methods now have correct
__module__
,__name__
, and (on Python 3)__qualname__
attributes.
17.3.0 - 2017-11-08¶
Backward-incompatible Changes¶
Attributes are no longer defined on the class body.
This means that if you define a class
C
with an attributex
, the class will not have an attributex
for introspection. Instead ofC.x
, useattr.fields(C).x
or look atC.__attrs_attrs__
. The old behavior has been deprecated since version 16.1. (#253)
Changes¶
super()
and__class__
now work with slotted classes on Python 3. (#102, #226, #269, #270, #272)Added type argument to
attr.ib()
and correspondingtype
attribute toattr.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 ofattr.Attribute.type
can alternately be set using variable type annotations (see PEP 526). (#151, #214, #215, #239)The combination of
str=True
andslots=True
now works on Python 2. (#198)attr.Factory
is hashable again. (#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, #229)
Added new option auto_attribs to
@attr.s
that allows to collect annotated fields without setting them toattr.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 asattr.ib(default=value)
– passing an instance ofattr.Factory
also works as expected. (#262, #277)Instances of classes created using
attr.make_class()
can now be pickled. (#282)
17.2.0 - 2017-05-24¶
Changes:¶
Validators are hashable again. Note that validators may become frozen in the future, pending availability of no-overhead frozen classes. #192
17.1.0 - 2017-05-16¶
To encourage more participation, the project has also been moved into a dedicated GitHub organization and everyone is most welcome to join!
attrs
also has a logo now!
Backward-incompatible Changes:¶
attrs
will set the__hash__()
method toNone
by default now. The way hashes were handled before was in conflict with Python’s specification. This may break some software although this breakage is most likely just surfacing of latent bugs. You can always makeattrs
create the__hash__()
method using@attr.s(hash=True)
. See #136 for the rationale of this change.Warning
Please do not upgrade blindly and do test your software! Especially if you use instances as dict keys or put them into sets!
Correspondingly,
attr.ib
’s hash argument isNone
by default too and mirrors the cmp argument as it should.
Deprecations:¶
attr.assoc()
is now deprecated in favor ofattr.evolve()
and will stop working in 2018.
Changes:¶
Fix default hashing behavior. Now hash mirrors the value of cmp and classes are unhashable by default. #136 #142
Added
attr.evolve()
that, given an instance of anattrs
class and field changes as keyword arguments, will instantiate a copy of the given instance with the changes applied.evolve()
replacesassoc()
, which is now deprecated.evolve()
is significantly faster thanassoc()
, and requires the class have an initializer that can take the field values as keyword arguments (likeattrs
itself can generate). #116 #124 #135FrozenInstanceError
is now raised when trying to delete an attribute from a frozen class. #118Frozen-ness of classes is now inherited. #128
__attrs_post_init__()
is now run if validation is disabled. #130Added
attr.validators.in_(options)
that, given the allowedoptions
, checks whether the attribute value is in it. This can be used to check constants, enums, mappings, etc. #181Added
attr.validators.and_()
that composes multiple validators into one. #161For convenience, the validator argument of
@attr.s
now can take a list of validators that are wrapped usingand_()
. #138Accordingly,
attr.validators.optional()
now can take a list of validators too. #161Validators can now be defined conveniently inline by using the attribute as a decorator. Check out the validator examples to see it in action! #143
attr.Factory()
now has a takes_self argument that makes the initializer to pass the partially initialized instance into the factory. In other words you can define attribute defaults based on other attributes. #165 #189Default factories can now also be defined inline using decorators. They are always passed the partially initialized instance. #165
Conversion can now be made optional using
attr.converters.optional()
. #105 #173attr.make_class()
now accepts the keyword argumentbases
which allows for subclassing. #152Metaclasses are now preserved with
slots=True
. #155
16.3.0 - 2016-11-24¶
Changes:¶
Attributes now can have user-defined metadata which greatly improves
attrs
’s extensibility. #96Allow for a
__attrs_post_init__()
method that – if defined – will get called at the end of theattrs
-generated__init__()
method. #111Added
@attr.s(str=True)
that will optionally create a__str__()
method that is identical to__repr__()
. This is mainly useful withException
s and other classes that rely on a useful__str__()
implementation but overwrite the default one through a poor own one. Default Python class behavior is to use__repr__()
as__str__()
anyways.If you tried using
attrs
withException
s and were puzzled by the tracebacks: this option is for you.__name__
is no longer overwritten with__qualname__
forattr.s(slots=True)
classes. #99
16.2.0 - 2016-09-17¶
Changes:¶
Added
attr.astuple()
that – similarly toattr.asdict()
– returns the instance as a tuple. #77Converters now work with frozen classes. #76
Instantiation of
attrs
classes with converters is now significantly faster. #80Pickling now works with slotted classes. #81
attr.assoc()
now works with slotted classes. #84The tuple returned by
attr.fields()
now also allows to access theAttribute
instances by name. Yes, we’ve subclassedtuple
so you don’t have to! Thereforeattr.fields(C).x
is equivalent to the deprecatedC.x
and works with slotted classes. #88
16.1.0 - 2016-08-30¶
Backward-incompatible Changes:¶
All instances where function arguments were called
cl
have been changed to the more Pythoniccls
. Since it was always the first argument, it’s doubtful anyone ever called those function with in the keyword form. If so, sorry for any breakage but there’s no practical deprecation path to solve this ugly wart.
Deprecations:¶
Accessing
Attribute
instances on class objects is now deprecated and will stop working in 2017. If you need introspection please use the__attrs_attrs__
attribute or theattr.fields()
function that carry them too. In the future, the attributes that are defined on the class body and are usually overwritten in your__init__
method are simply removed after@attr.s
has been applied.This will remove the confusing error message if you write your own
__init__
and forget to initialize some attribute. Instead you will get a straightforwardAttributeError
. In other words: decorated classes will work more like plain Python classes which was alwaysattrs
’s goal.The serious-business aliases
attr.attributes
andattr.attr
have been deprecated in favor ofattr.attrs
andattr.attrib
which are much more consistent and frankly obvious in hindsight. They will be purged from documentation immediately but there are no plans to actually remove them.
Changes:¶
attr.asdict()
’sdict_factory
arguments is now propagated on recursion. #45attr.asdict()
,attr.has()
andattr.fields()
are significantly faster. #48 #51Add
attr.attrs
andattr.attrib
as a more consistent aliases forattr.s
andattr.ib
.Add frozen option to
attr.s
that will make instances best-effort immutable. #60attr.asdict()
now takesretain_collection_types
as an argument. IfTrue
, it does not convert attributes of typetuple
orset
tolist
. #69
16.0.0 - 2016-05-23¶
Backward-incompatible Changes:¶
Python 3.3 and 2.6 are no longer supported. They may work by chance but any effort to keep them working has ceased.
The last Python 2.6 release was on October 29, 2013 and is no longer supported by the CPython core team. Major Python packages like Django and Twisted dropped Python 2.6 a while ago already.
Python 3.3 never had a significant user base and wasn’t part of any distribution’s LTS release.
Changes:¶
__slots__
have arrived! Classes now can automatically be slotted-style (and save your precious memory) just by passingslots=True
. #35Allow the case of initializing attributes that are set to
init=False
. This allows for clean initializer parameter lists while being able to initialize attributes to default values. #32attr.asdict()
can now produce arbitrary mappings instead of Pythondict
s when provided with adict_factory
argument. #40Multiple performance improvements.
15.2.0 - 2015-12-08¶
Changes:¶
15.1.0 - 2015-08-20¶
Changes:¶
15.0.0 - 2015-04-15¶
Changes:¶
Initial release.