Metadata-Version: 2.1
Name: attrs
Version: 20.3.0
Summary: Classes Without Boilerplate
Home-page: https://www.attrs.org/
Author: Hynek Schlawack
Author-email: hs@ox.cx
Maintainer: Hynek Schlawack
Maintainer-email: hs@ox.cx
License: MIT
Project-URL: Documentation, https://www.attrs.org/
Project-URL: Bug Tracker, https://github.com/python-attrs/attrs/issues
Project-URL: Source Code, https://github.com/python-attrs/attrs
Project-URL: Funding, https://github.com/sponsors/hynek
Project-URL: Tidelift, https://tidelift.com/subscription/pkg/pypi-attrs?utm_source=pypi-attrs&utm_medium=pypi
Keywords: class,attribute,boilerplate
Platform: UNKNOWN
Classifier: Development Status :: 5 - Production/Stable
Classifier: Intended Audience :: Developers
Classifier: Natural Language :: English
Classifier: License :: OSI Approved :: MIT License
Classifier: Operating System :: OS Independent
Classifier: Programming Language :: Python
Classifier: Programming Language :: Python :: 2
Classifier: Programming Language :: Python :: 2.7
Classifier: Programming Language :: Python :: 3
Classifier: Programming Language :: Python :: 3.5
Classifier: Programming Language :: Python :: 3.6
Classifier: Programming Language :: Python :: 3.7
Classifier: Programming Language :: Python :: 3.8
Classifier: Programming Language :: Python :: 3.9
Classifier: Programming Language :: Python :: Implementation :: CPython
Classifier: Programming Language :: Python :: Implementation :: PyPy
Classifier: Topic :: Software Development :: Libraries :: Python Modules
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.. image:: https://www.attrs.org/en/latest/_static/attrs_logo.png
   :alt: attrs Logo

======================================
``attrs``: Classes Without Boilerplate
======================================

.. image:: https://readthedocs.org/projects/attrs/badge/?version=stable
   :target: https://www.attrs.org/en/stable/?badge=stable
   :alt: Documentation Status

.. image:: https://github.com/python-attrs/attrs/workflows/CI/badge.svg?branch=master
   :target: https://github.com/python-attrs/attrs/actions?workflow=CI
   :alt: CI Status

.. image:: https://codecov.io/github/python-attrs/attrs/branch/master/graph/badge.svg
   :target: https://codecov.io/github/python-attrs/attrs
   :alt: Test Coverage

.. image:: https://img.shields.io/badge/code%20style-black-000000.svg
   :target: https://github.com/psf/black
   :alt: Code style: black

.. teaser-begin

``attrs`` is the Python package that will bring back the **joy** of **writing classes** by relieving you from the drudgery of implementing object protocols (aka `dunder <https://nedbatchelder.com/blog/200605/dunder.html>`_ methods).

Its main goal is to help you to write **concise** and **correct** software without slowing down your code.

.. teaser-end

For that, it gives you a class decorator and a way to declaratively define the attributes on that class:

.. -code-begin-

.. code-block:: pycon

   >>> import attr

   >>> @attr.s
   ... class SomeClass(object):
   ...     a_number = attr.ib(default=42)
   ...     list_of_numbers = attr.ib(factory=list)
   ...
   ...     def hard_math(self, another_number):
   ...         return self.a_number + sum(self.list_of_numbers) * another_number


   >>> sc = SomeClass(1, [1, 2, 3])
   >>> sc
   SomeClass(a_number=1, list_of_numbers=[1, 2, 3])

   >>> sc.hard_math(3)
   19
   >>> sc == SomeClass(1, [1, 2, 3])
   True
   >>> sc != SomeClass(2, [3, 2, 1])
   True

   >>> attr.asdict(sc)
   {'a_number': 1, 'list_of_numbers': [1, 2, 3]}

   >>> SomeClass()
   SomeClass(a_number=42, list_of_numbers=[])

   >>> C = attr.make_class("C", ["a", "b"])
   >>> C("foo", "bar")
   C(a='foo', b='bar')


After *declaring* your attributes ``attrs`` gives you:

- a concise and explicit overview of the class's attributes,
- a nice human-readable ``__repr__``,
- a complete set of comparison methods (equality and ordering),
- an initializer,
- and much more,

*without* writing dull boilerplate code again and again and *without* runtime performance penalties.

On Python 3.6 and later, you can often even drop the calls to ``attr.ib()`` by using `type annotations <https://www.attrs.org/en/latest/types.html>`_.

This gives you the power to use actual classes with actual types in your code instead of confusing ``tuple``\ s or `confusingly behaving <https://www.attrs.org/en/stable/why.html#namedtuples>`_ ``namedtuple``\ s.
Which in turn encourages you to write *small classes* that do `one thing well <https://www.destroyallsoftware.com/talks/boundaries>`_.
Never again violate the `single responsibility principle <https://en.wikipedia.org/wiki/Single_responsibility_principle>`_ just because implementing ``__init__`` et al is a painful drag.


.. -getting-help-

Getting Help
============

Please use the ``python-attrs`` tag on `StackOverflow <https://stackoverflow.com/questions/tagged/python-attrs>`_ to get help.

Answering questions of your fellow developers is also a great way to help the project!


.. -project-information-

Project Information
===================

``attrs`` is released under the `MIT <https://choosealicense.com/licenses/mit/>`_ license,
its documentation lives at `Read the Docs <https://www.attrs.org/>`_,
the code on `GitHub <https://github.com/python-attrs/attrs>`_,
and the latest release on `PyPI <https://pypi.org/project/attrs/>`_.
It’s rigorously tested on Python 2.7, 3.5+, and PyPy.

We collect information on **third-party extensions** in our `wiki <https://github.com/python-attrs/attrs/wiki/Extensions-to-attrs>`_.
Feel free to browse and add your own!

If you'd like to contribute to ``attrs`` you're most welcome and we've written `a little guide <https://www.attrs.org/en/latest/contributing.html>`_ to get you started!


``attrs`` for Enterprise
------------------------

Available as part of the Tidelift Subscription.

The maintainers of ``attrs`` and thousands of other packages are working with Tidelift to deliver commercial support and maintenance for the open source packages you use to build your applications.
Save time, reduce risk, and improve code health, while paying the maintainers of the exact packages you use.
`Learn more. <https://tidelift.com/subscription/pkg/pypi-attrs?utm_source=pypi-attrs&utm_medium=referral&utm_campaign=enterprise&utm_term=repo>`_


Release Information
===================

20.3.0 (2020-11-05)
-------------------

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 <https://gist.github.com/hynek/1e3844d0c99e479e716169034b5fa963#file-attrs_ng_plugin-py>`_ 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 <https://github.com/python-attrs/attrs/issues/668>`_


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 <https://github.com/python-attrs/attrs/issues/653>`_
- ``kw_only=True`` now works on Python 2.
  `#700 <https://github.com/python-attrs/attrs/issues/700>`_
- ``raise from`` now works on frozen classes on PyPy.
  `#703 <https://github.com/python-attrs/attrs/issues/703>`_,
  `#712 <https://github.com/python-attrs/attrs/issues/712>`_
- ``attr.asdict()`` and ``attr.astuple()`` now treat ``frozenset``\ s like ``set``\ s with regards to the *retain_collection_types* argument.
  `#704 <https://github.com/python-attrs/attrs/issues/704>`_
- The type stubs for ``attr.s()`` and ``attr.make_class()`` are not missing the *collect_by_mro* argument anymore.
  `#711 <https://github.com/python-attrs/attrs/issues/711>`_

`Full changelog <https://www.attrs.org/en/stable/changelog.html>`_.

Credits
=======

``attrs`` is written and maintained by `Hynek Schlawack <https://hynek.me/>`_.

The development is kindly supported by `Variomedia AG <https://www.variomedia.de/>`_.

A full list of contributors can be found in `GitHub's overview <https://github.com/python-attrs/attrs/graphs/contributors>`_.

It’s the spiritual successor of `characteristic <https://characteristic.readthedocs.io/>`_ and aspires to fix some of it clunkiness and unfortunate decisions.
Both were inspired by Twisted’s `FancyEqMixin <https://twistedmatrix.com/documents/current/api/twisted.python.util.FancyEqMixin.html>`_ but both are implemented using class decorators because `subclassing is bad for you <https://www.youtube.com/watch?v=3MNVP9-hglc>`_, m’kay?