Metadata-Version: 2.1
Name: attrs
Version: 19.2.0
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
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 :: 3.4
Classifier: Programming Language :: Python :: 3.5
Classifier: Programming Language :: Python :: 3.6
Classifier: Programming Language :: Python :: 3.7
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://attrs.visualstudio.com/attrs/_apis/build/status/python-attrs.attrs?branchName=master
   :target: https://attrs.visualstudio.com/attrs/_build/latest?definitionId=1&branchName=master
   :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.

.. -spiel-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.


.. -testimonials-

Testimonials
============

**Amber Hawkie Brown**, Twisted Release Manager and Computer Owl:

  Writing a fully-functional class using attrs takes me less time than writing this testimonial.


**Glyph Lefkowitz**, creator of `Twisted <https://twistedmatrix.com/>`_, `Automat <https://pypi.org/project/Automat/>`_, and other open source software, in `The One Python Library Everyone Needs <https://glyph.twistedmatrix.com/2016/08/attrs.html>`_:

  I’m looking forward to is being able to program in Python-with-attrs everywhere.
  It exerts a subtle, but positive, design influence in all the codebases I’ve see it used in.


**Kenneth Reitz**, creator of `Requests <https://github.com/psf/requests>`_ (`on paper no less <https://twitter.com/hynek/status/866817877650751488>`_!):

  attrs—classes for humans.  I like it.


**Łukasz Langa**, creator of `Black <https://github.com/psf/black>`_, prolific Python core developer, and release manager for Python 3.8 and 3.9:

  I'm increasingly digging your attr.ocity. Good job!


.. -end-

.. -project-information-

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 great way to help the project!


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, 3.4+, 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!


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

19.2.0 (2019-10-01)
-------------------

Backward-incompatible Changes
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

- Removed deprecated ``Attribute`` attribute ``convert`` per scheduled removal on 2019/1.
  This planned deprecation is tracked in issue `#307 <https://github.com/python-attrs/attrs/issues/307>`_.
  `#504 <https://github.com/python-attrs/attrs/issues/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 <https://github.com/python-attrs/attrs/issues/570>`_


Deprecations
^^^^^^^^^^^^

- 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 – just like with `dataclasses <https://docs.python.org/3/library/dataclasses.html>`_.

  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 <https://github.com/python-attrs/attrs/issues/574>`_


Changes
^^^^^^^

- Updated ``attr.validators.__all__`` to include new validators added in `#425`_.
  `#517 <https://github.com/python-attrs/attrs/issues/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 <https://github.com/python-attrs/attrs/issues/522>`_
- When collecting attributes using ``@attr.s(auto_attribs=True)``, attributes with a default of ``None`` are now deleted too.
  `#523 <https://github.com/python-attrs/attrs/issues/523>`_,
  `#556 <https://github.com/python-attrs/attrs/issues/556>`_
- Fixed ``attr.validators.deep_iterable()`` and ``attr.validators.deep_mapping()`` type stubs.
  `#533 <https://github.com/python-attrs/attrs/issues/533>`_
- ``attr.validators.is_callable()`` validator now raises an exception ``attr.exceptions.NotCallableError``, a subclass of ``TypeError``, informing the received value.
  `#536 <https://github.com/python-attrs/attrs/issues/536>`_
- ``@attr.s(auto_exc=True)`` now generates classes that are hashable by ID, as the documentation always claimed it would.
  `#543 <https://github.com/python-attrs/attrs/issues/543>`_,
  `#563 <https://github.com/python-attrs/attrs/issues/563>`_
- Added ``attr.validators.matches_re()`` that checks string attributes whether they match a regular expression.
  `#552 <https://github.com/python-attrs/attrs/issues/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 <https://github.com/python-attrs/attrs/issues/559>`_
- The fake filename for generated methods is now more stable.
  It won't change when you restart the process.
  `#560 <https://github.com/python-attrs/attrs/issues/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.
  `#568 <https://github.com/python-attrs/attrs/issues/568>`_
- 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 <http://www.attrs.org/en/stable/api.html#deprecated-apis>`_ on how to use it.
  `#580 <https://github.com/python-attrs/attrs/issues/580>`_

 .. _`#425`: https://github.com/python-attrs/attrs/issues/425

`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?