139 lines
5.1 KiB
ReStructuredText
139 lines
5.1 KiB
ReStructuredText
.. image:: https://www.attrs.org/en/latest/_static/attrs_logo.png
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:alt: attrs Logo
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======================================
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``attrs``: Classes Without Boilerplate
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======================================
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.. image:: https://readthedocs.org/projects/attrs/badge/?version=stable
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:target: https://www.attrs.org/en/stable/?badge=stable
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:alt: Documentation Status
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.. image:: https://attrs.visualstudio.com/attrs/_apis/build/status/python-attrs.attrs?branchName=master
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:target: https://attrs.visualstudio.com/attrs/_build/latest?definitionId=1&branchName=master
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:alt: CI Status
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.. image:: https://codecov.io/github/python-attrs/attrs/branch/master/graph/badge.svg
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:target: https://codecov.io/github/python-attrs/attrs
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:alt: Test Coverage
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.. image:: https://img.shields.io/badge/code%20style-black-000000.svg
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:target: https://github.com/psf/black
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:alt: Code style: black
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.. teaser-begin
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``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).
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Its main goal is to help you to write **concise** and **correct** software without slowing down your code.
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.. -spiel-end-
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For that, it gives you a class decorator and a way to declaratively define the attributes on that class:
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.. -code-begin-
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.. code-block:: pycon
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>>> import attr
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>>> @attr.s
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... class SomeClass(object):
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... a_number = attr.ib(default=42)
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... list_of_numbers = attr.ib(factory=list)
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...
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... def hard_math(self, another_number):
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... return self.a_number + sum(self.list_of_numbers) * another_number
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>>> sc = SomeClass(1, [1, 2, 3])
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>>> sc
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SomeClass(a_number=1, list_of_numbers=[1, 2, 3])
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>>> sc.hard_math(3)
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19
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>>> sc == SomeClass(1, [1, 2, 3])
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True
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>>> sc != SomeClass(2, [3, 2, 1])
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True
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>>> attr.asdict(sc)
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{'a_number': 1, 'list_of_numbers': [1, 2, 3]}
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>>> SomeClass()
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SomeClass(a_number=42, list_of_numbers=[])
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>>> C = attr.make_class("C", ["a", "b"])
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>>> C("foo", "bar")
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C(a='foo', b='bar')
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After *declaring* your attributes ``attrs`` gives you:
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- a concise and explicit overview of the class's attributes,
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- a nice human-readable ``__repr__``,
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- a complete set of comparison methods,
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- an initializer,
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- and much more,
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*without* writing dull boilerplate code again and again and *without* runtime performance penalties.
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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>`_.
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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.
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Which in turn encourages you to write *small classes* that do `one thing well <https://www.destroyallsoftware.com/talks/boundaries>`_.
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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.
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.. -testimonials-
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Testimonials
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============
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**Amber Hawkie Brown**, Twisted Release Manager and Computer Owl:
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Writing a fully-functional class using attrs takes me less time than writing this testimonial.
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**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>`_:
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I’m looking forward to is being able to program in Python-with-attrs everywhere.
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It exerts a subtle, but positive, design influence in all the codebases I’ve see it used in.
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**Kenneth Reitz**, creator of `Requests <https://github.com/psf/requests>`_ (`on paper no less <https://twitter.com/hynek/status/866817877650751488>`_!):
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attrs—classes for humans. I like it.
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**Łukasz Langa**, creator of `Black <https://github.com/psf/black>`_, prolific Python core developer, and release manager for Python 3.8 and 3.9:
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I'm increasingly digging your attr.ocity. Good job!
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.. -end-
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.. -project-information-
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Getting Help
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============
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Please use the ``python-attrs`` tag on `StackOverflow <https://stackoverflow.com/questions/tagged/python-attrs>`_ to get help.
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Answering questions of your fellow developers is also great way to help the project!
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Project Information
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===================
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``attrs`` is released under the `MIT <https://choosealicense.com/licenses/mit/>`_ license,
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its documentation lives at `Read the Docs <https://www.attrs.org/>`_,
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the code on `GitHub <https://github.com/python-attrs/attrs>`_,
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and the latest release on `PyPI <https://pypi.org/project/attrs/>`_.
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It’s rigorously tested on Python 2.7, 3.4+, and PyPy.
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We collect information on **third-party extensions** in our `wiki <https://github.com/python-attrs/attrs/wiki/Extensions-to-attrs>`_.
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Feel free to browse and add your own!
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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!
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