| .. image:: https://www.attrs.org/en/latest/_static/attrs_logo.png |
| :alt: attrs Logo |
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| ====================================== |
| ``attrs``: Classes Without Boilerplate |
| ====================================== |
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| .. image:: https://readthedocs.org/projects/attrs/badge/?version=stable |
| :target: https://www.attrs.org/en/stable/?badge=stable |
| :alt: Documentation Status |
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| .. image:: https://travis-ci.org/python-attrs/attrs.svg?branch=master |
| :target: https://travis-ci.org/python-attrs/attrs |
| :alt: CI Status |
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| .. image:: https://codecov.io/github/python-attrs/attrs/branch/master/graph/badge.svg |
| :target: https://codecov.io/github/python-attrs/attrs |
| :alt: Test Coverage |
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| .. image:: https://img.shields.io/badge/code%20style-black-000000.svg |
| :target: https://github.com/ambv/black |
| :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 |
| ... 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 |
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| >>> sc = SomeClass(1, [1, 2, 3]) |
| >>> sc |
| SomeClass(a_number=1, list_of_numbers=[1, 2, 3]) |
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| >>> sc.hard_math(3) |
| 19 |
| >>> sc == SomeClass(1, [1, 2, 3]) |
| True |
| >>> sc != SomeClass(2, [3, 2, 1]) |
| True |
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| >>> attr.asdict(sc) |
| {'a_number': 1, 'list_of_numbers': [1, 2, 3]} |
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| >>> SomeClass() |
| SomeClass(a_number=42, list_of_numbers=[]) |
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| >>> C = attr.make_class("C", ["a", "b"]) |
| >>> C("foo", "bar") |
| 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, |
| - a nice human-readable ``__repr__``, |
| - a complete set of comparison methods, |
| - an initializer, |
| - 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. |
| 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. |
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| .. -testimonials- |
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| Testimonials |
| ============ |
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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. |
| It exerts a subtle, but positive, design influence in all the codebases I’ve see it used in. |
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| **Kenneth Reitz**, author of `Requests <http://www.python-requests.org/>`_ and Developer Advocate at DigitalOcean, (`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**, prolific CPython core developer and Production Engineer at Facebook: |
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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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| 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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| ``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. |
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| 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! |
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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! |