137 lines
5.4 KiB
ReStructuredText
137 lines
5.4 KiB
ReStructuredText
.. raw:: html
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<p align="center">
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<a href="https://www.attrs.org/">
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<img src="./docs/_static/attrs_logo.svg" width="35%" alt="attrs" />
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</a>
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</p>
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<p align="center">
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<a href="https://www.attrs.org/en/stable/?badge=stable">
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<img src="https://img.shields.io/badge/Docs-Read%20The%20Docs-black" alt="Documentation" />
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</a>
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<a href="https://github.com/python-attrs/attrs/blob/main/LICENSE">
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<img src="https://img.shields.io/badge/license-MIT-C06524" alt="License: MIT" />
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</a>
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<a href="https://pypi.org/project/attrs/">
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<img src="https://img.shields.io/pypi/v/attrs" />
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</a>
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</p>
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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 methods <https://www.attrs.org/en/latest/glossary.html#term-dunder-methods>`_).
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`Trusted by NASA <https://docs.github.com/en/account-and-profile/setting-up-and-managing-your-github-profile/customizing-your-profile/personalizing-your-profile#list-of-qualifying-repositories-for-mars-2020-helicopter-contributor-badge>`_ for Mars missions since 2020!
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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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.. teaser-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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>>> from attrs import asdict, define, make_class, Factory
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>>> @define
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... class SomeClass:
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... a_number: int = 42
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... list_of_numbers: list[int] = 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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>>> 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 = 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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- equality-checking 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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**Hate type annotations**!?
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No problem!
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Types are entirely **optional** with ``attrs``.
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Simply assign ``attrs.field()`` to the attributes instead of annotating them with types.
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----
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This example uses ``attrs``'s modern APIs that have been introduced in version 20.1.0, and the ``attrs`` package import name that has been added in version 21.3.0.
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The classic APIs (``@attr.s``, ``attr.ib``, plus their serious business aliases) and the ``attr`` package import name will remain **indefinitely**.
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Please check out `On The Core API Names <https://www.attrs.org/en/latest/names.html>`_ for a more in-depth explanation.
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Data Classes
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============
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On the tin, ``attrs`` might remind you of ``dataclasses`` (and indeed, ``dataclasses`` `are a descendant <https://hynek.me/articles/import-attrs/>`_ of ``attrs``).
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In practice it does a lot more and is more flexible.
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For instance it allows you to define `special handling of NumPy arrays for equality checks <https://www.attrs.org/en/stable/comparison.html#customization>`_, or allows more ways to `plug into the initialization process <https://www.attrs.org/en/stable/init.html#hooking-yourself-into-initialization>`_.
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For more details, please refer to our `comparison page <https://www.attrs.org/en/stable/why.html#data-classes>`_.
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.. -getting-help-
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Getting Help
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============
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Please use the ``python-attrs`` tag on `Stack Overflow <https://stackoverflow.com/questions/tagged/python-attrs>`_ to get help.
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Answering questions of your fellow developers is also a great way to help the project!
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.. -project-information-
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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 3.5+ and PyPy.
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The last version with Python 2.7 support is `21.4.0 <https://pypi.org/project/attrs/21.4.0/>`_.
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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://github.com/python-attrs/attrs/blob/main/.github/CONTRIBUTING.md>`_ to get you started!
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``attrs`` for Enterprise
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------------------------
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Available as part of the Tidelift Subscription.
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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.
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Save time, reduce risk, and improve code health, while paying the maintainers of the exact packages you use.
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`Learn more. <https://tidelift.com/subscription/pkg/pypi-attrs?utm_source=pypi-attrs&utm_medium=referral&utm_campaign=enterprise&utm_term=repo>`_
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