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hynekhynek
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Refactor class creation (#272)
Instead of adding and possibly later deleting attributes, the class creation is delegated into a cleaner building pattern.
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‎CHANGELOG.rst‎

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^^^^^^^^
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- ``__slots__`` have arrived!
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Classes now can automatically be `slots <https://docs.python.org/3.5/reference/datamodel.html#slots>`_-style (and save your precious memory) just by passing ``slots=True``.
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Classes now can automatically be `slots <https://docs.python.org/3/reference/datamodel.html#slots>`_-style (and save your precious memory) just by passing ``slots=True``.
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`#35 <https://github.com/python-attrs/attrs/issues/35>`_
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- Allow the case of initializing attributes that are set to ``init=False``.
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This allows for clean initializer parameter lists while being able to initialize attributes to default values.

‎README.rst‎

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-- **Kenneth Reitz**, author of `requests <http://www.python-requests.org/>`_, Python Overlord at Heroku, `on paper no less <https://twitter.com/hynek/status/866817877650751488>`_
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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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Answering questions of your fellow developers is also great way to help the project!
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.. -end-
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.. -project-information-
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Project Information
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===================

‎changelog.d/269.change.rst‎

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``super()`` and ``__class__`` now work on Python 3 when ``slots=True``.

‎changelog.d/270.change.rst‎

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``super()`` and ``__class__`` now work on Python 3 when ``slots=True``.

‎changelog.d/272.change.rst‎

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``super()`` and ``__class__`` now work on Python 3 when ``slots=True``.

‎conftest.py‎

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collect_ignore = []
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if sys.version_info[:2] < (3, 6):
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collect_ignore.append("tests/test_annotations.py")
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collect_ignore.extend([
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"tests/test_annotations.py",
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"tests/test_init_subclass.py",
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])

‎docs/examples.rst‎

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This wastes space for objects having very few data attributes.
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The space consumption can become significant when creating large numbers of instances.
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Normal Python classes can avoid using a separate dictionary for each instance of a class by `defining <https://docs.python.org/3.5/reference/datamodel.html#slots>`_ ``__slots__``.
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Normal Python classes can avoid using a separate dictionary for each instance of a class by `defining <https://docs.python.org/3/reference/datamodel.html#slots>`_ ``__slots__``.
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For ``attrs`` classes it's enough to set ``slots=True``:
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.. doctest::
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...
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AttributeError: 'Coordinates' object has no attribute 'z'
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- Since non-slot classes cannot be turned into slot classes after they have been created, ``attr.s(.., slots=True)`` will *replace* the class it is applied to with a copy.
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- Since non-slot classes cannot be turned into slot classes after they have been created, ``attr.s(slots=True)`` will *replace* the class it is applied to with a copy.
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In almost all cases this isn't a problem, but we mention it for the sake of completeness.
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* One notable problem is that certain metaclass features like ``__init_subclass__`` do not work with slot classes.
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- Using :mod:`pickle` with slot classes requires pickle protocol 2 or greater.
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Python 2 uses protocol 0 by default so the protocol needs to be specified.
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Python 3 uses protocol 3 by default.

‎docs/how-does-it-work.rst‎

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Please note that ``attrs`` does *not* call ``super()`` *ever*.
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It will write dunder methods to work on *all* of those attributes which also has performance benefits due to fewer function calls.
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Once ``attrs`` knows what attributes it has to work on, it writes the requested dunder methods and attaches them to your class.
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Once ``attrs`` knows what attributes it has to work on, it writes the requested dunder methods and -- depending on whether you wish to have ``__slots__`` -- creates a new class for you (``slots=True``) or attaches them to the original class (``slots=False``).
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While creating new classes is more elegant, we've run into several edge cases surrounding metaclasses that make it impossible to go this route unconditionally.
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To be very clear: if you define a class with a single attribute without a default value, the generated ``__init__`` will look *exactly* how you'd expect:
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.. doctest::
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>>> import attr, inspect
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>>> @attr.s
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... class C:
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... class C(object):
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... x = attr.ib()
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>>> print(inspect.getsource(C.__init__))
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def __init__(self, x):

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