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Remove Django negativity; move converter to Rejected Ideas (#2488)

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Erik De Bonte 2022-03-30 19:12:17 -07:00 committed by GitHub
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@ -699,9 +699,6 @@ As this is not broadly applicable to dataclass libraries, this
additional logic is not accommodated with this proposal, so additional logic is not accommodated with this proposal, so
users of Django would need to explicitly declare the ``id`` field. users of Django would need to explicitly declare the ``id`` field.
This limitation may make it impractical to use the
``dataclass_transform`` mechanism with Django.
Class-wide default values Class-wide default values
------------------------- -------------------------
@ -714,33 +711,30 @@ We chose not to support this feature, since it is specific to
SQLAlchemy. Users can manually set ``default=None`` on these fields SQLAlchemy. Users can manually set ``default=None`` on these fields
instead. instead.
Open Issues
===========
``converter`` field descriptor parameter ``converter`` field descriptor parameter
---------------------------------------- ----------------------------------------
The attrs library supports a ``converter`` field descriptor parameter, The attrs library supports a ``converter`` field descriptor parameter,
which is a callable that is called by the generated which is a ``Callable`` that is called by the generated
``__init__`` method to convert the supplied value to some other ``__init__`` method to convert the supplied value to some other
desired value. This is tricky to support since the parameter type in desired value. This is tricky to support since the parameter type in
the synthesized __init__ method needs to accept uncovered values, but the synthesized ``__init__`` method needs to accept uncovered values,
the resulting field is typed according to the output of the converter. but the resulting field is typed according to the output of the
converter.
There may be no good way to support this because there's not enough
information to derive the type of the input parameter. We currently
have two ideas:
1. Add support for a ``converter`` field descriptor parameter but then
use the Any type for the corresponding parameter in the __init__
method.
2. Say that converters are unsupported and recommend that attrs users
avoid them.
Some aspects of this issue are detailed in a Some aspects of this issue are detailed in a
`Pyright discussion <#converters_>`_. `Pyright discussion <#converters_>`_.
There may be no good way to support this because there's not enough
information to derive the type of the input parameter. One possible
solution would be to add support for a ``converter`` field descriptor
parameter but then use the ``Any`` type for the corresponding
parameter in the ``__init__`` method.
We chose not to support this feature and recommend that attrs users
avoid converters.
References References
========== ==========
.. _#dataclass-docs: https://docs.python.org/3.11/library/dataclasses.html .. _#dataclass-docs: https://docs.python.org/3.11/library/dataclasses.html