python / python/cpython

Add `alias` as a `field()` parameter for dataclasses

Abierto
#101,192 8 comentarios 26 reacciones 1 asignado Ver en GitHub

@ericvsmith ya está trabajando en esto.

Desde el 20/1/2023.

stdlib type-feature
Lenguaje dominante
Python
Estrellas
77.2k
Forks
36k
Métricas de merge de PR
Métricas de PR pendientes

Descripción

Feature or enhancement

Add an alias parameter to dataclasses.field() which behaves like alias in attrs.field() (see here and search for "alias"). It has the effect that it changes the corresponding argument name in the synthesized __init__.

Pitch

Since attrs 22.2.0, attrs.field has an alias parameter that does the following:

from attrs import define, field

@define
class C:
    _name: tuple[str, str] = field(alias="name")

    @property
    def full_name(self) -> str:
        return " ".join(self._name)

c = C(name=("John", "Smith"))  # `name` not `_name`
print(c.full_name)

The typical use-case for this is private instance variables as in the above example. But there could be other use-cases as well, like

@define
class C:
    viewport: tuple[int, int] = field(alias="vp")

C(vp=(2, 4))  # constructor uses shorthand

Besides being a useful feature in and of itself, another reason to add this to the standard library is that it would bring dataclasses in line with dataclass_transform which already supports the alias parameter in field(): https://peps.python.org/pep-0681/#field-specifier-parameters . It is currently a bit strange that dataclass_transform has a feature that dataclasses.dataclass doesn't actually have.

Previous discussion

https://discuss.python.org/t/add-alias-as-a-field-parameter-for-dataclasses/22988/1

Guía de contribución

Abrir la guía de contribución

Primeros pasos

  1. Lee el issue completo y luego la guía de contribución del proyecto.
  2. Comenta en el issue que vas a ocuparte — evita que dos personas hagan lo mismo.
  3. Haz un fork del repositorio y trabaja en una rama.
  4. Abre un pull request que haga referencia al número del issue.

Evaluación

Este issue todavía no se ha evaluado.

Recibe los nuevos issues en tu correo

Un resumen breve de issues de GitHub para principiantes.