python / python/cpython

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

未關閉
#101,192 8 則留言 26 個 reaction 已指派 1 人 在 GitHub 檢視

@ericvsmith 已經在處理了。

開始於 2023年1月20日。

stdlib type-feature
主要語言
Python
星號
77.2k
分支
36k
PR 合併指標
PR 指標待擷取

描述

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

貢獻指南

開啟貢獻指南

從這裡開始

  1. 先讀完整個 Issue,再讀專案的貢獻指南。
  2. 在 Issue 下留言說明你要接手 —— 這能避免兩個人做同樣的事。
  3. Fork 儲存庫,在一個分支上完成修改。
  4. 送出 Pull Request,並在描述裡引用這個 Issue 編號。

評估

這個 Issue 還沒有評估資料。

把新 issue 寄到你的電子郵件信箱

精選適合新手參與的 GitHub issue 摘要。