attrs 22.2: Field Alias

Overview

attrs 22.2, released on December 21, 2022, adds the alias option for renaming fields at initialization.

Main Features

Field alias

The alias option defines an alternative name for the constructor parameter, useful for JSON APIs or Python reserved names.

import attrs

@attrs.define
class Item:
    name: str
    class_: str = attrs.field(alias='class')

# Using the alias name
item = Item(name='widget', **{'class': 'premium'})
print(item.class_)  # 'premium'

Internal improvements

Internal code now uses slots by default with attrs.define, improving performance and reducing memory usage.

import attrs

# attrs.define uses slots by default
@attrs.define
class Coord:
    x: float
    y: float
    z: float = 0.0

c = Coord(1.0, 2.0)
print(c.__slots__)  # ('x', 'y', 'z')

Sources

• attrs Changelog