Document dataclass field should not be reused

Documentation

The current implementation of dataclass modifies a field in place. Thereby, the following code will modify f:

from dataclasses import dataclass, field

f = field(kw_only=True)

@dataclass
class A:
    x: int = f
    y: int = f

print(f) # now f.name is filled
# furthermore, A is broken (or does not behave if we used two different field instance)

It can create issues when we have multiple fields that have the same spec and we reuse the same Field instance to set the same metadata to all of them. A class is created but it's garbage.

IMHO, in the docs, we should warn the user to NOT share any Field instance.

Linked PRs

• gh-145373
• gh-145387

Commencez par examiner la documentation de dataclass et de Field ainsi que les PR liés gh-145373 et gh-145387. Ajoutez un avertissement clair indiquant de ne pas réutiliser une instance de Field entre plusieurs champs de dataclass, et considérez l’exemple de l’issue comme complet lorsque les indications documentées traitent la mutation qui en résulte et le comportement défaillant de la classe.