如何解决 python3.11 dataclass 无法嵌套的问题？

  • Z时代
  • 2024-02-09
  • 分类：IT

如何解决 python3.11 dataclass 无法嵌套的问题？

from dataclasses import dataclass
@dataclass
class Address:
    street: str | None = None
    city: str | None = None
    state: str | None = None
@dataclass
class Person:
    name: str
    age: int
    address: Address = Address()

上面的代码，在 python3.10 下面没有问题

但是在 python3.11 上运行，就会报错

Traceback (most recent call last):
  File "/Users/ponponon/Desktop/code/me/ideaboom/3.py", line 11, in <module>
    @dataclass
     ^^^^^^^^^
  File "/opt/homebrew/Cellar/python@3.11/3.11.4/Frameworks/Python.framework/Versions/3.11/lib/python3.11/dataclasses.py", line 1230, in dataclass
    return wrap(cls)
           ^^^^^^^^^
  File "/opt/homebrew/Cellar/python@3.11/3.11.4/Frameworks/Python.framework/Versions/3.11/lib/python3.11/dataclasses.py", line 1220, in wrap
    return _process_class(cls, init, repr, eq, order, unsafe_hash,
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/homebrew/Cellar/python@3.11/3.11.4/Frameworks/Python.framework/Versions/3.11/lib/python3.11/dataclasses.py", line 958, in _process_class
    cls_fields.append(_get_field(cls, name, type, kw_only))
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/homebrew/Cellar/python@3.11/3.11.4/Frameworks/Python.framework/Versions/3.11/lib/python3.11/dataclasses.py", line 815, in _get_field
    raise ValueError(f'mutable default {type(f.default)} for field '
ValueError: mutable default <class '__main__.Address'> for field address is not allowed: use default_factory

回答：

from dataclasses import dataclass, field
@dataclass
class Address:
    street: str | None = None
    city: str | None = None
    state: str | None = None
@dataclass
class Person:
    name: str
    age: int
    address: Address = field(default_factory=Address)

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