[英]Python dataclass: Forcing a dictionary field to be a deep copy
I am working with a dataclass that contains a dict.我正在使用包含字典的数据类。
I want the dict to be a deepcopy, without having to rely on a post_init call, which would basically void to interest of a dataclass我希望 dict 成为一个深层副本,而不必依赖post_init调用,这基本上会使数据类失去兴趣
What would be a nice solution?什么是好的解决方案?
from dataclasses import dataclass, field
from typing import Dict
@dataclass
class ClassWithDict:
the_dict: Dict = field(default_factory=dict, kw_only=True)
toto = {"toto": "tata"}
the_class = ClassWithDict(the_dict=toto)
assert toto == the_class.the_dict
assert toto is not the_class.the_dict # FALSE
Solution, if not wanting to use a __post__init__
using the object.setattr
method to force a copy once the object is initialized, is to use a metaclass
:解决方案,如果不想使用
__post__init__
使用object.setattr
方法在初始化 object 后强制复制,则使用metaclass
:
import copy
from dataclasses import dataclass, field
from typing import Dict
class DataClassWithDeepCopyMeta(type):
def __call__(cls, *args, **kwargs):
args = copy.deepcopy(args)
kwargs = copy.deepcopy(kwargs)
return super().__call__(*args, **kwargs)
@dataclass
class ClassWithDict(metaclass=DataClassWithDeepCopyMeta):
the_dict: Dict = field(default_factory=dict)
toto = {"toto": "tata"}
the_class = ClassWithDict(toto)
assert toto == the_class.the_dict
assert toto is not the_class.the_dict
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