如何使非冻结数据类冻结，反之亦然？

我想知道制作数据类的简单方法bar frozen.

@dataclass
class Bar:
    foo: int
bar = Bar(foo=1)

换句话说，我想要一个如下所示的函数some_fn_to_freeze

frozen_bar = some_fn_to_freeze(bar)
frozen_bar.foo = 2 # Error

并且，反函数some_fn_to_unfreeze

bar = som_fn_to_unfrozen(frozen_bar)
bar.foo = 3 # not Error

变异的标准方法frozen数据类是使用dataclasses.replace:

old_bar = Bar(foo=123)
new_bar = dataclasses.replace(old_bar, foo=456)
assert new_bar.foo == 456

对于更复杂的用例，您可以使用以下位置的 dataclass utils 模块：https://github.com/google/etils https://github.com/google/etils

它添加了一个my_dataclass = my_dataclass.unfrozen()成员，允许变异frozen直接数据类

# pip install etils[edc]
from etils import edc

@edc.dataclass(allow_unfrozen=True)  # Add the `unfrozen()`/`frozen` method
@dataclasses.dataclass(frozen=True)
class A:
  x: Any = None
  y: Any = None


old_a = A(x=A(x=A()))

# After a is unfrozen, the updates on nested attributes will be propagated
# to the top-level parent.
a = old_a.unfrozen()
a.x.x.x = 123
a.x.y = 'abc'
a = a.frozen()  # `frozen()` recursively call `dataclasses.replace`

# Only the `unfrozen` object is mutated. Not the original one.
assert a == A(x=A(x=A(x = 123), y='abc'))
assert old_a == A(x=A(x=A()))

如示例所示，您可以返回unfrozen/frozen数据类的副本，它被明确设计为改变嵌套数据类。

@edc.dataclass还添加一个a.replace(**kwargs)数据类的方法（别名为dataclasses.dataclass)

a = A()
a = a.replace(x=123, y=456)
assert a == A(x=123, y=456)