archimedes.tree.struct.dataclass_transform¶

archimedes.tree.struct.dataclass_transform(*, eq_default: bool = True, order_default: bool = False, kw_only_default: bool = False, frozen_default: bool = False, field_specifiers: tuple[type[Any] | Callable[[...], Any], ...] = (), **kwargs: Any) → _IdentityCallable¶

Decorator to mark an object as providing dataclass-like behaviour.

The decorator can be applied to a function, class, or metaclass.

Example usage with a decorator function:

@dataclass_transform()
def create_model[T](cls: type[T]) -> type[T]:
    ...
    return cls

@create_model
class CustomerModel:
    id: int
    name: str

On a base class:

@dataclass_transform()
class ModelBase: ...

class CustomerModel(ModelBase):
    id: int
    name: str

On a metaclass:

@dataclass_transform()
class ModelMeta(type): ...

class ModelBase(metaclass=ModelMeta): ...

class CustomerModel(ModelBase):
    id: int
    name: str

The CustomerModel classes defined above will be treated by type checkers similarly to classes created with @dataclasses.dataclass. For example, type checkers will assume these classes have __init__ methods that accept id and name.

The arguments to this decorator can be used to customize this behavior: - eq_default indicates whether the eq parameter is assumed to be

True or False if it is omitted by the caller.

order_default indicates whether the order parameter is
assumed to be True or False if it is omitted by the caller.
kw_only_default indicates whether the kw_only parameter is
assumed to be True or False if it is omitted by the caller.
frozen_default indicates whether the frozen parameter is
assumed to be True or False if it is omitted by the caller.
field_specifiers specifies a static list of supported classes
or functions that describe fields, similar to dataclasses.field().
Arbitrary other keyword arguments are accepted in order to allow for
possible future extensions.

At runtime, this decorator records its arguments in the __dataclass_transform__ attribute on the decorated object. It has no other runtime effect.

See PEP 681 for more details.