Update to PEP 681 dataclasses (#4241)

* Update to PEP 681 dataclasses

* Add changes file

* Pre-commit

Co-authored-by: Samuel Colvin <s@muelcolvin.com>

changes/4241-multimeric.md

@@ -0,0 +1 @@
+The use of `__dataclass_transform__` has been replaced by `typing_extensions.dataclass_transform`, which is the preferred way to mark pydantic models as a dataclass under [PEP 681](https://peps.python.org/pep-0681/).

pydantic/dataclasses.py

@@ -36,12 +36,14 @@ class M:
 from functools import wraps
 from typing import TYPE_CHECKING, Any, Callable, ClassVar, Dict, Generator, Optional, Type, TypeVar, Union, overload
 
+from typing_extensions import dataclass_transform
+
 from .class_validators import gather_all_validators
 from .config import BaseConfig, ConfigDict, Extra, get_config
 from .error_wrappers import ValidationError
 from .errors import DataclassTypeError
 from .fields import Field, FieldInfo, Required, Undefined
-from .main import __dataclass_transform__, create_model, validate_model
+from .main import create_model, validate_model
 from .utils import ClassAttribute
 
 if TYPE_CHECKING:
@@ -88,7 +90,7 @@ def __validate__(cls: Type['DataclassT'], v: Any) -> 'DataclassT':
 
 if sys.version_info >= (3, 10):
 
-    @__dataclass_transform__(kw_only_default=True, field_descriptors=(Field, FieldInfo))
+    @dataclass_transform(kw_only_default=True, field_descriptors=(Field, FieldInfo))
     @overload
     def dataclass(
         *,
@@ -104,7 +106,7 @@ def dataclass(
     ) -> Callable[[Type[Any]], 'DataclassClassOrWrapper']:
         ...
 
-    @__dataclass_transform__(kw_only_default=True, field_descriptors=(Field, FieldInfo))
+    @dataclass_transform(kw_only_default=True, field_descriptors=(Field, FieldInfo))
     @overload
     def dataclass(
         _cls: Type[Any],
@@ -123,7 +125,7 @@ def dataclass(
 
 else:
 
-    @__dataclass_transform__(kw_only_default=True, field_descriptors=(Field, FieldInfo))
+    @dataclass_transform(kw_only_default=True, field_descriptors=(Field, FieldInfo))
     @overload
     def dataclass(
         *,
@@ -138,7 +140,7 @@ def dataclass(
     ) -> Callable[[Type[Any]], 'DataclassClassOrWrapper']:
         ...
 
-    @__dataclass_transform__(kw_only_default=True, field_descriptors=(Field, FieldInfo))
+    @dataclass_transform(kw_only_default=True, field_descriptors=(Field, FieldInfo))
     @overload
     def dataclass(
         _cls: Type[Any],
@@ -155,7 +157,7 @@ def dataclass(
         ...
 
 
-@__dataclass_transform__(kw_only_default=True, field_descriptors=(Field, FieldInfo))
+@dataclass_transform(kw_only_default=True, field_descriptors=(Field, FieldInfo))
 def dataclass(
     _cls: Optional[Type[Any]] = None,
     *,

pydantic/main.py

@@ -24,6 +24,8 @@
     overload,
 )
 
+from typing_extensions import dataclass_transform
+
 from .class_validators import ValidatorGroup, extract_root_validators, extract_validators, inherit_validators
 from .config import BaseConfig, Extra, inherit_config, prepare_config
 from .error_wrappers import ErrorWrapper, ValidationError
@@ -93,16 +95,6 @@
 _T = TypeVar('_T')
 
 
-def __dataclass_transform__(
-    *,
-    eq_default: bool = True,
-    order_default: bool = False,
-    kw_only_default: bool = False,
-    field_descriptors: Tuple[Union[type, Callable[..., Any]], ...] = (()),
-) -> Callable[[_T], _T]:
-    return lambda a: a
-
-
 def validate_custom_root_type(fields: Dict[str, ModelField]) -> None:
     if len(fields) > 1:
         raise ValueError(f'{ROOT_KEY} cannot be mixed with other fields')
@@ -126,7 +118,7 @@ def hash_function(self_: Any) -> int:
 _is_base_model_class_defined = False
 
 
-@__dataclass_transform__(kw_only_default=True, field_descriptors=(Field, FieldInfo))
+@dataclass_transform(kw_only_default=True, field_descriptors=(Field, FieldInfo))
 class ModelMetaclass(ABCMeta):
     @no_type_check  # noqa C901
     def __new__(mcs, name, bases, namespace, **kwargs):  # noqa C901