Add `decorator` argument to `dataclasses.make_dataclass` for custom dataclass transformation support

# Feature or enhancement

### Proposal:

[`typing.dataclass_transform`](https://typing.readthedocs.io/en/latest/spec/dataclasses.html#the-dataclass-transform-decorator) ([PEP 681 – Data Class Transforms](https://peps.python.org/pep-0681)) allows users define their own `dataclass` decorator that can be recognized by the type checker.

Here is a real-world example use case:

- [`flax.struct.dataclass`](https://flax.readthedocs.io/en/latest/_modules/flax/struct.html#dataclass)

Also, [`dataclasses.asdict`](https://docs.python.org/3/library/dataclasses.html#dataclasses.asdict) and [`dataclasses.astuple`](https://docs.python.org/3/library/dataclasses.html#dataclasses.astuple) allow users pass an extra argument for the factory of the returned instance.

https://github.com/python/cpython/blob/0fb18b02c8ad56299d6a2910be0bab8ad601ef24/Lib/dataclasses.py#L1299-L1317

https://github.com/python/cpython/blob/0fb18b02c8ad56299d6a2910be0bab8ad601ef24/Lib/dataclasses.py#L1380-L1397

However, the `make_dataclass` function does not support third-party `dataclass` factory (e.g., [`flax.struct.dataclass`](https://flax.readthedocs.io/en/latest/_modules/flax/struct.html#dataclass)):

https://github.com/python/cpython/blob/0fb18b02c8ad56299d6a2910be0bab8ad601ef24/Lib/dataclasses.py#L1441-L1528

It can only apply `dataclasses.dataclass` (see the `return` statement above).

This feature request issue will discuss the possibility of adding a new `dataclass_factory` argument to the [`dataclasses.make_dataclass`](https://docs.python.org/3/library/dataclasses.html#dataclasses.make_dataclass) to support third-party dataclasss transformation, similar to `dict_factory` for [`dataclasses.asdict`](https://docs.python.org/3/library/dataclasses.html#dataclasses.asdict).

```python
# dataclasses.py

def make_dataclass(cls_name, fields, *, bases=(), namespace=None, init=True,
                   repr=True, eq=True, order=False, unsafe_hash=False,
                   frozen=False, match_args=True, kw_only=False, slots=False,
                   weakref_slot=False, module=None,
                   dataclass_factory=dataclass):
    ...

    # Apply the normal decorator.
    return dataclass_factory(cls, init=init, repr=repr, eq=eq, order=order,
                             unsafe_hash=unsafe_hash, frozen=frozen,
                             match_args=match_args, kw_only=kw_only, slots=slots,
                             weakref_slot=weakref_slot)
```

### Has this already been discussed elsewhere?

https://discuss.python.org/t/add-dataclass-factory-argument-to-dataclasses-make-dataclass-for-custom-dataclass-transformation-support/53188

### Links to previous discussion of this feature:

_No response_


### Linked PRs
* gh-122723

	def asdict(obj, *, dict_factory=dict):
	"""Return the fields of a dataclass instance as a new dictionary mapping
	field names to field values.

	Example usage::

	@dataclass
	class C:
	x: int
	y: int

	c = C(1, 2)
	assert asdict(c) == {'x': 1, 'y': 2}

	If given, 'dict_factory' will be used instead of built-in dict.
	The function applies recursively to field values that are
	dataclass instances. This will also look into built-in containers:
	tuples, lists, and dicts. Other objects are copied with 'copy.deepcopy()'.
	"""

	def astuple(obj, *, tuple_factory=tuple):
	"""Return the fields of a dataclass instance as a new tuple of field values.

	Example usage::

	@dataclass
	class C:
	x: int
	y: int

	c = C(1, 2)
	assert astuple(c) == (1, 2)

	If given, 'tuple_factory' will be used instead of built-in tuple.
	The function applies recursively to field values that are
	dataclass instances. This will also look into built-in containers:
	tuples, lists, and dicts. Other objects are copied with 'copy.deepcopy()'.
	"""

	def make_dataclass(cls_name, fields, *, bases=(), namespace=None, init=True,
	repr=True, eq=True, order=False, unsafe_hash=False,
	frozen=False, match_args=True, kw_only=False, slots=False,
	weakref_slot=False, module=None):
	"""Return a new dynamically created dataclass.

	The dataclass name will be 'cls_name'. 'fields' is an iterable
	of either (name), (name, type) or (name, type, Field) objects. If type is
	omitted, use the string 'typing.Any'. Field objects are created by
	the equivalent of calling 'field(name, type [, Field-info])'.::

	C = make_dataclass('C', ['x', ('y', int), ('z', int, field(init=False))], bases=(Base,))

	is equivalent to::

	@dataclass
	class C(Base):
	x: 'typing.Any'
	y: int
	z: int = field(init=False)

	For the bases and namespace parameters, see the builtin type() function.

	The parameters init, repr, eq, order, unsafe_hash, frozen, match_args, kw_only,
	slots, and weakref_slot are passed to dataclass().

	If module parameter is defined, the '__module__' attribute of the dataclass is
	set to that value.
	"""

	if namespace is None:
	namespace = {}

	# While we're looking through the field names, validate that they
	# are identifiers, are not keywords, and not duplicates.
	seen = set()
	annotations = {}
	defaults = {}
	for item in fields:
	if isinstance(item, str):
	name = item
	tp = 'typing.Any'
	elif len(item) == 2:
	name, tp, = item
	elif len(item) == 3:
	name, tp, spec = item
	defaults[name] = spec
	else:
	raise TypeError(f'Invalid field: {item!r}')

	if not isinstance(name, str) or not name.isidentifier():
	raise TypeError(f'Field names must be valid identifiers: {name!r}')
	if keyword.iskeyword(name):
	raise TypeError(f'Field names must not be keywords: {name!r}')
	if name in seen:
	raise TypeError(f'Field name duplicated: {name!r}')

	seen.add(name)
	annotations[name] = tp

	# Update 'ns' with the user-supplied namespace plus our calculated values.
	def exec_body_callback(ns):
	ns.update(namespace)
	ns.update(defaults)
	ns['__annotations__'] = annotations

	# We use `types.new_class()` instead of simply `type()` to allow dynamic creation
	# of generic dataclasses.
	cls = types.new_class(cls_name, bases, {}, exec_body_callback)

	# For pickling to work, the __module__ variable needs to be set to the frame
	# where the dataclass is created.
	if module is None:
	try:
	module = sys._getframemodulename(1) or '__main__'
	except AttributeError:
	try:
	module = sys._getframe(1).f_globals.get('__name__', '__main__')
	except (AttributeError, ValueError):
	pass
	if module is not None:
	cls.__module__ = module

	# Apply the normal decorator.
	return dataclass(cls, init=init, repr=repr, eq=eq, order=order,
	unsafe_hash=unsafe_hash, frozen=frozen,
	match_args=match_args, kw_only=kw_only, slots=slots,
	weakref_slot=weakref_slot)

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Add `decorator` argument to `dataclasses.make_dataclass` for custom dataclass transformation support #118974

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Uh oh!

Add decorator argument to dataclasses.make_dataclass for custom dataclass transformation support #118974

Description

Feature or enhancement

Proposal:

Has this already been discussed elsewhere?

Links to previous discussion of this feature:

Linked PRs

Metadata

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Labels

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Development

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Add `decorator` argument to `dataclasses.make_dataclass` for custom dataclass transformation support #118974