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Oct 1, 2024
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gh-118974: Add decorator argument to make_dataclass #122723

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b889f37
gh-118974: Add `dataclass_factory` argument to `make_dataclass`
Viicos Aug 6, 2024
50b711c
📜🤖 Added by blurb_it.
blurb-it[bot] Aug 6, 2024
431addd
Docs
Viicos Sep 1, 2024
69698c5
Feedback
Viicos Sep 2, 2024
04ff33c
Merge branch 'main' into fix-issue-118974
ericvsmith Sep 27, 2024
cba7315
Rename parameter to `decorator`
Viicos Sep 30, 2024
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10 changes: 9 additions & 1 deletion Doc/library/dataclasses.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -399,7 +399,7 @@ Module contents
:func:`!astuple` raises :exc:`TypeError` if *obj* is not a dataclass
instance.

.. function:: 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)
.. function:: 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, decorator=dataclass)

Creates a new dataclass with name *cls_name*, fields as defined
in *fields*, base classes as given in *bases*, and initialized
Expand All @@ -415,6 +415,11 @@ Module contents
of the dataclass is set to that value.
By default, it is set to the module name of the caller.

The *decorator* parameter is a callable that will be used to create the dataclass.
It should take the class object as a first argument and the same keyword arguments
as :func:`@dataclass <dataclass>`. By default, the :func:`@dataclass <dataclass>`
function is used.

This function is not strictly required, because any Python
mechanism for creating a new class with :attr:`!__annotations__` can
then apply the :func:`@dataclass <dataclass>` function to convert that class to
Expand All @@ -438,6 +443,9 @@ Module contents
def add_one(self):
return self.x + 1

.. versionadded:: 3.14
Added the *decorator* parameter.

.. function:: replace(obj, /, **changes)

Creates a new object of the same type as *obj*, replacing
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6 changes: 3 additions & 3 deletions Lib/dataclasses.py
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Expand Up @@ -1550,7 +1550,7 @@ def _astuple_inner(obj, tuple_factory):
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):
weakref_slot=False, module=None, decorator=dataclass):
"""Return a new dynamically created dataclass.

The dataclass name will be 'cls_name'. 'fields' is an iterable
Expand Down Expand Up @@ -1630,8 +1630,8 @@ def exec_body_callback(ns):
if module is not None:
cls.__module__ = module

# Apply the normal decorator.
return dataclass(cls, init=init, repr=repr, eq=eq, order=order,
# Apply the normal provided decorator.
return decorator(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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17 changes: 17 additions & 0 deletions Lib/test/test_dataclasses/__init__.py
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Expand Up @@ -4317,6 +4317,23 @@ def test_funny_class_names_names(self):
C = make_dataclass(classname, ['a', 'b'])
self.assertEqual(C.__name__, classname)

def test_dataclass_decorator_default(self):
C = make_dataclass('C', [('x', int)], decorator=dataclass)
c = C(10)
self.assertEqual(c.x, 10)

def test_dataclass_custom_decorator(self):
def custom_dataclass(cls, *args, **kwargs):
dc = dataclass(cls, *args, **kwargs)
dc.__custom__ = True
return dc

C = make_dataclass('C', [('x', int)], decorator=custom_dataclass)
c = C(10)
self.assertEqual(c.x, 10)
self.assertEqual(c.__custom__, True)


class TestReplace(unittest.TestCase):
def test(self):
@dataclass(frozen=True)
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2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Library/2024-08-06-07-24-00.gh-issue-118974.qamsCQ.rst
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@@ -0,0 +1,2 @@
Add ``decorator`` parameter to :func:`dataclasses.make_dataclass`
to customize the functional creation of dataclasses.
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