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gh-105936: Fix frozen dataclasses with slots' __setattr__ and __delattr_#105937

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gh-105936: Fix frozen dataclasses with slots' __setattr__ and __delattr_#105937

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6641ed3
Fixed bug.
avboag Jun 20, 2023
4bf0b7e
Typo fix.
avboag Jun 20, 2023
f74a833
📜🤖 Added by blurb_it.
blurb-it[bot] Jun 20, 2023
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16 changes: 8 additions & 8 deletions Lib/dataclasses.py
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Original file line numberDiff line numberDiff line change
Expand Up@@ -635,7 +635,7 @@ def _repr_fn(fields, globals):
return _recursive_repr(fn)


def _frozen_get_del_attr(cls, fields, globals):
def _frozen_set_del_attr(cls, fields, globals):
locals ={'cls': cls,
'FrozenInstanceError': FrozenInstanceError}
condition = 'type(self) is cls'
Expand DownExpand Up@@ -1055,6 +1055,12 @@ def _process_class(cls, init, repr, eq, order, unsafe_hash, frozen,
(std_init_fields,
kw_only_init_fields) = _fields_in_init_order(all_init_fields)

# It's an error to specify weakref_slot if slots is False.
if weakref_slot and not slots:
raise TypeError('weakref_slot is True but slots is False')
if slots:
cls = _add_slots(cls, frozen, weakref_slot)

if init:
# Does this class have a post-init function?
has_post_init = hasattr(cls, _POST_INIT_NAME)
Expand DownExpand Up@@ -1115,7 +1121,7 @@ def _process_class(cls, init, repr, eq, order, unsafe_hash, frozen,
'functools.total_ordering')

if frozen:
for fn in _frozen_get_del_attr(cls, field_list, globals):
for fn in _frozen_set_del_attr(cls, field_list, globals):
if _set_new_attribute(cls, fn.__name__, fn):
raise TypeError(f'Cannot overwrite attribute{fn.__name__} '
f'in class{cls.__name__}')
Expand DownExpand Up@@ -1145,12 +1151,6 @@ def _process_class(cls, init, repr, eq, order, unsafe_hash, frozen,
_set_new_attribute(cls, '__match_args__',
tuple(f.name for f in std_init_fields))

# It's an error to specify weakref_slot if slots is False.
if weakref_slot and not slots:
raise TypeError('weakref_slot is True but slots is False')
if slots:
cls = _add_slots(cls, frozen, weakref_slot)

abc.update_abstractmethods(cls)

return cls
Expand Down
54 changes: 54 additions & 0 deletions Lib/test/test_dataclasses.py
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Original file line numberDiff line numberDiff line change
Expand Up@@ -2820,6 +2820,23 @@ class C:
self.assertEqual(c.i, 10)
with self.assertRaises(FrozenInstanceError):
c.i = 5
with self.assertRaises(FrozenInstanceError):
c.j = 5

self.assertEqual(c.i, 10)

def test_frozen_with_slots(self):
@dataclass(frozen=True, slots=True)
class C:
i: int

c = C(10)
self.assertEqual(c.i, 10)
with self.assertRaises(FrozenInstanceError):
c.i = 5
with self.assertRaises(FrozenInstanceError):
c.j = 5

self.assertEqual(c.i, 10)

def test_frozen_empty(self):
Expand DownExpand Up@@ -2970,6 +2987,43 @@ class S(D):
del s.cached
self.assertNotIsInstance(cm.exception, FrozenInstanceError)

def test_non_frozen_normal_derived_with_slots(self):
# See bpo-32953.

@dataclass(frozen=True, slots=True)
class D:
x: int
y: int = 10

class S(D):
pass

s = S(3)
self.assertEqual(s.x, 3)
self.assertEqual(s.y, 10)
s.cached = True

# But can't change the frozen attributes.
with self.assertRaises(FrozenInstanceError):
s.x = 5
with self.assertRaises(FrozenInstanceError):
s.y = 5
self.assertEqual(s.x, 3)
self.assertEqual(s.y, 10)
self.assertEqual(s.cached, True)

with self.assertRaises(FrozenInstanceError):
del s.x
self.assertEqual(s.x, 3)
with self.assertRaises(FrozenInstanceError):
del s.y
self.assertEqual(s.y, 10)
del s.cached
self.assertFalse(hasattr(s, 'cached'))
with self.assertRaises(AttributeError) as cm:
del s.cached
self.assertNotIsInstance(cm.exception, FrozenInstanceError)

def test_non_frozen_normal_derived_from_empty_frozen(self):
@dataclass(frozen=True)
class D:
Expand Down
1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Library/2023-06-20-10-14-29.gh-issue-105936.7VfFJW.rst
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Original file line numberDiff line numberDiff line change
@@ -0,0 +1 @@
Fixed frozen dataclasses with slots' ``__setattr__`` and ``__delattr_``.