diff options
| -rw-r--r-- | Lib/dataclasses.py | 10 | ||||
| -rw-r--r-- | Lib/test/test_dataclasses.py | 44 | ||||
| -rw-r--r-- | Misc/NEWS.d/next/Library/2023-03-10-13-21-16.gh-issue-102578.-gujoI.rst | 4 |
3 files changed, 52 insertions, 6 deletions
diff --git a/Lib/dataclasses.py b/Lib/dataclasses.py index 8bc8594..78a126f 100644 --- a/Lib/dataclasses.py +++ b/Lib/dataclasses.py @@ -616,21 +616,19 @@ def _repr_fn(fields, globals): def _frozen_get_del_attr(cls, fields, globals): locals = {'cls': cls, 'FrozenInstanceError': FrozenInstanceError} + condition = 'type(self) is cls' if fields: - fields_str = '(' + ','.join(repr(f.name) for f in fields) + ',)' - else: - # Special case for the zero-length tuple. - fields_str = '()' + condition += ' or name in {' + ', '.join(repr(f.name) for f in fields) + '}' return (_create_fn('__setattr__', ('self', 'name', 'value'), - (f'if type(self) is cls or name in {fields_str}:', + (f'if {condition}:', ' raise FrozenInstanceError(f"cannot assign to field {name!r}")', f'super(cls, self).__setattr__(name, value)'), locals=locals, globals=globals), _create_fn('__delattr__', ('self', 'name'), - (f'if type(self) is cls or name in {fields_str}:', + (f'if {condition}:', ' raise FrozenInstanceError(f"cannot delete field {name!r}")', f'super(cls, self).__delattr__(name)'), locals=locals, diff --git a/Lib/test/test_dataclasses.py b/Lib/test/test_dataclasses.py index 589f229..5486b2e 100644 --- a/Lib/test/test_dataclasses.py +++ b/Lib/test/test_dataclasses.py @@ -2767,6 +2767,19 @@ class TestFrozen(unittest.TestCase): c.i = 5 self.assertEqual(c.i, 10) + def test_frozen_empty(self): + @dataclass(frozen=True) + class C: + pass + + c = C() + self.assertFalse(hasattr(c, 'i')) + with self.assertRaises(FrozenInstanceError): + c.i = 5 + self.assertFalse(hasattr(c, 'i')) + with self.assertRaises(FrozenInstanceError): + del c.i + def test_inherit(self): @dataclass(frozen=True) class C: @@ -2890,6 +2903,37 @@ class TestFrozen(unittest.TestCase): 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: + pass + + class S(D): + pass + + s = S() + self.assertFalse(hasattr(s, 'x')) + s.x = 5 + self.assertEqual(s.x, 5) + + del s.x + self.assertFalse(hasattr(s, 'x')) + with self.assertRaises(AttributeError) as cm: + del s.x + self.assertNotIsInstance(cm.exception, FrozenInstanceError) + def test_overwriting_frozen(self): # frozen uses __setattr__ and __delattr__. with self.assertRaisesRegex(TypeError, diff --git a/Misc/NEWS.d/next/Library/2023-03-10-13-21-16.gh-issue-102578.-gujoI.rst b/Misc/NEWS.d/next/Library/2023-03-10-13-21-16.gh-issue-102578.-gujoI.rst new file mode 100644 index 0000000..7307148 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2023-03-10-13-21-16.gh-issue-102578.-gujoI.rst @@ -0,0 +1,4 @@ +Speed up setting or deleting mutable attributes on non-dataclass subclasses of +frozen dataclasses. Due to the implementation of ``__setattr__`` and +``__delattr__`` for frozen dataclasses, this previously had a time complexity +of ``O(n)``. It now has a time complexity of ``O(1)``. |