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Small speedup for dataclass __eq__ and __repr__ #104904

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Merged
merged 4 commits into from
May 30, 2023
Merged

Small speedup for dataclass __eq__ and __repr__ #104904

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88a816d
Faster __repr__ with str.__add__ moved inside the f-string.
rhettinger May 14, 2023
bce2e72
Almost there
rhettinger May 24, 2023
cfa5a06
Faster __eq__
rhettinger May 24, 2023
30439ce
Merge branch 'main' into faster_dataclasses
hauntsaninja May 25, 2023
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20 changes: 12 additions & 8 deletions Lib/dataclasses.py
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Original file line number Diff line number Diff line change
Expand Up @@ -627,7 +627,7 @@ def _init_fn(fields, std_fields, kw_only_fields, frozen, has_post_init,
def _repr_fn(fields, globals):
fn = _create_fn('__repr__',
('self',),
['return self.__class__.__qualname__ + f"(' +
['return f"{self.__class__.__qualname__}(' +
', '.join([f"{f.name}={{self.{f.name}!r}}"
for f in fields]) +
')"'],
Expand Down Expand Up @@ -1085,13 +1085,17 @@ def _process_class(cls, init, repr, eq, order, unsafe_hash, frozen,
if eq:
# Create __eq__ method. There's no need for a __ne__ method,
# since python will call __eq__ and negate it.
flds = [f for f in field_list if f.compare]
self_tuple = _tuple_str('self', flds)
other_tuple = _tuple_str('other', flds)
_set_new_attribute(cls, '__eq__',
_cmp_fn('__eq__', '==',
self_tuple, other_tuple,
globals=globals))
cmp_fields = (field for field in field_list if field.compare)
terms = [f'self.{field.name}==other.{field.name}' for field in cmp_fields]
field_comparisons = ' and '.join(terms) or 'True'
body = [f'if other.__class__ is self.__class__:',
f' return {field_comparisons}',
f'return NotImplemented']
func = _create_fn('__eq__',
('self', 'other'),
body,
globals=globals)
_set_new_attribute(cls, '__eq__', func)

if order:
# Create and set the ordering methods.
Expand Down