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bpo-32960: For dataclasses, disallow inheriting frozen from non-frozen classes and vice-versa, (GH-5919) (GH-5920)

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This restriction will be relaxed at a future date.
(cherry picked from commit 2fa6b9eae0)

Co-authored-by: Eric V. Smith <ericvsmith@users.noreply.github.com>
This commit is contained in:
Miss Islington (bot) 2018-02-26 17:59:55 -08:00 • committed by Eric V. Smith
parent a9a8a9814a
commit a93e3dc236
3 changed files with 77 additions and 29 deletions
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19
Lib/dataclasses.py
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@ -623,14 +623,21 @@ def _process_class(cls, repr, eq, order, unsafe_hash, init, frozen):
else:
setattr(cls, f.name, f.default)
# We're inheriting from a frozen dataclass, but we're not frozen.
if cls.__setattr__ is _frozen_setattr and not frozen:
raise TypeError('cannot inherit non-frozen dataclass from a '
'frozen one')
# We're inheriting from a non-frozen dataclass, but we're frozen.
if (hasattr(cls, _MARKER) and cls.__setattr__ is not _frozen_setattr
and frozen):
raise TypeError('cannot inherit frozen dataclass from a '
'non-frozen one')
# Remember all of the fields on our class (including bases). This
# marks this class as being a dataclass.
setattr(cls, _MARKER, fields)
# We also need to check if a parent class is frozen: frozen has to
# be inherited down.
is_frozen = frozen or cls.__setattr__ is _frozen_setattr
# Was this class defined with an explicit __hash__? Note that if
# __eq__ is defined in this class, then python will automatically
# set __hash__ to None. This is a heuristic, as it's possible
@ -654,7 +661,7 @@ def _process_class(cls, repr, eq, order, unsafe_hash, init, frozen):
if f._field_type in (_FIELD, _FIELD_INITVAR)]
_set_new_attribute(cls, '__init__',
_init_fn(flds,
is_frozen,
frozen,
has_post_init,
# The name to use for the "self" param
# in __init__. Use "self" if possible.
@ -696,7 +703,7 @@ def _process_class(cls, repr, eq, order, unsafe_hash, init, frozen):
f'in class {cls.__name__}. Consider using '
'functools.total_ordering')
if is_frozen:
if frozen:
for name, fn in [('__setattr__', _frozen_setattr),
('__delattr__', _frozen_delattr)]:
if _set_new_attribute(cls, name, fn):