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gh-74690: typing: Don't unnecessarily call _get_protocol_attrs twice in _ProtocolMeta.__instancecheck__ (#103141)

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Speed up `isinstance()` calls against runtime-checkable protocols
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Alex Waygood 2023-03-31 18:37:24 +01:00 • committed by GitHub
parent 80163e17d3
commit 9048d73f7a
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1 changed files with 21 additions and 10 deletions
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31
Lib/typing.py
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@ -1931,9 +1931,9 @@ def _get_protocol_attrs(cls):
return attrs
def _is_callable_members_only(cls):
def _is_callable_members_only(cls, protocol_attrs):
# PEP 544 prohibits using issubclass() with protocols that have non-method members.
return all(callable(getattr(cls, attr, None)) for attr in _get_protocol_attrs(cls))
return all(callable(getattr(cls, attr, None)) for attr in protocol_attrs)
def _no_init_or_replace_init(self, *args, **kwargs):
@ -2000,24 +2000,32 @@ class _ProtocolMeta(ABCMeta):
def __instancecheck__(cls, instance):
# We need this method for situations where attributes are
# assigned in __init__.
is_protocol_cls = getattr(cls, "_is_protocol", False)
if (
getattr(cls, '_is_protocol', False) and
is_protocol_cls and
not getattr(cls, '_is_runtime_protocol', False) and
not _allow_reckless_class_checks(depth=2)
):
raise TypeError("Instance and class checks can only be used with"
" @runtime_checkable protocols")
if ((not getattr(cls, '_is_protocol', False) or
_is_callable_members_only(cls)) and
issubclass(instance.__class__, cls)):
if not is_protocol_cls and issubclass(instance.__class__, cls):
return True
if cls._is_protocol:
protocol_attrs = _get_protocol_attrs(cls)
if (
_is_callable_members_only(cls, protocol_attrs)
and issubclass(instance.__class__, cls)
):
return True
if is_protocol_cls:
if all(hasattr(instance, attr) and
# All *methods* can be blocked by setting them to None.
(not callable(getattr(cls, attr, None)) or
getattr(instance, attr) is not None)
for attr in _get_protocol_attrs(cls)):
for attr in protocol_attrs):
return True
return super().__instancecheck__(instance)
@ -2074,7 +2082,10 @@ class Protocol(Generic, metaclass=_ProtocolMeta):
return NotImplemented
raise TypeError("Instance and class checks can only be used with"
" @runtime_checkable protocols")
if not _is_callable_members_only(cls):
protocol_attrs = _get_protocol_attrs(cls)
if not _is_callable_members_only(cls, protocol_attrs):
if _allow_reckless_class_checks():
return NotImplemented
raise TypeError("Protocols with non-method members"
@ -2084,7 +2095,7 @@ class Protocol(Generic, metaclass=_ProtocolMeta):
raise TypeError('issubclass() arg 1 must be a class')
# Second, perform the actual structural compatibility check.
for attr in _get_protocol_attrs(cls):
for attr in protocol_attrs:
for base in other.__mro__:
# Check if the members appears in the class dictionary...
if attr in base.__dict__: