Skip to content

Commit

Permalink
gh-74690: typing: Don't unnecessarily call _get_protocol_attrs twic…
Browse files Browse the repository at this point in the history
…e in `_ProtocolMeta.__instancecheck__` (#103141)

Speed up `isinstance()` calls against runtime-checkable protocols
  • Loading branch information
AlexWaygood authored Mar 31, 2023
1 parent 80163e1 commit 9048d73
Showing 1 changed file with 21 additions and 10 deletions.
31 changes: 21 additions & 10 deletions Lib/typing.py
Original file line number Diff line number Diff line change
Expand Up @@ -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):
Expand Down Expand Up @@ -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)

Expand Down Expand Up @@ -2074,7 +2082,10 @@ def _proto_hook(other):
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"
Expand All @@ -2084,7 +2095,7 @@ def _proto_hook(other):
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__:
Expand Down

0 comments on commit 9048d73

Please sign in to comment.