mirrors/cpython
1
0
Fork 0
mirror of https://github.com/python/cpython.git synced 2025-08-03 00:23:06 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 6

bpo-45081: Fix __init__ method generation when inheriting from Protocol (GH-28121)

Browse source 
Co-authored-by: Ken Jin <28750310+Fidget-Spinner@users.noreply.github.com>
(cherry picked from commit 0635e201be)

Co-authored-by: Yurii Karabas <1998uriyyo@gmail.com>
This commit is contained in:
Miss Islington (bot) 2021-09-02 23:26:53 -07:00 • committed by GitHub
parent 7aa58f5425
commit 79e9f5a584
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
3 changed files with 47 additions and 13 deletions
Download patch file Download diff file Expand all files Collapse all files

36
Lib/typing.py
View file

@ -1398,8 +1398,29 @@ def _is_callable_members_only(cls):
return all(callable(getattr(cls, attr, None)) for attr in _get_protocol_attrs(cls))
def _no_init(self, *args, **kwargs):
raise TypeError('Protocols cannot be instantiated')
def _no_init_or_replace_init(self, *args, **kwargs):
cls = type(self)
if cls._is_protocol:
raise TypeError('Protocols cannot be instantiated')
# Initially, `__init__` of a protocol subclass is set to `_no_init_or_replace_init`.
# The first instantiation of the subclass will call `_no_init_or_replace_init` which
# searches for a proper new `__init__` in the MRO. The new `__init__`
# replaces the subclass' old `__init__` (ie `_no_init_or_replace_init`). Subsequent
# instantiation of the protocol subclass will thus use the new
# `__init__` and no longer call `_no_init_or_replace_init`.
for base in cls.__mro__:
init = base.__dict__.get('__init__', _no_init_or_replace_init)
if init is not _no_init_or_replace_init:
cls.__init__ = init
break
else:
# should not happen
cls.__init__ = object.__init__
cls.__init__(self, *args, **kwargs)
def _caller(depth=1, default='__main__'):
try:
@ -1542,15 +1563,6 @@ class Protocol(Generic, metaclass=_ProtocolMeta):
# We have nothing more to do for non-protocols...
if not cls._is_protocol:
if cls.__init__ == _no_init:
for base in cls.__mro__:
init = base.__dict__.get('__init__', _no_init)
if init != _no_init:
cls.__init__ = init
break
else:
# should not happen
cls.__init__ = object.__init__
return
# ... otherwise check consistency of bases, and prohibit instantiation.
@ -1561,7 +1573,7 @@ class Protocol(Generic, metaclass=_ProtocolMeta):
issubclass(base, Generic) and base._is_protocol):
raise TypeError('Protocols can only inherit from other'
' protocols, got %r' % base)
cls.__init__ = _no_init
cls.__init__ = _no_init_or_replace_init
class _AnnotatedAlias(_GenericAlias, _root=True):