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gh-117182: Allow lazily loaded modules to modify their own __class__

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Chris Markiewicz 2024-04-08 23:08:48 -04:00 • committed by GitHub
parent ac45766673
commit 19a2202067
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3 changed files with 38 additions and 4 deletions
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12
Lib/importlib/util.py
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@ -178,15 +178,17 @@ class _LazyModule(types.ModuleType):
# Only the first thread to get the lock should trigger the load
# and reset the module's class. The rest can now getattr().
if object.__getattribute__(self, '__class__') is _LazyModule:
__class__ = loader_state['__class__']
# Reentrant calls from the same thread must be allowed to proceed without
# triggering the load again.
# exec_module() and self-referential imports are the primary ways this can
# happen, but in any case we must return something to avoid deadlock.
if loader_state['is_loading']:
return object.__getattribute__(self, attr)
return __class__.__getattribute__(self, attr)
loader_state['is_loading'] = True
__dict__ = object.__getattribute__(self, '__dict__')
__dict__ = __class__.__getattribute__(self, '__dict__')
# All module metadata must be gathered from __spec__ in order to avoid
# using mutated values.
@ -216,8 +218,10 @@ class _LazyModule(types.ModuleType):
# Update after loading since that's what would happen in an eager
# loading situation.
__dict__.update(attrs_updated)
# Finally, stop triggering this method.
self.__class__ = types.ModuleType
# Finally, stop triggering this method, if the module did not
# already update its own __class__.
if isinstance(self, _LazyModule):
object.__setattr__(self, '__class__', __class__)
return getattr(self, attr)