isinstance on runtime_checkable Protocol has side-effects for @property methods #102433
Description
For example:
from typing import Protocol, runtime_checkable
@runtime_checkable
class X(Protocol):
@property
def myproperty(self): ...
class Y:
@property
def myproperty(self):
raise RuntimeError("hallo")
isinstance(Y(), X)will raise the RuntimeError
This is an issue, for example, if myproperty is an expensive call, has unwanted side effects, or excepts outside of a context manager
Linked PRs
- gh-102433: Add tests for how classes with properties interact with
isinstance()checks ontyping.runtime_checkableprotocols #102449 - [3.11] gh-102433: Add tests for how classes with properties interact with
isinstance()checks ontyping.runtime_checkableprotocols (GH-102449) #102592 - [3.10] gh-102433: Add tests for how classes with properties interact with
isinstance()checks ontyping.runtime_checkableprotocols (GH-102449) #102593 - gh-102433: Use
inspect.getattr_staticintyping._ProtocolMeta.__instancecheck__#103034