Bug report
Bug description:
We noticed a behavior change between 3.11 and 3.12. The following code calls Foo.__bool__ once in 3.11 and twice in 3.12. Consequently for this contrived example, the expression evaluates to different results in 3.11 and 3.12.
class Foo: def __init__(self): self._a = True def __bool__(self): self._a = not self._a print(f"Foo.__bool__ -> {self._a}") return self._a Foo() and "a string" or 42
In Python 3.11:
>>> Foo() and "a string" or 42
Foo.__bool__ -> False
42
In Python 3.12 (and 3.13.0b2):
>>> Foo() and "a string" or 42
Foo.__bool__ -> False
Foo.__bool__ -> True
<__main__.Foo object at 0x7f0ae554c1a0>
Is this change intentional?
Note that I'm not necessarily asking to change this. We should arguably change the code to "a string" if Foo() else 42, which evaluates the same in 3.11 and 3.12.
CPython versions tested on:
3.12
Operating systems tested on:
Linux