On Wed, Jan 13, 2021 at 04:47:06AM +1100, Chris Angelico wrote:
> That'd leave open
> the option for "foo() if x else foo()" to be optimized down to just
> "foo()", although I don't think that particular one is needed.
That would be an unsafe optimization. Not all objets are representable
as truthy/falsey values, e.g. numpy arrays.
>>> bool(a)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: The truth value of an array with more than one element
is ambiguous. Use a.any() or a.all()
Not even all builtin values. This is in Python 3.9:
>>> bool(NotImplemented)
<stdin>:1: DeprecationWarning: NotImplemented should not be used in
a boolean context
True
I believe that 3.10 makes it an error. If not 3.10, then it will surely
happen soon. But even without the change to NotImplemented, it has never
been the case that *every* object is guaranteed to be either truthy or
falsey. At least not since the Python 1.x `__nonzero__` dunder was put
into the language.
--
Steve
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