[Python-Dev] Symmetry arguments for API expansion

[Nathaniel Smith]

On Mar 21, 2018 05:40, "Steven D'Aprano" <steve at pearwood.info> wrote:


I don't want to change the behaviour of pow(), but we shouldn't dismiss
the possibility of some other numeric function wanting to treat values
N.0 and N the same. Let's say, an is_prime(x) function that supports
floats as well as ints:

    is_prime(3.0)  # True
    is_prime(3.00001)  # False


For me this is an argument against is_integer() rather than for it :-).
is_prime(float) should *obviously*[1] be a TypeError. Primality is only
meaningfully defined over the domain of integers, and this is a case where
operator.index is exactly what you want.

Of course it's just an example, and perhaps there are other, better
examples. But it makes me nervous that this is the best example you could
quickly come up with.

-n

[1] Warning: I am not Dutch.
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