[Python-Dev] Symmetry arguments for API expansion
Serhiy Storchaka
storchaka at gmail.com
Mon Mar 12 15:53:51 EDT 2018
12.03.18 21:15, Guido van Rossum пише:
> There's a reason why adding this to int feels right to me. In mypy we
> treat int as a sub*type* of float, even though technically it isn't a
> sub*class*.. The absence of an is_integer() method on int means that
> this code has a bug that mypy doesn't catch:
>
> def f(x: float):
> if x.is_integer():
> "do something"
> else:
> "do something else"
What is the real use case of float.is_integer()?
I searched on GitHub and found only misuses of it like
(x/5).is_integer() (x % 5 == 0 would be more correct and clear) or
(x**0.5).is_integer() (returns wrong result for large ints and some
floats) in short examples. Some of these snippets look like book
examples, and they propagate bad practices (like "if a.is_integer() ==
True:").
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