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"
         "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:").

Python-Dev mailing list

Reply via email to