In Python 2, returning an int where a float was expected could break
existing code (since in Python 2 int and float behave differently under
division), but in Python 3 int is virtually a subclass of float (see PEP
3141). So it's not a crazy idea.
However, it's a bit of a slippery slope. Pretty much everything in the math
module always returns a float. Or do you propose that math.sin(0) also
return 1 instead of 1.0?
Also, how important is it to use this? I suspect the only reason it exists
as a builtin is that it handles -0.0 correctly. But that's really only of
interest to people doing serious floating point stuff. For everyone else,
it's pretty much this one-liner:
def copysign(x, y):
return abs(x) if y >= 0 else -abs(x)
On Thu, Nov 28, 2019 at 4:20 PM Marein
The math.copysign(x, y) function always returns a float, even when the given x is an int, i.e. math.copysign(3, -1) gives -3.0. This is documented behaviour, but I find it somewhat surprising given that the name suggests that it only copies a sign, and it's also annoying in situations when an int is strictly needed (i.e. as the step argument to range), requiring an additional cast.
I'm interested to hear whether it might be a good idea to preserve the int/float type of the argument in math.copysign. _______________________________________________ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-leave@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/OD5EVP... Code of Conduct: http://python.org/psf/codeofconduct/
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