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[Python-Dev] int() and math.trunc don't accept objects that only define __index__

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Le 15 mars 2019 à 03:49:19, Steven D'Aprano(steve at pearwood.info(mailto:steve at pearwood.info)) a écrit:> On Wed, Mar 13, 2019 at 03:21:31AM -0700, Rémi Lapeyre wrote:>> > When __index__ is defined it means that there is a lossless conversion> > to int possible. In this case, this means a lossless conversion to> > float and complex is also possible>> That's not correct:>> py> n = 2**64 + 1> py> n == int(float(n))> FalseThanks, I should have thought of that. Do you think __index__ shouldonly define__int__ then?> Python floats (C doubles) can lose digits when converting from ints> over 2**53 or so.>>> > (with the exception of overflows> > but anyone doing float(var) should expect them).>> I don't. I expect float(var) to overflow to infinity, if it is going to> overflow, and always forget that it can raise.>>> py> float("9e9999")> inf>> py> float(str(9*10**9999))> inf>> But:>> py> float(9*10**9999)> Traceback (most recent call last):> File "", line 1, in> OverflowError: int too large to convert to float>> This never fails to surprise me.>>>>> --> Steven> _______________________________________________> Python-Dev mailing list>Python-Dev at python.org>https://mail.python.org/mailman/listinfo/python-dev> Unsubscribe:https://mail.python.org/mailman/options/python-dev/remi.lapeyre%40henki.fr

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