[Python-Dev] int() and math.trunc don't accept objects that only define index (original) (raw)
Steven D'Aprano steve at pearwood.info
Thu Mar 14 22:45:42 EDT 2019
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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)) False
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
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