Mark Dickinson added the comment: This is a bit tricky. The first expression you suggest doesn't work at all for negative numbers (e.g., producing `-3.0` for `round(-1.8)`).
The second expression *mostly* works as you want, but not entirely. Some examples: >>> def f(n): return float(math.trunc(n + math.copysign(0.5, n))) ... >>> x = 0.5 - 2**-54 >>> x 0.49999999999999994 >>> f(x) # should be 0.0 1.0 >>> x = 5e15 + 3.0 >>> x 5000000000000003.0 >>> f(x) # should be x again 5000000000000004.0 And neither of these addresses the two-argument case of `round`. It may be better to simply flag this as something that 2to3 can't handle, and that needs a manual check. ---------- nosy: +mark.dickinson _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue24403> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
