Wolfgang Maier added the comment: After considering this for a while, I think:
return float(self.numerator / self.denominator) is the best solution: * it is simple and works reasonably well as a default * it fixes Rational.__float__ for cases, in which numerator / denominator returns a custom Real instance * in the problematic scenario brought up by Mark, in which truediv of the numerator and denominator returns another Rational creating a potentially infinite recursion, a RuntimeError will be raised when the maximum recursion limit is reached. This is not an unheard of error to run into while trying to implement a custom numeric type and will provide reasonable (though not ideal) information about the problem. * the workaround for the above is obvious: it is ok for self.numerator / self.denominator to return a Rational instance, but its type should overwrite Rational.__float__ to break the recursion. This could get documented in the docstring of Rational.__float__. I've attached a tentative patch. ---------- keywords: +patch Added file: http://bugs.python.org/file39217/Rational.__float__.patch _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue23975> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
