fractions.py 文件源码

def _richcmp(self, other, op):
        """Helper for comparison operators, for internal use only.

        Implement comparison between a Rational instance `self`, and
        either another Rational instance or a float `other`.  If
        `other` is not a Rational instance or a float, return
        NotImplemented. `op` should be one of the six standard
        comparison operators.

        """
        # convert other to a Rational instance where reasonable.
        if isinstance(other, Rational):
            return op(self._numerator * other.denominator,
                      self._denominator * other.numerator)
        # comparisons with complex should raise a TypeError, for consistency
        # with int<->complex, float<->complex, and complex<->complex comparisons.
        if isinstance(other, complex):
            raise TypeError("no ordering relation is defined for complex numbers")
        if isinstance(other, float):
            if math.isnan(other) or math.isinf(other):
                return op(0.0, other)
            else:
                return op(self, self.from_float(other))
        else:
            return NotImplemented