Rational, that means that we define __add__ and __radd__ as:
def __add__(self, other):
+ # Both types have numerators/denominator attributes,
+ # so do the operation directly
if isinstance(other, (int, long, Rational)):
- # Do the real operation.
return Rational(self.numerator * other.denominator +
other.numerator * self.denominator,
self.denominator * other.denominator)
- # float and complex don't follow this protocol, and
- # Rational knows about them, so special case them.
+ # float and complex don't have those operations, but we
+ # know about those types, so special case them.
elif isinstance(other, float):
return float(self) + other
elif isinstance(other, complex):
return complex(self) + other
- else:
- # Let the other type take over.
- return NotImplemented
+ # Let the other type take over.
+ return NotImplemented
def __radd__(self, other):
# radd handles more types than add because there's
return float(other) + float(self)
elif isinstance(other, Complex):
return complex(other) + complex(self)
- else:
- return NotImplemented
+ return NotImplemented
There are 5 different cases for a mixed-type addition on