Question

I’m trying to learn OOP in Python, and making the following code to overwrite the __plus__ method

class Fraction(object):
    '''Define a fraction type'''
    def __init__(self, num=0, denom=1):
        '''Create a new Fraction with numerator num and denominator demon'''
        self.numerator = num
        if denom != 0:
            self.denominator = denom
        else:
            raise ZeroDivisionError


    def __plus__(self, f):
        num = self.numerator + f.numerator      
        denom = self.numerator + f.denominator
        return "{0}/{1}".format(num, denom)

f = Fraction(1, 6)

print f + f # I want to result be 2/12

  File "<stdin>", line 1, in <module>
TypeError: unsupported operand type(s) for +: 'Fraction'

but it gives me an error, I don’t know how to solve the error, any idea?

Answer 1

You need to override the __add__ method instead of __plus__. Just try to replace __plus__ with __add__.