AttributeError: 'tuple' object has no attribute 'num'

Question

I started to learn Python 2 weeks ago, and I was doing an exercise about class (which consists of creating my own "Fraction" class) when I got the error in the title. Why ? And how to solve it ? Sorry, i'm not the type of person who often ask for help, but now I really don't know how to solve it. It seems that the error occurs only in "str" method.

Here you have my code(idk if this will appear properly..):

from math import gcd

class Fraction :

    def __init__(self,a,b):
        self.num = a
        self.den = b

    def __str__(self):
        return str(self.num)+" / "+str(self.den)

    def reduire(self):
        return self.num//gcd(self.num,self.den) , self.den//gcd(self.num,self.den)

frac = Fraction(30,40)
print(Fraction.__str__(Fraction.reduire(frac)))

reduire returns a tuple, and then you try to get the num field, and tuples don't have named fields. You probably want reduire to return a Fraction. — Silvio Mayolo
– Silvio Mayolo, Commented Aug 12, 2022 at 18:30
As a side, do you know Python 2 is not receiving updates since 2020? If you are learning just for the sake of knowing python or learning to program, you may want to consider using Python 3. — Ignatius Reilly
– Ignatius Reilly, Commented Aug 12, 2022 at 18:37
Suggestions to slow down the learning speed - try to get the basics covered/familiar then OOP — Daniel Hao
– Daniel Hao, Commented Aug 12, 2022 at 18:37

trincot · Accepted Answer · 2022-08-12 18:38:37Z

1

First of all, you call reduire as if it is a class/static method, but it is an instance method, so it is more natural to call it as frac.reduire()

The error comes from your call of __str__ (which again you call as if it is a class/static method) and you pass it the value that reduire returns (a tuple) instead of the frac instance. The __str__ function expects the fraq instance (self) as argument. This can be done better with str(fraq), in a separate statement.

But as your goal is to print, this call of str (and __str__) can actually be omitted. print already takes care of this. So just do:

frac.reduire()
print(frac)  # this implicitly calls `__str__`

edited Aug 12, 2022 at 18:38

answered Aug 12, 2022 at 18:33

trincot

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