Welcome to the Treehouse Community

The Treehouse Community is a meeting place for developers, designers, and programmers of all backgrounds and skill levels to get support. Collaborate here on code errors or bugs that you need feedback on, or asking for an extra set of eyes on your latest project. Join thousands of Treehouse students and alumni in the community today. (Note: Only Treehouse students can comment or ask questions, but non-students are welcome to browse our conversations.)

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and a supportive community. Start your free trial today.

Python Object-Oriented Python Advanced Objects Multiplication

The Question is: Adding in __imul__, which does in-place multiplication.

what is the problem, i can't undrestand...

numstring.py
class NumString:
    def __init__(self, value):
        self.value = str(value)

    def __str__(self):
         return self.value

    def __int__(self):
        return int(self.value)

    def __float__(self):
        return float(self.value)

    def __add__(self, other):
        if '.' in self.value:
            return float(self) + other
        return int(self) + other

    def __radd__(self, other):
        return self + other

    def __iadd__(self, other):
        self.value = self + other
        return self.value

    def __mul__(self, other):
        if '.' in self.value:
            return float(self) * other
        return int(self) * other

    def __rmul__(self, other):
        if '.' in self.value:
            return float(self) * other
        return int(self) * other

    def __imul__(self, other):
        if '.' in self.value:
            return float(self) *= other
        return int(self) *= other

2 Answers

Chris Freeman
MOD
Chris Freeman
Treehouse Moderator 67,989 Points

You are very close. Notice how in the in-place method __iadd__, the value of self.value is updated before the return. This is what makes it work in place: the object value changes and is not just used to return a value. Add assignments to self.value and it should pass.

Post back if you have more questions! Good luck!!

it works. Thank you so much

Nadia Hussein
Nadia Hussein
646 Points

How are you supposed to know to change the object value and not just the return value? Is it because they ask for "in-place" multiplication?

Chris Freeman
Chris Freeman
Treehouse Moderator 67,989 Points

Correct, in-place, implies changing the object value