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

Challenge Task 2 of 2 Now wrap it up by adding in __imul__, which does in-place multiplication. Be sure to update self.

i really dot get it

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):
        return self * other

    def __imul__(self, other): 
        self.value = self.value * other   
        return self.value

1 Answer

Chris Freeman
MOD
Chris Freeman
Treehouse Moderator 68,082 Points

You are close to having the correct answer. The goal of __imul__ is to retain the object type of self.value as a str.

Let's break down what you've tried:

    def __imul__(self, other): 
        self.value = self.value * other   
        return self.value

Since self.value is a string, multiplying it by a integer will result in a repeated string, not a new string containing the updated number. With the __mul__ method is available, use it to do the multiplication. To trigger the use of __mul__, use self as the multiplicand in place of self.value. This gives us:

        self.value = self * other   

One drawback is __mul__ returns an integer instead of string. To fix this, wrap the multiplication with str():

        self.value = str(self * other)

Post back if you need more help. Good luck!!

thank you id figure it out :D