Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

Python Object-Oriented Python Advanced Objects Multiplication

Posted by Siddhartha Kala
Siddhartha Kala
4,170 Points

What is wrong with __rmul__

What am i doing wrong with rmul. I keep getting error that says cannot multiply number to NumString

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) * float(other)
        else: 
            return int(self) * int(other) 

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

1 Answer

Steven Parker
Steven Parker
230,995 Points
Steven Parker
Steven Parker
230,995 Points

Try using the existing __add__ and __radd__ methods as models, and just changing the math operator.

Siddhartha Kala
Siddhartha Kala
4,170 Points

Thats the first thing I tried, but, keep getting the following error message:

 Bummer! Can't multiply a number with a `NumString` (i.e. `10 * NumString`)

Here is what i tried:

def rmul(self, other): return self * other

Steven Parker
Steven Parker
230,995 Points
Steven Parker
Steven Parker
230,995 Points

That looks good, now what about __mul__?

Siddhartha Kala
Siddhartha Kala
4,170 Points

I got it now. Thanks a lot. Had to remove float and int from other in mul