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 Subclassing Built-ins

Juneau Lim
Juneau Lim
13,362 Points
Posted by Juneau Lim
Juneau Lim
13,362 Points

Question about my Liar

question about my Liar When I did below, it didn't work.

class Liar(list):
    def __len__(self):
        truth = super().__len__()
        return truth * 2  # error

However, when I changed the last line to +, it was ok.

        return truth + 2  # OK

What is the difference? I have no idea.

1 Answer

Steven Parker
Steven Parker
215,396 Points
Steven Parker
Steven Parker
215,396 Points

The challenge wants your function to always return an incorrect value (a "lie").

The problem with "truth * 2" is that when the actual value is 0, your function will return the true value.

Juneau Lim
Juneau Lim
13,362 Points
Juneau Lim
Juneau Lim
13,362 Points

Wow, that's a gotcha. I haven't think about that case. Thanks for the answer!

Juneau Lim
Juneau Lim
13,362 Points
Juneau Lim
Juneau Lim
13,362 Points

Sorry I thought I did it. :-(