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Python Object-Oriented Python Advanced Objects Subclassing Built-ins

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

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

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

Juneau Lim
Juneau Lim
13,362 Points

Sorry I thought I did it. :-(