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Python Object-Oriented Python Advanced Objects Frustration

Chris Grazioli
Chris Grazioli
31,225 Points
Posted by Chris Grazioli
Chris Grazioli
31,225 Points

Override the __len__ method so that it always returns the wrong number of items in the list. For example, if a list has

Kenneth Love I know I'm missing something trivial here... what is it? Your overriding the len to be incorrect, but the Challenge suggests using super(), which to me, means using the correct len for list and then changing it

frustration.py 
class Liar(list):
    def __len__(self, items):
        real_length= super().__len__(items)
        return real_length+=3

5 Answers

Kent Åsvang
Kent Åsvang
18,823 Points
Kent Åsvang
Kent Åsvang
18,823 Points

Here's how I usually implement this type of code: 

class Liar(list):

    def __len__(self):
        return super(Liar, self).__len__() + 2
Christopher Carucci
Christopher Carucci
1,971 Points

Wish you would comment your code.

Graham Usai
Graham Usai
16,688 Points

this worked

Christopher Shaw
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PLUS
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Christopher Shaw
Python Web Development Techdegree Graduate 58,248 Points
Christopher Shaw
.a{fill-rule:evenodd;}techdegree seal-36
Christopher Shaw
Python Web Development Techdegree Graduate 58,248 Points

Just two things to look at:

len is the length of the list, you don't provide the items, so: 

def __len__(self):

# and

real_length= super().__len__()

Lastly, remove the = from your return statement, you are not setting the value of real_length, just returning a value. return real_length + 3

tmsmth
tmsmth
10,543 Points
tmsmth
tmsmth
10,543 Points

Christopher Shaw Simply curious here why

super().__len__(self)

doesnt work ?

Katsiaryna Krauchanka
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Katsiaryna Krauchanka
Full Stack JavaScript Techdegree Graduate 22,154 Points

Because super().__len__(self) is wrong syntax.

__len__() does not take any arguments.

The following code works

class Liar(list):
    def __len__(self):
        return super().__len__() + 1

You can refer to the documentation https://docs.python.org/3/library/functions.html#super

Ikuyasu Usui
Ikuyasu Usui
36 Points
Ikuyasu Usui
Ikuyasu Usui
36 Points

Can you explain why this doesn't work?

class Liar(list):
    def __init__(self, *args, **kwargs):
        super().__init__()

    def __len__(self):
        return self.__len__()

I get "RecursionError: maximum recursion depth exceeded" which is all right, but I don't know why it doesn't work. After super().__init__(), self should be simply a list.

ryan forte
ryan forte
2,691 Points
ryan forte
ryan forte
2,691 Points

In Python3 we do not need to add the SubClass and instance when we call super. Nor do we need the dunder init, as Python3 will interpret it as a List. So simply we can call it like this:

class Liar(list):
    def __len__(self):
        return super().__len__() + 5