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'classmethod' object not callable

In the "Construction Zone" challenge, I copied and pasted all of the code from the challenge (including my solution, which passed) into my console. When I tried to test the from_string method I got an error message.

Here is how I attempted to test the from_string method:

ns = from_string(Letter, 'dash-dot-dash-dash-dot')

And here is the error I received:

TypeError: 'classmethod' object is not callable

So, the classmethod is defined, and so is the parent class (Letter). Why is this classmethod error popping up? Am I not calling the from_string method correctly?

5 Answers

Rich Zimmerman
Rich Zimmerman
24,063 Points

Without seeing the entire code to be sure. If you're calling a class' method, you need to define which class is you're calling it from. Something like:

Class Foo:
        return baz

# You'd can't just call bar() alone. You'd have to define which class' method is it like:
a = Foo.bar()

Does this help?

Thanks for the reply Rich. I'm trying to call test a method inside a class method. Here's the code I copied and pasted into Terminal:

class Letter:
    def __init__(self, pattern=None):
        self.pattern = pattern

    def __iter__(self):
        yield from self.pattern

    def __str__(self):
        output = []
        for blip in self:
            if blip == '.':
        return '-'.join(output)

    def from_string(cls, string):
        convert_list = string.split('-')
        output = []
        for i in convert_list:
            if i == 'dash':
            elif i == 'dot':
        return cls(output)

And here's the method I'm trying to test:

ns = from_string(Letter, 'dot-dash-dot-dot-dash-dot')

When I type "ns" at the command prompt, I'm expecting to see output of ['.', '', '.', '.', '', '.']. Instead I'm getting the TypeError.

TypeError: 'classmethod' object is not callable

So, again, just not sure what I'm doing wrong.

Rich Zimmerman
Rich Zimmerman
24,063 Points

It should work with

ns = Letter.from_string('dot-dash-dot-dot-dash-dot')

I believe

That one gave me

AttributeError: type object 'Letter' has no attribute 'from_string'
Rich Zimmerman
Rich Zimmerman
24,063 Points

Sorry, I was doing some googling here.. I'm not entirely sure.

I did come across one stack overflow question with the same issue where the person had an error in his module import lines at the top of the file.

Are you importing the Letter class from another module? If so, how?

Brian, I am looking through comments on this challenge to find an answer to your question. I had a similar one in that i initially tried calling the super class' (Letter) from_string() method from an S() instance. I couldn't get it to work. Then, I found an answer I posted here: https://teamtreehouse.com/community/debugging-3

The answer calls it without S(), i.e., only using Letter(). So, I went with that for now, but was confused as to the purpose of including the S class at all in that challenge....probably to confuse dummies like me ;)

Lastly, I, too, did lots of research trying to figure out how, but I never found a solution with class methods using @classmethod