Learn Special Methods by Building a Vector Space - Step 34

Python
1

Tell us what’s happening:

I’m seeing ‘calling getattribute’ by printing

print(getattr(v1, v1.x))
print(v1.x)

But still my code doesn’t pass.

Your code so far

class R2Vector:
    def __init__(self, *, x, y):
        self.x = x
        self.y = y

    def norm(self):
        return sum(val**2 for val in vars(self).values())**0.5

    def __str__(self):
        return str(tuple(getattr(self, i) for i in vars(self)))

    def __repr__(self):
        arg_list = [f'{key}={val}' for key, val in vars(self).items()]
        args = ', '.join(arg_list)
        return f'{self.__class__.__name__}({args})'
    
    def __getattribute__(self, attr):                
        return 'calling __getattribute__'

class R3Vector(R2Vector):
    def __init__(self, *, x, y, z):
        super().__init__(x=x, y=y)
        self.z = z

v1 = R2Vector(x=2, y=3)
v2 = R3Vector(x=2, y=2, z=3)
# print(f'v1 = {v1}', f'\nrepr = {repr(v1)}')
# print(f'v2 = {v2}', f'\nrepr = {repr(v2)}')

# User Editable Region

print(getattr(v1, v1.x))
print(v1.x)

# User Editable Region

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Challenge Information:

Learn Special Methods by Building a Vector Space - Step 34

2

You’re not using the correct syntax for getattr(). You would not use dot notation within getattr()

1 Like
3

Thanks, @pkdvalis … I was missing the quotation marks…

4

Quotes makes it a string, which is how you reference the attribute, yes. However you also do not use dot notation there:

class Person:
  name = "John"
  age = 36
  country = "Norway"

x = getattr(Person, 'age')

You just refer to the attribute by name. The object is already referenced in the first argument.

https://www.w3schools.com/python/ref_func_getattr.asp

5

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