curriculum/challenges/english/blocks/learn-special-methods-by-building-a-vector-space/65f9b17a638f0d0dcce8c354.md
To create a vector space, you need to define how vectors should behave in several cases. Vectors can be added, forming a new vector.
The special method __add__ can be implemented to override what happens by default when two objects are added together using the + operator.
Right now, trying to add two instances of R2Vector or R3Vector would raise an exception. Create an empty __add__ method within the R2Vector class and give it two parameters: self, and other.
You should define an __add__ method within the R2Vector class.
({ test: () => assert(runPython(`_Node(_code).find_class("R2Vector").has_function("__add__")`)) })
Your __add__ method should have two parameters, self and other.
({ test: () => assert(runPython(`_Node(_code).find_class("R2Vector").find_function("__add__").has_args("self, other")`)) })
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})'
--fcc-editable-region--
--fcc-editable-region--
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}')
print(f'v2 = {v2}')