# FAQ: Learn Python - Classes - Building useful classes

This community-built FAQ covers the “Building useful classes” exercise in Codecademy’s lessons on Python.

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i couldnt guess this part: my_point = Point3D(1, 2, 3)

ithough as the instructions says to asign to x, y, z, like my_point.Point3D(x =1, y=2, z =3) somethings i find really difficult to guess…

2 Likes

Thats my code, that shows the error message "it looks like you didn’t print “(1,2,3)”. For me is the same that is in the solution. What is wrong?

class Point3D(object):
def init(self,x,y,z):
self.x=x
self.y=y
self.z=z

def repr(self):
return “(%d,%d,%d)” % (self.x,self.y,self.z)

my_point = Point3D(1,2,3)
print my_point

``````class Point3D(object):
def __init__(self, x, y, z):
self.x = x
self.y = y
self.z = z
def __repr__(self, x, y, z):
return "( %d, %d, %d )" % (str(self.x), str(self.x), str(self.x))
my_point = Point3D(1, 2, 3)
print my_point
``````

dont understand error…

Output:
Traceback (most recent call last):
File “python”, line 9, in
TypeError: repr() takes exactly 4 arguments (1 given)

``````class Point3D(object):
def __init__(self, x, y, z):
self.x = x
self.y = y
self.z = z
def __repr__(self):
return "( %s, %s, %s )" % (str(self.x), str(self.y), str(self.z))
my_point = Point3D(1, 2, 3)
print my_point
``````

got it now works perfect

1 Like