Error when trying to overload an operator “/”

Question

I recently start teaching myself game programming. Someone recommend me to start with Python and I got the book "Beginning game development with Python and Pygame: From novice to professional". I got to a part where they teach about Vectors and creating a Vector2 class. Everything was going well until I tried to overload the division operator. My code goes like this:

class Vector2(object):

  def __init__(self, x=0.0, y=0.0):
    self.x = x
    self.y = y

  def __str__(self):
    return "(%s, %s)"%(self.x, self.y)

  @classmethod
  def from_points(cls, P1, P2):
    return cls(P2[0] - P1[0], P2[1] - P1[1])

  def __add__(self,rhs):
    return Vector2(self.x + rhs.x, self.y + rhs.y)

  def __sub__(self,rhs):
    return Vector2(self.x - rhs.x, self.y - rhs.y)

  def __mul__(self, scalar):
    return Vector2( self.x*scalar, self.y*scalar)

  def __div__(self, scalar):
    return Vector2( self.x/scalar, self.y/scalar)

Now, when I tried to call the "/" operator, this shows up:

AB = Vector2(10.0,25.0)
print(AB)   # <<<<(10.0, 25.0)
v1 = AB + Vector2(20.,10.)
print(v1)   # <<<<(30.0, 35.0)
v2 = AB - Vector2(20.,10.)
print(v2)   # <<<<(-10.0, 15.0)
v3 = AB * 3
print(v3)   # <<<<(30.0, 75.0)
print(v3 / 3)
TypeError: unsupported operand type(s) for /: 'Vector2' and 'int'

This was all in Python 3.3 but if I run it with Python 2.7, everything works correctly. Where's the problem?

Answer 1

In Python 3.x, you need to overload the __floordiv__ and __truediv__ operators, not the __div__ operator. The former corresponds to the // operation (returns an integer) and the latter to / (returns a float).

Answer 2

In Python 3, the division operators are called __truediv__ and __floordiv__. See the Data model documentation for more information.