numeric_finished.py

# Example file for Advanced Python: Language Features by Joe Marini
# give objects number-like behavior

# Refer to:
#   https://docs.python.org/3/reference/datamodel.html#emulating-numeric-types


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

    def __repr__(self):
        return "<Point x:{0},y:{1}>".format(self.x, self.y)

    # implement addition
    def __add__(self, other):
        return Point(self.x + other.x, self.y + other.y)

    # implement subtraction
    def __sub__(self, other):
        return Point(self.x - other.x, self.y - other.y)

    # implement in-place addition
    def __iadd__(self, other):
        self.x += other.x
        self.y += other.y
        return self


# Declare some points
p1 = Point(10, 20)
p2 = Point(30, 30)
print(p1, p2)

# Add two points
p3 = p1 + p2
print(p3)

# subtract two points
p4 = p2 - p1
print(p4)

# Perform in-place addition
p1 += p2
print(p1)