Question

One of my exercises says to write an add method for Points that works with either a Point object or a tuple:

• If the second operand is a Point, the method should return a new Point whose x coordinate is the sum of the x coordinates of the operands, and likewise for the y coordinates.
• If the second operand is a tuple, the method should add the first element of the tuple to the x coordinate and the second element to the y coordinate, and return a new Point with the result.

This how far I got and I’m not sure if the tuple portion of my code is accurate. Can someone shed some light how I would call this program for the tuple portion. I think I nailed the first part.

Here is my code:

Class Point():
    def__add__(self,other):
            if isinstance(other,Point):
                    return self.add_point(other)
            else:
                    return self.print_point(other)

    def add_point(self,other):
            totalx = self.x + other.x
            totaly = self.y + other.y
            total = ('%d, %d') % (totalx, totaly)
            return total

    def print_point(self):
            print ('%d, %d) % (self.x, self.y)

    blank = Point()
    blank.x = 3
    blank.y = 5
    blank1 = Point()
    blank1.x = 5
    blank1.y = 6

That’s what I’ve built so far and I’m not sure how to actually run this with the tuple part. I know if it did blank + blank1 the if portion would run and call the add_point function but how do I initiate the tuple. I’m not sure if I wrote this correctly… please assist.

Answer 1

Alternatively, if you want to be able to use point.x and point.y syntax, you could implement the following:

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

    def __add__(self, other): 
        if isinstance(other, Point):
            return Point(self.x + other.x, self.y + other.y)
        elif isinstance(other, tuple):
            return Point(self.x + other[0], self.y + other[1])
        else:
            raise TypeError("unsupported operand type(s) for +: 'Point' and '{0}'".format(type(other)))

    def __repr__(self):
        return u'Point ({0}, {1})'.format(self.x, self.y) #Remove the u if you're using Python 3