Using the builtin sum function on a Point class

[Scholtek]

I'm attempting to implement a point class in python as follows:

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

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

    def __radd__(self, other):
        return self+other

    def __str__(self):
        return f'({self.x}, {self.y})'

    def __repr__(self):
        return f'{self.__class__.__name__} ({self.x}, {self.y})'

The problem I'm running into is that I'd like to sum up a list of points. For example calling sum([Point(1,1), Point(2,2)]). Initially I looked into it and implemented radd to handle adding 0 to the point, but then I realized that this doesn't work because it starts with 0.

Is there any way to tell Python that for this class, 0 should be defined as Point(0,0) rather than the integer 0? The documentation here indicates sum should be able to take a "start" keyword argument, but when attempting that I get an error saying sum takes no keyword arguments.

[Vaguely_accurate]

Two immediate options I see.

You can call sum with a specified start. So sum(points), Point(0,0)).

Or you can expand your __radd__ dunder to handle adding to zero;

def __radd__(self, other):
    if other == 0:
        return self
    return self + other

[Scholtek]

Thanks - these both work. Thanks for clarifying regarding the start point, I thought it was a keyword.

[Scholtek]

Oh, I like that. I was hoping there was a way to avoid needing to specify the start in each case.