Data Model

Operator Overloading

Operator methods let objects define arithmetic and comparison syntax.

__add__ defines how the + operator combines two objects.

Source

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

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

    def __repr__(self):
        return f"Vector({self.x}, {self.y})"

print(Vector(2, 3) + Vector(4, 5))

Output

Vector(6, 8)

__eq__ defines value equality for ==. Without it, user-defined objects compare by identity.

Source

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

    def __eq__(self, other):
        return (self.x, self.y) == (other.x, other.y)

print(Vector(1, 1) == Vector(1, 1))

Output

True

A useful __repr__ makes operator results inspectable while debugging.

Source

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

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

    def __repr__(self):
        return f"Vector({self.x}, {self.y})"

print(repr(Vector(2, 3) + Vector(4, 5)))

Output

Vector(6, 8)

Notes

Overload operators only when the operation is unsurprising.
Return NotImplemented when an operand type is unsupported.
Implement equality deliberately when value comparison matters.

Run the complete example

Expected output

Vector(6, 8)
True

Execution time appears here after you run the example.

Operator Overloading

See also

Run the complete example

Example code

Expected output