Python Operator Overloading

1. What is Operator Overloading

Operator overloading allows custom classes to define how standard operators behave using special (dunder) methods.

class Number:
    def __init__(self, value):
        self.value = value

    def __add__(self, other):
        return self.value + other.value

n1 = Number(10)
n2 = Number(20)

print(n1 + n2)  # Output: 30

The + operator is redefined for the Number class.

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2. Overloading the Addition Operator (+)

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

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

v1 = Vector(5)
v2 = Vector(7)
v3 = v1 + v2

print(v3.x)  # Output: 12

Implements vector addition logic.

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3. Overloading the Subtraction Operator (-)

class Balance:
    def __init__(self, amount):
        self.amount = amount

    def __sub__(self, other):
        return Balance(self.amount - other.amount)

b1 = Balance(100)
b2 = Balance(40)

result = b1 - b2
print(result.amount)  # Output: 60

Custom logic for subtraction.

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4. Overloading Multiplication Operator (*)

class Repeater:
    def __init__(self, text):
        self.text = text

    def __mul__(self, times):
        return self.text * times

r = Repeater("AI ")
print(r * 3)  # Output: AI AI AI 

Defines how objects behave with *.

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5. Overloading Division Operator (/)

class Calculator:
    def __init__(self, value):
        self.value = value

    def __truediv__(self, other):
        return self.value / other.value

c1 = Calculator(100)
c2 = Calculator(4)

print(c1 / c2)  # Output: 25.0

Implements custom division logic.

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6. Overloading Equality Operator (==)

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

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

p1 = Point(5)
p2 = Point(5)

print(p1 == p2)  # True

Controls object comparison behavior.

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7. Overloading Less Than and Greater Than

class Score:
    def __init__(self, marks):
        self.marks = marks

    def __lt__(self, other):
        return self.marks < other.marks

    def __gt__(self, other):
        return self.marks > other.marks

s1 = Score(85)
s2 = Score(70)

print(s1 > s2)  # True

Supports sorting and ranking operations.

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8. Overloading In-place Operators (+=)

class Counter:
    def __init__(self, value):
        self.value = value

    def __iadd__(self, other):
        self.value += other
        return self

c = Counter(10)
c += 5
print(c.value)  # Output: 15

Modifies object in-place.

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9. Overloading String Representation (str())

class Product:
    def __init__(self, name, price):
        self.name = name
        self.price = price

    def __str__(self):
        return f"{self.name} costs ${self.price}"

p = Product("Laptop", 1200)
print(p)  # Laptop costs $1200

Enhances readability of object display.

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10. Comprehensive Operator Overloading Example

class ComplexNumber:
    def __init__(self, real):
        self.real = real

    def __add__(self, other):
        return ComplexNumber(self.real + other.real)

    def __sub__(self, other):
        return ComplexNumber(self.real - other.real)

    def __str__(self):
        return str(self.real)

c1 = ComplexNumber(10)
c2 = ComplexNumber(3)

print(c1 + c2)  # 13
print(c1 - c2)  # 7

Fully custom arithmetic for a domain-specific class.

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