Operator Overloading

In Python, operators like +, -, and == have special meanings for built-in data types. For example:

• + adds numbers: 3 + 4 gives 7.
• + can also join strings: "Hello" + "World" gives "HelloWorld".

But what if you have a custom object, and you want + or ==to work with it? That’s where operator overloading comes in! It lets you define how operators should behave for your objects.

Why use operator overloading?

It makes your code more intuitive and readable. Instead of calling a method like add_objects(obj1, obj2), you can simply write obj1 + obj2.

How does it work?

Python has special methods (also called "magic methods") that correspond to operators. For example:

• __add__: Defines the behavior of the + operator.
• __sub__: Defines the behavior of the - operator.
• __eq__: Defines the behavior of the == operator.

You override these methods in your class to customize operator behavior.

Example: Adding two custom objects

Imagine you’re working with a Book class where each book has a certain number of pages. You want to "add" two books together to get the total number of pages.

Step 1: Create the class

class Book:
    def __init__(self, title, pages):
        self.title = title
        self.pages = pages

Step 2: Overload the + operator

Use the __add__ method to define what happens when you use + with two Book objects.

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

Step 3: Try it out

book1 = Book("Python Basics", 300)
book2 = Book("Advanced Python", 450)

total_pages = book1 + book2
print(f"Total pages: {total_pages}")  # Output: Total pages: 750

Here’s what happens:

• When you write book1 + book2, Python automatically calls book1.__add__(book2).

Example: Comparing two objects

What if you want to check if two books have the same number of pages using ==? You can overload the __eq__ method.

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

Now, you can do this:

book3 = Book("Python Basics", 300)
print(book1 == book3)  # Output: True (same number of pages)

Real-life analogy

Think of operator overloading as teaching your object how to behave with certain actions. For example:

• + for numbers means add, but for strings, it means combine.
• By overloading operators, you decide what these actions mean for your objects.