Introduction to Dunder Python

Dunder Python, also known as "Double Underscore" or "Magic Methods", refers to a set of special methods in Python that begin and end with double underscores. These methods allow developers to define how objects of a class behave in various scenarios, such as arithmetic operations, comparisons, and string representations.

Key Features

Here are some of the most commonly used dunder methods in Python:

• __init__(self[, args...]): Constructor method that is called when an instance of the class is created.

• __str__(self): Returns a string representation of the object.

• __eq__(self, other): Determines if two objects are equal.

• __lt__(self, other): Determines if one object is less than another.

• __add__(self, other): Performs addition between two objects.

• __len__(self): Returns the length of the object.

• __getitem__(self, key): Returns the value of an item in the object, based on a given key.

• __setitem__(self, key, value): Sets the value of an item in the object, based on a given key.

Examples

Here are some examples of how dunder methods can be used in Python:

class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age

    def __str__(self):
        return f"{self.name} ({self.age} years old)"

    def __eq__(self, other):
        return self.name == other.name and self.age == other.age

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

person1 = Person("Alice", 25)
person2 = Person("Bob", 30)

print(person1)
# Output: Alice (25 years old)

print(person1 == person2)
# Output: False

print(person1 < person2)
# Output: True

In the above example, we define a Person class with an __init__ method, a __str__ method, an __eq__ method, and an __lt__ method. We then create two instances of the Person class and demonstrate how these dunder methods can be used to compare and manipulate the objects.

Conclusion

Dunder Python provides a powerful way for developers to extend the functionality of their classes and objects. By using the built-in dunder methods in Python, you can define how your objects behave in a wide variety of scenarios, making your code more efficient and easier to read.