Introduction

In this article, you'll learn how self is used in Python, and why it is used instead of this.

If you wanna jump to the answer, read the source directly by clicking here.

How self is used in Python

In short, It's more of a convention used for representing the instance of a Class.

From the Official Python Documentation:

Often, the first argument of a method is called self. This is nothing more than a convention: the name self has absolutely no special meaning to Python. Note, however, that by not following the convention your code may be less readable to other Python programmers, and it is also conceivable that a class browser program might be written that relies upon such a convention.

Example:

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

    def get_name(self):
        print(self.name)

    def get_age(self):
        print(self.age)

    def get_pno(self):
        print(self.pno)

    def set_name(self):
        new_name = input("Enter New Name: ")
        self.name = new_name

    def set_age(self):
        new_age = int(input("Enter New Age: "))
        self.age = new_age

    def set_pno(self):
        new_pno = input("Enter New Phone Number: ")
        self.pno = new_pno

    def __repr__(self):
        """This method let's users print the details of the Person
        when a user attempts to print the object."""
        return f'{self.__class__.__name__}(name="{self.name}", age={self.age}, pno="{self.pno}")'


if __name__ == "__main__":
    # Create an Object
    jack = Person("Jack", 21, "+91-788888765")

    print(jack)

    # Update Phone Number
    jack.set_pno()

    # Update Age Number
    jack.set_age()

    # Print Phone Number
    jack.get_pno()

    print(jack)

    # Output:
    # Person(name="Jack", age=21, pno="+91-788888765")
    # Enter New Phone Number:
    # Input: +91-1234567890
    # Output:
    # Enter New Age:
    # Input: 23
    # Output:
    # +91-1234567890
    # Person(name="Jack", age=23, pno="+91-1234567890")

In the above example, self is used for accessing the data members of the class. Also, I could have given some examples of how self can be used for calling methods inside a class as well, but you'll be able to find plenty of them on the internet 😉.

Though, here's a must read answer about the purpose of the word self in Python on Stack Overflow.

The Ultimate Question, Why self instead of this?

Students are curious why the first parameter to bound methods is self, not this. I'm guessing to make it clear that it doesn't actually work quite the same as this in other OO langs?

Tweeted by @pamelafox

The ANSWER

I don’t recall the reason I chose self, but I imagine it was an act of rebellion against C++ this. Just like ‘None’ rebelled against C NULL. Basically just being a little ornery (like naming it after an irreverent tv show instead of a famous scientist or engineer).

Tweeted by Guido Van Rossum (Creator of Python)

Link to the Original Tweets

twitter.com/gvanrossum/status/1448523212329..

Read more about OOP in Python

docs.python.org/3/tutorial/classes.html

Fin: Thanks for reading