The self Parameter in Python

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The self Parameter in Python

In Python, self is a reference to the current object (instance) of a class. It allows methods inside a class to access and modify the object’s own data and behavior.

Whenever you work with instance variables or methods, self is required.

Using self to Access Object Properties

Attributes that belong to an object are accessed using the self keyword.

Example: Access Attributes with self

class Profile: def __init__(self, username, points): self.username = username self.points = points def show_profile(self): print(f"User: {self.username}, Points: {self.points}") p1 = Profile("Arjun", 120) p1.show_profile()

User: Arjun, Points: 120

Here:

• self.username and self.points belong to the specific object p1
• Each object has its own unique values

Why self Is Necessary

Without self, Python would not know which object’s data a method should use.

Example: Linking Methods to Objects

class Student: def __init__(self, name): self.name = name def display_name(self): print(self.name) s1 = Student("Neha") s2 = Student("Karan") s1.display_name() s2.display_name()

Neha Karan

Each method call works on a different object, even though the same class is used.

Rule: self Must Be the First Parameter

In every instance method, self must be the first parameter. Python automatically passes the current object when the method is called.

self Is a Convention, Not a Keyword

Technically, self can be named anything, but using self is strongly recommended for readability and consistency.

Example: Using a Different Name (Not Recommended)

class Device: def __init__(obj, name): obj.name = name def show(obj): print(obj.name) d1 = Device("Printer") d1.show()

Printer

Even though this works, using self makes the code easier for others to understand.

Accessing Multiple Properties with self

You can use self to access any number of object attributes.

Example: Display Object Information

class Laptop: def __init__(self, brand, ram, price): self.brand = brand self.ram = ram self.price = price def details(self): print(f"{self.brand} | {self.ram}GB RAM | ₹{self.price}") lap1 = Laptop("HP", 16, 65000) lap1.details()

HP | 16GB RAM | ₹65000

Calling One Method from Another Using self

Methods inside the same class can call each other using self.

Example: Method Calling Another Method

class Greeting: def __init__(self, name): self.name = name def say_hello(self): return f"Hello {self.name}" def full_message(self): print(self.say_hello() + ", have a great day!") g1 = Greeting("Rohit") g1.full_message()

Hello Rohit, have a great day!

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