Classes and Object in Python

In Python, a class is a blueprint defining attributes and methods, while an object is an instance of that class, embodying its specific characteristics. Classes facilitate code organization, encapsulation, and reusability, enabling the creation of multiple objects with shared behaviors.

While it may not apply universally, I often find it straightforward to illustrate: In the context of Object-Oriented Programming (OOP), one can represent MySQL tables to classes and rows to objects. For instance, envisioning a students_table as a Student class, the record corresponding to John Doe becomes an object instantiated from the Student class.

Classes:

• Definition: A class is a blueprint or a template for creating objects. It defines attributes (variables) and methods (functions) that characterize the objects instantiated from the class.

  • Creation:

    class User:
        def __init__(self, user_id, username, email):
            self.user_id = user_id
            self.username = username
            self.email = email
    
        def display_info(self):
            print(f"User ID: {self.user_id}, Username: {self.username}, Email: {self.email}")
    

    class User: defines a class called User that serves as a blueprint for creating objects representing users in a system.

    __init__(self, user_id, username, email):

    • Constructor: initializes a new User object with the given information:
      • self.user_id: Stores the unique ID assigned to the user.
      • self.username: Stores the user's chosen username.
      • self.email: Stores the user's email address.
    • Attributes: Variables like user_id, username, and email define details of objects created from Student Class
    • Method: display_info(self): Prints the user's information to the console in a formatted way:
      • It uses an f-string to interpolate the values of user_id, username, and email into the output string.
      • The output would look like this: User ID: 123, Username: johndoe, Email: johndoe@example.com
    • Key Points:
      • The User class encapsulates the core information and a basic method for displaying that information related to a user.
      • It provides a foundation for managing user data and actions within a system.
      • You can create instances of this class to represent different users, each with their own unique attributes.

Objects:

• Definition: An object is an instance of a class, representing a specific entity with its unique attributes and behaviors.

• Instantiation:

  user1 = User(123, "johndoe", "johndoe@example.com")
  

• Attributes: Each object, like uset1, has its own set of attributes (e.g., name and email).

• Methods: Objects can perform actions defined by the methods (e.g., display_info(self)).

• Example:

  # Create a User object
  user1 = User(123, "johndoe", "johndoe@example.com")
  
  # Call the display_info method to print the user's information
  user1.display_info()  # Output: User ID: 123, Username: johndoe, Email: johndoe@example.com
  

📝 Key Concepts:

• Self: The self parameter refers to the instance of the class. It is a convention in Python to use self as the first parameter of instance methods.
• *init* Method: The __init__ method is a special method used for initializing object attributes when an object is created.

⚡ Why Classes and Objects?

• Code Organization: Classes provide a way to structure code, making it more organized and modular.
• Code Reusability: Objects enable the reuse of code templates, fostering efficiency and reducing redundancy.
• Abstraction: OOP promotes abstraction, allowing developers to focus on essential details while hiding complexity.