- Python Introduction
- Python - Overview
- Python - History and Evolution
- Python - Significance in Modern Development
- Python - Understanding Python's design philosophy and the Zen of Python
- Python - Installing Python and Setting up the Development Environment
- Python - Setting Up the Development Environment
- Python - Basic Syntax and Execution of Python Scripts
- Python - Getting Started to Python
- Python Basics
- Python - Control flow (If statements, Loops - For and While)
- Python - Operators (Arithmetic, Comparison, Logical, Assignment)
- Python - Arithmetic Operators
- Python - Comparison Operators
- Python - Logical Operators
- Python - Assignment Operators
- Python - Integers (int)
- Python - Floats (float)
- Python - Strings (str)
- Python - Loop Control Statements
- Python - Loops
- Python - If Statements
- Python - Python's built-in functions
- Python - Using Built-in Functions
- Python - Examples of Common Built-in Functions
- Python Data Structures
- Python - Understanding Lists, Tuples, Sets, and Dictionaries
- Python - Lists
- Python - Tuples
- Python - Sets
- Python - Dictionaries
- Python - Operations on Data Structures (Indexing, Slicing, Appending, Removing)
- Python - Advanced Usage
- Python - Advanced Data Manipulation Techniques (List Comprehension, Dictionary comprehension)
- Python - List Comprehensions
- Python - Dictionary Comprehensions
- Python Functions and Modules
- Python - Defining a Function
- Python - Function arguments and return values
- Python - Function Arguments
- Python - Return Values
- Python - Defining and calling functions
- Python - Using the Return Value
- Python - Calling the Function with Arguments
- Python - Creating a Module
- Python - Importing a Module
- Python - Creating a Package
- Python - Importing from a Package
- Python - Creating and importing modules and packages
- Python - Introduction to Python standard libraries.
- Python - File and Directory Access
- Python - Internet Data Handling
- Python - Networking
- Python - Data Persistence and Serialization
- Python - Data Compression and Archiving
- Python - Concurrent Execution
- Python - Mathematics
- Python - Date and Time
- Python - Development Tools
- Python Object-Oriented Programming
- Python - Understanding classes and objects
- Python - Understanding Classes
- Python - Understanding Objects
- Python - Inheritance, encapsulation, and polymorphism
- Python - The constructor, class variables, and instance variables
- Python - Magic methods and their importance
- Python Error Handling and Debugging
- Python - Exceptions
- Python - Working Code Sample Demonstrating Both
- Python - Handling exceptions with try-except blocks
- Python - Syntax Errors versus Exceptions
- Python - Using logging for Debugging and Error tracking
- Python Working with Files
- Python - Reading from and writing to files
- Python - Writing to a File
- Python - Reading from a File
- Python - Combined Example of Reading and Writing
- Python - Understanding file handling modes
- Python - Common File Handling Modes
- Python - Working with different file formats (text, CSV, JSON)
- Python - Working with Text Files
- Python - Working with JSON Files
- Python - Working with CSV Files
- Python Web Scraping
- Python - Introduction to Beautiful Soup and requests library
- Python - Beautiful Soup
- Python - Requests Library
- Python - Legality of Web Scraping
- Python - Overview of web scraping and its legality
- Python - Combined Example: Using Both Requests and Beautiful Soup
- Python - Conclusion
Python - The constructor, class variables, and instance variables
Constructor, Class Variables, and Instance Variables in Python
Classes in Python combine behavior and data into a single unit. Understanding constructors, class variables, and instance variables is essential to writing object-oriented programs efficiently.
Constructor
The __init__ function acts as the constructor of a Python class. It is called immediately as soon as a new instance of the class is generated. This sets the initialization parameters of the instance and provides an opportunity to complete any necessary configuration.
Class Variables
Every instance of a class shares its class variables. Although these are not included in any methods, they are declared inside the class. Class names or instances can be used to access class variables.
Instance Variables
Each instance of a class has its own instance variables. They store instance-specific data and are specified within the methods themselves.
Example
This example shows how object-oriented programming concepts are applied to produce organized and encapsulated code using constructors, class variables, and instance variables.
class Vehicle:
#Class variable
vehicle_count = 0
def __init__(self, make, model):
#Instance variables
self.make = make
self.model = model
#Modifying the class variable
Vehicle.vehicle_count += 1
def display_info(self):
print(f"Make: {self.make}, Model: {self.model}")
#Creating instances of the Vehicle class
car1 = Vehicle("Toyota", "Corolla")
car2 = Vehicle("Honda", "Civic")
#Accessing instance variables
print(car1.make) # Output: Toyota
print(car2.model) # Output: Civic
#Accessing class variable through the class name and an instance
print(Vehicle.vehicle_count) # Output: 2
print(car1.vehicle_count) # Output: 2 (accessible via instance as well)
#Calling an instance method
car1.display_info()Output
Toyota
Civic
2
2
Make: Toyota, Model: Corolla
Explanations
Vehicle is a class, composed of the instance variables make and model, as well as the class variable vehicle_count.
When a new vehicle instance is created, the __init__ method (constructor) initializes the instance variable and increments the vehicle_count class variable.
It is possible to print the make and model of a vehicle with the display_info instance function.
Two instances of the Vehicle class – Car1 and Car2 – are created, with different makes and models.
Accessible via both class name and instance, the vehicle_count class variable keeps track of the total number of vehicle instances generated.
