What are `self` and `__init__` in Python Object-Oriented Programming?-Python Tutorial-php.cn

Home

Backend Development

Python Tutorial

What are `self` and `__init__` in Python Object-Oriented Programming?

Susan Sarandon

Dec 26, 2024 am 08:00 AM

What are `self` and `__init__` in Python Object-Oriented Programming?

Understanding init and self in Python OOP

When learning object-oriented programming (OOP) in Python, one may encounter the init method and the self variable. These concepts play a crucial role in class definitions and object instantiation.

What is self?

In Python OOP, self is a special variable that represents an instance of the class. It is conventionally used as the first parameter of instance methods and functions, as seen in the example:

def method(self, blah):
    # ...

The self variable is a reference to the current instance of the class. It allows access to the instance's attributes and methods within the method. Without explicitly declaring self, the method would only accept one argument instead of two.

What is __init__?

The init method is a special method that serves as the constructor for a class. It is called automatically when an object of that class is created. Its purpose is to initialize the instance's attributes and set up any necessary class properties.

For example:

class A(object):
    def __init__(self):
        self.x = 'Hello'

    def method_a(self, foo):
        print(self.x + ' ' + foo)

In this example, the init method initializes the instance attribute x with the value 'Hello'. The method_a method then prints the value of x concatenated with the foo parameter.

Necessity of init and self

Both init and self are essential components of OOP in Python. They allow objects to have state (attributes) and methods that operate on that state. Without self, it would be impossible to access instance-specific attributes and methods within methods. Similarly, without the init method, it would not be possible to initialize instance attributes when an object is created.

The above is the detailed content of What are `self` and `__init__` in Python Object-Oriented Programming?. For more information, please follow other related articles on the PHP Chinese website!

Statement

The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

How Do I Use Beautiful Soup to Parse HTML?Mar 10, 2025 pm 06:54 PM

This article explains how to use Beautiful Soup, a Python library, to parse HTML. It details common methods like find(), find_all(), select(), and get_text() for data extraction, handling of diverse HTML structures and errors, and alternatives (Sel

Mathematical Modules in Python: StatisticsMar 09, 2025 am 11:40 AM

Python's statistics module provides powerful data statistical analysis capabilities to help us quickly understand the overall characteristics of data, such as biostatistics and business analysis. Instead of looking at data points one by one, just look at statistics such as mean or variance to discover trends and features in the original data that may be ignored, and compare large datasets more easily and effectively. This tutorial will explain how to calculate the mean and measure the degree of dispersion of the dataset. Unless otherwise stated, all functions in this module support the calculation of the mean() function instead of simply summing the average. Floating point numbers can also be used. import random import statistics from fracti

Serialization and Deserialization of Python Objects: Part 1Mar 08, 2025 am 09:39 AM

Serialization and deserialization of Python objects are key aspects of any non-trivial program. If you save something to a Python file, you do object serialization and deserialization if you read the configuration file, or if you respond to an HTTP request. In a sense, serialization and deserialization are the most boring things in the world. Who cares about all these formats and protocols? You want to persist or stream some Python objects and retrieve them in full at a later time. This is a great way to see the world on a conceptual level. However, on a practical level, the serialization scheme, format or protocol you choose may determine the speed, security, freedom of maintenance status, and other aspects of the program

How to Perform Deep Learning with TensorFlow or PyTorch?Mar 10, 2025 pm 06:52 PM

This article compares TensorFlow and PyTorch for deep learning. It details the steps involved: data preparation, model building, training, evaluation, and deployment. Key differences between the frameworks, particularly regarding computational grap

How to solve the permissions problem encountered when viewing Python version in Linux terminal?Apr 01, 2025 pm 05:09 PM

Solution to permission issues when viewing Python version in Linux terminal When you try to view Python version in Linux terminal, enter python...

What are some popular Python libraries and their uses?Mar 21, 2025 pm 06:46 PM

The article discusses popular Python libraries like NumPy, Pandas, Matplotlib, Scikit-learn, TensorFlow, Django, Flask, and Requests, detailing their uses in scientific computing, data analysis, visualization, machine learning, web development, and H

Scraping Webpages in Python With Beautiful Soup: Search and DOM ModificationMar 08, 2025 am 10:36 AM

This tutorial builds upon the previous introduction to Beautiful Soup, focusing on DOM manipulation beyond simple tree navigation. We'll explore efficient search methods and techniques for modifying HTML structure. One common DOM search method is ex

How to Create Command-Line Interfaces (CLIs) with Python?Mar 10, 2025 pm 06:48 PM

This article guides Python developers on building command-line interfaces (CLIs). It details using libraries like typer, click, and argparse, emphasizing input/output handling, and promoting user-friendly design patterns for improved CLI usability.

See all articles