Table of Contents
1. Basic application
2. Practical application
3. Note
Home Backend Development Python Tutorial What are the methods for rewriting parent classes in Python?

What are the methods for rewriting parent classes in Python?

May 04, 2023 pm 11:52 PM
python

1. Basic application

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

class Animal(object):

    def eat(self):

        print("动物吃东西")

 

 

class Cat(Animal):

    def eat(self):

        print("猫吃鱼")

        # 格式一:父类名.方法名(对象)

        Animal.eat(self)

        # 格式二:super(本类名,对象).方法名()

        super(Cat, self).eat()

        # 格式三:super()方法名()

        super().eat()

 

 

cat1 = Cat()

cat1.eat()

print(cat1)

Copy after login

2. Practical application

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

#用元类实现单例模式

class SingletonType(type):

    instance = {}

 

    def __call__(cls, *args, **kwargs):

        if cls not in cls.instance:

            # 方式一:

            # cls.instance[cls] = type.__call__(cls, *args, **kwargs)

            # 方式二

            # cls.instance[cls] = super(SingletonType, cls).__call__(*args, **kwargs)

            # 方式三

            cls.instance[cls] = super().__call__(*args, **kwargs)

        return cls.instance[cls]

 

 

class Singleton(metaclass=SingletonType):

    def __init__(self, name):

        self.name = name

 

 

s1 = Singleton('1')

s2 = Singleton('2')

print(id(s1) == id(s2))

Copy after login

3. Note

1. When a class has multiple inheritance, it inherits from multiple parents The classes have the same parent class A. When rewriting its parent class, you need to pay attention to

Method 1: Parent class name.Method name (object)

  • Parent class A Will be called multiple times (according to the number of inheritance)

  • Pass the required parameters as needed when overriding the parent class

Method 2 :super(class name, object).Method name()

  • The parent class A will only be called once

  • Rewrite the parent Class methods must pass all parameters

2. When a class has inheritance and the corresponding variables have been overridden in the subclass, changing the variables of the parent class will not affect the subclass.

1

2

3

4

5

6

7

8

9

10

11

12

13

14

class Parent(object):

    x = 1

 

class Child1(Parent):

    pass

 

class Child2(Parent):

    pass

 

print(Parent.x, Child1.x, Child2.x)

Child1.x = 2

print(Parent.x, Child1.x, Child2.x)

Parent.x = 3

print(Parent.x, Child1.x, Child2.x)

Copy after login

Output result

1 1 1
1 2 1
3 2 3

The above is the detailed content of What are the methods for rewriting parent classes in Python?. For more information, please follow other related articles on the PHP Chinese website!

Statement of this Website
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

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

Hot Topics

Java Tutorial
1664
14
PHP Tutorial
1268
29
C# Tutorial
1248
24
PHP and Python: Different Paradigms Explained PHP and Python: Different Paradigms Explained Apr 18, 2025 am 12:26 AM

PHP is mainly procedural programming, but also supports object-oriented programming (OOP); Python supports a variety of paradigms, including OOP, functional and procedural programming. PHP is suitable for web development, and Python is suitable for a variety of applications such as data analysis and machine learning.

Choosing Between PHP and Python: A Guide Choosing Between PHP and Python: A Guide Apr 18, 2025 am 12:24 AM

PHP is suitable for web development and rapid prototyping, and Python is suitable for data science and machine learning. 1.PHP is used for dynamic web development, with simple syntax and suitable for rapid development. 2. Python has concise syntax, is suitable for multiple fields, and has a strong library ecosystem.

PHP and Python: A Deep Dive into Their History PHP and Python: A Deep Dive into Their History Apr 18, 2025 am 12:25 AM

PHP originated in 1994 and was developed by RasmusLerdorf. It was originally used to track website visitors and gradually evolved into a server-side scripting language and was widely used in web development. Python was developed by Guidovan Rossum in the late 1980s and was first released in 1991. It emphasizes code readability and simplicity, and is suitable for scientific computing, data analysis and other fields.

How to run sublime code python How to run sublime code python Apr 16, 2025 am 08:48 AM

To run Python code in Sublime Text, you need to install the Python plug-in first, then create a .py file and write the code, and finally press Ctrl B to run the code, and the output will be displayed in the console.

Python vs. JavaScript: The Learning Curve and Ease of Use Python vs. JavaScript: The Learning Curve and Ease of Use Apr 16, 2025 am 12:12 AM

Python is more suitable for beginners, with a smooth learning curve and concise syntax; JavaScript is suitable for front-end development, with a steep learning curve and flexible syntax. 1. Python syntax is intuitive and suitable for data science and back-end development. 2. JavaScript is flexible and widely used in front-end and server-side programming.

Golang vs. Python: Performance and Scalability Golang vs. Python: Performance and Scalability Apr 19, 2025 am 12:18 AM

Golang is better than Python in terms of performance and scalability. 1) Golang's compilation-type characteristics and efficient concurrency model make it perform well in high concurrency scenarios. 2) Python, as an interpreted language, executes slowly, but can optimize performance through tools such as Cython.

Where to write code in vscode Where to write code in vscode Apr 15, 2025 pm 09:54 PM

Writing code in Visual Studio Code (VSCode) is simple and easy to use. Just install VSCode, create a project, select a language, create a file, write code, save and run it. The advantages of VSCode include cross-platform, free and open source, powerful features, rich extensions, and lightweight and fast.

How to run python with notepad How to run python with notepad Apr 16, 2025 pm 07:33 PM

Running Python code in Notepad requires the Python executable and NppExec plug-in to be installed. After installing Python and adding PATH to it, configure the command "python" and the parameter "{CURRENT_DIRECTORY}{FILE_NAME}" in the NppExec plug-in to run Python code in Notepad through the shortcut key "F6".

See all articles