理解Instance, Class, Static Methods in Python

Overview

理解decorator pattern in Python

How many types of methods in Python

Generally, there are three types of methods in Python:

1. Instance Methods
2. Class Methods
3. Static Methods

Knowing the differences isn’t always required to code basic Python scripts, but once you advance into OOP, the differences can make a big change.

Instance Methods

The regular instance method takes the parameter self which points to an instance of Class when the method id called.

Class Methods

The class methods take a cls parameter that points to the class - not the object instance - when the method is called.

They can call other static methods.

That means it can’t modify object instance state;

Static Methods

The static methods takes neither a self nor a cls parameter (but of course it’s free to accept an arbitrary number of other parameters).

That means a static method can neither modify object state or class state.

Static methods are restricted in what data they can access - and they’re primarily a way to namespace your methods.

When to Use Each Method Type

1. Instance Methods

   The most common method type.

   Able to access data and properties unique to each instance.

2. Static Methods

   Cannot access anything else in the class.

   Totally self-contained code.

3. Class Methods

   Can access limited methods in the class.

   Can modify class specific details.

References