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Introduction to Static Variables in Python

Table of Contents

Static variables, often referred to as class variables in Python, play a crucial role in object-oriented programming. Unlike instance variables that are specific to each object, static variables are shared across all instances of a class. This article delves into the concept of static variables, their usage, and how they differ from instance variables.

Defining Static Variables

What Are Static Variables?

Static variables are variables that are declared within a class but outside any methods. These variables are not tied to any particular instance of the class. Therefore, they are shared by all instances, making them an efficient way to store class-level data.

Declaring Static Variables

Declaring a static variable in Python is straightforward. You define it within a class but outside any methods:

class MyClass:
    static_variable = 10  # This is a static variable

    def method(self):
        pass

In this example, static_variable is accessible by all instances of MyClass.

Usage of Static Variables

Shared Attributes

Since static variables are shared across instances, they are ideal for representing data that should remain consistent across all instances of a class. For example, if you have a class Employee, and you want to keep track of the total number of employees, a static variable would be appropriate.

class Employee:
    total_employees = 0  # Static variable

    def __init__(self, name):
        self.name = name
        Employee.total_employees += 1

Accessing Static Variables

Static variables can be accessed using the class name or an instance of the class:

print(Employee.total_employees)  # Accessing through the class name
employee = Employee("John")
print(employee.total_employees)  # Accessing through an instance

Static vs Instance Variables

Key Differences

The primary difference between static and instance variables lies in their association. While static variables are associated with the class itself, instance variables are tied to specific instances of the class.

class MyClass:
    static_variable = 10  # Static variable

    def __init__(self, instance_variable):
        self.instance_variable = instance_variable  # Instance variable

In this example, static_variable is shared, whereas instance_variable is unique to each instance.

Modifying Values

Modifications to static variables reflect across all instances, whereas changes to instance variables are specific to each instance.

Conclusion

Understanding the distinction between static and instance variables is crucial in Python programming, particularly in object-oriented design. Static variables offer a shared, class-level scope, making them ideal for data that is common to all instances of a class. This feature enhances efficiency and consistency in your Python programs.

Nisha Kumari

Nisha Kumari

Nisha Kumari, a Founding Engineer at Bito, brings a comprehensive background in software engineering, specializing in Java/J2EE, PHP, HTML, CSS, JavaScript, and web development. Her career highlights include significant roles at Accenture, where she led end-to-end project deliveries and application maintenance, and at PubMatic, where she honed her skills in online advertising and optimization. Nisha's expertise spans across SAP HANA development, project management, and technical specification, making her a versatile and skilled contributor to the tech industry.

Written by developers for developers

This article was handcrafted with by the Bito team.

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