The Difference Between Class Attribute or Property and the Class Variable

In Python, you can store data within a class using properties/attributes or class variables.

Properties/Attributes

Properties, also called attributes, are variables that store data within a class instance. They are defined within the class, but outside of any methods. Here's an example:

class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age

In the example above, name and age are attributes of the Person class. They are created and assigned values within the __init__ method using the self keyword. You can access and modify these attributes using dot notation, like so:

person = Person("John", 30)
print(person.name)  # Output: John
person.age = 31
print(person.age)   # Output: 31

Class Variables

Class variables are variables that are shared among all instances of a class. They are defined within the class, but outside of any methods and are prefixed with the class name. Here's an example:

class Person:
    count = 0

    def __init__(self, name, age):
        self.name = name
        self.age = age
        Person.count += 1

In the example above, count is a class variable that is used to keep track of the number of Person instances that have been created. It is incremented every time a new instance is created within the __init__ method. You can access class variables using the class name, like so:

person1 = Person("John", 30)
person2 = Person("Jane", 28)
print(Person.count)  # Output: 2

Difference

The main difference between attributes/properties and class variables is that attributes are specific to each instance of a class, while class variables are shared among all instances.

Attributes are defined within the __init__ method and can be different for each instance. Class variables are defined outside of any methods and are shared by all instances.

Another difference is that attributes/properties can be accessed and modified using dot notation on an instance of a class, while class variables are accessed using the class name.

In general, if you need to store data that is specific to each instance of a class, use attributes/properties. If you need to store data that is shared among all instances of a class, use class variables.

References

python - difference between class variable and class attribute - Stack Overflow