Difference between Class Attributes and Instance Attributes in Python.

class_attributes.py

#!/usr/bin/env python3


class MyPersonClass:
    # Class attributes
    count_instances = 0

    def __init__(self, name: str, surname: str, years: int):
        MyPersonClass.count_instances += 1

        # Instance attributes
        self.name = name
        self.surname = surname
        self.years = years

    def __str__(self):
        return "{}, {} ({})".format(self.surname, self.name, self.years)


def main():
    p1 = MyPersonClass("Peter", "Parker", 26)
    p2 = MyPersonClass("Bruce", "Banner", 38)
    p3 = MyPersonClass("Tony", "Stark", 36)
    p4 = MyPersonClass("Steve", "Rogers", 103)

    print(p1)
    print(p2)
    print(p3)
    print(p4)

    print("Instances of MyPersonClass: {}".format(MyPersonClass.count_instances))    
        
        
if __name__ == "__main__":
    main()