OOP in Python3

Object-oriented programming (OOP) is a programming paradigm that allows developers to organize and structure their code in a way that represents real-world objects and their interactions. In this tutorial, we will show you how to use OOP in Python3.

A class is a blueprint for creating objects (a particular data structure), providing initial values for state (member variables or attributes), and implementations of behavior (member functions or methods).

First, let’s create a simple class called Person:

class Person:
    pass

This class doesn’t have any attributes or methods yet, but it’s a starting point. We can create an instance of the class by calling the class name as a function:

p = Person()

We can give our class a __init__ method, which is a special method that gets called when an object is created. The __init__ method is used to initialize the state of the object.

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

Now, when we create an instance of the Person class, we need to provide values for the name and age attributes:

p = Person("John", 30)

We can also give our class methods, which are functions that are associated with a class and its objects.

class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age
        
    def say_hello(self):
        print(f"Hello, my name is {self.name} and I am {self.age} years old.")

p = Person("John", 30)
p.say_hello()

This will print “Hello, my name is John and I am 30 years old.”

We can also define class variables, which are variables that are shared among all instances of a class. We define class variables outside of any method, usually at the top level of the class definition.

class Person:
    species = "Homo Sapiens"
    
    def __init__(self, name, age):
        self.name = name
        self.age = age
        
    def say_hello(self):
        print(f"Hello, my name is {self.name} and I am {self.age} years old.")

p = Person("John", 30)
print(p.species) # Homo Sapiens

Inheritance is a way to create a new class that is a modified version of an existing class. The new class is called the derived class, and the existing class is called the base class.

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

s = Student("Alice", 20, "123456")
s.say_hello()
print(s.student_id) # 123456

In the above example, the Student class inherits from the Person class, and it has an additional attribute called student_id.