Object-oriented programming (OOP) in Python

1 - The concept of OOP in Python 

Object-oriented programming (OOP) is a type of programming based on the creation of classes and objects via a method called instantiation. A class is a prototype (model) encoded into a programming language whose goal is to create objects with a set of methods and attributes that characterize any object in the class. The attributes are data types (class variables and instance variables) and methods, accessible via point concatenation. In object-oriented programming, the declaration of a class groups together methods and properties (attributes) that are common to a given object. Thus one could say that a class represents a category of objects. It also appears as a factory for creating objects with a set of common attributes and methods.
Since its creation, Python is an object-oriented programming language. For this reason, creating and using classes and objects in Python is a fairly simple operation. This course will help you learn step-by-step how to use object-oriented programming in Python.

 2 - Classes in Python 

To create a class in Python, use the statement:

class class_name

We then create a method to build the objects, called constructor via the instruction:

def __init __ (self):

Example. Person class

class Person:
    def __init __ (self, name, age):
       self.name = name
       self.age = age
P = Person ("Albert", 27)
print ("The name of the person is:", P.name)
print ("The age of the person is:", age, "years")
# display after execution: The name of the person is: Albert
# The age of the person is: 27 years old

Example: rectangle class

class Rectangle:
    def __init __ (self, L, l):
       self.Longueur = L
      self.width = l
monRectangle = Rectangle (7.5)
print ("The length of my rectangle is:", myRectangle.Length)
print ("The width of my rectangle is:", myRectangle.Width)

Display after execution:
The length of my rectangle is: 7 
The width of my rectangle is: 5 
 The class can also be improved by adding methods to perform different tasks.

 3 - Class methods in Python 

A class method is a function or procedure named within the class that defines properties or behaviors of instance objects.

 Example. adding method that calculates the surface of the rectangle

class Rectangle:
    def __init __ (self, L, l):
        self.Longueur = L
        self.width = l

    # method that calculates the surface
    def surface (self):
        return self.Length * self.Largeur

# creation of a rectangle of length 7 and width 5
monRectangle = Rectangle (7,5)
print ("The surface of my rectangle is:", myRectangle.surface ())

Display after execution:
 The surface of my rectangle is: 35

 4 - Static methods 

A static method is a class method that has the property of being executed without going through instantiation. A static method is declared by adding the annotation: @staticmethod

Example. static method

class myClass:
    def __init __ (self):
       pass
    # creation of a static method
   @staticmethod
   def myStaticMethod ():
       print ("Here is an example of static method in Python")
myClass.myStaticMethod ()

Younes Derfoufi