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Object Oriented Programming (OOP) in Python – Part VI

Object Oriented Programming (OOP) in Python – Part VI

Posted May 27, 2021 at 1:03 pm
Jay Parmar

Review Part I,  Part II , Part III,  Part IV and Part V for an overview of Python classes and their objects.

What is init method?

You might have guessed what __init__ does and means? If not, here you go, __init__ means initialisation. We use this method to initiate the attributes with values provided by the object when it gets created. In other words, the __init__ methods gets called as soon as a new object is created. Let’s implement it in our Car class and see how we can leverage it.

class Car:

def __init__(self, uColour, uSeatingCapacity):

self.colour = uColour
self.seating_capacity = uSeatingCapacity

def drive_forward(self, meters):
print(f’Driving {meters} meters ahead’)

def lower_windows(self):
print(‘Lowering windows on all doors’)
print(‘Windows lowered’)

In this implementation of the class, we define all variables (and methods) in the __init__ that needs to be assigned (and called) upon creating a new object. How? As demonstrated in the below code:

car_4 = Car(uColour=’Ocean Blue’, uSeatingCapacity=2)

We provide the values to be assigned to colour and seating_capacity attributes while creating an object. This way, we can overcome the requirement to set each object’s attribute values after they have been created.

If we access the newly created object’s attributes, it would have the values we provided while creating them.

print(‘The colour of Car 4 is:’, car_4.colour)
print(‘The seating capacity of Car 4 is:’, car_4.seating_capacity)

The output would be as shown below:

The colour of Car 4 is: Ocean Blue
The seating capacity of Car 4 is: 2

We can also place a method within the body of __init__ to ensure that the method gets executed upon creation of an object. Those of you who come from any other object-oriented programming language should be able to relate the __init__ method with the constructor method.

You might have noticed that while defining these methods, __init__ or any normal for that purpose, the first parameter these methods take is the self keyword.

Why is this keyword necessary, and why do we need to provide this keyword? We discuss it next.

Visit QuantInsti to read more about this research:

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