3.5 init method

This method is used to define the attributes of a class which we want that class to have right upon its creation. This means the code in init method is executed at the time of creation of an instance of class. Thus we use init method to initialize the class, hence name init. It can be anywhere inside class but convention is to put it at the top inside a class.

class Insan:
    def __init__(self):
        self.legs = '2 legs'
        print("__init__ method inside class is being executed!")

x = Insan()
x.legs

__init__ method inside class is being executed!

'2 legs'

we see that although we only created an instance of class (we call it initialization of an instance as well) and the code inside init method (we don’t use the word function for it anymore) got executed. The proper way to add taruf method to our Insan class is:

class Insan:

    def __init__(self, name=None, legs='2 legs'):
        self.name = name
        self.legs = legs

    def taruf(self):
        if self.name:
            print("Salam, I am " + self.name + ' and I have ' + self.legs)
        else:
            print("Salam, I am a Insan but my name has not yed been defined" + ' and I have ' + self.legs)

x = Insan()
x.taruf()

Salam, I am a Insan but my name has not yed been defined and I have 2 legs

y = Insan("Ali", legs='1 leg')
y.taruf()

Salam, I am Ali and I have 1 leg

Notice how we passed the string Ali when we were creating class instance and got it transferred to the method taruf without being explicitly doing it. The method taruf takes no input arguments (actually it takes one, which it does implicitly) however it prints the value of name which we provided to it when we were creating the class instance y.

Let’s create a new class instance and use a different name

y = Insan("Hasan")
y.taruf()  # >> Salam, I am Hasan

Salam, I am Hasan and I have 2 legs

The attribute name is shared by the whole class and can be accessed anywhere in the class by using the word self at its start. This is because we initialized it inside init method.

print(y.name)

Hasan

print(y.legs)

2 legs

print(y.__dict__)

{'name': 'Hasan', 'legs': '2 legs'}