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Why sometime there are self pass into the bracket and called as parameter and why sometime none?

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#1

class Shape:

def __init__(self):

    self.sides = 0

def getArea(self):

    pass

why sometime self are pass into bracket as parameter and sometime none ?

#2

Hi @Sean_Chrollo,
In object-oriented programming (OOP) with Python, the use of self as a parameter in class methods is a common practice, but it’s important to understand when and why it is used.

  1. When self is Passed as a Parameter:
    When we define methods within a class, we typically include self as the first parameter in these methods. self is a reference to the instance of the class. When a method is called on an instance of the class, Python automatically passes that instance as the self parameter. This allows us to access and manipulate instance-specific attributes and methods. For example, the __init__ method in the Shape, Rectangle, and Circle classes accepts self as the first parameter. When an object of one of these classes is created, self refers to that specific object, and we can use it to set and access object-specific attributes (like self.width and self.height in the Rectangle class).

  2. When self is Not Passed as a Parameter:
    In some methods, you may see self not explicitly passed as a parameter. This is because Python automatically handles passing self when the method is called on an instance. So, when we call some_instance.some_method(), Python internally passes some_instance as self to some_method.

For example, in your getArea methods in the Rectangle and Circle classes, you don’t see self as a parameter in the method definition, but it is still accessible within the method because it refers to the instance on which the method is called.

I hope that helps.
Regards!