self in Python¶

self is a reference to the invoking class instance. Consider the following code

 class Point:

     def __init__(self):
         print 'Self identifier:: ',id(self)


if __name__ == '__main__':
     # create an instance of the class
     p = Point()
     print 'Point object identifier', id(p)

     # create an instance of the class p = Point()
     print 'Point object identifier', id(p)

As you can see, a class (that does nothing) called Point is defined and then two objects/instances are created. To verify that self is really a reference to the invoking object, we print the identifier for the calling object and self. Unsurprisingly, both are the same.

It is to be noted that it is just a convention to use self as a reference to the invoking object. You can use anything else, for example, this

class Point:

    def __init__(this):
        print 'This identifier:: ',id(this)

if __name__ == '__main__':
    #create an instance of the class p =
    Point()

    print 'Point object identifier', id(p)

    # create an instance of the class p = Point()
    print 'Point object identifier', id(p)