Python, Overriding an inherited class method

Question

I have two classes, Field and Background. They look a little bit like this:

class Field( object ):
    def __init__( self, a, b ):
         


        

Answer 1

I expected Background init() to be called

Actually Background init() is getting called..

But take a look at your Background class..

class Background( Field ):
    def __init__( self, a, b, c ):
        super(Background, self).__init__( a, b )
        self.field = self.buildField( c )

So, the first statement of __init__ is invoking the super class(Field) init method.. and passing the self as argument.. Now this self is actually a reference of Background class..

Now in your Field class: -

class Field( object ):
    def __init__( self, a, b ):

        print self.__class__  // Prints ``
        self.a = a
        self.b = b
        self.field = self.buildField()

Your buildField() method is actually invoking the one in the Background class.. This is because, the self here is instance of Background class(Try printing self.__class__ in your __init__ method of Field class).. As you passed it while invoking the __init__ method, from Background class..

That's why you are getting error..

The error "TypeError: buildField() takes exactly 2 arguments (1 given).

As you are not passing any value.. So, only value passed is the implicit self.