Learning Outcome

At the end of this lesson, you will be able to:

• understand and use inheritance in OOP

Review

• OOP

Lesson

• go over Using OOP, Chapter 9
  • Computer Based Problem Solving
  • "Inheritance"
• also read this: http://thepythonguru.com/python-inheritance-and-polymorphism/

Key OOP Concepts

• Inheritance
  • Super class and sub class
    • sub class gets all the "goodies" of the supper class

Activity

• demo of inheritance for Bicycle class
  • the subclass inherits from the super class

class TandemBike(Bicycle)

• add any new fields

self.__seats = 2

• add the new field into the constructor

def __init__(self, gear, cadence = 0):

        # private fields

        Bicycle.__init__(self, gear, cadence = 0)

        self.__seats = 2

• change any methods you need
  • remember to call the base, don't copy code!

def current_state(self):

        # returns the current state of the tandem bicycle as a string 

        # this varaible is local to this method

        return_string = Bicycle.current_state(self) + ' # of seats: ' + str(self.__seats)

        return return_string

• video review of OOP Inheritance here

Daily Assignment

• Add a second class, under your vehicle class called CubeVan
  • as you know a cube van has a large box on the back used to move things in
  • this box has a certain volume that is set when the van is built
  • normal vehicles do not have this kind of storage space (a trunk is different)
  • create a field that will hold the volume value
    • it should be set to 400 (for 400 cu. ft. )
  • you will also need to create a constructor and a ReadOnly Property in your class as well to handle the new property

Extra

• work on weekly assignment

Homework!

• read over Using OOP, Chapter 9
  • Computer Based Problem Solving
  • "Class Diagrams Again" & "Polymorphism"