Exercise 13.1

Does anything about these two classes “smell” wrong?

class Dog:     
    def __init__(self, name='', bites=True):
        self.name = name
        self.genus = 'canis'
        self.bites = bites     
    def get_sound(self):
        return 'woof'

class Cat:
    def __init__(self, name, lives=9):
        self.name = name
        self.genus = 'felis'
        self.lives = lives
    def get_sound(self):
        return 'meow'

Exercise 13.2

Draw an appropriate hierarchy for the following.

• Animal
• Cat
• Dog
• Flea
• Tree

Exercise 13.3

Build an hierarchy that distinguishes dogs, cats and fleas, supporting the following features.

• A parent class, Dog, with name and genus
• Child classes
  • Dog — name, bites
  • Cat — name, lives
  • Flea — name
• An overloaded method, get_sound(), that returns suitable sound for each animal.

Exercise 13.4

Label the following as either instantiation, inheritance or composition.

1. dog — Phydeaux
2. animal — dog
3. Fifi — flea
4. Phydeaux — Fifi