Overriding Methods

22_3_Overriding-Methods.py

class Book():
    def __init__(self, title, author):
        self.title = title
        self.author = author
    def __str__(self):
        return '"{}" by {}'.format(self.title, self.author)


class PaperBook(Book):
    def __init__(self, title, author, numPages):
        Book.__init__(self, title, author)
        self.numPages = numPages


class EBook(Book):
    def __init__(self, title, author, size):
        Book.__init__(self, title, author)
        self.size = size 


class Library:
    def __init__(self):
        self.books = []
    def addBook(self, book):
        self.books.append(book)
    def getNumBooks(self):
        return len(self.books)
    

myBook = EBook('A Brief History of Time', 'Stephen Hawking', 2)
myPaperBook = PaperBook('A Brief History of Time', 'Stephen Hawking', 101)

mylib = Library()
mylib.addBook(myBook)
mylib.addBook(myPaperBook)

print(mylib.getNumBooks())


# Let’s return to our idea of making Cats, Dogs, and other pets generate a string for their “mood” differently.
# Here’s the original Pet class again.

from random import randrange

# Here's the original Pet class
class Pet():
    boredom_decrement = 4
    hunger_decrement = 6
    boredom_threshold = 5
    hunger_threshold = 10
    sounds = ['Mrrp']
    def __init__(self, name = "Kitty"):
        self.name = name
        self.hunger = randrange(self.hunger_threshold)
        self.boredom = randrange(self.boredom_threshold)
        self.sounds = self.sounds[:]  # copy the class attribute, so that when we make changes to it, we won't affect the other Pets in the class

    def clock_tick(self):
        self.boredom += 1
        self.hunger += 1

    def mood(self):
        if self.hunger <= self.hunger_threshold and self.boredom <= self.boredom_threshold:
            return "happy"
        elif self.hunger > self.hunger_threshold:
            return "hungry"
        else:
            return "bored"

    def __str__(self):
        state = "     I'm " + self.name + ". "
        state += " I feel " + self.mood() + ". "
        # state += "Hunger %d Boredom %d Words %s" % (self.hunger, self.boredom, self.sounds)
        return state

    def hi(self):
        print(self.sounds[randrange(len(self.sounds))])
        self.reduce_boredom()

    def teach(self, word):
        self.sounds.append(word)
        self.reduce_boredom()

    def feed(self):
        self.reduce_hunger()

    def reduce_hunger(self):
        self.hunger = max(0, self.hunger - self.hunger_decrement)

    def reduce_boredom(self):
        self.boredom = max(0, self.boredom - self.boredom_decrement)

# Now let’s make two subclasses, Dog and Cat. Dogs are always happy unless they are bored and hungry. Cats, on the 
# other hand, are happy only if they are fed and if their boredom level is in a narrow range and, even then, only 
# with probability 1/2.

class Cat(Pet):
    sounds = ['Meow']

    def mood(self):
        if self.hunger > self.hunger_threshold:
            return "hungry"
        if self.boredom <2:
            return "grumpy; leave me alone"
        elif self.boredom > self.boredom_threshold:
            return "bored"
        elif randrange(2) == 0:
            return "randomly annoyed"
        else:
            return "happy"

class Dog(Pet):
    sounds = ['Woof', 'Ruff']

    def mood(self):
        if (self.hunger > self.hunger_threshold) and (self.boredom > self.boredom_threshold):
            return "bored and hungry"
        else:
            return "happy"

c1 = Cat("Fluffy")
d1 = Dog("Astro")

c1.boredom = 1
print(c1.mood())
c1.boredom = 3
for i in range(10):
    print(c1.mood())
print(d1.mood())