22.6. Exercises

For exercises, you can expand the Tamagotchi game even further. Try these out.

Here’s all the code we just saw for our new and improved game, with a few additions. You can run this and play the game again.

1. 1. Change the above code to allow you to adopt a Tiger pet (that you’re about to create). HINT: look at the whichtype function, and think about what’s happening in the code for that function.

   2. Now, modify the code to define a new class, Tiger. The Tiger class should inherit from the Cat class, but its default meow count should be 5, not 3, and it should have an extra instance method, roar, that prints out the string ROOOOOAR!.

   3. Next, modify the code so that when the hi method is called for the Tiger class, the roar method is called. HINT: You’ll have to call one instance method inside another, and you’ll have to redefine a method for the Tiger class. See the overriding methods section.

   4. Now, modify the code to define another new class, Retriever. This class should inherit from Lab. It should be exactly like Lab, except instead of printing just I found the tennis ball! when the fetch method is called, it should say I found the tennis ball! I can fetch anything!.

   5. Add your own new pets and modifications as you like – remember, to use them in the game, you’ll also have to alter the whichtype function so they can be used in game play. Otherwise, you’ll have different classes that may work just fine, but you won’t see the effects in the game, since the code that actually makes the game play is found in the second half of the provided code (look for the while loop!).

   from random import randrange 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) class Dog(Pet): # in the Dog class, Dog pets should express their hunger and boredom differently than generic Pets def mood(self): if self.hunger <= self.hunger_threshold and self.boredom <= self.boredom_threshold: return "happy, arf! Happy" elif self.hunger > self.hunger_threshold: return "hungry already, arrrf" else: return "bored, so you should play with me" class Cat(Pet): # in the Cat class, cats express their hunger and boredom a little differently, too. They also have an extra instance, variable meow_count. def __init__(self, name="Fluffy", meow_count=3): Pet.__init__(self, name) self.meow_count = meow_count def hi(self): for i in range(self.meow_count): print(self.sounds[randrange(len(self.sounds))]) self.reduce_boredom() def mood(self): if self.hunger <= self.hunger_threshold and self.boredom <= self.boredom_threshold: return "happy, I suppose" elif self.hunger > self.hunger_threshold: return "mmmm...hungry" else: return "a bit bored" class Lab(Dog): def fetch(self): return "I found the tennis ball!" def hi(self): print(self.sounds[randrange(len(self.sounds))] + self.fetch()) class Poodle(Dog): def dance(self): return "Dancin' in circles like poodles do." def hi(self): print(self.dance()) Dog.hi(self) class Bird(Pet): sounds = ["chirp"] def __init__(self, name="Kitty", chirp_number=2): Pet.__init__(self, name) # call the parent class's constructor # basically, call the SUPER -- the parent version -- of the constructor, with all the parameters that it needs. self.chirp_number = chirp_number # now, also assign the new instance variable def hi(self): for i in range(self.chirp_number): print(self.sounds[randrange(len(self.sounds))]) self.reduce_boredom() def whichone(petlist, name): for pet in petlist: if pet.name == name: return pet return None # no pet matched pet_types = {'dog': Dog, 'lab': Lab, 'poodle': Poodle, 'cat': Cat, 'bird': Bird} def whichtype(adopt_type="general pet"): return pet_types.get(adopt_type.lower(), Pet) def play(): animals = [] option = "" base_prompt = """ Quit Adopt <petname_with_no_spaces> <adopt_type - choose dog, cat, lab, poodle, or another unknown pet type> Greet <petname> Teach <petname> <word> Feed <petname> Choice: """ feedback = "" while True: action = input(feedback + "\n" + base_prompt) feedback = "" words = action.split() if len(words) > 0: command = words[0] else: command = None if command == "Quit": print("Exiting...") return elif command == "Adopt" and len(words) > 1: if whichone(animals, words[1]): feedback += "You already have a pet with that name\n" else: # figure out which class it should be if len(words) > 2: Cl = whichtype(words[2]) else: Cl = Pet # Make an instance of that class and append it animals.append(Cl(words[1])) elif command == "Greet" and len(words) > 1: pet = whichone(animals, words[1]) if not pet: feedback += "I didn't recognize that pet name. Please try again.\n" print() else: pet.hi() elif command == "Teach" and len(words) > 2: pet = whichone(animals, words[1]) if not pet: feedback += "I didn't recognize that pet name. Please try again." else: pet.teach(words[2]) elif command == "Feed" and len(words) > 1: pet = whichone(animals, words[1]) if not pet: feedback += "I didn't recognize that pet name. Please try again." else: pet.feed() else: feedback+= "I didn't understand that. Please try again." for pet in animals: pet.clock_tick() feedback += "\n" + pet.__str__() import sys sys.setExecutionLimit(60000) play()

22.6.1. Contributed Exercises

If this is a homework problem instead of an example in the text then the assignment text should go here. The assignment text ends with the line containing four tilde ~ print("hello world") ==== print("Hidden code, such as unit tests come after the four = signs")

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