relationship we have been able to model with classes

the relationship that we’ve modeled so far is know as the “has a” relationship

class hierachy

 `Animal`  base class

       ↑

`Lizard`   `Dog` derived class 

              ↑

    `poodle`

# animal.py

class Animal:

	def __init__(self):
		print("You made an Animal")
		self.age = 0

	def eat(self):
		print("Animal eating...")

	def sleep(self):
		print("Animal is sleeping...")

# dog.py

from animal import Animal

class Dog(Animal):
	# omit __init__ for a minute

	def __init__(self):
	
		# call aninmal's init
		super().__init__(self)

		self.breed = 'not set'

		print("You made a dog")

	def do_trick(self):
		print("Dog doing trick!")

	def sleep(self):
		print("ruf. roof. roooof. rof.")			
		print("dog is sleeping")

# main.py

from animal import Animal
from dog import Dog

def play_with_animal(some_animal):
	some_animal.eat()
	some_animal.sleep()

def main():

	my_animal = Animal()
	my_dog = Dog()

	play_with_animal(my_animal)
	# polymorphism - the coee you executing is called on the fly based on how its define
	# it lets the object decide which version of the medthod to execute 

	play_with_animal(my_dog)	

	# do stuff with Animal
	my_animal.eat()
	my_animal.sleep()
	# my_animal.do_trick() AttributeError:  'Animal' object has no attribute 'do_trick'

	# do stuff with Dog
	my_dog.eat()
	my_dog.sleep()
	my_dog.do_trick()

	print(my_animal.age)
	# print(my_dog.age) AttributeError:  'Dog' object has no attribute 'age'

	print("end")

main()

owner@morgan source % python3 main.py

You made an Animal
You made an Animal

Animal is eating...
Animal is sleeping...

Animal is eating....
ruf. roof. roooof. rof.
dog is sleeping

end

owner@morgan source % python3 main.py

You made an Animal
You made an Animal

Animal is eating...
Animal is sleeping...

Animal is eating...
ruf. roof. roooof. rof

end

place the following into a class hieracy

✓ jet plane
✓ car
sail boat
✓ airplane
✓ race car
vehicle
segway
helicopter
boat

         [vehicle]
             ↑
 [car]     [boat] [airplane]
   ↑ 
[race car]