Example code illustrating some simple Object-Oriented Programming concepts.

oo_example.py

class Animal:
    # This is our base class that describes an Animal.
    
    sound = "..."  # The default sound an animal makes.
    
    def __init__(self, sound=None):
        # This is a constructor method. It will 
        # set up an animal's sound.
        if sound:
            self.sound = sound 
    
    def say(self):
        # Print the sound an animal makes.
        print(self.sound)


class MotionMixin:
    # This is a class that describes motion.
    # It can be used alongside the Animal class
    how = 'walk'

    def move(self):
        print("The {} {}s".format(self.__class__.__name__, self.how))


class Dog(MotionMixin, Animal):
    # The dog class inherits from both MotionMixin and 
    # Animal. This is an example of multiple inheritance.
    sound = "bark"
    
    def say(self):
        print("The dog says, '{}'".format(self.sound))


class Cat(Animal):
    # The Cat class inherits only from Animal. 
    sound = "MEOOOOW"


if __name__ == "__main__":
    # This is our "main program". Run it with: python oo_example.py
    
    # Create a dog using the Dog class and call its methods.
    dog = Dog()
    dog.say()
    dog.move()
    
    # Create a cat using the Cat class and call its methods.
    cat = Cat()
    cat.say()
    cat.move()