ex42.py

'''
对象、类及从属关系
'''

class Animal(object):
    pass

## ??
class Dog(Animal):

    def __init__(self, name):
        ## ??
        self.name = name


## ??
class Cat(Animal):

    def __init__(self, name):
        ## ??
        self.name = name


## ??
class Person(object):

    def __init__(self, name):
        ## ??
        self.name = name
        ## Person has-a pet of some kind
        self.pet = None


## ??
class Employee(Person):

    def __init__(self, name, salary):
        ## ?? hmm what is this strange magic?
        super(Employee, self).__init__(name)
        ## ??
        self.salary = salary


## ??
class Fish(object):
    pass


## ??
class Salmon(Fish):
    pass


## ??
class Halibut(Fish):
    pass


## rover is-a Dog
rover = Dog("Rover")

## ?
satan = Cat("Satan")

## ?
mary = Person("Mary")


## ??
mary.pet = satan

## ?
frank = Employee("Frank", 120000)

##  ?
frank.pet = rover

## ?
flipper = Fish()

## ??
crouse = Salmon()

## ?
harry = Halibut()