重新梳理Python基础（10）

1. 今天学了一些概念。（书的第41~43章）

用这个方法可以分清楚class、object、instance

## Animal is-a object (yes, sort of confusing) look at the extra credit
class Animal(object):
    pass

## Dog is-a animal, it has-a name
class Dog(Animal):

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

## Cat is-a animal, it has-a name
class Cat(Animal):

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

## Person is-a object, it has-a name and pet
class Person(object):

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

        ## Person has-a pet of some kind
        self.pet = None

## Employee is-a Person, it has-a name and salary
class Employee(Person):

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

## Fish is-a object
class Fish(object):
    pass

## Salmon is-a Fish
class Salmon(Fish):
    pass

## Halibut is-a Fish
class Halibut(Fish):
    pass


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

## satan is-a Cat
satan = Cat("Satan")

## mary is-a Person
mary = Person("Mary")

## mary has-a pet, satan
mary.pet = satan

## frank is-a employee, it has-a salary 120000
frank = Employee("Frank", 120000)

## frank has-a pet, rover
frank.pet = rover

## flipper is-a fish
flipper = Fish()

## crouse is-a salmon
crouse = Salmon()

## harry is-a halibut
harry = Halibut()

用这种方式可以比较清楚的明白对象、类和实例的概念。

2. OOP

1. Write or draw about the problem.
2. Extract key concepts from #1 and research them.
3. Create a class hierarchy and object map for the concepts.
4. Code the classes and a test to run them.
5. Repeat and refine.