ex39

代码

class Song(object):

    def __init__(self, lyrics):
        self.lyrics = lyrics

    def sing_me_a_song(self):
        for line in self.lyrics:
            print (line)

happy_bday = Song(["Happy birthday to you"
                 "I don't want to get sued ",
                 "So I'll stop right there"])

bulls_on_parade = Song(["They rally around the family",
                        "With pockets full of shells"])

happy_bday.sing_me_a_song()

bulls_on_parade.sing_me_a_song()

运行结果

"C:\Program Files\Python36\python.exe" "D:/小克学习/python/项目/week three/ex39.py"
Happy birthday to youI don't want to get sued 
So I'll stop right there
They rally around the family
With pockets full of shells

Process finished with exit code 0

列表和字典有何不同？
列表是有序排列的一些物件，而字典是将一些物件（ keys ）对应到另外一些物件（ values ）的数据结构。
字典能用在哪里？
各种你需要通过某个值去查看另一个值的场合。其实你可以把字典当做一个“查询表”。
列表能用在哪里？
列表是专供有序排列的数据使用的。你只要知道索引就能查到对应的值了。
有没有办法弄一个可以排序的字典？
看看 Python 里的 collections.OrderedDict 数据结构。上网搜索一下文档和用

这章虽然写出来的了，但是没搞懂呀。

40

class Song(object):

    def __init__(self, lyrics):
        self.lyrics = lyrics

    def sing_me_a_song(self):
        for line in self.lyrics:
            print (line)

happy_bday = Song(["Happy birthday to you",
                   "I don't want to get sued",
                   "So I'll stop right there"])

bulls_on_parade = Song(["They rally around family",
                        "With pockets full of shells"])#他们团结在家庭”，“口袋里满是贝壳”

happy_bday.sing_me_a_song()
bulls_on_parade.sing_me_a_song()

代码运行

"C:\Program Files\Python36\python.exe" "D:/小克学习/python/项目/week three/ex40.py"
Happy birthday to you
I don't want to get sued
So I'll stop right there
They rally around family
With pockets full of shells

Process finished with exit code 0

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总结：

这一章没怎么理解，所以专门抄下笔记，准备没事看看，帮助自己理解。

为什么创建 init 或者别的类函数时需要多加一个 self 变量？
如果你不加 self ， cheese = 'Frank' 这样的代码意义就不明确了，它指的既可能
是实例的 cheese 属性，或者一个叫做 cheese 的局部变量。有了 self.cheese =
'Frank' 你就清楚地知道了这指的是实例的属性 self.cheese 。

EX41

代码

##Animal is object ( yes , sort of confusing) look at the extra credit #动物是对象（是的，有点迷惑）看额外的信用等级动物（对象）：
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):#人（对象）

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

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

## ??
class Employee(Person):#雇员（人）

    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")

## ??