20201224-4

1-1
# dog

class Dog():
    """A simple attempt to model a dog."""
    
    def __init__(self, name, age):
        """Initialize name and age attributes."""
        self.name = name
        self.age = age
        
    def sit(self):
        """Simulate a dog sitting in response to a command."""
        print(self.name.title() + " is now sitting.")

    def roll_over(self):
        """Simulate rolling over in response to a command."""
        print(self.name.title() + " rolled over!")
        

my_dog = Dog('willie', 6)
your_dog = Dog('lucy', 3)

print("My dog's name is " + my_dog.name.title() + ".")
print("My dog is " + str(my_dog.age) + " years old.")
my_dog.sit()

print("
My dog's name is " + your_dog.name.title() + ".")
print("My dog is " + str(your_dog.age) + " years old.")
your_dog.sit()
--->
My dog's name is Willie.
My dog is 6 years old.
Willie is now sitting.

My dog's name is Lucy.
My dog is 3 years old.
Lucy is now sitting.

2-1

使用模块collections中的OrderedDict类。OrderedDict实例的行为 几乎与字典相同，区别只在于记录了键—值对的添加顺序
创建了OrderedDict 类的一个实例，并将其存储到favorite_languages中。
请注意，这里没有使用花括号，而是调用 OrderedDict()来创建一个空的有序字典，并将其存储在favorite_languages中
这是一个很不错的类，它兼具列表和字典的主要优点（在将信息关联起来的同时保留原来的 顺序）。
等你开始对关心的现实情形建模时，可能会发现有序字典正好能够满足需求。

# favorite languages

from collections import OrderedDict

favorite_languages = OrderedDict()

favorite_languages['jen'] = 'python'
favorite_languages['sarah'] = 'c'
favorite_languages['edward'] = 'ruby'
favorite_languages['phil'] = 'python'

for name, language in favorite_languages.items():
    print(name.title() + "'s favorite language is " +
        language.title() + ".")