【Python学习记录——从入门到放弃】八、类（下）

给子类定义属性和方法

class Car():def __init__(self, make, model, year，odometer_reading=0):self.make = makeself.model = modelself.year = yearself.odometer_reading = odometer_readingdef get_descriptive_name(self):long_name = str(self.yesr) + ' ' + self.make + ' ' + self.modelreturn long_name.title()def read_odomter(self):print("This car has " + str(self.odometer_reading) + " miles on it.")def updata_odometer(self, mileage):self.odometer_reading = mileagedef increment_odometer(self, miles):self.odometer_reading += milesclass ElectricCar(Car):def __init__(self, make, model, year):# ...super(ElectricCar, self).__init__(make, model, year)self.battery_size = 70def describe_battery(self):print("This car has a " + str(self.battery_size) + "-kWh battery.")my_tesla = ElectricCar('tesla', 'model s', 2016)
print(my_tesla.get_descriptive_name())
my_tesla.describe_battery()

给子类定义属性和方法其实和创建一个类差不多，该怎么创建就怎么创建，继承只是多了super哪一句还有开始指明父类，来继承父类的属性和方法。

重写父类的方法

class Car():def __init__(self, make, model, year，odometer_reading=0):self.make = makeself.model = modelself.year = yearself.odometer_reading = odometer_readingdef get_descriptive_name(self):long_name = str(self.yesr) + ' ' + self.make + ' ' + self.modelreturn long_name.title()def read_odomter(self):print("This car has " + str(self.odometer_reading) + " miles on it.")def updata_odometer(self, mileage):self.odometer_reading = mileagedef increment_odometer(self, miles):self.odometer_reading += milesdef fill_gas_tank():print("This car need a gas tank!")class ElectricCar(Car):def __init__(self, make, model, year):# ...super(ElectricCar, self).__init__(make, model, year)def fill_gas_tank():print("This car doesn't need a gas tank!")

如果你在子类内重新定义父类的方法，当你想要使用这个方法时，那么程序将会使用你重写的方法。

将实例用作属性

class Car():def __init__(self, make, model, year，odometer_reading=0):self.make = makeself.model = modelself.year = yearself.odometer_reading = odometer_readingdef get_descriptive_name(self):long_name = str(self.yesr) + ' ' + self.make + ' ' + self.modelreturn long_name.title()def read_odomter(self):print("This car has " + str(self.odometer_reading) + " miles on it.")def updata_odometer(self, mileage):self.odometer_reading = mileagedef increment_odometer(self, miles):self.odometer_reading += milesclass Battery():def __init__(self, battery_size=70):self.battery_size = battery_sizedef describe_battery(self):print("This car has a " + str(self.battery_size) + "-kWh battery.")class ElectricCar(Car):def __init__(self, make, model, year):super().__init__(make, model, year)self.battery = Battery()my_tesla = ElectricCar('tesla', 'model s', 2016)print(my_tesla.get_descriptive_name())
my_tesla.battery.describe_battery()

上面这个例子就是把类Battery实例化给类ElectricCar作为属性。
这样做的好处就是在属性和方法过多时，可以使其更加整洁，也容易查找和修改。

模拟实物
这个意思大概是，不能被语法困住，学习编程不仅仅只是学习它的语法，更应该学习在编程前的思考逻辑，如何能够快速，方便地解决一个问题，这种思考才是最重要的。

动手试一试：

# 9-6
class Restaurant():def __init__(self, restaurant_name, restaurant_type):self.restaurant_name = restaurant_nameself.restaurant_type = restaurant_typedef describe_restaurant(self):print("\n这家餐厅的名字是：" + self.restaurant_name + "\n这家餐厅的类型是" + self.restaurant_type)def open_restaurant(self):print("\n这家餐厅开始营业！")class IceCreamStand(Restaurant):def __init__(self, restaurant_name, restaurant_type):super().__init__(restaurant_name, restaurant_type)self.flavors = []def add_flavors(self, flavor):self.flavors.append(flavor)print('添加了' + flavor + '口味的')def read_flavors(self):print('我喜欢的冰淇淋口味有：')for flavor in self.flavors:print('\t' + flavor)my_icecreamstand = IceCreamStand('小小冰淇淋', '冰淇淋店')
my_icecreamstand.add_flavors('抹茶')
my_icecreamstand.add_flavors('香草')
my_icecreamstand.add_flavors('草莓')
my_icecreamstand.read_flavors()

# 9-7
class User():def __init__(self, first_name, last_name, **kd):self.first_name = first_nameself.last_name = last_nameself.preperties = {}for key, value in kd.items():self.preperties[key] = valuedef describe_user(self):print('\nfirst name: ' + self.first_name + '\nlast name: ' + self.last_name)for key, value in self.preperties.items():print(key + ': ' + value + '\n')class Admin(User):def __init__(self, first_name, last_name, **kd):super().__init__(first_name, last_name, **kd)self.privileges = ['can add post', 'can delete post', 'can ban user']def show_privileges(self):print(self.first_name + '所拥有的权限有：')for privilege in self.privileges:print('\t' + privilege)my_admin = Admin('admin', 'admin')
my_admin.show_privileges()

# 9-8
class User():def __init__(self, first_name, last_name, **kd):self.first_name = first_nameself.last_name = last_nameself.preperties = {}for key, value in kd.items():self.preperties[key] = valuedef describe_user(self):print('\nfirst name: ' + self.first_name + '\nlast name: ' + self.last_name)for key, value in self.preperties.items():print(key + ': ' + value + '\n')class Privileges():def __init__(self):self.privileges = ['can add post', 'can delete post', 'can ban user']def show_privileges(self):print('你所拥有的权限有：')for privilege in self.privileges:print('\t' + privilege)class Admin(User):def __init__(self, first_name, last_name, **kd):super().__init__(first_name, last_name, **kd)self.privileges = Privileges()my_admin = Admin('admin', 'admin')
my_admin.privileges.show_privileges()

# 9-9
class Car():def __init__(self, make, model, year，odometer_reading=0):self.make = makeself.model = modelself.year = yearself.odometer_reading = odometer_readingdef get_descriptive_name(self):long_name = str(self.yesr) + ' ' + self.make + ' ' + self.modelreturn long_name.title()def read_odomter(self):print("This car has " + str(self.odometer_reading) + " miles on it.")def updata_odometer(self, mileage):self.odometer_reading = mileagedef increment_odometer(self, miles):self.odometer_reading += milesclass Battery():def __init__(self, battery_size=70):self.battery_size = battery_sizedef describe_battery(self):print("This car has a " + str(self.battery_size) + "-kWh battery.")def get_range(self):if self.battery_size == 70:range = 240elif self.battery_size == 85:range = 270message = "This car can go approximately " + str(range)message += " miles on a full charge."print(message)def upgrade_battery(self):if self.battery_size != 85:self.battery_size = 85class ElectricCar(Car):def __init__(self, make, model, year):super().__init__(make, model, year)self.battery = Battery()my_tesla = ElectricCar('tesla', 'model s', 2016)print(my_tesla.get_descriptive_name())
my_tesla.battery.describe_battery()
my_tesla.battery.get_range()
my_tesla.battery.upgrade_battery()
my_tesla.battery.describe_battery()
my_tesla.battery.get_range()

四、导入类

导入单个类

# 这里保存在car.py
class Car():def __init__(self, make, model, year，odometer_reading=0):self.make = makeself.model = modelself.year = yearself.odometer_reading = odometer_readingdef get_descriptive_name(self):long_name = str(self.yesr) + ' ' + self.make + ' ' + self.modelreturn long_name.title()def read_odomter(self):print("This car has " + str(self.odometer_reading) + " miles on it.")def updata_odometer(self, mileage):self.odometer_reading = mileagedef increment_odometer(self, miles):self.odometer_reading += miles

# 这里保存在my_car.py
from car import Carmy_new_car = Car('audi', 'a4', 2016)
print(my_new_car.get_descriptive_name())    my_new_car.odometer_reading = 23
my_new_car,read_odomter()

在一个模块中存储多个类

# 这是保存为car.py
class Car():def __init__(self, make, model, year，odometer_reading=0):self.make = makeself.model = modelself.year = yearself.odometer_reading = odometer_readingdef get_descriptive_name(self):long_name = str(self.yesr) + ' ' + self.make + ' ' + self.modelreturn long_name.title()def read_odomter(self):print("This car has " + str(self.odometer_reading) + " miles on it.")def updata_odometer(self, mileage):self.odometer_reading = mileagedef increment_odometer(self, miles):self.odometer_reading += milesclass Battery():def __init__(self, battery_size=70):self.battery_size = battery_sizedef describe_battery(self):print("This car has a " + str(self.battery_size) + "-kWh battery.")def get_range(self):if self.battery_size == 70:range = 240elif self.battery_size == 85:range = 270message = "This car can go approximately " + str(range)message += " miles on a full charge."print(message)class ElectricCar(Car):def __init__(self, make, model, year):super().__init__(make, model, year)self.battery = Battery()

# 这是保存为my_electric_car.py
from car import ElectricCarmy_tesla = ElectricCar('tesla', 'model s', 2016)print(my_tesla.get_descriptive_name())
my_tesla.battery.describe_battery()
my_tesla.battery.get_range()

从一个模块中导入多个类

这里保存在my_cars.py
from car import Car, ElectricCarmy_beetle = Car('Volkswagen', 'beetle', 2016)
print(my_beetle.get_descriptive_name())my_tesla = ElectricCar('tesla', 'model s', 2016)
print(my_tesla.get_descriptive_nameJ())

导入整个模块

import carmy_beetle = car.Car('Volkswagen', 'beetle', 2016)
print(my_beetle.get_descriptive_name())my_tesla = car.ElectricCar('tesla', 'model s', 2016)
print(my_tesla.get_descriptive_nameJ())

导入模块中的所有类

from car import *my_beetle = Car('Volkswagen', 'beetle', 2016)
print(my_beetle.get_descriptive_name())my_tesla = ElectricCar('tesla', 'model s', 2016)
print(my_tesla.get_descriptive_nameJ())

在一个模块中导入另一个模块

# 这是保存为car.py
class Car():def __init__(self, make, model, year，odometer_reading=0):self.make = makeself.model = modelself.year = yearself.odometer_reading = odometer_readingdef get_descriptive_name(self):long_name = str(self.yesr) + ' ' + self.make + ' ' + self.modelreturn long_name.title()def read_odomter(self):print("This car has " + str(self.odometer_reading) + " miles on it.")def updata_odometer(self, mileage):self.odometer_reading = mileagedef increment_odometer(self, miles):self.odometer_reading += miles

# 这里保存在electric_car.py
from car import Carclass Battery():def __init__(self, battery_size=70):self.battery_size = battery_sizedef describe_battery(self):print("This car has a " + str(self.battery_size) + "-kWh battery.")def get_range(self):if self.battery_size == 70:range = 240elif self.battery_size == 85:range = 270message = "This car can go approximately " + str(range)message += " miles on a full charge."print(message)class ElectricCar(Car):def __init__(self, make, model, year):super().__init__(make, model, year)self.battery = Battery()

# 这里保存在my_cars.py
from car import Car
from electric_car import ElectricCarmy_beetle = Car('Volkswagen', 'beetle', 2016)
print(my_beetle.get_descriptive_name())my_tesla = ElectricCar('tesla', 'model s', 2016)
print(my_tesla.get_descriptive_nameJ())

自定义工作流程
233
自定义
把握好每个类

动手试一试：

# 9-10
# 这里保存在restaurant.py
class Restaurant():def __init__(self, restaurant_name, restaurant_type):self.restaurant_name = restaurant_nameself.restaurant_type = restaurant_typedef describe_restaurant(self):print("\n这家餐厅的名字是：" + self.restaurant_name + "\n这家餐厅的类型是" + self.restaurant_type)def open_restaurant(self):print("\n这家餐厅开始营业！")
# 这里保存在my_restaurant.py
from restaurant import Restaurantmy_restaurant = Restaurant('北京烤鸭', '烤鸭店')
your_restaurant = Restaurant('糖醋排骨', '排骨店')
his_restaurant = Restaurant('宫保鸡丁', '鸡肉店')my_restaurant.describe_restaurant()
your_restaurant.describe_restaurant()
his_restaurant.describe_restaurant()

# 9-11
# 这里保存在users.py
class User():def __init__(self, first_name, last_name, **kd):self.first_name = first_nameself.last_name = last_nameself.preperties = {}for key, value in kd.items():self.preperties[key] = valuedef describe_user(self):print('\nfirst name: ' + self.first_name + '\nlast name: ' + self.last_name)for key, value in self.preperties.items():print(key + ': ' + value + '\n')class Privileges():def __init__(self):self.privileges = ['can add post', 'can delete post', 'can ban user']def show_privileges(self):print('你所拥有的权限有：')for privilege in self.privileges:print('\t' + privilege)class Admin(User):def __init__(self, first_name, last_name, **kd):super().__init__(first_name, last_name, **kd)self.privileges = Privileges()
# 这里保存在my_admin.py
from users import Adminmy_admin = Admin('admin', 'admin')
my_admin.privileges.show_privileges()

# 9-11
# 这里保存在user.py
class User():def __init__(self, first_name, last_name, **kd):self.first_name = first_nameself.last_name = last_nameself.preperties = {}for key, value in kd.items():self.preperties[key] = valuedef describe_user(self):print('\nfirst name: ' + self.first_name + '\nlast name: ' + self.last_name)for key, value in self.preperties.items():print(key + ': ' + value + '\n')
# 这里保存在admin.py
from user import Userclass Privileges():def __init__(self):self.privileges = ['can add post', 'can delete post', 'can ban user']def show_privileges(self):print('你所拥有的权限有：')for privilege in self.privileges:print('\t' + privilege)class Admin(User):def __init__(self, first_name, last_name, **kd):super().__init__(first_name, last_name, **kd)self.privileges = Privileges()
# 这里保存在my_admin.py
from admin import Adminmy_admin = Admin('admin', 'admin')
my_admin.privileges.show_privileges()

五、Python标准库
Python标准库是一组Python自带的模块，可以方便用户的操作。

from collections import OrderedDictfavorite_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() + '.')

动手试一试：

# 9-13
"""
# 6-4的代码
types = {'int':'整数型','float':'浮点型','boolean':'布尔型','string':'字符串','char':'字节'}for key, value in types.items():print(key + ':' + value)types['print'] = '打印'
types['if'] = '条件检测'
types['for'] = '循环'
types['[]'] = '列表'
types['{}'] = '字典'for key, value in types.items():print(key + ':' + value)
"""
from collections import OrderedDicttypes = OrderedDict()types['int'] = '整数型'
types['float'] = '浮点型'
types['boolean'] = '布尔型'
types['string'] = '字符串'
types['char'] = '字节'for key, value in types.items():print(key + ':' + value)types['print'] = '打印'
types['if'] = '条件检测'
types['for'] = '循环'
types['[]'] = '列表'
types['{}'] = '字典'for key, value in types.items():print(key + ':' + value)

# 9-14
from random import randintclass Die():def __init__(self, sides=6):self.sides = sidesdef roll_die(self):print(randint(1, self.sides))count = 1
six_Die = Die()
while count <= 10:six_Die.roll_die()count += 1count = 1
ten_Die = Die(10)
while count <= 10:ten_Die.roll_die()count += 1count = 1
twenty_Die = Die(20)
while count<=10:twenty_Die.roll_die()count += 1

六、类编码风格

驼峰命名法：SixDie（不用下划线，每个单词首字母大写）
实例名和模块名都采用小写格式，单词与单词之间用下划线：six_die
每个类和模块要注释功能文档
在类中，使用一个空行来分隔方法；在模块中，使用两个空行来分隔类
导入模块时，先编写导入标准库的语句，然后用一个空行分隔，接着写导入自己编写的模块的语句。

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