类的模板导入

有时候我们给类添加的内容很长，是的文件显得冗长，我们就可以单独来一个文件放我们写好的类，在主文件中去导入这个模板的类然后在主文件中使用

导入的格式：from 文件名 import 类名

#类模板，文件名是carClassTemplate.py
class Car():
    def __init__(self,make,model,year):
        self.make = make
        self.model = model
        self.year = year
        self.odometer_read = 0

    def get_descriptive_name(self):
        long_name = str(self.year)+" "+ self.make + " " + self.model
        return long_name

    def read_odometer(self):
        print("the car's odometer is " + self.odometer_read + " !")

    def update_odometer(self,mlies):
        self.odometer_read = mlies

    def increament_odometer(self,increament_mlies):
        self.odometer_read += increament_mlies

    def read_odometer(self):
        print("the car's odometrs is "+ str(self.odometer_read) + " !")


#主文件
#使用导入类(从文件carClassTemplate.py中导入了一个类Car)
from carClassTemplate import Car
my_new_car = Car('audi','A6','2020')
my_new_car.update_odometer(200)

my_new_car.read_odometer() #the car's odometrs is 200 !

my_new_car.increament_odometer(98)
my_new_car.read_odometer()  #the car's odometrs is 298 !

可以同时导入多个类(下面把Battery类的实例作为my_car类的属性为例）：

#类模板，文件名是carClassTemplate.py
class Car():
    def __init__(self,make,model,year):
        self.make = make
        self.model = model
        self.year = year
        self.odometer_read = 0

    def get_descriptive_name(self):
        long_name = str(self.year)+" "+ self.make + " " + self.model
        return long_name

    def read_odometer(self):
        print("the car's odometer is " + self.odometer_read + " !")

    def update_odometer(self,mlies):
        self.odometer_read = mlies

    def increament_odometer(self,increament_mlies):
        self.odometer_read += increament_mlies

    def read_odometer(self):
        print("the car's odometrs is "+ str(self.odometer_read) + " !")


class Battery():
    def __init__(self):
        self.battery_size = 70
    def update_battery_size(self,new_battery_size):
        self.battery_size = new_battery_size
    def read_battery_size(self):
        print("the car's batter size is " + str(self.battery_size) + " !")



#主文件
#使用导入类(从文件carClassTemplate.py中导入了类Car,类Battery
from carClassTemplate import Car , Battery

class my_car(Car):
    def __init__(self,make,model,year):
        super(my_car,self).__init__(make,model,year)
        self.battery_size = Battery()

my_new_car = my_car('audi','A6',2020)
car_info  = my_new_car.get_descriptive_name()
print(car_info)   #2020 audi A6

my_new_car.battery_size.read_battery_size()  #the car's batter size is 70 !

my_new_car.battery_size.update_battery_size(90)
my_new_car.battery_size.read_battery_size() #the car's batter size is 90 !

my_new_car.update_odometer(90)
my_new_car.read_odometer()   #the car's odometrs is 90 !

my_new_car.update_odometer(200)
my_new_car.read_odometer()   #the car's odometrs is 200 !

my_new_car.increament_odometer(90)
my_new_car.read_odometer()   #the car's odometrs is 290 !

也可以导入整个模板，但是这时候就需要使用点来读取具体的类名称

import carClassTemplate   #导入整个模板
class my_car(carClassTemplate.Car):
    def __init__(self,make,model,year):
        super(my_car,self).__init__(make,model,year)
        self.battery_size = carClassTemplate.Battery()

my_new_car = my_car('audi','A6',2020)
car_info  = my_new_car.get_descriptive_name()
print(car_info)   #2020 audi A6

my_new_car.battery_size.read_battery_size()  #the car's batter size is 70 !

my_new_car.battery_size.update_battery_size(90)
my_new_car.battery_size.read_battery_size() #the car's batter size is 90 !

my_new_car.update_odometer(90)
my_new_car.read_odometer()   #the car's odometrs is 90 !

my_new_car.update_odometer(200)
my_new_car.read_odometer()   #the car's odometrs is 200 !

my_new_car.increament_odometer(90)
my_new_car.read_odometer()   #the car's odometrs is 290 !

from carClassTemplate import *  #导入所有模板的类

上边是导入所有的类模板中的类，不推荐这种写法，原因有没有明确指出用到了哪些模板中类，这在接下来使用其他类的时候会有起名称有冲突的风险