1、#比如我们现在有一个案例如下：#有一辆货车，有车牌号，总体积，货物列表。#然后每个货物有自己的名字和体积。
2、class Cargo: def __init__ (self): pass#首先我们需要创建一个货物类，接着开始初始化这个货物类。
3、class Cargo: def __init__ (self, name, volume): self.name = name self.volume = volume#我们设置两个参数，需要输入货物名称和体积。
4、class Cargo: def __init__ (self, name, volume): self.name = name self.volume = volume def __str__ (self): return "The volume of %s is %f." %(self.name, self.volume) #这里设置一下货物返回的字符串。
5、class Cargo: def __init__ (self, name, volume): self.name = name self.volume = volume def __str__ (self): return "The volume of %s is %.2f." %(self.name, self.volume) chair = Cargo("chair", 3)desk = Cargo("desk", 5)computer = Cargo("computer", 1)print(chair)print(desk)print(computer)#这里我们让对象运用这个货物类，并且进行打印。
6、class Truck: def __init__ (self, number, volume): self.number = number self.volume = volume rest_volume = self.volume cargo_list = [] #初始化货车类，接着设置一下属性。
7、class Truck: def __init__ (self, number, volume): self.number = number self.volume = volume rest_volume = self.volume cargo_list = [] def __str__ (self): return ("The licence of the truck is %s. And the rest of the volume is %.2f. We have the %s in this truck." %(self.number, rest_volume, cargo_list)) #这里设置一下这个类要返回的字符串。
8、class Truck: def __init__ (self, number, volume): self.number = number self.volume = volume rest_volume = self.volume cargo_list = [] def __str__ (self): return ("The licence of the truck is %s. And the rest of the volume is %.2f. We have the %s in this truck." %(self.number, rest_volume, cargo_list)) def add_cargo (self, cargo): print("Add the %s" %cargo)#这里设置一下方法，显示添加的货物。
9、class Truck: def __init__ (self, number, volume): self.number = number self.volume = volume rest_volume = self.volume cargo_list = [] def __str__ (self): return ("The licence of the truck is %s. And the rest of the volume is %.2f. We have the %s in this truck." %(self.number, rest_volume, cargo_list)) def add_cargo (self, cargo): print("Add the %s" %cargo) truck_AAA = Truck("AAA", 15)print(truck_AAA)#这里出错了，是因为我们必须在剩余的面积和货物列表那里加上self.，因为要调用对象。
10、clas衡痕贤伎s Truck: def __init__ (self, number, volume): self.number = 荏鱿胫协number self.volume = volume self.rest_volume = volume self.cargo_list = [] def __str__ (self): return ("The licence of the truck is %s.\nAnd the rest of the volume is %.2f.\nWe have the %s in this truck." %(self.number, self.rest_volume, self.cargo_list)) def add_cargo (self, cargo): print("Add the %s" %cargo) truck_AAA = Truck("AAA", 15)print(truck_AAA)#这里设置火车对象，并且打印一下这个对象看看返回什么。
11、clas衡痕贤伎s Cargo: def __init__ (self, name, volume): self.name = name self.volume = volume def __str__ (self): return "The volume of %s is %.2f." %(self.name, self.volume) class Truck: def __init__ (self, number, volume): self.number = number self.volume = volume self.rest_volume = volume self.cargo_list = [] def __str__ (self): return ("The licence of the truck is %s.\nAnd the rest of the volume is %.2f.\nWe have the %s in this truck." %(self.number, self.rest_volume, self.cargo_list)) def add_cargo (self, cargo): print("Add %s" %cargo) chair = Cargo("chair", 3)desk = Cargo("desk", 5)computer = Cargo("computer", 1)print(chair)print(desk)print(computer)truck_AAA = Truck("AAA", 15)print(truck_AAA)truck_AAA.add_cargo(desk)#这里我们把对象桌子的返回字符串引入到货车对象的方法里面，并且返回字符串。
12、clas衡痕贤伎s Cargo: def __init__ (self, name, volume): self.name = name self.volume = volume def __str__ (self): return "The volume of %s is %.2f." %(self.name, self.volume) class Truck: def __init__ (self, number, volume): self.number = number self.volume = volume self.rest_volume = volume self.cargo_list = [] def __str__ (self): return ("The licence of the truck is %s.\nAnd the rest of the volume is %.2f.\nWe have the %s in this truck." %(self.number, self.rest_volume, self.cargo_list)) def add_cargo (self, cargo): print("Add %s" %cargo) chair = Cargo("chair", 3)desk = Cargo("desk", 5)computer = Cargo("computer", 1)print(chair)print(desk)print(computer)truck_AAA = Truck("AAA", 15)print(truck_AAA)truck_AAA.add_cargo(chair)truck_AAA.add_cargo(desk)truck_AAA.add_cargo(computer)#全部定义进去。
13、clas衡痕贤伎s Cargo: def __init__ (self, name, volume): self.name = name self.volume = volume def __str__ (self): return "The volume of %s is %.2f." %(self.name, self.volume) class Truck: def __init__ (self, number, volume): self.number = number self.volume = volume self.rest_volume = volume self.cargo_list = [] def __str__ (self): return ("The licence of the truck is %s.\nAnd the rest of the volume is %.2f.\nWe have the %s in this truck." %(self.number, self.rest_volume, self.cargo_list)) def add_cargo (self, cargo): self.cargo_list.append(cargo.name) print("Add %s" %cargo.name) print(self.cargo_list) self.rest_volume -= cargo.volume chair = Cargo("chair", 3)desk = Cargo("desk", 5)computer = Cargo("computer", 1)print(chair)print(desk)print(computer)truck_AAA = Truck("AAA", 15)truck_AAA.add_cargo(chair)truck_AAA.add_cargo(desk)truck_AAA.add_cargo(computer)print(truck_AAA)#这个时候我们可以把货物添加入列表，并且让体积自动计算。在add_cargo方法里面务虽然参数是cargo，但是是可以指定输入对象的属性的，比如cargo.name和carogo.volume.。
