导出为Python中的文本

Question

我的部分任务是在用户选择该选项时导出为文本。除了那一部分，我似乎什么都对。有人能告诉我哪里出了问题吗？我需要在代码中的其他地方添加一些东西才能正常工作吗？当我选择选项6时，我得到了一个错误automobilelist没有被定义

class Automobile:
    # constructor, it takes parameters make, model, year and mileage
    def __init__(self,aMake,aModel,aColor,aYear,aMileage):
        # assign passed values to instance variables
        self.setMake(aMake)  # string
        self.setModel(aModel)  # string
        self.setColor(aColor) # string
        self.setYear(aYear)   # int
        self.setMileage(aMileage)  # int

    # setter of make
    # it takes 1 parameter make
    # it doesn't returns anything
    def setMake(self, aMake):
        self.__make = aMake

    # getter of make
    # it doesn't take any parameters
    # it returns make
    def getMake(self):
        return self.__make

    # setter of model
    # it takes 1 parameter model
    # it doesn't returns anything
    def setModel(self, aModel):
        self.__model = aModel

    # getter of model
    # it doesn't take any parameters
    # it returns model
    def getModel(self):
        return self.__model

    # setter of color
    # it takes 1 parameter color
    # it doesn't returns anything
    def setColor(self, aColor):
        self.__color = aColor
        return True

    # getter of color
    # it doesn't take any parameters
    # it returns color
    def getColor(self):
        return self.__color

    # setter of year
    # it takes 1 parameter year
    # it doesn't returns anything
    def setYear(self, aYear):
        self.__year = aYear

    # getter of year
    # it doesn't take any parameters
    # it returns year
    def getYear(self):
        return self.__year

    # setter of mileage
    # it takes 1 parameter year
    # it doesn't returns anything
    def setMileage(self, aMileage):
        self.__mileage = aMileage

    # getter of mileage
    # it doesn't take any parameters
    # it returns mileage
    def getMileage(self):
        return self.__mileage

    # string representation of the instance variables
    # it doesn't take any parameters
    # it returns string form of object
    def __str__(self):
        return "{}, {}, {}, {}, {}".format(self.getMake(),self.getModel(),self.getColor(),self.getYear(),self.getMileage())

class Automobiledealership:

    # constructor
    # it initializes the empty automobile list
    def __init__(self):
        self.__automobilelist = []

    # adds automobile to dealership
    # it takes automobile class object as parameter
    # it doesn't returns anything
    def addAutomobile(self, automobile):
        self.__automobilelist.append(automobile)

    # removes automobile from dealership
    # it takes index of automobile in the list as parameter
    # it doesn't returns anything
    def removeAutomobile(self, index):
        del self.__automobilelist[index-1]

    # returns automobile from dealership
    # it takes index of automobile in the list as parameter
    # it returns automobile object located at that index
    def getAutomobile(self, index):
        return self.__automobilelist[index-1]

    # prints the list of automobiles
    # it doesn't take any parameters
    # it doesn't returns anything
    def printAutomobileList(self):
        if len(self.__automobilelist)==0:
            print("No automobiles in dealership")
        else:
            for i in range(len(self.__automobilelist)):
                print("{}. {}".format(i+1,self.__automobilelist[i]))


    # add some automobiles to the dealership for Sample Inventory
def addSampleAutomobiles(automobiles):
    automobiles.addAutomobile(Automobile("Ford", "Focus", "Red", 2019, 8000))
    automobiles.addAutomobile(Automobile("Toyota","Corolla","White",2007,65000))
    automobiles.addAutomobile(Automobile("Ford","Endura","Black",2019,5000))
    automobiles.addAutomobile(Automobile("Audio","A1","White",2016,23000))
    automobiles.addAutomobile(Automobile("Toyota", "Camry", "Red", 2000, 25000))
    automobiles.addAutomobile(Automobile("Ford","Everest","Black",2017,16000))
    automobiles.addAutomobile(Automobile("Mazda","MX5","Red",2015,33000))
    automobiles.addAutomobile(Automobile("Ford","Escape","Grey",2018,15000))
    automobiles.addAutomobile(Automobile("Toyota", "Prius", "Red", 2010, 35000))

def addAutomobile(automobiles):
    make = input("Please enter Make >> ")
    model = input("Please enter Model >> ")
    color = input("Please enter Color >> ")
    year = int(input("Please enter Year >> "))
    mileage = int(input("Please enter Mileage >> "))
    automobiles.addAutomobile(Automobile(make,model,color,year,mileage))

def removeAutomobile(automobiles):
    index = int(input("Please enter number of the automobile to be removed >> "))
    automobiles.removeAutomobile(index)

def updateAutomobile(automobiles):
    index = int(input("Please enter number of the automobile to be updated >> "))
    automobile = automobiles.getAutomobile(index)
    make = input("Please enter Make (enter 0 to skip) >> ")
    model = input("Please enter Model (enter 0 to skip) >> ")
    color = input("Please enter Color (enter 0 to skip) >> ")
    year = int(input("Please enter Year (enter 0 to skip) >> "))
    mileage = int(input("Please enter Mileage (enter -1 to skip) >> "))
    if make!='0':
        automobile.setMake(make)
        print("Automobile make is updated")
    if model!='0':
        automobile.setModel(model)
        print("Automobile model is updated")
    if color!='0':
        automobile.setColor(color)
        print("Automobile color is updated")
    if year!=0:
        automobile.setYear(year)
        print("Automobile year is updated")
    if mileage!=-1:
        automobile.setMileage(mileage)
        print("Automobile mileage is updated")

    # create automobile dealership object
automobiles = Automobiledealership()
choice = -1
    # start loop
while choice!=0:
    print()
    print("1. Add sample automobiles to dealership")
    print("2. Display automobiles in the dealership")
    print("3. Add automobile to dealership")
    print("4. Remove automobile from dealership")
    print("5. Update automobile at dealership")
    print("6. Export automobile Inventory")
    print("0. Exit program")

    choice = int(input("Your choice >> "))
    print()

    if choice==1:
        addSampleAutomobiles(automobiles)
    elif choice==2:
        automobiles.printAutomobileList()
    elif choice==3:
        addAutomobile(automobiles)
    elif choice == 4:
        removeAutomobile(automobiles)
    elif choice == 5:
        updateAutomobile(automobiles)
    elif choice == 6:
        f = open('AutomobileList.txt', 'w')
        f.write(str(automobilelist))
        f.close()

Answer 1

出现此错误是因为automobilelist确实没有在Automobiledealership类的范围之外定义

如果要从类中获取字段，应调用<实例名称><字段名>；，在你的例子中是automobiles.__automobilelist

但对你来说还是不行。当您在\u automobilelist前面加上双下划线时，您将其定义为Automobiledealership类的私有成员，因此您还应该为automobilelist创建getter函数（与getAutomobile一样）

可以在类中使用的简单getter函数：

def getAutoMobileList(self):
    return self.__automobilelist

然后调用automobiles.getAutoMobileList()

另一种解决方法是：

您调用了str(automobilelist)，如上所述，它应该是str(automobiles.getAutoMobileList())，反过来可以转换为automobiles.__str__()。这意味着您可以定义一个__str__函数而不是上面提到的getter函数。 因此，对于换行分隔值，可以定义：

def __str__(self):
    return '\n'.join(str(i) for i in self.__automobilelist)

然后打电话给str(automobiles)

Answer 2

可以尝试在类中创建getter函数

def getAutoMobileList(self):
    return self.__automobilelist