为什么这样，即使我将其放置在一个类中，也始终收到未定义Driver Sponsor的错误？

Question

I have been trying my hand at a NASCAR project, where I would have to use a class to create 20 unique vehicles and then have them race ( or to see who would reach 500 miles first, through the means of repeatedly choosing a different speed between 1 and 120 and adding it to an increasing odometer). I made what you see below and ran it, and it boots well into the Python IDLE. However, it will always tell me that NameError: name 'Driver_sponsor' is not defined. See, I have been facing this error for a while now, and I have tried placing the Driver_sponsor list into a class, placing it into the Main def and placing the keyword self. before it. No matter what I did, I faced this error. I am going to go back into my class book to see what I can do, but I am hoping that someone here can tell me what I am missing within my code, since, really, I am extremely lost.

from random import randint
import time 

class Car:
    def __init__(self,Driver_Name,Sponsor):
        self.__Total_Odometer_Miles = 0
        self.__Speed_Miles_Per_Hour = 0
        self.__Driver_Name = Driver_Name
        self.__Sponsor = Sponsor
        self.__Driver = ('Drivers name Missing')
        self.__Sponsor = ('Sponsor Missing')
        self.__Driver_sponsor = {'A.J.Allmendinger:3M','Aric Almirola:Allegiant ','Trevpr Bayne:AMR ','Ryan Blaney:Camping World ','Clint Bowyer:Chevrolet ',
                              'Chris Buesher:Coca-Cola','Kurt Busch:Coca-light ','Kyle Busch:Credit One ','Landon Cassill:Ford','Matt DiBenedetto:FDP',
                              'Austin Dillon:','Ty Dillon:','Dale Earnhardt:Jacob Companies ','Chase Elliott: M & M ','Denny Hamlin: Microsoft ',
                              'Kevin Harvick:GoodYear ','Jimmie Johnson:Nationwide','Erik Jones:SUNOCO','Kasey Kahne:Toyota','Matt Kenseth:Visa ' }
    def Name(self,Driver_Name):
        self.__Driver_Name = Driver_Name
    def Retrieve_Name(self):
        return self.__Driver_Name
    def __mutualize__(self):
        self.__Total_Odometer_Miles = 0
        self.__Speed_Miles_Per_Hour = 0
    def sponsors(self):
        self.__Driver_sponsor = {'A.J.Allmendinger:3M','Aric Almirola:Allegiant ','Trevpr Bayne:AMR ','Ryan Blaney:Camping World ','Clint Bowyer:Chevrolet ',
                              'Chris Buesher:Coca-Cola','Kurt Busch:Coca-light ','Kyle Busch:Credit One ','Landon Cassill:Ford','Matt DiBenedetto:FDP',
                              'Austin Dillon:','Ty Dillon:','Dale Earnhardt:Jacob Companies ','Chase Elliott: M & M ','Denny Hamlin: Microsoft ',
                              'Kevin Harvick:GoodYear ','Jimmie Johnson:Nationwide','Erik Jones:SUNOCO','Kasey Kahne:Toyota','Matt Kenseth:Visa ' }
    def Retrieve_sponsor(self,Driver_sponsor):
         return self.__Driver_sponsor

def main():
    for key in Driver_sponsor():
            CurrentCar = Car()
            CurrentCar.Driver = key
            CurrentCar.Sponsor = val
            CurrentCar.MPH = randint(1,120)
            time.sleep(.05)
            time = 5
            currentCar.ODT = 5
            CurrentCar.ODT = CurrentCar.ODT + CurrentCar.MPH*Time
            print(CurrentCar.Driver,CurrentCar.ODT)
            if CurrentCar.ODT >= 500:
                print('\ the winner is',key,'t\ sponsored by',val)

main()

Answer 1

There are a few issues with your code.

First, you're getting this error because you're calling a variable that isn't set.

But more importantly, you're trying to access the driver-sponsor dict before you've initialized an instance of Car (which currently only happens inside the loop that iterates over Driver_sponsor !).

If you want to loop over driver-sponsor pairs and initialize a new Car for each one, then do you really need the full Driver_sponsor dict initialized for every Car ? If so, just pass it as an argument when constructing Car and populate self.__Driver_sponsor .

For example:

driver_sponsor_pairs = {'A.J.Allmendinger:3M',...,'Matt Kenseth:Visa'}

class Car:
    def __init__(self, driver_sponsor):
        # ...
        self.driver_sponsor = driver_sponsor

CurrentCar = Car(driver_sponsor=driver_sponsor_pairs)

# now refer to CurrentCar.driver_sponsor

Second, you are only asking for key when looping over the Driver_sponsor dict, but you call on both key (for Driver ) and val (for Sponsor ) in each loop . Extract both key and val in your loop creation. You'll need the .items() dict method to get both values:

for key, val in driver_sponsor_pairs.items():
    ...

Third, your Car __init__ expects Driver and Sponsor arguments, but you try to define CurrentCar = Car() and then populate CurrentCar.Driver and CurrentCar.Sponsor afterwards. Continuing with the above updates, try instead:

CurrentCar = Car(Driver=key, Sponsor=val)

Fourth, you won't need the Retrieve_sponsor() method if you already have the .Sponsor attribute set.

There are a lot of misunderstandings here about Object syntax and design. You may find it frustrating to try and debug at this level of complexity. I would suggest starting very simply, say, with Car() having just one attribute. Test that, make sure it works as you want, and then build more attributes and methods from there.