在 Python 中的一系列函数后无法 return 变量

Question

我正在尝试 return 一个通过一系列函数操作的变量 ('brand')。如果我通过第一个函数 (brandSelector) 找到变量和数组之间的交集，则变量是 returned。但是，如果在第一个失败的情况下选择了次要子路由，则变量会到达 brandDetectionFailure()，但它不会 return 开始（Main() 函数）。我试过使用 'global brand' 但它没有用。我将不胜感激关于强制变量 returned 到开始的任何建议，而不是在主函数打印回时接收 None。

主程序流控注意事项： Returns 跟随 brandSelector() --> brandDetectionFailure()（来自异常处理程序）--> defineBrand()

#Import Modules
import sys, warnings, string

#Define Globals
brands = ["apple", "android", "windows"]
brand = None

def init():
    #Define
    #warnings.filterwarnings("ignore") #Disable for debuggings
    #Main Menu
    print("--Welcome to Troubleshooting Applet--")
    print("In your query please include the brand of your device and the problem / symptom of your current issue. \n")

def Main():
    init()
    query = input("Enter your query: ").lower()
    brand = brandSelector(query) #Returns here after following brandSelector --> brandDetectionFailure (from exception handler) --> defineBrand
    print(brand)
    #secondaryMain(query)
    print("END")

def secondaryMain(query):
    #Push required variables to next stage
    print(query)

##START Brand Selection Route
def brandSelector(query):
    try:
        #Format Brands Query
        brand = set(brands).intersection(query.split())
        brand = ', '.join(brand)
        #Check Condition After Setting
        int_cond = confirmIntersection(brand)
        if int_cond == False:
            raise NameError("No Intersection")
            #brandDetectionFailure()
        return brand
    except NameError:
        print("\nNo Intersection found between query defined brand and brands array\n")
        brandDetectionFailure()

def confirmIntersection(brand):
    if brand in brands:
        return True
    else:
        return False
##END Brand Selection Route

##START Brand Selection Route | SUB: Failed Selection
def brandDetectionFailure():
    print("-Brand could not be found-")
    print("Query still stored for your issue")
    if userConfirm("Would you like to redefine a brand and continue?"):
        defineBrand()
    else:
        end()

def defineBrand():
    brand = input("Enter your device's brand: ")
    int_cond = confirmIntersection(brand)
    if int_cond == False:
        if userConfirm("Try again?"):
            defineBrand()
        else:
            end()
    else:
        print("End of Sub Route") #STILL NEEDS WORK
        return brand
##END Brand Selection Route | SUB: Failed Selection

##START Generic Functions
def userConfirm(question):
    reply = str(input(question+' (y/n): ')).lower().strip()
    if reply[0] == 'y':
        return True
    if reply[0] == 'n':
        return False
    else:
        return userConfirm("Please confirm using yes or no")

def end():
    print("Have a good day. Bye.")
    sys.exit()
##END Generic Functions

if __name__ == '__main__':
    Main()

谢谢，

山姆

Answer 1

感谢 Barmar (https://whosebug.com/users/1491895/barmar)，

我遵循了他的解决方案：

"brandDetectionFailure doesn't have a return statement. And your except block in brandSelector doesn't have a return statement. So nothing gets returned in that case."

随后对

进行了澄清

"It should be return brandDetectionFailure(). And brandDetectionFailure needs to have return defineBrand()."

综上所述，"Every function needs to return something."

在 Python 中的一系列函数后无法 return 变量

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