Python not waiting for return function, and continuing without a response-CodePudding

I have a function that saves files to the user's computer in Tkinter. I am trying to create a prompt for the user if they are trying to save a file that already exists, asking them if they'd like to overwrite the existing file, or not. I'm not going to include the whole code as it is 3000 lines, but an example of what I'm trying to do:

I understand os.path.save() is not valid, I'm using Shutil to copy an existing file from another location, this is just for example purposes.

def overWritePrompt():
    promptFrame = tk.Frame(maniWin, bg=_blk)
    promptFrame.place(relx=.4,rely=.2,relheight=.1,relwidth=.2)

    promptHead = tk.Label(promptFrame, bg=_blk, fg=_wht, text="Overwrite existing route?")
    promptHead.place(relx=0,rely=0,relheight=.4,relwidth=1)
    
    promptYes = tk.Button(promptFrame, bg=_dgrn, fg=_wht, text="Yes", relief="sunken", activebackground=_dgrn, activeforeground=_wht, command=lambda:(selection(True)), borderwidth=0)
    promptYes.place(relx=.1,rely=.5,relheight=.4,relwidth=.35)
    
    promptNo = tk.Button(promptFrame, bg=_red, fg=_wht, text="No", relief="sunken", activebackground=_red, activeforeground=_wht, command=lambda:(selection(False)), borderwidth=0)
    promptNo.place(relx=.45,rely=.5,relheight=.4,relwidth=.35)

    def selection(response):
        promptFrame.destroy()
        return response

def saveFile(fileName):
    overwrite = False
    if os.path.exists(os.path.join(directory, fileName)):
        overwrite = overwritePrompt()
    if overwrite:
        os.path.remove(fileName)
        os.path.save(fileName) 
    else:
        os.path.save(fileName)

I expect this to display the prompt to the user and wait for a response before continuing to the saving portion, however it just immediately returns None for the overwrite bool, and continues on with the rest of the code.

Why isn't overwrite = overwritePrompt() waiting for overWritePrompt() to return before continuing?

I have tried adding while loops in different places to keep the code from moving on until the user inputs their answer, but that just freezes the app completely.

CodePudding user response：

The nested function selection() doesn't iteract with the outer function overwritePrompt at all so its return statement doesn't affect the value returned by the outer function. selection() is just a normal function like any other in that regard.

You could simplify the whole thing by using a built-in Tk message box:

def saveFile(fileName):
    if os.path.exists(os.path.join(directory, fileName)):
        overwrite = tkinter.messagebox.askokcancel("Confirm", "Overwrite file?")
        if overwrite:
            os.path.remove(fileName)
    os.path.save(fileName)

CodePudding user response：

The solution I found was having the "save" button, call on the overWritePrompt() first, then have the prompt check if the file exists, then pass the result of the user input to the saveFile() function.

def overWritePrompt(fileName):
    promptFrame = ""

    def clearPrompt():
        promptFrame.destroy()

    if os.path.exists(os.path.join(directory, fileName)):
        promptFrame = tk.Frame(maniWin, bg=_blk)
        promptFrame.place(relx=.4,rely=.2,relheight=.1,relwidth=.2)

        promptHead = tk.Label(promptFrame, bg=_blk, fg=_wht, text="Overwrite existing route?")
        promptHead.place(relx=0,rely=0,relheight=.4,relwidth=1)
        
        promptYes = tk.Button(promptFrame, bg=_dgrn, fg=_wht, text="Yes", relief="sunken", activebackground=_dgrn, activeforeground=_wht, command=lambda:(clearPrompt, saveFile(fileName, True)), borderwidth=0)
        promptYes.place(relx=.1,rely=.5,relheight=.4,relwidth=.35)
        
        promptNo = tk.Button(promptFrame, bg=_red, fg=_wht, text="No", relief="sunken", activebackground=_red, activeforeground=_wht, command=lambda:(clearPrompt, saveFile(fileName, False)), borderwidth=0)
        promptNo.place(relx=.45,rely=.5,relheight=.4,relwidth=.35)

    else: saveFile(fileName, False)

def saveFile(fileName, overwrite):
    if overwrite:
        os.path.remove(fileName)
        os.path.save(fileName) 
    else:
        os.path.save(fileName)