use a variable defined in a function outside the function

Question

I have this function here.

def choose_file():
    file = askopenfile(mode ='r', filetypes =[('xodr Files', '*.xodr')])
    if file:
        res = "selected:", file
    else:
        res = "file not selected"
    return(res)

I have this button to open the dialog and choose a file

e3=Button (scalF, text='Wählen Sie ein Dokument',font=('Bahnschrift SemiLight',12),command=choose_file, bg='blue')
e3.pack(side='top')

after choosing a file and closing the dialog I want to display the value of the variable defined res in the choose_file() in the label below

chosenFile = Label(scalF,text="I want to write here",font=('Bahnschrift SemiLight', 10))
chosenFile.pack(side='top')

can you explain how to read the variable resfrom the global scope?

user459872 · Accepted Answer · 2021-09-30 09:37:27Z

1

You can use tk.StringVar to hold the strings variables.

file_result = tk.StringVar()

def choose_file():
    file = askopenfile(mode ='r', filetypes =[('xodr Files', '*.xodr')])
    if file:
        res = "selected: {0}".format(file.name)
    else:
        res = "file not selected"
    file_result.set(res)

Then this variable(file_result) can be passed to Labels textvariable argument(Whose value will be used in place of the text).

chosenFile = Label(scalF, font=('Bahnschrift SemiLight', 10), textvariable=file_result)

edited Sep 30, 2021 at 9:37

answered Sep 30, 2021 at 9:31

user459872

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1 Comment

sffgsfgs Over a year ago

It works. Thanks!! @Abdul Niyas P M just one question: i don't have my function choose_file() inside the root = Tk() so i moved file_result = tk.StringVar() under root = Tk(). is that the best thing to do or should i move the function under the root = Tk() as well?

Dashfast · Accepted Answer · 2021-09-30 09:20:07Z

0

one of the ways i can recommend is : add global res to the 1st line of ur function.

answered Sep 30, 2021 at 9:20

Dashfast

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Comments

kinshukdua · Accepted Answer · 2021-09-30 09:20:20Z

0

You can use the variable in the global scope by declaring it using the global keyword.

def choose_file():
    global res
    file = askopenfile(mode ='r', filetypes =[('xodr Files', '*.xodr')])
    if file:
        res = "selected:", file
    else:
        res = "file not selected"
    return(res)

If you wanna explore more, you can learn about namespaces in python

answered Sep 30, 2021 at 9:20

kinshukdua

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Comments

Metapod · Accepted Answer · 2021-09-30 09:41:16Z

0

You could use a class:

class File():
    def __init__(self):
        self.res = None

        e3=Button (scalF, text='Wählen Sie ein Dokument', font=('Bahnschrift SemiLight',12), command=self.choose_file, bg='blue')
        e3.pack(side='top')

    def choose_file(self):
        # Your implementation but updating self.res, without return

    def get_res(self):
        return self.res

answered Sep 30, 2021 at 9:41

Metapod

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