python how to change the global variables

Question

I would like to get some kind of confirmation that the upload is success, I have my methods defined similar to the following. However the value of global variable is not changing. Please help

global upload_confirm
upload_confirm = False

def confirm_upload():
    upload_confirm = True

def start_new_upload():
    confirm_upload()
    while (upload_confirm != True):
        print "waiting for upload to be true"
        time.sleep(5)
    if (upload_confirm == True):
        print "start Upload"

start_new_upload()

score 3 · Answer 1 · answered Sep 28 '14 at 14:17

3

You could try this:

def confirm_upload():
    global upload_confirm
    upload_confirm = True

Since you are doing upload_confirm = True in a local scope, Python treat it like a local variable. Hence, your global variable stays the same.

answered Sep 28 '14 at 14:17

Pablo Santa Cruz

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If I want just to read a global variable, can I skip the `global` declaration at start of each function? – SomethingSomething Sep 28 '14 at 14:20

score 1 · Answer 2 · answered Sep 28 '14 at 14:17

1

You need to put the global statement in that scope where you want to access the global variable, i.e.:

upload_confirm = False

def confirm_upload():
    global upload_confirm
    upload_confirm = True

answered Sep 28 '14 at 14:17

poke

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score 1 · Answer 3 · answered Sep 28 '14 at 14:18

1

Try this inside your confirm_upload() method.

def confirm_upload():
    global upload_confirm #Add this line
    upload_confirm = True

You need to declare it as global inside methods else it will be by default local.

answered Sep 28 '14 at 14:18

venki421

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score 0 · Answer 4 · answered Sep 28 '14 at 14:17

0

global statement should be inside the function.

def confirm_upload():
    global upload_confirm
    upload_confirm = True

Otherwise, upload_confirm = .. will create a local variable.

answered Sep 28 '14 at 14:17

falsetru

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python how to change the global variables

4 Answers4