Python: Is there a way to access variables from other functions without using 'global'?

Question

Here's an example on what I'm thinking:

def check_args():
    if len(sys.argv) < 2:
        sys.exit('Reason')
    if not os.path.exists(sys.argv[1]):
        sys.exit('ERROR: Folder %s was not found!' % sys.argv[1])
    global path
    path = sys.argv[1]

As you can tell after check_args() completes succefully the "path" variable has universal meaning - you can use it in other functions as de-facto variable.

So I'm thinking if there is a way to access "path" e.g. check_args.path?

How about in python v3?

This might just be an example, but if this is close to your actual code, you might want to look into a commandline parsing library (argparse is the most recent one to be included with python). — mgilson
– mgilson, Commented Jun 15, 2012 at 19:19
You don't have to put the code into a function. Just define a global path variable by defining it somewhere near the top of your module. You can store it as an attribute of a function as in @lanzz's answer, but that's almost the same thing since your function is a global module object. — martineau
– martineau, Commented Jun 15, 2012 at 19:24
Is there a good reason for check_args not to simply return the value, and let the caller worry about where it is saved? — Blckknght
– Blckknght, Commented Jun 15, 2012 at 19:37

lanzz · Accepted Answer · 2012-06-15 19:16:19Z

3

Python functions are objects. You can define whatever custom properties you want on them:

def a():
    a.test = 123

a()
a.test # => 123

answered Jun 15, 2012 at 19:16

lanzz

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1 Comment

Cat Plus Plus Over a year ago

Needing attributes on functions is usually a sign of you wanting a class, possibly with __call__.

bmu · Accepted Answer · 2012-06-15 20:47:18Z

0

You can simply return the value

def check_args():
    if len(sys.argv) < 2:
        sys.exit('Reason')
    if not os.path.exists(sys.argv[1]):
        sys.exit('ERROR: Folder %s was not found!' % sys.argv[1])
    path = sys.argv[1]
    return path

my_path = check_args()

or when using if __name__ ...:

if __name__ == '__main__':
    my_path = check_args()
    results = do_something(path)

edited Jun 15, 2012 at 20:47

answered Jun 15, 2012 at 20:41

bmu

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