Which GUI can have indefinite loop ?

[deanhystad]

This works as YOU would expect.

a = 42

def func():
    return a

print(func())

Output:
42

Because a is not assigned a value in func(), the function does not create a local "a" variable and the "a" used in func() is the a from the global scope (a = 42)

This is going to surprise you.

a = 42

def func():
    a = "Hi Mom"
    print("a inside func =", a)

func()
print("a outside func =", a)

a inside func = Hi Mom
a outside func = 42

Here we have two variables named "a"; on in the global scope (a = 42) and one in the function scope (a = "Hi Mom"). func() does not use the global "a" because func() assigns a value to "a" it creates its own "a" variable.

And for completeness:

a = 42

def func():
    global a
    a = "Hi Mom"
    print("a inside func =", a)

func()
print("a outside func =", a)

Output:
a inside func = Hi Mom
a outside func = Hi Mom

In this example there is only one variable named "a". The "global a" inside func() tells python to use "a" from the global scope instead of creating a local variable.