Functions

Global and Nonlocal

global and nonlocal choose which outer binding assignment should update.

global tells assignment to update a module-level binding. Without it, count += 1 would try to assign a local count.

Source

count = 0

def bump_global():
    global count
    count += 1

bump_global()
print(count)

Output

nonlocal tells assignment to update a binding in the nearest enclosing function scope. This is useful for small closures that keep state.

Source

def make_counter():
    total = 0
    def bump():
        nonlocal total
        total += 1
        return total
    return bump

counter = make_counter()
print(counter())
print(counter())

Output

1
2

Notes

Assignment inside a function is local unless declared otherwise.
Prefer nonlocal for closure state and avoid global unless module state is truly intended.
Passing values and returning results is usually easier to test than rebinding outer names.

Run the complete example

Expected output

1
1
2

Execution time appears here after you run the example.

Global and Nonlocal

See also

Run the complete example

Example code

Expected output