Python non-local variables

Question

Isn't it supposed to return 'inner: nonlocal' and 'outer: local'?? Can someone explain what's happening, thanks.

>>>>def outer():
        x = 'local'
        def inner():
            nonlocal x
            x='nonlocal'
            print('inner:',x)
        inner()
        print('outer:',x)

>>>outer()
 inner: nonlocal
 outer: nonlocal

The nonlocal statement causes the listed identifiers(in this case its x) to refer to previously bound variables in the nearest enclosing scope excluding globals — user459872
– user459872, Commented Mar 17, 2020 at 12:57

Robey · Accepted Answer · 2020-03-17 12:57:36Z

1

You are setting x to 'nonlocal' by calling inner(). Thus, x is set to 'nonlocal' no matter where you try to print it from within outer(). Put the print statement before the call to inner() and it will work.

answered Mar 17, 2020 at 12:57

Robey

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3 Comments

GoodDeeds Over a year ago

That is only because the nonlocal statement is used.

Robey Over a year ago

@GoodDeeds Did I imply anything else?

GoodDeeds Over a year ago

Sorry, I misphrased my comment. While your answer is correct, I think the OP is asking why the x set in the scope of inner() is visible in outer(), and this is because of the nonlocal x statement in inner(). (as addressed by the other answer).

abhiarora · Accepted Answer · 2020-03-17 12:59:26Z

See enter link description here link for information on non-local.

The nonlocal statement causes the listed identifiers to refer to previously bound variables in the nearest enclosing scope excluding globals. This is important because the default behavior for binding is to search the local namespace first. The statement allows encapsulated code to rebind variables outside of the local scope besides the global (module) scope.

In short, it lets you assign values to a variable in an outer (but non-global) scope.

If you remove the keyword nonlocal and try your program, you will observe:

inner: nonlocal
outer: local

Program:

def outer():
    x = 'local'
    def inner():
        x='nonlocal'
        print('inner:', x)
    inner()
    print('outer:', x)


outer()

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