Objects in Python

[Steven D'Aprano]

On Mon, 27 Aug 2012 00:54:05 +1000, Chris Angelico wrote:

> On Mon, Aug 27, 2012 at 12:18 AM, Steven D'Aprano
> <steve+comp.lang.python at pearwood.info> wrote:
>> Also, built-ins require a name lookup too. As you point out, locals are
>> special, but Python will search an arbitrarily deep set of nested
>> nonlocal scopes, then globals, then builtins.
> 
> Ah, builtins, forgot that. So yes, global scope involves potentially two
> name lookups. But nonlocals aren't searched at run time.

Well, whaddyaknow. You're right.

x = 'globals'
def test(switch):
    def a():
        if switch == 1:
            x = 'a'
        def b():
            if switch == 2:
                x = 'b'
            def c():
                print "x found in", x
            c()
        b()
    a()


Tried that in Jython, IronPython and Python 2.7, and I get the same 
result: only test(2) succeeds.

I even tried it in Python 2.2, which does the same thing.

(2.1 and older don't have nested scopes, so there's no point in going 
back further.)


-- 
Steven